CN105911703B - Linear laser projection device and method, and laser distance measuring device and method - Google Patents

Abstract

A linear laser projection device is disclosed, which splices linear laser beams through two stages of optical elements to obtain a linear laser beam with a large radiation angle and uniform intensity distribution. The two stages of optical elements can be diffractive optical elements, preferably binary optical elements. A linear laser projection method using the above device, as well as a laser ranging device and method, are also disclosed.

Description

Linear laser projection device and method, and laser distance measuring device and method

technical field

The invention relates to the field of optics, in particular to a device and method for projecting linear laser light, and a corresponding laser distance measuring device and method.

Background technique

In fields such as depth measurement, structured light needs to be projected into the measurement space in order to facilitate measurement. In practical applications, linear light can be projected into the measured area, and the depth information of the measured space can be obtained by photographing the reflected light spot and processing the image of the light spot.

Existing technologies use cylindrical lenses (see Figure 1A) or Fresnel lenses (linear Fresnel gratings, see Figure 1B) to capture linear laser light and use them in applications such as autonomous cleaning robots. The volume of the cylindrical lens is too large, which is not conducive to the compactness of the laser projection or distance measuring device. Although the Fresnel lens is compact in size, it has the problem that the radiation angle is too small or the detection distance is too short. This is because the intensity of light transmitted through the Fresnel lens is Gaussian distributed along the inline, that is, the brightness at the center is high and the brightness at both ends is weak. When the scattering angle increases to a certain level (such as 90° or 100°), the brightness at both ends of the line laser will become very weak. According to the test requirements of the safety laser, the strongest brightness of the projection part must also be below the safety standard. This greatly limits the projection distance or projection angle of the laser. The laser ranging scheme using the existing laser projection scheme is also limited accordingly.

Therefore, there is a need for a linear laser projection device and method capable of solving at least one of the above problems, as well as a corresponding laser distance measuring device and method.

Contents of the invention

In order to solve at least one of the above problems, the present invention provides a linear laser projection device and method, which can provide a linear laser with a large radiation angle and/or a long projection distance through secondary diffraction.

According to one aspect of the present invention, a linear laser projection device is provided, including: a first-level optical element designed to split an incident light beam into N sub-beams in a first direction, and two adjacent sub-beams The included angle α between them is the same, wherein N is an odd number; and the second-level optical element is designed to diffract the N sub-beams into N linear beams with a radiation angle of α in the first direction, respectively, Moreover, the first-level optical element and the second-level optical element are designed such that the N linear beams are spliced together in the first direction, thereby forming a linear beam with a radiation angle of N×α.

According to another aspect of the present invention, there is provided a linear laser projection device, comprising: a first-stage optical element designed to diffract an incident light beam into a linear laser with a radiation angle of α in a first direction; and a second-stage an optical element designed to diffract the linear laser light into N linear beams with a radiation angle α in the first direction, and the first-level optical element and the second-level optical element are designed to The N linear beams are spliced together in the first direction to form a linear beam with a radiation angle of N×α, where N is an odd number.

Therefore, multiple linear light beams are rationally spliced through the secondary optical element, thereby realizing linear light with a large radiation angle and uniform intensity distribution.

Preferably, the first-order optical element and the first-order optical element may be optical diffraction elements, more preferably, may be binary optical elements. In this way, more compact optics and linear light with a more uniform intensity distribution can be achieved.

Preferably, the first-level optical element or the second-level optical element can also be designed such that the energy of the line beams on both sides of the N line beams is higher than the energy of other line beams. In this way, the vignetting during imaging can be properly compensated according to the actual situation.

Preferably, the first-stage optical element is also designed to collimate the incident beam before splitting or diffracting the incident beam. In this way, the projection device of the present invention is further compacted by incorporating the collimation function.

Preferably, the first-level optical element may include a plurality of optical diffraction elements, and the plurality of optical diffraction elements split the incident light beam step by step, so as to form the N sub-beams.

