RU2243630C2 - Optical device for spatial handling of particles - Google Patents

Abstract

FIELD: optical devices.

SUBSTANCE: proposed device designed for spatial handling of both separate particles and mass of particles irrespective of their optical properties, mass, and size, including their clamping in desired position and moving in desired direction has optical radiation source, optical system, spatial displacement system for moving particles in medium communicating with optical system and/or with movable stage, additional optical unit disposed past main optical system, parameters of this unit being interrelated with those of optical system. Radiation source may be of continuous type incorporating radiation intensity modulator or of pulsed design. Additional unit provides for desired distribution of radiation in near-particle medium and has lens or set of lenses, or any other optical component. Optical source wavelength and medium optical parameters and composition ensure radiation absorption in medium proper; time and power characteristics of optical radiation source afford thermal or thermal and acoustic gradients in near-object medium for its spatial clamping within desired space or moving in desired direction. Light energy can be distributed in near-particle medium in the form of single light spot or narrow rectangular strip, or line, or circle arc, or in the form of semi-sickle, and the like.

EFFECT: enlarged functional capabilities.

23 cl, 9 dwg

Description

Technical field

The invention relates to the field of technical physics with a wide range of possible applications in chemistry, electronics, optics, materials science, nanotechnology, biotechnology, pharmacology, biology, medicine, theater performances, the field of advertising, and relates to the manipulation of the spatial position of objects of various types from single cells and biomolecules to metal and dielectric particles in gases or liquids.

State of the art

Quite well numerous devices are known for manipulating individual objects with the help of mechanical devices such as micro forceps, forceps, microneedles, etc. The disadvantage of such devices is the need for mechanical contact with the object. In the case of small samples with characteristic sizes of the order of units of microns, their control using similar devices is a rather difficult task. At the same time, there is a risk of mechanical damage or deformation, the introduction of undesirable contaminants, or the sample may “stick” to the surface of the instrument due to various physicochemical effects. The listed problems are especially critical for the case of working with microobjects such as single cells or biomolecules.

An alternative solution for fixing and changing the spatial position of various objects is the use of various types of radiation from ultrasound to laser. The greatest progress was achieved with the creation of the so-called "optical forceps", the principle of operation of which is based on the use of the effect of light pressure. This effect provides the formation of optical gradient forces that hold the irradiated particles in the field of highly focused radiation from a laser operating in a continuous single-mode mode [1-3]. An example of controlled particles can serve as transparent dielectric spheres in the size range from 20 nm to tens of microns, and biological objects in the form of viruses, bacteria and cells. These devices, commercially available [4] and widely used in various fields of medicine and biology, nevertheless have certain disadvantages and limitations. To create sufficient holding gradient forces, it is necessary to use strong focusing of the laser beam with the help of micro lenses with a large aperture, which sharply reduces the volume of the zone within which bioobjects can be manipulated. This method is mainly applicable only to transparent objects with a refractive index exceeding the refractive index of the environment. Thus, it does not allow manipulating with particles having a refractive index close to that of refraction, or with objects that are highly absorbing or even completely opaque to radiation. The need to use strong focusing of radiation directly into the sample leads to the formation of a sufficiently high radiation intensity (up to 5-10 MW / cm ² ), which can lead to unpredictable effects on biological objects of the accompanying thermal or photodynamic effects up to their significant damage. This effect is somewhat reduced, but not completely excluded, when using near-infrared lasers (approximately 700-900 nm), where most biological molecules have minimal absorption. In addition, the optical gradient forces are very small (piconewton units), which imposes restrictions on the ability to manipulate transparent particles of only small sizes, not more than several tens of microns. In addition, the method is intended for the manipulation of single particles, that is, it does not allow the simultaneous manipulation of several particles or at their high concentration in the medium.

Methods and corresponding devices are also known in which the possibility of forced movement of radiation absorbing particles is realized through the use of temperature or pressure gradients induced in the particles themselves due to the absorption of relatively high-power pulsed laser radiation in them. In one of these methods proposed for cleaning various surfaces, the separation of dust particles from the surface is achieved due to the sharp thermal expansion of the irradiated particle [5]. In another method of asymmetric laser ablation of a particle, its non-isotropic irradiation (for example, only on one side) leads to rapid thermal evaporation of part of the particle or the formation of a plasma torch and, as a result, to the formation of a recoil effect, as in jet engines, which makes the particle move in the direction opposite to the direction of emission of ablation products [6]. The movement of individual parts of the object is possible due to the formation of quasi-hydrostatic pressure in the liquid under the influence of absorption of laser radiation in it. In particular, in one of the technical solutions, the laser radiation through the hole in the solid sample, made by the laser itself, was directed deep into the sample and due to the strong hydrostatic pressure in the liquid entering the sample, the sample split into separate parts, which scattered in different directions [7]. In another solution, laser radiation is absorbed in a small closed volume of liquid, which, due to the emerging hydrostatic pressure, is ejected at high speed through a small hole in the wall bounding the volume [8]. In another device, laser radiation is first used to cut samples and, at the final stage, a laser pulse of increased energy is sent to the “undercut” small jumper region, which ensures the final separation of the parts of the sample, which, due to the pressure arising, fly apart at high speed (catapult) [9] . A definite drawback of all the considered optical methods and their various modifications [10–13] is the need for direct irradiation of the sample or part of it with high-intensity radiation, which can lead to a change in its properties or damage. In addition, the use of these methods according to the proposed schemes makes it possible to ensure only a large initial particle acceleration, that is, the issue of retaining these particles or accurately manipulating their spatial position, including targeted slow movement in any given direction, has not been resolved. In addition, these methods do not allow multiple particles to be controlled simultaneously.

Free from this drawback are methods based on the use of ultrasound (US) energy for the movement of particles [14-17]. However, these methods require placement of ultrasonic wave sources near the particles or the presence of an additional chamber, to the wall of which these sources are docked, made, for example, in the form of a line of piezoelectric elements. All these methods are relatively complex and require careful synchronization of the work of individual sources or their movement for transporting particles, which imposes certain difficulties on their practical implementation. Moreover, in these methods it is difficult to ensure high accuracy of particle manipulation due to the technical complexity of creating acoustic microlenses to form a small wavelength of ultrasonic vibrations.

The closest in technical essence is the solution [18-19], which offer optical forceps for manipulating reflective objects. In the first invention [18], radiation is focused, including onto the edge of the particle, when a little is captured and the boundary region directly adjacent to the sample. A laser in a continuous mode is used as a radiation source, creating gradient forces due to the described light pressure effect. That is, these forces are not of a thermal or acoustic nature, and the presence of a medium around the object is not fundamentally necessary. Since these forces are already repulsive, and not confining, as in the case of transparent particles with a higher refractive index, it was proposed to use high-speed scanning of the laser beam around the particle to spatially stabilize the position of the particle in a given position. The disadvantage of this scheme is the complexity of the technical implementation, which requires, in particular, an additional scanning mirror. It is technically simpler to use simultaneously three beams uniformly spaced around the perimeter of the particle [19]. To implement this scheme, one can use well-known methods of splitting one beam into several, including the use of diffraction elements. However, many of the already described drawbacks of the schemes of all optical forceps are inherent in this scheme, including the direct irradiation of part of the sample, the small holding forces, the inability to manipulate transparent particles having a refractive index close to the refractive index of the environment, and opaque particles with strong absorption and relatively large the dimensions.

The aim of the present invention is to eliminate these drawbacks, i.e. providing the ability to manipulate the spatial position of both individual particles and the array of particles, including their fixation in any given position, their movement in any direction at any speed, and the particles are not subject to strict requirements both in terms of optical properties (they can have any refractive index, be opaque, etc.), both in size and weight, and the manipulation is carried out in the absence of direct irradiation of the particle, which excludes the possibility of radiation damage to them.

This goal is achieved by the fact that in the device for optical manipulation of the spatial position of objects in a medium, including an optical radiation source, an optical system, a system for spatial movement of an object in a medium associated with an optical system and / or with a mobile table on which the object can be located, the source optical radiation is selected to operate in a continuous mode of radiation and to modulate the intensity of this radiation, an additional optical radiation modulator associated with bound source. An alternative solution is to select a pulsed radiation source.

In addition, an additional optical unit located after the main optical system was introduced, and the parameters of this unit are interconnected with the parameters of the optical system. The specified block is made in such a way as to provide a given distribution of radiation in the medium near the object, and includes a lens or lens system, and / or a diaphragm, and / or spatial filter, and / or holographic elements, and / or diffraction elements, and / or interference elements, and / or optical elements for spatial scanning of a light beam around an object, and / or one or more flexible optical fibers, and / or various combinations of these elements. The wavelength of the optical source and the optical parameters and composition of the medium are selected so as to ensure absorption of radiation in the medium itself. The time and energy parameters of the optical source are selected based on the conditions for the dynamic formation of thermal and / or acoustic gradients in the medium near the object, which, in turn, directly or through the accompanying effects provide a force effect on this sample sufficient to move it in the desired direction with a given speed or fixing this object in the required volume.

It is proposed to select the parameters of the specified additional optical unit in such a way as to ensure in the environment near the object the distribution of light energy in the form of a single light spot, and / or a narrow rectangular strip (line), and / or circular arc, and / or in the form of a half-serpent, and / or in the form of a light ring around an object, and / or in the form of a continuous light spot with a radiation intensity decreasing towards the center, and / or in the form of a light ring around an object, and / or in the form of a light ring, in the center of which there is a separate light e spot, and / or their various combinations, and the energy distribution in them can be either continuous or discrete, that is, consisting of separate light spots, and / or strips, and / or half-rings, circular arcs, and / or their various combinations.

