CN209327694U - A vortex beam generating device - Google Patents

Abstract

A kind of vortex beams generating device, including light-beam generator, the light beam of light-beam generator outgoing, which is incident in the polarizer, obtains linearly polarized light, and the linearly polarized light of polarizer outgoing is incident in spiral phase plate after collimator and extender device and diaphragm obtains vortex beams.A kind of vortex beams generating device provided by the embodiment of the utility model, design advantages of simple, diaphragm and collimator and extender device are equipped with, effectively improve the diffraction efficiency of single-stage vortex diffraction light, spatial light modulator is replaced with spiral phase plate, so that the vortex beams generating device effectively reduces cost on the basis of guaranteeing that topological charge number is adjustable.

Description

A vortex beam generating device

technical field

The utility model relates to the field of optoelectronic technology, in particular to a vortex beam generating device.

Background technique

Vortex beams refer to a special class of beams with continuous spiral wavefront phase and definite photon orbital angular momentum. The light intensity at the center of the helical phase is zero, and the phase at the center cannot be determined. The most general feature is that its electric field expression contains a phase factor exp(imθ), where m is called the number of topological charges. Due to the application of vortex beams in optical trapping, manipulation of tiny particles, new super-resolution optical microscopy and astronomy, people are paying more and more attention to the research of vortex beams. At present, the more common and efficient method used to generate vortex beams in the laboratory is to use spatial light modulators (Spattical Light Modulators, SLM). The combination of various spatial light modulators and computational holography makes this method useful in generating optical The vortex aspect just got more convenient. However, a major problem with computational holography is the presence of multiple orders of diffraction. Although optical vortices with different topological charges can be generated at the same time, the diffraction efficiency of each order of vortex diffracted light is not high enough, and the structure of the spatial light modulator is complex, and the configuration of supporting devices is also relatively expensive.

Utility model content

The utility model provides a vortex beam generating device, which can effectively improve the diffraction efficiency of single-stage vortex diffracted light, effectively reduce the cost on the basis of ensuring that the number of topological charges can be adjusted, and solve the problems existing in the prior art.

The technical scheme that the utility model adopts for solving the problems of the technologies described above is:

A vortex beam generating device, including a beam generator, the beam emitted by the beam generator is incident on a polarizer to obtain linearly polarized light, and the linearly polarized light emitted by the polarizer is incident on the The vortex beam is obtained in the spiral phase plate; the spiral phase plate includes a sealed cylinder with a cavity, the sealed cylinder is transparent, and one side of the cavity is fixed with a transparent first spiral phase plate, the cavity The inner side close to the helical surface of the first helical phase plate is filled with a medium solution, and the medium solution forms a liquid second helical phase plate next to the helical phase plate, and the first helical phase plate and the second helical phase plate are complementary.

Preferably, the first spiral phase plate is made of K9 glass.

Preferably, the collimating beam expander includes a base, the base is provided with a screw and a guide rail in parallel, and a collimating mirror is slid on the guide rail, and the bottom of the collimating mirror is fixedly installed on the nut of the lead screw; A beam expander is also fixedly arranged on the 35 seats, and the beam expander is arranged close to the aperture.

Preferably, the beam generator is a He-Ne laser.

Preferably, the sealing cylinder is provided with a liquid inlet.

A vortex beam generating device provided by the embodiment of the utility model has a simple and reasonable design, and the cooperative arrangement of the aperture and the collimating beam expander can effectively improve the diffraction efficiency of the single-stage vortex diffracted light, and use a spiral phase plate to replace the spatial light The modulator enables the vortex beam generating device to effectively reduce the cost on the basis of ensuring that the number of topological charges can be adjusted.

Description of drawings

Fig. 1 is a schematic structural diagram of a vortex beam generating device provided by an embodiment of the present invention.

In the figure, 1. beam generator, 2. polarizer, 3. collimating beam expander, 31. base, 32. lead screw, 33. nut, 34. guide rail, 35. collimating mirror, 36. beam expander Mirror, 4, diaphragm, 5, spiral phase plate, 51, sealing cylinder, 52, first spiral phase plate, 53, second spiral phase plate, 54, liquid inlet.

Detailed ways

In order to clearly illustrate the technical features of this solution, the utility model will be described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

As shown in FIG. 1 , the embodiment of the present invention provides a vortex beam generating device. The vortex beam generating device includes a beam generator 1, the beam emitted by the beam generator 1 is incident on a polarizer 2 to obtain linearly polarized light, and the linearly polarized light emitted by the polarizer 2 passes through a collimating beam expander 3 and an aperture 4 and then incident into the helical phase plate 5 to obtain a vortex beam.