According to another aspect of the present invention, a laser distance measuring device is provided, which includes the above-mentioned linear laser projection device or its preferred solution for projecting a linear laser to the space to be measured; There is an imaging device with a predetermined relative spatial position relationship between them, and the linear laser reflected by the obstacle in the measured space is imaged by the imaging device; and according to the above imaging result and the predetermined relative spatial position relationship, the measured A processor that measures the depth distance of obstacles in the space.

Therefore, by projecting linear light with a large radiation angle and uniform intensity distribution, more accurate depth distance measurement with a larger coverage is realized.

According to still another aspect of the present invention, a linear laser projection method is provided, including: splitting the incident beam into N sub-beams in the first direction by a first-level optical element, and the angle between two adjacent sub-beams is α is the same, where N is an odd number; and the N sub-beams are diffracted by the second-level optical element into N linear beams with a radiation angle of α in the first direction, and passed through the first-level optical element And the second-level optical element itself and related structures enable the N linear beams to be spliced together in the first direction to form a linear beam with a radiation angle of N×α.

According to still another aspect of the present invention, there is provided a linear laser projection method, comprising: diffracting the incident light beam into a linear laser with a radiation angle of α in the first direction through the first-level optical element; and through the second-level optical element diffracting the linear laser light into N linear beams with a radiation angle of α in the first direction, and making the N The linear beams are spliced together in the first direction to form a linear beam with a radiation angle of N×α, where N is an odd number.

According to another aspect of the present invention, a laser ranging method is provided, which uses the above-mentioned linear laser projection method to project a linear beam, and images the linear laser reflected by the obstacles in the measured space, and according to the above-mentioned imaging Obtain the depth distance of obstacles in the measured space based on the results of the results and the spatial positional relationship between the device for projecting the linear laser and the device for imaging.

By using the projection/distance measuring device and method of the present invention, it is possible to obtain a linear laser with a large radiation angle and uniform intensity distribution without significantly increasing the difficulty or volume of the optical system, thereby achieving higher precision and wider coverage. Depth measurement.

Description of drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing the exemplary embodiments of the present disclosure in more detail with reference to the accompanying drawings, wherein, in the exemplary embodiments of the present disclosure, the same reference numerals generally represent same parts.

Fig. 1 is the prior art using cylindrical lens and Fresnel lens.

Fig. 2 schematically shows a schematic side view of an optical device according to the invention.

Fig. 3 schematically shows a schematic side view of another optical device according to the invention.

Fig. 4 shows a side view of a binary optical element that can be used in the linear laser projection device of the present invention.

Fig. 5 shows a real photo of the final projection of the linear laser projection device according to the principle of the present invention.

Detailed ways

Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[first embodiment]

Fig. 2 schematically shows a schematic side view of an optical device according to the invention.

The light source 1 may be a laser generator for generating a laser beam 100 . In one embodiment, the light source may have a collimating device, for example, the light source may be a collimated laser capable of directly generating a collimated laser beam 100 .

The light beam 100 is incident on the linear laser projection device 2 .

The device 2 comprises a primary optical element 10 and a secondary optical element 20 .

The first-stage optical element 10 splits the incident light beam 100 . In one embodiment, the first-stage optical element 10 can be designed to split the incident light beam into N sub-beams 200 in the first direction, and the included angle α between two adjacent sub-beams is the same, where N is an odd number. The N sub-beams 200 may be N point lasers. Although three sub-beams 200 are shown in the figure (that is, N is 3), in practical applications N can be 5, 7, 9, or even more.

The first direction may be a horizontal direction or a vertical direction. Correspondingly, the second direction described below may be a vertical direction or a horizontal direction. In some cases, the first direction and the second direction may also be directions perpendicular to each other but forming an included angle with the horizontal direction. This included angle is an acute angle.

The second-level optical element 20 diffracts the N sub-beams 200 . In one embodiment, the second optical element 20 can be designed to diffract N sub-beams into N linear beams 300 with a radiation angle α in the first direction. The first-level optical element 10 and the second-level optical element 20 are designed to splice the N linear beams 300 together in the first direction, so as to form a linear beam 400 with a radiation angle of N×α.