The specified optical unit may be made in the form of a cylindrical lens, and / or a spherical cylindrical lens, and / or one or more optical plates with an adjustable tilt angle with respect to the optical axis of the main optical system, and / or various combinations of these elements.

It is proposed between the additional optical unit and the object to introduce additional optical elements located in the environment next to the object. These elements can be an optically transparent plate for radiation, or a similar plate, but with an absorbing coating on the surface facing the object, or similar to the first plate with an additional absorbing film on the specified surface, or only one absorbing film, so that the planes of these elements are oriented perpendicular to the optical axis of the indicated block.

To influence the object, it is proposed to use the technique of acoustic lenses, in which laser radiation is used to generate acoustic vibrations. To do this, an acoustic lens is placed next to the object, oriented in space so that the radiation falls on the input surface of this lens, the focus of the lens coincides with the position of the object. Absorbent coatings are applied to the input or output surfaces of the lens. Additionally, for the case of a source with continuous radiation, an introduction of a block for changing the frequency of modulation of the radiation intensity associated with the main modulator is provided. In the case of using pulsed radiation, the function of this unit includes changing the repetition frequency of optical pulses. These frequencies determine the corresponding frequencies (wavelengths) of acoustic waves acting on the object. A change in the frequency is necessary for the spatial movement of the object due to the spatial shift of the focus of the acoustic lens, the position of which depends on the frequency (wavelength) of acoustic vibrations. An alternative solution is to introduce a block of mechanical movement of the lens associated with this lens.

It is also proposed to combine individual acoustic lenses into a ruler, and to make the optical system so that it ensures the formation of several light beams, each of which falls on the corresponding lens. In addition, a phase delay unit is introduced, connected to each of the lenses and the radiation source. All these measures are necessary to ensure the operation of the line of acoustic lenses in phase acoustic antenna mode.

As one of the technical solutions, it is proposed to introduce a second additional optical unit, which is connected with the first unit and the optical system. This block can be made in the form of beam splitting plates and / or diffraction elements and / or light guides oriented in space so as to ensure separation of the main light beam into several other at least two light beams. In turn, these beams can be oriented at an angle relative to each other and the magnitude of this angle lies in the range from 1 to 180 °. In particular, the beams can be directed at right angles or towards each other. In the latter case, the beams can be located coaxially, and it is allowed to mismatch their optical axes so that they are parallel offset from each other. In this case, the position of the foci of individual beams can coincide, lie in the same plane or be displaced along the optical axis relative to each other.

It is also proposed, by choosing the parameters of the additional optical unit, which are consistent with the parameters of the main optical system, to provide a three-dimensional energy distribution in the medium around the object in the form of a single cylinder, and / or a concave lens, and / or a sphere with an object inside this sphere, and / or two intersecting cylindrical beams with an object inside the region of their intersection, and / or periodic spatial gratings with different steps from units of microns to several millimeters, and / or their various combinations.

To create the necessary spatial spatial distribution of radiation, it is proposed, along with the selection of appropriate optics parameters, the introduction of additional sources of optical radiation with independent main optical systems and additional optical units.

One of the possible applications of the present invention is the manipulation of objects inside various tubes. For practical implementation of this, it is proposed to use tubes with optical transparent walls. The optical system provides a given distribution of light energy already inside this tube, and the orientation of the light beam with respect to the optical axis of the tube can be either perpendicular or parallel (coaxial). Such schemes provide for the use of various spatial configurations of optical beams, in particular a beam with a flat geometry perpendicular to the axis of the specified tube, two flat beams between which the object is located, and / or a beam of cylindrical geometry of the optical beam, and / or their various combinations.

To be able to manipulate the movement of the object along the axis of the tube described above, the introduction of an additional modulator is proposed, interconnected with an additional optical unit. The latter is made in such a way as to ensure the cylindrical geometry of the light beam with a cross section in the form of a ring and an independent central part. The additional modulator is designed to provide modulation of intensity only in the central part of the light beam, independent of the modulation of the peripheral annular part. In the case of using a pulsed source, the functions of this modulator are reduced to controlling the temporal and energy parameters of radiation only in the central part of the beam.

The additional optical unit can also be made in the form of an optical fiber, which is fixed in space with an additional holder so that the end of the fiber is near the object. In the holder itself, an additional device is provided for moving the holder together with the fiber in any given direction. It is also possible to use several fibers with different spatial orientations of their distal ends around the object from the ruler to the location on a circle or on the surface of a sphere around the object.

An option is also provided for applying an absorbent coating to the fiber end face or fixing a special tip absorbing radiation on it. In another embodiment, the fiber end has a concave surface and / or a radiation absorbing coating is applied to said concave surface. An acoustic lens with an absorbing coating on the input flat surface or on the output concave surface can also be docked to the fiber end.

A typical embodiment of the technical implementation of the invention is the manipulation of objects using microscopes, including with an inverted optical scheme.

The object in this case is between the coverslips or on top, only on an optical transparent substrate. All these elements are located on a standard mobile table, for precise control of the position of which it is possible to use a joystick.

It is possible that the optical system together with an additional unit provides light distribution of energy near the object, which partially contacts the object in one or several boundary zones at the same time, including touching along the entire perimeter of the object.

In all of the above options, radiation-absorbing liquids and / or liquid solutions and / or gases and / or gas mixtures, including air, and / or gels, and / or biological media, different in properties and composition, can be used as a medium; and / or their various combinations. In particular, a scheme is allowed when the optical system provides a predetermined distribution of radiation inside the medium, such as living biological tissues or individual cells, and the object is a medicine and / or medicine capsules made, for example, in the form of liposomes and / or various microcarriers of the type polystyrene microspheres with attached biological elements, and / or various fluorescent probes, and / or photothermal samples in the form of chemical compounds, various metal and nonmetallic microspheres ics, and / or their various combinations.

In the case when the initial medium does not absorb radiation or the absorption is so weak that it is not possible to create temperature and pressure gradients sufficient for manipulating objects, the necessary absorption level in such media can be achieved by including absorbing components of various nature in the composition of the medium. These components can be delivered to the area of manipulation with the flow of gas or liquid, and these flows can be supplied from the respective additional units both continuously and discretely in time, that is, in separate portions. In particular, the use of aerosol flow is allowed. Special blocks for creating the corresponding flows can have a different spatial arrangement with respect to the optical beam, including including the coaxial and perpendicular directions of these flows relative to the axis of the optical beam and various spatial geometry of these flows from cylindrical to flat.

In addition to manipulating objects in the volume of gas or liquid media, the invention also allows their control on the surface of various solids, for which the optical system together with an additional optical unit provide a given distribution of radiation in the medium in contact with the surface of these bodies. As an example of solids, we can mention semiconductor and optical materials, and as tasks, respectively, control objects of nanotechnology, microelectronics, biotechnology, chemistry, biology, medicine, etc.

As a radiation source, the use of a wide variety of radiation sources, including lamps and LEDs with an emphasis on lasers, is implied. It is allowed to use lasers operating in a continuous mode of radiation, which is modulated in intensity using appropriate modulators (mechanical, optical, electro-optical, acousto-optical, etc.), in a wide frequency range from units of Hz to hundreds of MHz. It is also intended to use sources of pulsed radiation with a pulse duration lying in the range from 10 ^-3 to 10 ^-15 sec. At the same time, if necessary, an additional unit is introduced, connected to these sources and providing a repetition mode for individual pulses in the range from units of Hz to hundreds of MHz. As such sources, many well-known gas, solid-state, and semiconductor lasers and dye lasers operating in continuous and pulsed modes, including a pulsed nitrogen laser, near-infrared semiconductor lasers, a neodymium laser (first and second harmonics), holmium and erbium, can be used as such sources. lasers, sapphire laser, ruby laser, carbon dioxide laser with the maximum set of characteristic wavelengths for the marked lasers.

Thus, the proposed device compares favorably with the prototype in a number of ways, which makes it possible to achieve a new goal related to manipulating the spatial position of various particles regardless of their optical properties without their optical damage. Its main difference from various versions of optical forceps is that the light is not used to create gradient optical forces due to pressure effects of the light itself, but already to create thermal and acoustic gradients, the periodic action of which on the object sets the latter in motion. In all versions of the optical forceps, one of which is taken as a prototype, only continuous-wave lasers are used without any modulation. The present invention proposes to use both pulsed sources operating in the pulse repetition mode with the required frequency, and continuous radiation sources that are modulated in intensity to create periodic thermal and acoustic waves acting on the sample.

The source of acoustic gradients can be many physical phenomena, including absorption, electrostriction, optical breakdown, plasma formation, coherent Raman scattering, etc. (see, for example, [20]). The most universal and not requiring significant energy costs is the photoacoustic effect arising from the absorption of radiation and the subsequent sharp expansion of the volume heated by the radiation. The changes in volume and the displacement of the heated layer that arise in this process lead to the formation of significant mechanical forces that can significantly accelerate small particles in the vicinity of the laser beam, so that they can fly even several meters [8]. The pressure near a focused laser pulse, for example, during optical breakdown in water with a pulse duration in the picosecond range, can be very significant, up to thousands of atmospheres [21]. But for this purpose it is enough to have much lower pressures, the adjustment of which is achieved due to a smooth change in the energy parameters of the lasers, which allows, in turn, to manipulate the movement of objects in a wide range of speeds, up to fairly small ones. The propagation of both the acoustic waves themselves and the accompanying acoustic flows, and their subsequent effect on the biological object, sets it in motion under the influence of both acoustic pressure forces and is involved in the movement by acoustic microflows. The achieved temperatures in the absorption region can also be low - at the level of tenths of a degree Celsius. In principle, this temperature level does not damage biological structures. In addition, in the proposed device, temperature gradients are formed not in the object itself, but in the vicinity of it, so that they cannot directly affect it. In the prototype, continuous radiation with a power of up to hundreds of mW is used, which, with strong focusing directly on a biological object (cell, bacterium, etc.), in many cases can modify its structure, up to its damage.

