Structured light laser with built-in diffraction lens

Abstract

A structured light laser device with a built-in diffraction lens comprises a pump light source, a laser gain medium, a pump light plane reflector, a plane total reflector, a concave partial reflector, an optical resonant cavity, a diffraction lens and a focusing lens. The laser of the invention causes the laser light beam oscillating in the resonant cavity to undergo coherent superposition through the diffraction effect of the diffraction lens on the light beam, so that the concave partial reflector can output laser light beams with different transverse structures, thereby realizing the adjustment of the laser output mode. The invention can improve the stability of the structured light laser output mode, can improve the adjustment range of the structured light laser output mode, and can reduce the complexity of the structured light laser optical system.

Description

Technical Field

[0001] The invention relates to a diffraction device, in particular to a structured light laser device with a built-in diffraction lens. Background Art

[0002] The resonant cavity is one of the three main components of a laser. In the simplest case, it can be constructed by appropriately placing two mirrors at both ends of the laser gain medium. The resonant cavity mainly has two functions. The first function is to provide positive feedback so that the radiation generated in the gain medium passes through the medium many times, and the radiation is amplified in the resonant cavity and self-excited oscillation is established. The second function is to select and amplify the mode of the light beam oscillation in the cavity, so that the self-excited oscillation established in the cavity is limited to a few intrinsic modes determined by the cavity. After multiple amplifications of the gain medium, strong coherent light with good monochromaticity and directionality is finally obtained, that is, laser. Therefore, the resonant cavity plays a decisive role in the stability of the output laser and the controllability of the mode.

[0003] Diffraction lenses have similar beam focusing characteristics to refractive lenses, but compared to traditional single-focus refractive lenses, diffraction lenses can produce multiple focal points on the optical axis. At the same time, diffraction lenses have unique advantages such as small size, light weight, low manufacturing cost, high diffraction efficiency, special dispersion performance, more design freedom and a wide range of material options. They have been widely used in many fields such as micro-optical systems, laser focusing, optical coupling, wavefront multiplexing, optical sensors and optical storage. So far, there have been no reports on the application of diffraction lenses in structured light lasers. Therefore, this patent proposes a structured light laser with a built-in diffraction lens. The device can output laser beams of different transverse modes to achieve the adjustment of the output mode of the structured light laser, improve the stability of the output mode of the structured light laser, improve the adjustment range of the output mode of the structured light laser, and reduce the complexity of the optical system of the structured light laser. Summary of the invention

[0004] The present invention provides a structured light laser device with a diffraction lens placed inside to adjust the laser output mode. The device inserts a diffraction lens into an optical resonant cavity, and then uses the diffraction effect of the diffraction lens on the light beam to make the laser light beam oscillating in the resonant cavity coherently superimpose, thereby outputting laser light beams of different transverse modes to adjust the laser output mode. The device can improve the stability of the structured light laser output mode, can improve the adjustment range of the structured light laser output mode, and can reduce the complexity of the structured light laser optical system.

[0005] The technical solution of the present invention is as follows:

[0006] A structured light laser with a built-in diffraction lens is characterized in that it comprises an optical resonant cavity, a pump light source, a pump light plane reflector, a first three-dimensional translation stage, a second three-dimensional translation stage, an imaging detector, a third three-dimensional translation stage and a computer; the optical resonant cavity is composed of a plane total reflector, a diffraction lens, a laser gain medium, a focusing lens and a concave partial reflector placed in sequence on the same optical axis, the plane total reflector is fixed on the first three-dimensional translation stage, the concave partial reflector is fixed on the second three-dimensional translation stage, the imaging detector is fixed on the third three-dimensional translation stage, and the output end of the imaging detector is connected to the input end of the computer;

[0007] The pump light source is vertically incident on the laser gain medium, and the transmitted light transmitted through the laser gain medium is incident on the pump light plane reflector, and is reflected back into the laser gain medium through the pump light plane reflector;

[0008] The laser gain medium is stimulated to emit, generating laser oscillation in the optical resonant cavity, and after the diffraction effect of the diffraction lens causes the oscillating laser beams to be coherently superimposed, the concave partial reflector outputs laser beams of different transverse modes;

[0009] By moving the first three-dimensional translation stage and the second three-dimensional translation stage, the imaging detector detects laser beams with different transverse modes;

[0010] The pump light plane reflector is coated with a total reflection film for the wavelength of the pump light source;

[0011] The light-transmitting surface of the focusing lens is coated with a transmission-enhancing film for the emission wavelength of the laser gain medium;

[0012] The diffraction lens is a zone plate, a photon sieve and other modulation devices with lens function;

[0013] The imaging detector is a CCD camera, a CMOS image sensor and a thermoelectric array camera.