The primary optical element 10 and the secondary optical element 20 may be diffractive optical elements. In the present invention, the optical diffraction element is an optical element that uses the principle of light wave diffraction to deflect the direction of light wave propagation. The optical axes of the first optical element 10 and the second optical element 20 may coincide, as shown by the dotted line 500 in the figure.

When N is set to 3, there are only two angles between the three point laser beams. Since diffractive optics has the property of centrosymmetry, the two included angles must be the same. In a preferred embodiment, α=40° can be taken. In another embodiment, if N=5, that is, there are four included angles among the five point laser beams, then α=30° can be taken, for example.

In one embodiment, the primary optical element 10 may include a plurality of diffractive optical elements. A plurality of optical diffraction elements split the incident light beam step by step to form N sub-beams. For example, the first-level optical element 10 may include a third optical diffraction element and a fourth optical diffraction element (not shown in the figure). The third optical diffraction element is designed to split the incident light beam into N3 sub-beams in the first direction, and the N3 sub-beams include 1 zero-order sub-beam and N3-1 non-zero-order sub-beams. The energy of the N3-1 non-zero-order sub-beams is basically the same, and the energy of the zero-order sub-beam is higher than that of the non-zero-order sub-beams, wherein N3 is an odd number. For example, N3=3, the energy of the zero-order sub-beam in the middle is higher, and the energy of one first-order sub-beam on each side is the same and lower than the energy of the zero-order sub-beam.

The fourth optical diffraction element is designed to split the zero-order sub-beam into N4 sub-beams with substantially the same energy in the first direction, where N4 is an odd number. On the other hand, the fourth optical diffraction element does not diffract non-zero-order sub-beams. For example, the active area of the fourth optical diffraction element can be small, and the diffraction effect is only applied to the area where the zero-order sub-beam passes, and the non-zero-order sub-beam passes directly without being further diffracted.

Thus, N3−1+N4=N.

For example, N4=3. That is, the third optical diffraction element splits the incident light beam into three sub-beams. The fourth optical diffraction element splits the zero-order sub-beam with relatively strong intermediate energy (for example, three times the energy of the first-order sub-beam) into three sub-beams with substantially the same energy. Thus, 3-1+3=5 sub-beams with substantially the same energy are generated.

The N sub-beams obtained by the first optical element 10 are then incident on the second optical element 20 . The second-level optical element 20 can diffract the incident N sub-beams into N linear beams 300 with a radiation angle of α. Further, the N linear beams 300 can be spliced together in the first direction by properly designing the first-level optical element 10 and the first-level optical element 20, thereby forming a linear beam 400 with a radiation angle of N×α . In the above example where N=3 and α=40°, a linear laser with a radiation angle of 120° in the first direction can finally be obtained. However, in the above example where N=5 and α=30°, a linear laser with a radiation angle of 150° in the first direction can finally be obtained.

Since the brightness of both ends of the projected linear laser light 300 is slightly lower, a certain degree of overlapping of adjacent linear light beams 300 can be allowed, as shown by the bright lines 301 and 302 in FIG. 2 . In practical applications, overlaps within 100 pixels can be allowed.

When the distance between the two optical elements is very short (for example, close to zero), it can be regarded as that N sub-beams are incident from one incident point. If the distance between the two optical elements is widened, it can be regarded as N sub-beams incident from N incident points. As the distance between the two-stage optical elements increases, the distance between the spliced lines (that is, the N lines of light emitted from the second-stage optical element) will increase. Therefore, the distance between the two optical elements can be properly designed to ensure proper splicing of the N linear beams.