One of the features of the invention is the use of an intermittent radiation flux forming a periodic action of pressure gradients. The pressure generation mode is most effective when using pulsed radiation in a wide range of durations from milliseconds to picoseconds and even femtoseconds, at which the temperature in the radiation interaction region is relatively small and the magnitude of the resulting pressure is relatively large. However, pressure can be generated by modulating the power of continuous radiation in a wide frequency range from units of Hz to several MHz. From the point of view of a reasonable compromise between the efficiency of converting light energy into acoustic energy and the simplicity of technical implementation, the most preferred ultrasonic (US) frequency range is approximately in the range of 10-50 kHz.

Thus, the laser in this solution is used to generate ultrasonic vibrations, which can be used further in circuits close to “ultrasonic forceps” [14-17]. The creation using microoptical systems of light distribution close to the geometry of microacoustic lenses will allow the formation of ultrasonic vibrations with a very small wavelength, theoretically even shorter than the used wavelength of light. The advantage of this method of generating ultrasonic waves is the ease of spatial movement of the source of generation of these vibrations in the form of an optical image of acoustic lenses, which are devoid of pure acoustic systems for the formation of ultrasonic waves. Thus, in accordance with the proposed schemes, it is possible to create “photoacoustic forceps”, which, depending on the ratio of the acoustic constants of the particle, will either be attracted to the focus area of ultrasonic vibrations (the difference between the products of the density and the speed of sound in the medium surrounding the particle and the particle itself is positive), or conversely, eject particles if the indicated difference is negative. An example of the first particles are light polystyrene beads or single cells, an example of the second are metal balls. It is most simple to create cylindrical photoacoustic lenses using optics, although the creation of concave spherical lenses should not run into fundamental difficulties. In particular, the application of two cylindrical lenses with mutually perpendicular axes is possible. In the case of a strongly absorbing medium, it is easy enough to create an acoustic lens on the surface of the liquid due to the spatial distribution of light intensity in the beam cross section, for example, with a minimum of intensity in the central part.

It is interesting to note that, in principle, it is possible to use unmodulated continuous radiation, which, due to heating of the liquid, can lead to thermal convection in the vicinity of the laser beam. These microconvection flows can draw fairly light small particles into the movement. This is especially easy to achieve with a vertical arrangement of an optical beam with a cylindrical geometry, in which particles will be raised upward by the heat flux, and additional intensity modulation will keep the particles within this beam due to acoustic waves arising in the "walls" of the cylindrical beam. However, due to a sufficiently high general concomitant heating of the liquid, this may be unsafe for biological objects.

The nature and direction of the acoustic pressure forces acting on the sample depends primarily on the nature of the distribution of absorbed energy around the sample.

In the present invention, the forces of the gradient pressure will in most cases push the particle, rather than attract it. Therefore, to fix the spatial position of such particles repelled by the forces of acoustic pressure, it is necessary to create acoustic gradients distributed discretely or evenly around the particle.

In this case, it is possible to use the already known solutions for the formation of several light beams around an object, at least three or a continuous ring, which was previously proposed for optical tongs [18-19]. Similar schemes, for example, based on diffraction elements or a system of individual optical elements, can be used here with slight modifications, however, producing effects that are completely different in physical essence and mechanism with other light sources and their operating modes, that is, generate acoustic pressure, and not pressure light, as in the prototype.

The difference of the present invention from analogues, which use, for example, thermal effects to remove particles from the surface of the substrates [5], lies in the fact that in the present invention thermal gradients are created near single objects in the absence of direct irradiation of objects. Thus, the contact of the latter with the additional surface is not required. In the noted analogue, the object itself is irradiated and its contact with the substrate is required so that the sharp thermal expansion of the particles induced by laser radiation allows one to create acceleration that overcome the forces of adhesion of the particle to the substrate (Van der Walses, electrostatic, chemical, etc. ) To overcome this, it is necessary to use significant energies of laser pulses, which even lead to the melting of metal particles. Thus, in the analogue and other similar devices according to the proposed schemes it is impossible to control the position of the particle and, in addition, the proposed acceleration mechanisms require high energies that damage the object itself.

To create acoustic waves in the present invention uses the effect of absorption of radiation in the medium directly surrounding the object. For biology and medicine, water or other physiological solvents are usually used as such a medium. Water in the visible region of 400–700 nm has a relatively low absorption at the level of 10 ^–3 cm ^–1 , but nevertheless is quite sufficient to generate significant acoustic effects when using laser radiation sources [20]. In addition, it is possible to use lasers of both the UV range (nitrogen, excimer, etc.) and the IR range (semiconductor, neodymium, holmium, erbium, etc.), where the absorption of water and other solvents is somewhat greater, but together however, they still remain transparent for observing particles in transmitted light. Numerous existing solutions implemented in inverted microscopes, as well as commercially developed optical forceps [4] and laser micro-dissection systems for biological samples and their ejection [9], can be used as optical schemes.

Even in the simplest case, with one beam of light focused next to the object, it is possible to control both the speed and the rough direction of particle motion by moving the relative position of the light spot around the object. In this case, energy can be supplied using optical fiber. The latter can be used as a traditional device for mechanical contact manipulation with a particle in the absence of radiation, and in the absence of direct mechanical contact in the acoustic control mode when the laser is on. In the case of choosing a source with strong absorption in the medium, acoustic waves are generated directly at the fiber exit, since the radiation is absorbed in a small area adjacent to the fiber end. In the case of relatively weak absorption, either absorbing the coating at the end of the fiber is used to create the necessary acoustic waves, or a special highly absorbing tip is put on the latter.

It is more convenient to control the motion of the particle when focusing the radiation with a cylindrical lens into a light spot in the form of a line or with the help of special spherical-cylindrical optics in a spot in the form of a sickle. Fixing the position is achieved, as already noted, by creating a light distribution in the form of individual spots or rings around the particles. Moreover, the radius of such a distribution can vary depending on the size of the particles or even several particles that can be captured together. At the moment of capture, the radiation can be turned off, and the position of the light spot can be determined using an additional pilot beam, for example, from a semiconductor laser or an LED operating in the visible range of the spectrum. Such a scheme is convenient for controlling particles in a two-dimensional plane, some approximation of which is the volume between two microscope coverslips. With a larger distance between these glasses, that is, if it is necessary to control in a three-dimensional volume, it is necessary to use already two beams directed at an angle to each other. The size of the particle capture volume depends on the angle between the beams and is minimal when the cylindrical beams are mutually perpendicular. The intersection of these cylinders will create a zone in the intersection area in which the intensity is absent or minimal. A particle is captured by such a peculiar light trap, the walls of which constantly emit acoustic impulses, and move in the required direction. If it is necessary to dock one particle with another at the moment the particle approaches the light trap with another particle, the radiation is turned off for a short moment in order to allow the particles to come into contact, since when the radiation is on, the second particle can be repelled by acoustic pulses from the nearest part of the light trap. Then one such trap can hold already two or more particles inside the non-irradiated volume, including many particles with a high concentration in the medium.

Creating a two-dimensional or three-dimensional temperature distribution in the medium, for example, biological tissue, will allow you to control the movement of not only individual particles, but also finely divided substances or chemical compounds and drugs. For example, in this way it is possible to control the position of a small capsule, in particular a liposome, with a drug inside even one cell. Creating a temperature or acoustic gradient in the medium will allow you to control the transport of drugs in biological tissues and direct it to the desired zone (target). One of the additional mechanisms of such control is the dependence of the diffusion coefficient on temperature, that is, in this case, thermal diffusion is realized.

It should be noted that in the present invention there are no strict requirements for the quality of the optical beam, since it is required to create essentially only a thermal gradient next to the particle. In addition, a small irradiation of the particle itself with the wing of a light beam is quite acceptable, the power of which is much lower compared to the distribution of radiation near the center of the light spot. Estimates show that for the case of the simplest fairly light biological objects, the energy parameters of radiation will be less than the similar parameters of lasers already widely used in optical light forceps. This means that in the present invention, firstly, there will be no danger of damage during the accidental emission of radiation onto the particle itself, secondly, it is possible to use the effect of partial asymmetric expansion for particles when only a small area of the particle is irradiated near its boundary, and thirdly, it is possible to combine the proposed invention with existing optical forceps. In the latter case, to implement the proposed scheme, it will be necessary to provide only additional modulation of the laser beam. Controlling the particle’s motion due to the asymmetric thermal expansion of only a small irradiated part of its surface has an advantage over the known close solutions [4, 9] (see above), since the effect is non-destructive, and it is possible to smoothly control the direction of motion by changing the position of the light spot along the perimeter of the particle.

Thus, a regime is possible when the radiation is directed only to the edge of the particle, which, due to slight heating and the accompanying effects of expansion or radiation pressure, comes into motion.

For the convenience of work and determining the position of the light spot of the radiation, a test beam of the visible spectrum can be introduced, combined with the main beam. Such a scheme is useful for initial adjustment in the absence of the main source or when the radiation of the latter is invisible to the eye, for example, when it lies in the infrared or ultraviolet region of the spectrum.

Thus, the present invention compares favorably with the prototype, since it is more universal due to the ability to control the position of any particles in the absence of special requirements for their optical properties, and the acting force, and therefore, the magnitude and speed of movement of the particles can be quite simply controlled by changing energy parameters of the sources used. Laser sources are most suitable for this, although in principle conventional sources can also be used, including lamps that can be easily integrated into existing microscopes. Such schemes are useful for forming the spatial distribution of light due to, for example, interference effects.

The invention is illustrated by the following drawings.