[0014] The technical effects and advantages of the present invention are as follows:

[0015] 1. The present invention has a simple structure, small size, simple operation and low environmental requirements.

[0016] 2. The present invention causes the laser beams oscillating in the resonant cavity to coherently superimpose through the diffraction effect of the diffraction lens on the light beam, so that the laser beams in different transverse modes can be output by the concave partial reflector, thereby achieving the adjustment of the laser output mode.

[0017] 3. The present invention can improve the stability of the output mode of the structured light laser, can improve the adjustment range of the output mode of the structured light laser, and can reduce the complexity of the optical system of the structured light laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the structured light laser device with built-in diffraction lens of the present invention

[0019] Figure 2 Schematic diagram of the photon sieve structure used in the present invention

[0020] Figure 3 The output light field of the present invention is an intensity distribution diagram of 18 "petals"

[0021] Figure 4 Schematic diagram of the zone plate structure used in the present invention

[0022] Figure 5 The output light field of the present invention is an intensity distribution diagram of 18 "petals"

[0023] Figure 6 The output light field of the present invention is a 24-petal intensity distribution diagram DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0025] Please refer to Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of a structured light laser device with a built-in diffraction lens, comprising an optical resonant cavity 7, a pump light source 1, a pump light plane reflector 3, a first three-dimensional translation stage 4, a second three-dimensional translation stage 8, an imaging detector 11, a third three-dimensional translation stage 12 and a computer 13; the optical resonant cavity 7 is composed of a plane total reflection mirror 5, a diffraction lens 9, a laser gain medium 2, a focusing lens 10 and a concave partial reflection mirror 6 which are placed in sequence on the same optical axis, the plane total reflection mirror 5 is fixed on the first three-dimensional translation stage 4, the concave partial reflection mirror 6 is fixed on the second three-dimensional translation stage 8, the imaging detector 11 is fixed on the third three-dimensional translation stage 12, and the output end of the imaging detector 11 is connected to the input end of the computer 13;

[0026] The pump light source 1 is vertically incident on the laser gain medium 2, and the transmitted light transmitted through the laser gain medium 2 is incident on the pump light plane reflector 3, and is reflected back into the laser gain medium 2 through the pump light plane reflector 3;

[0027] The laser gain medium 2 is stimulated to emit, and laser oscillation is generated in the optical resonant cavity 7. After the diffraction effect of the diffraction lens 9 causes the oscillating laser beam to be coherently superimposed, the concave partial reflector 6 outputs laser beams of different transverse modes.

[0028] By moving the first three-dimensional translation stage 4 and the second three-dimensional translation stage 8, the imaging detector 11 detects laser beams with different transverse modes;

[0029] The pump light plane reflector 3 is coated with a total reflection film for the wavelength of the pump light source 1;

[0030] The light-transmitting surface of the focusing lens 10 is coated with a transmission-enhancing film for the emission wavelength of the laser gain medium 2;

[0031] The diffraction lens 9 is a zone plate, a photon sieve or other modulation device having a lens function;

[0032] The imaging detector 11 is a CCD camera, a CMOS image sensor or a pyroelectric array camera.

[0033] The distance between the plane total reflection mirror 5 and the diffraction lens 9, the distance between the diffraction lens 9 and the focusing lens 10, and the distance between the focusing lens 10 and the partial concave reflection mirror 6 need to be determined according to the stability conditions of the laser complex cavity.

[0034] Example 1: Diffractive lens as photon sieve

[0035] The pump light source 1 is a laser diode (abbreviated as LD), the laser gain medium 2 is neodymium-doped yttrium aluminum garnet (Nd:YAG, whose output wavelength is 1.06μm and length is 20mm), the transmittance of the partially concave reflector 6 is 40% and the radius of curvature is 113cm, and the diffraction lens 9 is a 65mm photon sieve (such as Figure 2 As shown in FIG. 1 ), the focal length of the focusing lens 10 is 80 mm, and the imaging detector 11 is a CCD camera with a resolution of 1392*1040. The distance between the diffraction lens 9 and the plane total reflection mirror 5 is 100 mm; the distance between the focusing lens 10 and the concave partial reflection mirror 6 is 100 mm; and the equivalent distance between the diffraction lens 9 and the focusing lens 10 is 80 mm. At this time, the output beam generated by the device is a petal-shaped laser pulse with 18 "petals" (such as Figure 3 As shown), a structured light laser device based on a built-in diffraction lens is specifically implemented: Figure 1As shown, it consists of an LD light source 1, a Nd:YAG laser gain medium 2, a pump light plane reflector 3, a first three-dimensional translation stage 4, a plane total reflector 5, a concave partial reflector 6, an optical resonant cavity 7, a second three-dimensional translation stage 8, a photon sieve 9, a focusing lens 10, a CCD camera 11, a third three-dimensional translation stage 12 and a computer 13.