Usually, in order to obtain a linear laser with uniform intensity, it is hoped that the energy of the N linear beams obtained through the second-level optical element is the same. But considering the image vignetting problem usually encountered in lens design and imaging (that is, the imaging brightness on both sides of the image is slightly lower than the center brightness), so the first-level optical element and the second-level optical element can be designed so that N The energy of the linear beams on both sides of the linear beams is higher than the energy of the other linear beams. This can be realized by designing the first-level optical element so that among the N point lasers, the energy of the point lasers on both sides is higher than that of other point lasers. In the case of N=3, that is, in the case of three point laser beams, the laser energy on both sides may be slightly higher than that of the center laser by about 5%. In addition, it can also be realized by adjusting the design of the secondary optical element.

The above shows a linear laser projection device according to an embodiment of the present invention. Thus, through the splicing of the light beams by the secondary optical elements, a linear laser with a large radiation angle and uniform intensity within the range of the radiation angle can be obtained.

Although the laser 1 is shown in the figure as a separate component from the linear laser projection device 2 , in one embodiment, the laser generator 1 may also be incorporated as a part of the linear laser projection device 2 . In addition, although the figure shows the collimated beam emitted from the laser 1 , in one embodiment, the collimation function of the laser 1 can also be realized by the first-level optical element 10 . In other words, the first-stage optical element 10 can also be designed to collimate the incident light beam before splitting the incident light beam.

[Second Embodiment]

Fig. 3 schematically shows a schematic side view of another optical device according to the invention.

Similar to FIG. 2 , the light source 1 may be a laser generator for generating a laser beam 100 , such as a collimated laser.

The light beam 100 is incident on the linear laser projection device 2'.

The device 2' comprises a primary optical element 10 and a secondary optical element 20'.

The incident light beam 100 is diffracted by the primary optical element 10'. In one embodiment, the first-stage optical element 10' can be designed to diffract the incident light beam into a line-shaped laser with a radiation angle α in the first direction.

The second-level optical element 20' replicates and splices the linear laser light with a radiation angle of α. In one embodiment, the second-level optical element 20' can be designed to diffract the linear laser light into N linear beams with a radiation angle α in the first direction. The first-level optical element 10' and the second-level optical element 20' are designed such that N linear beams are spliced together in the first direction, thereby forming a linear beam with a radiation angle of N×α, where N is an odd number . Although three sub-beams 200 are shown in the figure (that is, N is 3), in practical applications N can be 5, 7, 9, or even more.

Similarly, the first-level optical element 10' and the second-level optical element 20' can also be optical diffraction elements, and the optical axes of the two can coincide, as shown by the dotted line 500 in the figure.

The linear laser beam with radiation angle α obtained by the first optical element 10' is then incident on the second optical element 20'. The second-level optical element 20' can replicate the incident linear beams into N linear beams 300 with a radiation angle of α. Further, the N linear light beams 300 can be spliced together in the first direction by properly designing the first-level optical element 10' and the first-level optical element 20', so as to form a line-shaped light beam with a radiation angle of N×α Beam 400.

Similarly, adjacent linear beams 300 can be allowed to overlap to a certain extent, as shown by bright lines 301 and 302 in FIG. Element 10 ′ performs collimation of light beam 100 . In addition, the second-level optical element can also be designed so that the energy of the line beams on both sides of the N line beams is higher than the energy of other line beams to compensate for the vignetting effect.

Thus, also through splicing the light beams by the secondary optical elements, a linear laser with a large radiation angle and uniform intensity within the range of the radiation angle can be obtained.

[Third Embodiment]

The primary optical element and/or the secondary optical element of the linear laser projection device may be a diffractive optical element (DOE). For example, the collimated beam can be diffracted by the second-order Fresnel lens after splitting by the first-stage optical element. Since the linear light diffracted by the Fresnel lens has a Gaussian distribution in the first direction, multiple adjacent linear lights can be overlapped to obtain a spliced linear light with a more uniform intensity distribution. In the case of using a Fresnel lens as the second-level optical element, N=7, 9 or more is selected to optimize the intensity distribution of the spliced linear light.