Figure 1. The general scheme of the device.

1 - source of optical radiation (laser); 2 - optical beam; 3 - medium (liquid); 4 - object (particle); 5 - a mirror; 6 - the main optical system; 7 - additional optical system; 8 - mobile table; 9 - coverslips; 10 - heat release region; 11 - acoustic waves; 12 - block mechanical control the position of the mobile table; 13 - block spatial movement of the optical beam.

Figure 2. Schemes with different spatial geometry of the light beam in cross section near the bioobject.

1 - light beam; 2 - object; 3 - acoustic waves.

A - one bundle with a round shape in cross section; B - one light strip (line); In - a sickle or circular arc; G - individual light beams around the object; D is the annular shape of the light beam; E - partial superposition of the light beam on the object; W - a combination of two or more light strips; 3-combination of light arcs (or sickles).

Figure 3. Schemes of manipulating objects (particles) using photoacoustic lenses.

A - optical image of a curved lens: 1 - optical beam; 2 - focused ultrasonic vibrations; 3 - object.

B - photoacoustic lens with the generation of ultrasonic vibrations on the input surface: 1 - radiation; 2 - absorbing coating; 3 - an acoustic lens of optical material; 4 - acoustic vibrations; 4 - object.

B - a photoacoustic lens with the generation of ultrasonic vibrations on the surface of a microlens: 1 - an optical beam; 2 - an acoustic lens; 3 - absorbing coating; 4 - focused ultrasonic vibrations; 5 is an object.

G - photoacoustic lens on the surface of the absorbing liquid: 1 - radiation; 2 - liquid; 3 - absorption region; 4 - focused ultrasonic vibrations; 5 - object; 6 - dotted line shows an approximate intensity distribution in the cross section of the laser beam, 7 - optical plate.

D - a line of photoacoustic lenses: 1 - laser beams; 2 - a line of photoacoustic lenses; 3 - focused phased ultrasonic vibrations; 4 - object.

Figure 4. Scheme of optical manipulation of microobjects using optical fiber.

A - general scheme: 1 - radiation; 2 - optical fiber; 3 - absorption region in the liquid; 4 - acoustic waves; 5 is an object.

B - scheme with an absorbing coating on the fiber end: 1 - radiation, 2 - fiber; 3 - absorbing coating; 4 - acoustic waves; 5 is an object.

B - scheme with an additional tip: 1 - radiation, 2 - fiber; 3 - tip; 4 - end absorbing wall, 5 - acoustic waves; 6 - object.

G - optical fiber with a photoacoustic lens at the end: 1 - fiber; 2 - a concave surface at the end of the fiber with an absorbing coating; 3 - acoustic waves; 4 - object.

D - optical fiber with a photoacoustic nozzle: 1 - fiber; 2 - acoustic lens; 3 - absorbing film; 4 - acoustic vibrations; 5 is an object.

Figure 5. Scheme of the photoacoustic detachment of a particle from a substrate.

1 - radiation; 2 - optical substrate, 3 - medium (liquid); 4 - object; 5 - region of absorption (heat release).

6. Scheme of a light trap (cell) with two cylindrical beams (their axial section is shown).

1 - the first laser beam of cylindrical geometry; 2 - the second laser beam; 3 - object; 4 - pressure forces.

7. Schemes with one cylindrical beam (photoacoustic tunnel).

A - the use of vertical convection flows: 1 - a cylindrical bundle; 2 - object; 3 - acoustic vibrations; 4 - convective heat fluxes.

B - the use of thermal axial acceleration using a central beam: 1 - an optical beam of cylindrical geometry; 2 - object; 3 - acoustic vibrations; 4 - radiation in the central part of the beam.

Fig. 8. Motion control of an object in a pipe: 1 - a pipe with optical transparent cylindrical walls; 2 - optical beam of plane geometry (section is shown); 3 - object; 4 - acoustic vibrations; 5 - an alternative (axial) version of the laser exposure.

Fig.9. Using an additional flow of absorbing gas or liquid: 1 - optical beam; 2 - object; 3 - acoustic waves; 4 - additional modules with radiation absorbing components; 5 - flows with absorbing components.

Depicted in figure 1, the device operates as follows. The optical source 1, preferably a laser, forms an optical beam 2 directed into the medium 3, in which the object 4 to be manipulated is located. An example of the medium surrounding the object can be gas, including air, a condensed medium in the form of a liquid, solution, gel, biological tissue, single cell, solid surface, etc. For a possible change in the beam direction, which is necessary, for example, in inverted microscope circuits, an additional mirror 5 is used. A predetermined distribution of optical energy in the region where the object is located is formed using the main 6 and additional 7 optical systems. In the case of using microscope elements, the object is placed on a movable stage 8 between two coverslips 9. As a result of optical absorption of radiation in the medium, part of the absorbed energy is converted into thermal energy of the medium due to non-radiative transitions, which leads to its heating. The rapid thermal expansion of the heated local volume 10 leads to the formation of an acoustic wave 11 propagating towards the object 4. Further, due to the direct or indirect action of this wave on the object 4, forces arise that act on this object and cause it to move. We can distinguish the following main reasons for the formation of such forces on the example of a liquid medium: the radiation force of acoustic pressure, the formation of so-called acoustic flows, the manifestation of the effect of added masses, etc. [22]. It should also be noted that during periodic exposure with a high acoustic frequency, the particles also begin to oscillate with the frequency of acoustic vibrations. The necessary movement of the object 4 in the medium 3 (for example, liquid) can be achieved either by moving the stage 8, controlled by the scanning unit 12 at a fixed position of the optical system, or by moving the elements of the optical system 6 and 7, or by an integrated optical scanner controlled by using block 13. As particular examples of possible scanning schemes, lens oscillation, mirror movement, periodic displacement of the fiber end, or the use of an acousto-optical modulator can be noted. It is also possible combined movement using simultaneously two marked methods. A joystick can also be introduced to manually manipulate the position of the object in the environment.

Figure 2 shows various options (but they do not exhaust all possible schemes) of the distribution of radiation intensity in the cross section of the laser beam in the plane of the object. The simplest scheme is A with one round beam 1 in cross section located next to object 2. With this geometry, diverging acoustic vibrations 3 are formed, which allows moving the object in only one transverse direction with relatively low accuracy. Nevertheless, this rather simple scheme that is implemented in practice is convenient for rough transportation of an object in a given direction based on the use of standard microscopes, in which only an optical attachment with an additional laser is added. Since in this scheme there is no adjustment of movement in the longitudinal (along the axis of the optical beam) direction, this scheme is applicable for one-dimensional movement in pipes of small diameter or two-dimensional manipulation in the space between two closely spaced planes. An example of the latter is the space between two microscope coverslips. When the radiation is focused in line 1 (Scheme B), which is realized in the simplest case with the help of a cylindrical lens, a plane acoustic wave already affects object 2, which slightly increases the accuracy of its targeted spatial movement in a given direction. In addition, a plane wave can provide an impact in a large volume of the medium, which allows you to control the movement of several objects simultaneously. A similar scheme is also convenient for dividing an array of particles into separate parts. With this axis geometry, a piston action of pressure from the heat release region is formed. Thus, the advantage of this scheme is the relative simplicity of the technical implementation, for example, when using the marked cylindrical optics and the ease of controlling the particle displacement in one direction, but the accuracy of setting the exact trajectory is nonetheless low. It should be noted that it is possible to use only two adjacent separate beams in this scheme (scheme A, but with two beams), which is easily implemented in practice by implementing an additional system 7 (Fig. 1) in the form of a translucent plate placed in the path of the optical beam. Depending on the degree of transparency of the plate, such a system allows you to form any desired number of light beams oriented in a line. By changing the angle with respect to the optical axis, the distance between these beams can also be changed. Nevertheless, scheme B with the image of the optical beam 1 in the form of an arc segment has more accuracy. In this case, an already converging acoustic wave 3 will act on the object 2. The accuracy will increase with increasing size of the arc, that is, the area of the object covered by the light beam. This geometry can be realized using an optical system with deliberate aberrations that distort the optical beam in the desired direction, in particular, forming a sickle-shaped spot shape, as shown in the drawing. The advantage of such a geometry, as in the case of a pure arc, is the possibility of a small focusing of acoustic waves on a particle due to the manifestation of the effect of an acoustic lens. A similar geometry can also be formed through the use, as described above, of several discrete optical beams of circular shape, one of which is shown in scheme A (figure 2). This can be achieved in various ways, for example, using a system of dividing mirrors, several optical fibers, several lasers, etc. To keep the object in a predetermined position or controlled movement in any given direction, the most preferable scheme is Г using individual point sources 1, the minimum number of which should be 3 or better 4. Moreover, object 2 is located in the geometric center of these sources. In this case, a spherical acoustic wave propagates from each source, and with the simultaneous action of these waves, object 2 will be in the region of minimum pressure, i.e., when the acoustic pressure is equal approximately in the center. Since each source will push the object away from itself (with a certain ratio of acoustic properties, as noted above), the stabilization of the position of the object will be dynamic and the object may experience small spatial fluctuations, that is, as if to “tremble” or “dance”. It is desirable to arrange the sources evenly around the particle, but this is not critical enough, since possible unevenness will lead only to a small asymmetric displacement of the particle with respect to light spots. In addition, due to asymmetry, the inequality of the acoustic pressure forces of individual zones is also possible. If the optical system allows, such a small imbalance can be compensated by changing the power of individual beams.