The beam generator 1 is a He-Ne laser. The helium-neon laser is equipped with helium-neon gas in a quartz tube. Under the excitation of an electronic oscillator, an inelastic collision occurs to make electrons transition and emit infrared rays.

The collimating beam expander 3 includes a base 31, on which a lead screw 32 and a guide rail 34 are arranged in parallel, on which a collimating mirror 35 is slidably arranged, and the bottom of the collimating mirror 35 is fixedly mounted on the lead screw 32 On the nut 33; the base 31 is also fixed with a beam expander 36, and the beam expander 36 is arranged close to the aperture 4.

The beam expander 36 is used to expand the laser beam emitted by the laser to increase the spot size of the laser; the collimator 35 is used to maintain the collimation of the beam between the two optical elements, and the collimator 35 is arranged on the wire On the nut 33 of the bar 32, the staff can precisely adjust the distance between the collimating mirror 35 and the beam expander 36 by adjusting the lead screw 32, and the focus between the collimating mirror 35 and the beam expander 36 is accurate, which can improve The precision of the vortex beam emitted by the spiral phase plate 5.

The aperture 4 is used to control the effective area of the parallel light beam incident on the spiral phase plate 5 .

The spiral phase plate 5 includes a sealed cylinder 51 with a cavity. The sealed cylinder 51 is transparent. One side of the cavity is fixed with a transparent first spiral phase plate 52. The cavity is close to the first spiral phase plate. One side of the helicoid of the helical phase plate 52 is filled with a medium solution, and the medium solution forms a liquid second helical phase plate 53 next to the helical phase plate 5 , and the first helical phase plate 52 and the second helical phase plate 53 are complementary.

The first spiral phase plate 52 is made of K9 glass. K9 glass is an optical glass, which is crystal clear and very suitable for optical applications.

The sealing cylinder 51 is provided with a liquid inlet 54 . It is used to replace the medium solution. Different medium solutions have different refractive indices. The staff can change the topological charge of the optical vortex emitted by the spiral phase plate 5 by changing the medium solution. The relationship is:

Where: Δn _m =n _x -ny , n _{x is} the refractive index of the first helical limiting plate, _ny is the refractive index of the second helical limiting plate, and m is the topological charge of the optical vortex;

Δa=a _max -a _min , a _max is the width of the thickest part of the first helical phase plate 52, and a _min is the width of the thinnest part of the first helical phase plate 52;

λ is the wavelength of the light wave.

The beam generating device, polarizer 2, collimator beam expander 3, aperture 4 and spiral phase plate 5 are co-installed and arranged, the optical path structure is simple, the operation is convenient, and the collimator expander can greatly reduce the cost. The setting of the lead screw 32 in the beam device 3 has improved the accuracy of the staff adjusting the distance between the collimating mirror 35 and the beam expander 36; In the range of application, by changing the medium solution, the parameters of the helical phase plate 5 can be adjusted, and the topological charges that generate the optical vortex can be flexibly controlled.

The above-mentioned specific implementation manners cannot be regarded as limitations on the protection scope of the present utility model. For those skilled in the art, any alternative improvements or transformations made to the embodiments of the present utility model fall within the protection scope of the present utility model.

The parts of the utility model that are not described in detail are the known techniques of those skilled in the art.

Claims (5)

1. A vortex beam generating device, characterized in that: it comprises a beam generator, the beam emitted by the beam generator is incident into a polarizer to obtain linearly polarized light, and the linearly polarized light emitted by the polarizer is collimated and expanded The vortex beam is obtained by incident into the spiral phase plate after the beam device and the diaphragm; the spiral phase plate includes a sealed cylinder with a cavity, the sealed cylinder is transparent, and one side of the cavity is fixed with a transparent The first helical phase plate, the side of the cavity close to the helical surface of the first helical phase plate is filled with a medium solution, and the medium solution forms a liquid second helical phase plate next to the helical phase plate, the second helical phase plate A helical phase plate is complementary to the second helical phase plate. 2. A vortex beam generating device according to claim 1, characterized in that: the first helical phase plate is made of K9 glass. 3. A vortex beam generating device according to claim 1, characterized in that: said collimating beam expander comprises a base, said base is provided with a lead screw and a guide rail in parallel, and said guide rail is slidably provided with A collimating mirror, the bottom of the collimating mirror is fixedly installed on the nut of the lead screw; a beam expander is also fixed on the base, and the beam expander is arranged close to the aperture. 4. A vortex beam generator according to claim 1, characterized in that: said beam generator is a He-Ne laser. 5. A vortex beam generating device according to claim 1, characterized in that: said sealing cylinder is provided with a liquid inlet.