In the present invention, the linear laser projection device (for example, 2 and 2' in the figure) is preferably realized by a binary optical element. Here, it can be considered that the binary optical element refers to the diffraction theory based on light waves, using computer-aided design, and using a very large-scale integration (VLSI) circuit manufacturing process, etching on the substrate (or the surface of traditional optical devices) to produce two or The relief structure with multiple step depths forms a type of diffractive optical element with pure phase, coaxial reproduction, and extremely high diffraction efficiency.

In one embodiment, one of the first and second optical elements, preferably the second optical element, may be a binary optical element. For example, the first order optical element is a conventional optical diffractive element and the second order optical element is a binary optical element. In one embodiment, the primary optical element and the secondary optical element may both be binary optical elements. In yet another embodiment, the primary optical element and the secondary optical element can be combined into one binary optical element.

Since the binary optical element is a pure phase diffractive optical element, in order to obtain high diffraction efficiency, it can be made into a relief structure with multiple phase orders. Generally, L (=2N) phase orders can be obtained by using N templates, and the diffraction efficiency is: η=|sin(π/L)/(π/L)|2. From this calculation, when L=2, 4, 8 and 16, there are V=40.5%, 81%, 94.9% and 98.6%, respectively. Utilizing subwavelength microstructures and continuous phase profiles, an efficiency close to 100% can be achieved.

As L increases, processing difficulty and cost also increase accordingly. Therefore, in practical applications, the efficiency and cost will be balanced by selecting an appropriate order. Fig. 4 shows a side view of a binary optical element that can be used in the linear laser projection device of the present invention. Thus, the linear laser projection device according to the present invention can finally obtain linear laser light with a relatively uniform intensity distribution and a large radiation angle. Fig. 5 shows a real photo of the final projection of the linear laser projection device according to the principle of the present invention. In this example, the intensity ratio of the sides to the center can be as high as 9:10.

Due to the limitations of the existing technology, although the binary optical element can diffract out linear light with uniform intensity distribution, the diffraction angle for a single beam of light rarely exceeds 90 degrees. Through the above-mentioned secondary diffraction setting according to the present invention, it is possible to realize the expansion of the diffraction angle under the condition of ensuring the uniform intensity distribution, so as to meet various requirements in practical applications.

[Fourth embodiment]

Preferred embodiments of the linear laser projection device according to the present invention have been described above with reference to FIGS. 2-5. The novel linear laser projection method can be realized using the above-described device.

In an embodiment, a linear laser projection method may include: splitting an incident beam into N sub-beams in a first direction by a first-level optical element, and the included angle α between two adjacent sub-beams is the same, wherein N is an odd number; and diffracting the N sub-beams into N linear beams with a radiation angle of α in the first direction through the second-level optical element, and passing through the first-level optical element and the second-level The optical element itself and related structures enable N linear beams to be spliced together in the first direction to form a linear beam with a radiation angle of N×α.

In another embodiment, a linear laser projection method may include: diffracting an incident light beam into a linear laser with a radiation angle of α in a first direction through a first-level optical element; Diffraction of the linear laser light into N linear beams with a radiation angle of α in the first direction, and through the first-level optical element and the second-level optical element themselves and related structures, the N linear beams are are spliced with each other in the first direction to form a linear beam with a radiation angle of N×α, where N is an odd number.

Likewise, the above-mentioned first-level optical element and second-level optical element may be diffraction elements or binary optical elements. Thus, the beneficial effect of projecting a line-shaped laser with a large radiation angle and relatively uniform intensity is achieved through simple second-order diffraction.

[Fifth Embodiment]

According to the above linear laser projection device and method, the present invention can obtain a novel laser distance measuring device and method.

In an embodiment, a laser distance measuring device may include the linear laser projection device, an imaging device and a processor as described in the above embodiments.

The linear laser projection device (for example, the linear laser projection device 2 or 2' can project a large radiation angle and a uniform intensity linear laser to the measured space. There is a predetermined relative spatial position relationship between the imaging device and the linear laser projection device, and for all The linear laser reflected by the obstacles in the measured space is used for imaging. The processor obtains the depth distance of the obstacles in the measured space according to the above imaging results and the predetermined relative spatial position relationship.