The most optimal solution is the formation of a light ring 1 (circuit D) around the object 2. In this case, the pressure forces 3 will evenly act on all sides, which ensures a stable position of the object in the center or its purposeful movement in a given direction. The simplest way is to implement this scheme with a laser beam in the center of which an intensity dip is created in one way or another, for example, due to aberrations, the use of spatial filters, diaphragms, including with an opaque central part, the use of diffraction effects, etc. The light ring can also be formed by quickly scanning the laser beam in a circle, for example, using a scanning optical system based on a rotating mirror. It is also possible to use a laser beam scan in a spiral with the help of scanners used in laser skin treatment. In this case, it is possible to capture an object in a sufficiently large area with its subsequent transportation to the center of the specified spiral.

It should be noted that in such schemes pressure forces also arise, which are directed into the outer space. They can play both a positive and a negative role. In particular, when transporting an object, they can seem to push unwanted other objects on their way. On the other hand, they can impede the close proximity of the moving object with another object. The solution may be to turn off the laser for a short time at the moment of approach of these objects. When capturing another object, they can then be held together with the help of the described scheme.

When developing the proposed devices, it should also be taken into account that the same acoustic wave can have the opposite effect on particles with different acoustic properties (see above): it can attract particles that are “light” in the acoustic plane (see above), and repel heavy particles . Sorting particles with different properties can be based on this. In the future, unless otherwise specified, the case of acoustic repulsion of particles will be implied.

The size of the spatial fixation area can be adjusted by changing the diameter of the light ring. It should also be noted that, in principle, it is permissible in some cases to touch the radiation of an object, if at the same time there is no problem of its radiation damage. For example, this is true for an optically transparent object or a relatively low radiation intensity, in particular, when the object is touched by a substantially weakened in intensity laser beam wing with a Gaussian intensity distribution in the cross section. On the other hand, with such a geometry (Scheme E), when radiation 1 is absorbed, asymmetric forces can arise in the part of object 2 that are sufficient to move the object. For example, it can be the thermal expansion of a small zone at the particle boundary, which will create a kind of reactive force of movement in the direction opposite to the expansion. For the case of light objects, this may be secondary radio pressure due to the emission of a heated zone of infrared radiation. These schemes of non-destructive sample exposure favorably with those already known (see above), because they do not use the reactive return of laser adlation products or plasma leaving the object, which destroy the sample. In addition, they allow you to very smoothly adjust the position of the object, while in the analogues creates a fairly large initial acceleration, and the direction of this acceleration is quite difficult to regulate. As already noted, the creation of the necessary configuration of the laser beam can be achieved through the use of individual beams, and schemes using several linear elements (scheme G) located, for example, along the tangent of the desired virtal ring, or several circular arcs may be useful in this direction. , or sickles (scheme 3). In these cases, one can use the separation of one beam into several others or even use separate lasers to create them, for example, compact and inexpensive semiconductor lasers.

One of the advantages of the present invention is the relative simplicity of creating acoustic lenses of various configurations using laser radiation, for example, due to the formation of their corresponding optical image in the medium. In addition, in combined lenses, which can arbitrarily be called photoacoustic (FA), in contrast to the traditional scheme of generating ultrasonic vibrations (using piezoelectric elements docked to the lens), the source of these vibrations is a thin layer of absorbing radiation from a coating or film irradiated by laser radiation. It is desirable to choose these coatings with a high coefficient of thermal expansion. The mechanism of generation of ultrasonic waves is based on the rapid periodic thermal expansion of these elements. Several options for such schemes are possible (FIG. 3). In the first of these, the profile of the acoustic lens is formed due to the volumetric curvilinear configuration of the laser beam in the absorbing medium, which, due to the FA effect, forms acoustic vibrations 2 in the medium (Fig. 3 shows their front), propagating to object 3 along the normal to the image surface such a FA lens. An advantage of such a scheme is the remote nature of the formation of an acoustic lens of any practical configuration. It is most simple to realize a cylindrical FA lens, although there are no fundamental restrictions on the creation of a three-dimensional FA lens, for example, using holography methods, or using interference and diffraction effects. In addition, a combination of two or three cylindrical FA lenses is possible. Scheme B already uses the traditional design of an acoustic lens in which ultrasonic vibrations are formed upon absorption of laser radiation 1 in an absorbing coating 2 deposited on the outer surface of the acoustic lens 3. Further, these ultrasonic vibrations 4 propagate to a surface with high curvature, which ensures the concentration of focused Ultrasonic vibrations 4 at object 5. The advantage of such a scheme is the relative ease of variation of the necessary parameters of the ultrasonic wave due to changes in the parameters of laser radiation, n Example frequency and phase of the acoustic oscillations. The difference between the following scheme B is the use of laser radiation 1 to generate ultrasonic vibrations already directly at the output of the acoustic system 2 using an absorbing coating 3 deposited on the curved surface of the acoustic lens. In the case of relatively strong absorption of radiation in the medium itself, the generation of ultrasonic vibrations is possible due to the absorption of radiation in a thin layer of liquid directly in contact with the curved surface of the acoustic lens. In particular, in the case of an aqueous medium, an erbium laser and a carbon dioxide laser are suitable for this. Scheme D shows the fundamental possibility of creating the effect of an acoustic lens by absorbing radiation 1 in a liquid 2 directly on its surface 3. The formation of converging acoustic waves 4 acting on object 5 is achieved by a corresponding change in the intensity profile of radiation 6 in the beam cross section, which provides amplification the amplitude of the vibrations towards the focus area. In addition, you can use the principles of phase gratings, for example, based on the use of an additional plate 7 with appropriate filters or a specific configuration of the absorbing film on its surface. The same plate 7, located on the surface of the liquid, provides additional amplification of the amplitude of the acoustic waves due to the introduction of severe boundary conditions during the formation of the acoustic wave. It should be noted that the role of such a plate may be the transparent walls of the chamber in which the object is located, and in this case the vertical geometry of the FA lens is possible. In Scheme D, the concentration of acoustic vibrations in the focus region is achieved already due to phase matching of acoustic waves from individual FA lenses assembled in a line. These waves are generated using separate laser beams 1 in the line of absorbing targets 2, acting as a phased antenna, providing an appropriate concentration of vibrations 3 on object 4. In all the described circuits, high-frequency acoustic vibrations can be generated using cw lasers whose power modulation is in the required frequency range (1-100 MHz) is achieved using electro-optical and acousto-optical modulators. It is also possible to use pulsed lasers with a high frequency of filling packets of individual pulses. In the described circuits, the idea of using focused ultrasonic waves, the source of which is the region of rapid heat release of the absorbed laser energy, is essentially realized. Among the potential implementations of such schemes, it should be noted that the laser radiation focuses in one of the foci of an elliptical acoustic mirror, which refocuses the emerging acoustic vibrations in the region of the second focus, which can be located in a zone difficult to access for optical radiation, for example, inside a living organism. In this case, the phenomenon of optical breakdown can be used to generate acoustic waves [8]. In this way, acoustic waves can be focused to a greater depth into the skin and into various internal organs using an aqueous medium on the surface of the body for the necessary acoustic matching. One potential application is to accelerate the selective delivery of drugs to the desired area, for example, by acoustic and photoacoustic amplification of directed diffusion of drugs.

The implementation of the invention is also possible with the help of simpler schemes using optical fibers (figure 4), which, however, are of great practical importance. In all these schemes, in particular, A, the delivery of laser radiation 1 is carried out using optical fibers 2 placed in the appropriate medium. The resulting acoustic vibrations at the end of the fiber 4 then act on the object 5. The mechanism for generating acoustic vibrations can be different. For example, this may be absorption in the medium itself near the end of the fiber, which leads to the release of thermal energy and the subsequent formation of acoustic vibrations. An absorbing coating 3 may be applied to the end face of fiber 2 (Scheme B), the absorption of which leads to the formation of acoustic vibrations 4. The difference in Scheme C is the fixation of the tip 3 at the end of the fiber 2 with the absorbing element 4 at its end. As such an element, various absorbent films can be used. It is also possible to place an absorbing liquid in the space between the fiber end and the flexible film, sharp thermal expansion due to the absorption of radiation will lead to a sharp movement of the specified film and ultimately to the generation of acoustic vibrations 5 acting on the object 6. Scheme D shows that due to changing the curvature of the end of the fiber 1 and applying an absorbing coating 2 on it, it is possible to create a fiber optic FA lens. An acoustic lens can also be docked to the end of fiber 1 (scheme E) as a separate nozzle 2. The principle of operation of this acoustic nozzle, like the previous scheme, was described in the description of the schemes in Fig.3. Similar schemes are a close analogue of scheme A in figure 2. but using fiber optic beam formation near the object. However, it should be noted that due to the absorption of radiation in these coatings in fiber-optic systems, the problem of radiation damage to the object is eliminated, so that the fiber can be brought to the object in any direction. It is also interesting to note the potential possibility of creating optical breakdown at the end of the fiber in a transparent liquid, which, in addition to increasing the amplitude of the acoustic wave, avoids the direct hit of radiation on the object due to its almost complete absorption in the region of optical breakdown (a peculiar effect of the optical “black hole”). Direct placement of the fiber in the medium also has its advantages in controlling relatively large-sized objects. For example, a similar scheme using an endoscope can be used to move stones in the bladder in the desired direction or fixation in the desired position, in particular, with intracorporeal or extraporal lithotripsy. The difference from the use of standard micro-tools such as mechanical manipulators, tweezers, needles, etc. is the non-contact nature of the impact through acoustic vibrations. In addition, it is possible to combine such microneedles and fiber delivery of radiation by placing the fiber in a hollow microneedle. As a result, it becomes possible to control the object in two modes: contact and non-contact. By analogy with the use of many laser beams to create their desired spatial geometry (figure 2), a similar approach can be implemented using optical fibers. As an example, the use of two fibers located opposite each other, a line of fibers or their placement around the object so that the distal ends of the fibers form a discrete ring or even a ball in the center of which the object is located.

In parallel with the fiber, a hollow microtubule can also be placed close to it, through which a slow suction of liquid or gas from the manipulation volume is carried out. Thus, you can create the effect of a vacuum cleaner, attracting particles to the suction hole with a strainer at the end and fixing them, thus fixing them near the end of the fiber. By adjusting the amount of suction and photoacoustic repulsion of the particles, it is possible to arrange the particles at a certain distance from the end of the fiber. This mode is promising in case of artificial insemination, when several spermatozoa are attracted to the egg location area, when studying the interaction of various cells with each other and drugs, and the formation of spatially selective chemical and photochemical reactions. By adjusting such sticking and detaching effects, it is possible to ensure separation of particles from the walls and precision cleaning of the walls themselves.

One of the problems with microscopic examination of microbioobjects is sometimes the difficulty of tearing them off the substrate on which they are placed or adhered due to various adhesive forces (Van der Wals, electrostatic, electrochemical, etc.). To solve this problem, that is, the separation of a stuck object from the substrate, you can use a very simple private scheme, presented in figure 5. The laser radiation 1 is directed from the side of the substrate 2 transparent for this radiation to the medium 3 where the object 4 is located. In order to avoid damage to the object, the radiation wavelength is selected in the range of strong absorption of the medium. For example, in the case of an aqueous medium, it can be an erbium laser with a wavelength of about 2.89 μm, which is almost completely absorbed in the water layer 5 with a thickness of only a few microns. The resulting piston action of acoustic pressure forces easily tears the particle from the surface. A significant difference between this scheme and the method of cleaning the surface of the samples noted at the beginning is the reverse radiation scheme, which avoids the direct action of radiation on the object. Another solution may be to place an additional opaque film on the surface of the plate 2, if this is allowed by the research task. In this case, when radiation is absorbed in the liquid or in the film itself, it will itself begin to move and act on the object, which will completely exclude the possibility of even a small part of the radiation reaching the object.

As already noted, the presented schemes allow you to manipulate the position of the particles mainly in one-dimensional and two-dimensional volumes. For example, the ring geometry of only one light beam will allow the particle to move without additional measures only in the transverse direction when the beam moves perpendicular to its axis. This is convenient for the case of two-dimensional volumes created, for example, by two closely spaced planes, as in the case of coverslips in microscopy. Movement in three-dimensional measurement provides a scheme using two cylindrical beams 1 and 2, located at an angle to each other (Fig.6). In this case, object 3 is located inside the volume thus formed, and pressure forces act on it from all sides of this volume. The angle is selected based on the research task. For example, with a relatively small angle - from units to several tens of degrees, a volume somewhat elongated in space is formed. The convenience of such a scheme is the placement of two beams or two separate sources close to each other. With mutually perpendicular orientation of the beams, the smallest possible volume of a kind of light trap is formed. However, this necessitates a substantial spatial separation of both beams. These patterns resemble the case of several spotlights directed at different angles into one zone. The only difference is the cylindrical shape of the laser beams. Thus, it is quite possible to manipulate the position of light objects in the air, for example, with geodetic balls or promotional materials. At an angle of 180 °, the beams are oriented towards each other. Their small focusing and displacement of the optical axes and foci relative to each other provides additional opportunities for the formation of an acceptable geometry necessary for the corresponding manipulation of objects. The movement of the object is provided by the synchronized movement of both beams. The minimum required number of beams is two, but to increase the acting forces it is possible to increase their number.

In principle, a number of special cases are possible, which allow for certain manipulations with objects using fairly simple technical solutions. Examples of such cases are shown in Fig.7-9. Fig. 7A shows a diagram for realizing the vertical movement of a particle along the axis of a cylindrical beam 1, inside which there is an object 2. The object is kept inside such a beam due to acoustic pressure forces 3, which are formed as a result of absorption of radiation by the medium only in the region of distinctive optical walls. Thus, a "photoacoustic (FA) tunnel" is formed, only inside which a particle can move. Vertical movement can be provided by gravitational forces. Since heat is generated during the absorption of radiation in the region of the walls of the FA tunnel, this can lead to the formation of convective flows of medium 4, rushing upward and involving object 2 in motion.

In Scheme B, the movement of the object 2 up is ensured by the presence in the central part of the cylindrical beam of radiation 4 acting on the object. The movement of the object will provide periodic thermal expansion of the irradiated part of the surface of the object, as described previously. That is, in this case, the direct absorption of laser radiation in the central part by the object can lead to the creation of reactive thrust that ensures the longitudinal movement of the object. It is only necessary to ensure a decrease in intensity in the central part of the beam relative to the walls, otherwise the object can be ejected from the beam due to the dominance of acoustic forces in the central part.

The movement in the transverse direction can be ensured by moving the beam in the transverse direction in one way or another, for example, as a result of angular rotation of the beam. On Fig presents another private scheme of manipulating an object 3 when it is located in a transparent tube 1, perpendicular to which laser radiation of plane geometry 2 is transmitted. In this case, a plane acoustic wave 4 is formed, acting on object 3. By analogy with the previous schemes, two flat beams located on opposite sides of the object or the use of the cylindrical geometry of the optical beam inside which the object is located. It is also possible to use the axial geometry of the laser beam 5 (shown by a dotted line), the absorption of which is carried out either in an absorbing medium, for example in air, or in the object itself.

For this purpose, a special absorbing coating with a high coefficient of thermal expansion can be applied to the object. Another solution, already described above, is to place an absorbing film on which the object is placed. Piston forces will form both in the film itself and in the medium in front of this film. In the latter case, the thermal expansion of the layer of the absorbing medium will involve the film in motion, and the film will already act on the object (model of the laser piston). In this case, there is no longer a requirement for optical transparency of said tube. The use of such a scheme for transporting biological objects through such tubes is especially promising. In particular, in the analogue [9], only the process of catapulting the separated particles into the corresponding tubes is carried out, but the question of further control of these particles inside the tube is not resolved. Therefore, the present invention can advantageously complement the capabilities of existing commercial systems, and combining the two systems will not present difficulties, since it will be possible to use the same laser that is used in this analogue.

The fundamental condition in the present invention is the presence of an absorbing medium in which the object is located. The type of this medium, for example gas, in particular air or liquid, does not matter. The difference will be manifested only in the manifestation of the physical mechanism of generation of acoustic gradients and the magnitude of the pressure forces acting on the object. The amplification of pressure gradients can be achieved both by increasing the energy of laser radiation, and by increasing the absorption in the medium, for example, by adding various absorbing additives. One of the technical solutions is shown in Fig. 9 for the case of a cylindrical beam 1, inside which there is an object 2. The amplification of the acoustic forces 3 acting on it is achieved by adding one of several modules 4, which ensure the formation of the flow of the absorbing medium 5 (gas or liquid), directed to object manipulation area. These additional flows can also be of various geometries: cylindrical, flat, etc. and can be directed at different angles to the axis of the laser beam, including propagation along the axis or perpendicular to it, as shown in Fig.9.

Practical examples

1. Photoacoustic forceps with a pulsed laser for manipulating the position of biological objects (cells, molecules, viruses, etc.). This device is implemented on the basis of a standard scheme of an invert microscope, in which an optical set-top box with an acting laser is used as an additional module. In accordance with the invert circuit of the specified microscope, the impact on objects is carried out by supplying laser radiation to the stage from below. As the medium used standard physiological aqueous solutions. A pulsed nitrogen laser with the following parameters is used as a radiation source: energy range 10 ^-6 -10 ^-3 J, pulse duration l0 ^-8 -10 ^-9 sec, pulse repetition rate from units of Hz to tens of kHz.

Due to the relatively strong absorption in water, this laser allows you to create quite high pressure values in the range of tens and hundreds of bars, which are sufficient to move objects of sizes up to several tens and even hundreds of microns. As numerous studies show (see, for example, [21]), the magnitude of such pressure has virtually no effect on biological structures due to the proximity of the acoustic properties of the environment and cells containing a large amount of water. It should be noted that such a system can be quite simply implemented on the basis of existing commercial systems designed using a laser of similar characteristics for optical cutting of bioobjects and their final separation by ejection [9].

2. Photoacoustic forceps with a continuous laser for manipulating the position of biological objects (cells, molecules, viruses, etc.). The difference between this scheme and the previous one is the use of near-infrared lasers as radiation sources, where the absorption of most biological objects is minimal.

This is an additional factor that reduces the likelihood of damage to objects during direct exposure. An example of optical sources is a semiconductor laser with a wavelength in the spectral range of 750-900 nm or a neodymium laser with a wavelength of 1.06 μm with a power of both lasers in the range of 10-200 mW. The necessary modulation is carried out using an electro-optical modulator in the frequency range up to 100 kHz. Such a system is close to the design of the commercial laser-forceps apparatus [4], the principle of which is based on the creation of optical gradient forces due to the effect of light pressure. The difference will be in adding to this system only the specified modulator, since the analog uses a laser in continuous mode. The objects and environment are the same as in the first example of practical implementation. The increase in acoustic pressure is achieved by introducing various absorbent additives into the solution. For example, in the case of using a semiconductor laser, unicycyanin green in the concentration range of 0.01-0.2%, having a maximum absorption band in the region of 800 nm, can be used as such an additive. In both devices, it is easiest to implement a scheme with a single laser beam with a round transverse geometry (Fig.2A) or in the form of a light bar (Fig.2B) by adding a cylindrical lens to the main optical system. The formation of several optical beams is achieved using well-known schemes using a system of fission mirrors or diffraction schemes described in [19].

3. Fiber optic device for manipulating bioobjects (“photoacoustic whip”). In this device, the end of an optical fiber made of quartz with a polymer coating and a diameter in the range from 60 to 800 microns is placed in physiological saline.