Due to the inclusion of the linear laser projection device according to the present invention, the laser distance measuring device can project a linear laser with a large radiation angle and uniform intensity, thereby ensuring that the large radiation angle can be measured as much as possible without changing the power. to a larger area. The uniformity of intensity improves the overall measurement accuracy.

In addition, in one embodiment, the present invention also relates to a laser ranging method, which can use the above-mentioned linear laser projection device to project a linear laser with a large radiation angle and uniform intensity, which is reflected by obstacles in the space to be measured. performing imaging with the linear laser; and obtaining the depth distance of the obstacle in the measured space according to the imaging result and the spatial position relationship between the device for projecting the linear laser and the imaging device.

The linear laser projection device and method, and the laser distance measuring device and method according to the present invention have been described in detail above with reference to the accompanying drawings.

In addition, the method according to the present invention can also be implemented as a computer program, and the computer program includes computer program code instructions for executing the above-mentioned steps defined in the above-mentioned method of the present invention. Alternatively, the method according to the present invention can also be implemented as a computer program product, which includes a computer-readable medium on which a computer for performing the above-mentioned functions defined in the above-mentioned method of the present invention is stored. program. Those of skill would also appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code that includes one or more Executable instructions. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. It should also be noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by a dedicated hardware-based system that performs the specified functions or operations , or may be implemented by a combination of dedicated hardware and computer instructions.

Having described various embodiments of the present invention, the foregoing description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and alterations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principle of each embodiment, practical application or improvement of technology in the market, or to enable other ordinary skilled in the art to understand each embodiment disclosed herein.

Claims (6)

1. a kind of linear laser grenade instrumentation, comprising:

First order optical element is designed to for incident beam being diffracted into the linear laser that radiation angle in a first direction is α；With And

Second level optical element is designed to for the linear laser to be diffracted to N number of radiation angle in said first direction to be α Linear beam, and the first order optical element and the second level optical element be designed so that it is described N number of linear Light beam, which mutually splices in said first direction and exists between adjacent linear beam, to be overlapped, to form a radiation angle For the linear beam of N × α, wherein N is odd number,

Wherein, the first order optical element and the second level optical element are binary optical elements and are incorporated to a binary Optical element.

2. the apparatus according to claim 1, wherein the first order optical element or the second level optical element also by The energy for being designed such as the linear beam of two sides in N number of linear beam is higher than the energy of other linear beams.

3. the apparatus according to claim 1, wherein

The first order optical element be additionally designed to the incident beam carry out diffraction before to the incident beam into Row collimation.

4. a kind of laser ranging system, comprising:

To the linear laser grenade instrumentation as claimed in any one of claims 1-3 of detected space projection linear laser；

With the imaging device of predetermined relative tertiary location relationship between the linear laser grenade instrumentation, by the tested sky The linear laser of interior barrier reflection is imaged by the imaging device；And

According to barrier in detected space described in the result of above-mentioned imaging and the predetermined relative tertiary location Relation acquisition The processor of depth distance.

5. a kind of linear laser projective techniques, comprising:

Incident beam is diffracted into the linear laser that radiation angle in a first direction is α by first order optical element；And

The linear laser is diffracted to the line that N number of radiation angle in said first direction is α by second level optical element Shaped light beam, and the excessively described first order optical element and the second level optical element itself and relative configurations make it is described N number of Linear beam, which mutually splices in said first direction and exists between adjacent linear beam, to be overlapped, to form a spoke Firing angle is the linear beam of N × α, and wherein N is odd number, wherein the first order optical element and the second level optical element It is binary optical elements and is incorporated to a binary optical elements.

6. a kind of laser distance measurement method, comprising:

Linear laser projective techniques according to claim 5 project linear laser to detected space；

The linear laser reflected by barrier in the detected space is imaged；And

It is obtained according to the spatial relation between the device of the device and imaging of the result of above-mentioned imaging and projection linear laser Take the depth distance of barrier in the detected space.