The spatial position of the end of the fiber in the solution can be observed using standard microscopes, including those described above. For spatial manipulation of objects, the fiber can be rigidly fixed using an additional holder, and the necessary spatial movement is provided by the movable table on which the object is located. A pulsed neodymium laser with the following parameters is used as a radiation source: wavelength 1.06 μm, energy range 10 ^-7 -10 ^-4 J, range of pulse durations 10 ^-7 10 ^-9 sec. To increase absorption, finely dispersed powder prepared from medical coal is added to the solution.

4. A photoacoustic device for manipulating objects using a standard acoustic lens. The operation of this device is based on the principle of acoustic forceps, in which particles are captured in the focus area of a standard acoustic lens. However, to create high-frequency acoustic vibrations, a photoacoustic effect is used in the absorbing coating at the entrance of this lens.

The parameters of this lens (FIG. 3B): a sapphire cylinder (Al ₂ O ₃ material) with a thin absorbing film of zinc oxide, used in the usual mode for receiving and generating acoustic vibrations. This film is irradiated by a pulsed neodymium laser with the following parameters (see description in [20]): wavelength 1.06 μm, duration of one pulse 200 ps, the distance between individual pulses 5 ns (that is, the fundamental frequency of about 200 MHz), half-width one burst of pulses is 200 ns and its repetition rate is 2.7 kHz. The radius of the acoustic lens is 200 microns. With laser generation of ultrasonic waves, in addition to the main optical frequency, higher harmonics, in particular the fourth, with a frequency of about 800 MHz are possible. The selection of vibrations can be carried out by choosing the size of the acoustic lens. At the specified radius, this lens focuses the acoustic vibrations initiated by the described laser in an aqueous medium into a spot of about 2 microns in size. In order to avoid radiation damage to the absorbing coating, the radiation power should not exceed 2 kW. However, this is not critical, since it does not concern the impact on the object itself. Therefore, the generation of acoustic vibrations is possible due to the formation of plasma on the surface of the absorbing target. Such a system allows the formation of acoustic vibrations in principle in a wide frequency range from 50 MHz to 2 GHz.

5. A photoacoustic device with optical imaging of an acoustic lens in water. As noted earlier, in principle, optical formation of a three-dimensional image of a cylindrical acoustic lens directly in water is possible, for example, due to the targeted use of aberration or holographic effects. Moreover, it does not represent fundamental technical limitations due to the electro-optical modulation of laser radiation, the formation of acoustic vibrations with a frequency of 3.5 MHz (as in acoustic tongs [14]), which is sufficient for capture and manipulation with polystyrene balls up to 0.2 mm in size [14]. In this case, for the capture stability, it is possible to use the counter geometry of two laser beams and the corresponding FA lenses. Another solution is to use two cylindrical beams with mutually perpendicular orientation relative to each other.

6. Photoacoustic tunnel. A relatively powerful pulsed carbon dioxide laser, widely used for processing various materials, is used as a radiation source. Its parameters: wavelength 10.6 μm, pulse repetition rate up to 100 Hz, average power up to 2 kW. In such a laser, a cylindrical geometry of the laser beam with an external diameter of 10 cm and an internal 8 cm is formed. This geometry is easily achieved by using an opaque central diaphragm that shields only the central part of the beam. A similar geometry can also be achieved by changing the parameters of the resonator itself, although external control is more preferable. Due to the absorption of radiation from such a laser in air, significant acoustic vibrations are formed on carbon dioxide molecules and water vapor, which can be heard even with the naked ear. Such a system allows you to capture and hold relatively light objects such as a small balloon or light plastic products inside the laser beam. Nevertheless, it can be used for surveying or theater or advertising purposes. Motion along such a peculiar photoacoustic tunnel with a vertical arrangement of the laser beam can be caused by purely thermal convection. It is also possible periodic overlapping of the Central part of the beam due to, for example, oscillations of the specified diaphragm. In this case, the movement will be provided due to the periodic thermal expansion of the irradiated part of the object. If partial radiation damage to an object is not terrible, then an upward movement of the object is possible due to the previously described reactive force generated due to the recoil effect during the evaporation of laser ablation products, or the formation of plasma effects on the surface of the object. To avoid damage to the object itself, it can be coated with a special reflective coating or placed inside a special protective capsule. To enhance absorption, it is possible to use the addition of various absorbing additives to the basic medium. For example, in the case of using the described laser, SF ₆ gas can be blown into the air, which has a very strong absorption at the wavelength of the carbon dioxide laser.

A smaller effect, but also very noticeable, can be achieved by blowing water vapor into the laser beam, for example, by thermal evaporation of water, and for this you can use the radiation of the same laser. Such systems are very promising for manipulating various aggressive chemical compounds, when working with chemical reactors, etc., or in medicine for moving sterilized preparations in the absence of mechanical contact with them.

Calculations show that when using gas-dynamic carbon dioxide lasers with an output of up to several hundred kW existing in industry, it is quite possible to transport relatively light objects weighing tens and possibly hundreds of grams over distances of at least several hundred meters. Thus, with the help of the invention, photoacoustic levitation of various objects in air is possible for the first time, and in the case of using infrared invisible to the eye laser radiation for outside observation, the mechanism of such levitation will not be obvious, which can be used in theatrical and circus performances.

7. Optical manipulation of objects on the surface of solids. As objects, microelectronics or optics elements can be used that are non-contact, that is, in the absence of possible contamination, moving along the surface of the corresponding substrate. It is advisable to use a laser with minimal absorption in the substrate as a radiation source in order to avoid its possible optical damage. For example, in the case of a substrate of semiconductor materials, in particular Germany, it is advisable to use a neodymium laser with parameters similar to those described in Example 2. To move microobjects in the desired direction on the surface of the substrate, the distribution of light energy in the form of a light strip measuring 20 by 3 μm is most suitable.

Other examples include the hypothetical ability to control the flow of drugs or special samples (liposomes, antibodies embedded on microspheres, gold microparticles, fluorescent or photothermal probes, etc.) inside cells, various tissues, in blood and lymph vessels due to optical formation temperature and thermal gradients of a given profile. Thus, it is quite possible to create directed flows of drugs into the desired area, including against the forces of hydrostatic pressure in vessels, interstitial fluid, in the eye space or inside some oncological formations.

If the object is small enough, then it is known to experience Brownian chaotic motion. Laser-generated thermal local sources near the object can form the effect of “directed Brownian motion”. It is interesting to note that the random spatial fluctuations of the laser radiation around the object, formed, for example, by speckle inferometry, can both significantly enhance the Brownian motion, and so weaken it, as happens when the phases of the fluctuating optical radiation and natural thermal fluctuations of the medium are subtracted.

In this case, the thermal motion of the particles, as well as the chaotic acoustic vibrations accompanying them, formed due to the known effect of the acoustic emission of heated bodies, can influence an object. This effect is also manifested in the absence of modulation of the heat source, and the range of acoustic frequencies is quite wide, up to several tens of MHz.

In addition to directional thermal diffusion, the invention also allows for directional thermal convection due to the corresponding spatial orientation of the point heat sources induced by the laser. For example, their orientation in the form of a ring in microscopic studies in two-dimensional space between coverslips allows particles to be concentrated in the region of the center of this ring. Even focusing radiation near a particle allows convection from the irradiation zone to ensure particle movement away from this zone.

Such schemes, in addition to manipulating the position of individual particles, allow their sorting in the desired zone due to the difference in particle mass and acoustic properties.

In the present invention, only an acoustic wave acts on the particle, which, as already noted, has practically no effect on the properties of the object, at least this possible effect is much less than in the case of direct exposure to laser radiation, as in the prototype. With a close proximity of the light beam to the object, a thermal effect on the object is possible due to the diffusion of heat from the zone heated by the radiation. However, with short laser pulse durations of less than 10 ^-6 sec or high modulation frequencies of more than tens of kHz, the diffusion length is small enough (units and tens of microns) to have a significant effect on the object. Nevertheless, this issue in each case requires a separate consideration, in particular when using the previously described schemes of directed thermal diffusion or convection. It is very useful for the convenience of control and safety purposes in many cases in which radiation invisible to the eyes is used, the introduction of an additional pilot laser, the radiation of which is combined with the light beam from the main laser. As such pilot lasers, semiconductor lasers or LEDs with radiation in the red spectrum are most suitable.

LITERATURE

1.K.Svoboda, S.M. Black. Biological application of optical forces. Annu. Rev. Biophys. Biomol.Struc. 23, 244-285, 1994.

2. A. Ashkin, Proc. Natl. Acad. Sci. 94: 4853-4860, 1997.

3. US Patent No. 4893886, A. Ashkin et al. "Non-destructive optical trap for biological particles and method of doing same, January 16, 1990.

4. Laser Tweezers 1000 and 1064/1500, website Cell Robotics, Inc. Albuquerque, NM.

5. J. D. Kelley, F. E. Howis. A thermal detachment mechanism for particle removal from surfaces by pulsed laser irradiation. Microelectronic Engineering 20, 159-170, 1993.

6. J.A. Askaryan, UE.M. Moroz. Recoil pulse during laser ablation. J. Theor. and Exp. Fiz. 43, 2787-2995, 1962.

7. Copyright certificate for the invention No. 14977792B V.P. Zharov and others. The method of laser destruction of solid materials. Priority December 4, 1986, issued April 1, 1989

8. V.P. Zharov, A.V. Kilpio, V.I. Lotchilov, V. B. Shashkov. Application of power optoacoustic methods and instruments in medicine and biology. In book: Photoacoustics and Photothermal 5. Phenomena, Springer Series in Optical Sciences (Springer, Berlin,) Vol. 58, 533-547, 1987.

9. Laser Pressure Catapulting. website P.A.L.M. Mikrolaser Technologies. Inc.

10. US Patent No. 4772786. R.M. Langdon "Photothermal oscillator force sensor. September 20.1988.

11. US Patent No. 6067859. J. A. Kas et al. Optical stretcher. May 30, 2000.

12. US Patent No. 6055106. D.G. Grier at al. Apparatus for applying optical gradient forces. April, 25,2000.

13. US Patent No. 5512745. J. Finer et al. Optical trap system and method. April 30, 1996.

14. J.Wu. Acoustic tweezers. J. Acoustical Soc. Am. 5, 2140-2143, 1991.

15. US Patent No. 6216538. K. Yasuda et al. Particle handling apparatus for handling particles in fluid by acoustic radiation pressue. April 17, 2001.

16. US Patent No. 5902489 K. Yasuda et al. Particle handling method by acoustic radiation force and apparatus therefore. May 11, 1999.

17. US Patent No. 6245207. K. Yasuda et al. Cell separation device using ultrasound and electrophoresis. June 12, 2001.

18. US Patent No. 5212382 K. Sasaki et al. Laser trapping and method for applications thereof. May 18, 1993.

19. 15.US Patent No. 5939716, D.R. Neil "Three dimentional light trap for reflective particles" August 17, 1999.

20. V.P. Zharov, V. S. Letokhov. Laser Optoacoustis Spectroscopy (book), Springer Series in Optical Sciences, vol. 37, Springer-Verlag (Berlin Heidelberg New York), 320 p, 1986.

21. E.N. Beilin, V.I. Lotchilov. V.P. Zharov. Investigation of ulrtashort laser acoustic effects in water and their influence on cellular structure. Sov. Phys. Acoust 33, 344-349, 1987.

22. Q. Qi, G.J. Brereton. Mechanisms of removal of micron-sized particles by high-frequency ultrasonic waves. IEEE Transaction of Ultrasonics, Ferroelectrics, and Frequency Control. 42, 619-629, 1995.

Claims (23)

1. A device for optical manipulation of the spatial position of objects in a medium, including a source of optical radiation, an optical system, a system of spatial movement of an object in a medium associated with an optical system and / or a movable table, an additional optical unit located after the main optical system, the parameters of this block are interconnected with the parameters of the optical system, characterized in that the radiation source is continuous and introduced a modulator of radiation intensity associated with a source, or the radiation source is pulsed, the additional unit is designed in such a way as to provide a given distribution of radiation in the medium near the object and includes a lens, or a lens system, or a diaphragm, or a spatial filter, or holographic elements, or diffraction elements, or interference elements, or optical elements for spatial scanning of a light beam around an object, or one or more flexible optical fibers, the wavelength of the optical source and optical The parameters and composition of the medium are chosen in such a way as to ensure the absorption of radiation in the medium itself, the time and energy parameters of the optical source are selected based on the conditions for providing thermal or thermal and acoustic gradients in the medium around the object, sufficient for its spatial fixation in a given volume or movement in a given direction. 2. The device according to claim 1, characterized in that the parameters of the additional optical unit are selected in such a way as to ensure in the environment near the object the distribution of light energy in the form of a single light spot, or a narrow rectangular strip, or a line, or an arc of a circle, or in the form a half-serpus, either in the form of a light ring around an object, or in the form of a continuous light spot with a radiation intensity decreasing toward the center, or in the form of a light ring around an object, or in the form of a light ring in the center of which there is a separate a wind spot, and the energy distribution in them can be either continuous or discrete, that is, consisting of separate light spots, or strips, or half-grays, or circular arcs. 3. The device according to claim 1 or 2, characterized in that the optical unit is made in the form of a cylindrical lens, or a spherical cylindrical lens, or one or more optical plates with an adjustable angle of inclination with respect to the optical axis of the main optical system. 4. The device according to claim 1, characterized in that between the additional optical unit and the object introduced additional optical elements located in the environment next to the object and representing a plate optically transparent for radiation, or a plate with an absorbing coating on the surface facing the object, or a plate with an additional absorbing film on the specified surface, or only one absorbing film, so that the planes of these elements are oriented perpendicular to the optical axis of the indicated block. 5. The device according to claim 1, characterized in that an acoustic lens oriented in space so that radiation enters the input surface of the lens is placed next to the object, the focus of the lens coincides with the position of the object, and absorbing coatings are applied to the input or output surfaces of the lens and additionally provided is a unit for changing the frequency of optical exposure associated with the optical source, or a unit for mechanical movement of the lens associated with this lens. 6. The device according to claim 5, characterized in that the individual acoustic lenses are combined in a line, the optical system is designed to provide the formation of several light beams, each of which falls on the corresponding lens, and a phase delay unit connected to each of the lenses is introduced and a radiation source to ensure the operation of the line of lenses in phase acoustic antenna mode. 7. The device according to claim 1, characterized in that a second additional optical unit is introduced associated with the first unit and the optical system, made in the form of beam splitting plates or diffraction elements or optical fibers oriented in space so as to ensure separation of the main light beam into several other, at least two, light beams that are oriented at an angle relative to each other, the value of this angle lies in the range of 1-180 °, for example, the beams can be oriented perpendicular to each other or towards each other, and in the latter case the beams may be arranged as a coaxial and the optical axes thereof can be parallel displaced relative to each other, and the focus position can be the same, lie in the same plane or be displaced along the optical axis relative to each other. 8. The device according to claim 1 or 7, characterized in that the parameters of the additional optical unit together with the parameters of the optical system are selected so as to provide a three-dimensional energy distribution in the environment near the object in the form of a single cylinder, or a concave lens, or a sphere with an object inside this sphere, or two intersecting cylindrical beams with an object inside the region of their intersection, or periodic spatial lattices with different steps from units of microns to several millimeters, or their various combinations. 9. The device according to any one of claims 1 to 8, characterized in that additional optical radiation sources with independent main optical systems and additional optical units are introduced to create the necessary spatial spatial distribution of radiation near the object. 10. The device according to any one of claims 1 to 3, characterized in that an additional tube with optical transparent walls and the environment inside which the object is located is introduced, and the optical system provides a given distribution of light energy already inside this tube when the axis of the optical beam is oriented along or perpendicular to the axis of the specified tube, including the flat geometry of one light beam, the plane of which is oriented perpendicular to the axis of the specified tube, or two flat beams between which the object is located, or a cylinder the optical geometry of the beam. 11. The device according to claim 1, characterized in that the modulator is introduced, connected to an additional optical unit, this unit is made in such a way as to provide a cylindrical geometry of the light beam with a cross section in the form of a ring and an independent central part, the modulator is made so that provide modulation of the intensity of the Central part of the light beam, independent of the modulation of the peripheral annular part. 12. The device according to claim 1, characterized in that the additional optical unit is made in the form of an optical fiber, which is fixed in space with an additional holder so that the end of the fiber is near the object, and in the holder itself an additional device for moving the holder along with fiber in any given direction. 13. The device according to item 12, wherein the absorbent coating is applied to the fiber end and / or the radiation absorbing tip is fixed on it, or the fiber end has a concave surface, or the radiation absorbing coating is applied to the concave surface, or is attached to the fiber end acoustic lens with an absorbing coating on the input flat surface or on the output concave surface. 14. The device according to claim 1, characterized in that microscopic coverslips are introduced, located on a movable table, between which there is a medium with a sample, an invert microscope scheme is used as an optical system, and a joystick type system is introduced for precise control of the mobile table. 15. The device according to any one of claims 1 to 14, characterized in that the optical system provides light distribution of energy around the object, which partially comes into contact with the object in one or several boundary zones at the same time, including touching around the entire perimeter of the object. 16. The device according to any one of claims 1 to 15, characterized in that the medium uses various absorbing radiation fluids, or solutions of liquids, or gases, or mixtures of gases, including air, or gels, or biological media. 17. The device according to clause 16, characterized in that the optical system provides a predetermined distribution of radiation within the environment such as living biological tissues or individual cells, and the object is a medicine or drug capsules made, for example, in the form of liposomes, or various microcarriers such as polystyrene microspheres with attached biological elements, or various fluorescent probes, or photothermal samples in the form of chemical compounds, various metal and nonmetallic beads ov. 18. The device according to claim 1, characterized in that the necessary absorption in the medium is ensured by ensuring the composition of the medium, which includes absorbing radiation components of various nature. 19. The device according to any one of claims 1 to 18, characterized in that one or more additional feed units for absorbing additives are introduced into the irradiation region, which provide both discrete and continuous supply of these flows, including the use of an aerosol stream, said block or blocks have different orientations with respect to the optical beam, including including the coaxial and perpendicular directions of these flows relative to the axis of the optical beam and different spatial geometry of these flows from cylindrical to flat. 20. The device according to claim 1, characterized in that the optical system provides a given radiation distribution in a medium in contact with the surface of solid substrates of various nature, including semiconductor or optical elements, and objects are placed on the surface of these elements. 21. The device according to any one of claims 1 to 20, characterized in that a laser operating in a continuous mode is used as a radiation source, and an additional modulator is inserted, coupled to the laser to provide power modulation in a wide frequency range from units of Hz to hundreds of MHz . 22. The device according to any one of claims 1 to 20, characterized in that the source of radiation is a pulse radiation source with a pulse duration lying in the range of 10 ^-3 -10 ^-15 s, and an additional unit connected to this source is introduced and providing a mode of repetition of individual pulses in the range from units of Hz to hundreds of MHz. 23. The device according to any one of claims 1 to 20, characterized in that many known gas, solid-state, semiconductor and dye lasers operating in continuous or pulsed modes, including a pulsed nitrogen laser, semiconductor lasers in near infrared, neodymium laser (first and second harmonics), sapphire laser, erbium, ruby and holmium lasers, carbon dioxide laser.

Images