[0036] The optical resonant cavity 7 is composed of a plane total reflection mirror 5, a photon sieve 9, a Nd:YAG laser gain medium 2, a focusing lens 10 and a concave partial reflection mirror 6 which are placed in sequence on the same optical axis. The plane total reflection mirror 5 is fixed on the first three-dimensional translation stage 4, the concave partial reflection mirror 6 is fixed on the second three-dimensional translation stage 8, the imaging detector 11 is fixed on the third three-dimensional translation stage 12, and the output end of the imaging detector 11 is connected to the input end of the computer 13;

[0037] The pump light source 1 is vertically incident on the Nd:YAG laser gain medium 2, and the transmitted light transmitted through the Nd:YAG laser gain medium 2 is incident on the pump light plane reflector 3, and is reflected back into the Nd:YAG laser gain medium 2 through the pump light plane reflector 3;

[0038] The Nd:YAG laser gain medium 2 is stimulated to emit, and laser oscillation is generated in the optical resonant cavity 7. After the oscillating laser beam is coherently superimposed by the diffraction effect of the photon sieve 9, the concave partial reflector 6 outputs laser beams of different transverse modes.

[0039] The pump light plane reflector 3 is coated with a total reflection film for the wavelength of the pump light source 1;

[0040] The light-transmitting surface of the focusing lens 10 is coated with a transmission-enhancing film for the emission wavelength of the Nd:YAG laser gain medium 2;

[0041] The first three-dimensional translation stage 4 and the second three-dimensional translation stage 8 are moved so that the CCD camera 11 detects a petal-shaped transverse mode laser beam having 18 “petals”.

[0042] Example 2: Diffractive lens is a zone plate

[0043] The pump light source 1 is a laser diode (abbreviated as LD), the laser gain medium 2 is neodymium-doped yttrium aluminum garnet (Nd:YAG, whose output wavelength is 1.06μm and length is 20mm), the partial concave reflector 6 has a transmittance of 40% and a curvature radius of 113cm, and the diffraction lens 9 is a zone plate with a focal length of 52.6mm and 85.1mm (such as Figure 4As shown in FIG. 1 ), the focal length of the focusing lens 10 is 80 mm. The distance between the diffraction lens 9 and the plane total reflection mirror 5 is 100 mm; the distance between the focusing lens 10 and the concave partial reflection mirror 6 is 100 mm; and the equivalent distance between the diffraction lens 9 and the focusing lens 10 is 90 mm. At this time, the output beam generated by the device is a petal-shaped laser pulse with 18 "petals" (such as Figure 5 As shown), a structured light laser device based on a built-in diffraction lens is specifically implemented: Figure 1 As shown, it consists of an LD light source 1, a Nd:YAG laser gain medium 2, a pump light plane reflector 3, a first three-dimensional translation stage 4, a plane total reflector 5, a concave partial reflector 6, an optical resonant cavity 7, a second three-dimensional translation stage 8, a zone plate 9, a focusing lens 10, a CCD camera 11, a third three-dimensional translation stage 12 and a computer 13.

[0044] The optical resonant cavity 7 is composed of a plane total reflection mirror 5, a wave zone plate 9, a Nd:YAG laser gain medium 2, a focusing lens 10 and a concave partial reflection mirror 6 which are placed in sequence on the same optical axis. The plane total reflection mirror 5 is fixed on the first three-dimensional translation stage 4, the concave partial reflection mirror 6 is fixed on the second three-dimensional translation stage 8, and the imaging detector 11 is fixed on the third three-dimensional translation stage 12, and the output end of the imaging detector 11 is connected to the input end of the computer 13;

[0045] The pump light source 1 is vertically incident on the Nd:YAG laser gain medium 2, and the transmitted light transmitted through the Nd:YAG laser gain medium 2 is incident on the pump light plane reflector 3, and is reflected back into the Nd:YAG laser gain medium 2 through the pump light plane reflector 3;

[0046] The Nd:YAG laser gain medium 2 is stimulated to emit, and laser oscillation is generated in the optical resonant cavity 7. After the diffraction effect of the wavelength plate 9 causes the oscillating laser beam to be coherently superimposed, the concave partial reflector 6 outputs laser beams of different transverse modes.

[0047] The pump light plane reflector 3 is coated with a total reflection film for the wavelength of the pump light source 1;

[0048] The light-transmitting surface of the focusing lens 10 is coated with a transmission-enhancing film for the emission wavelength of the Nd:YAG laser gain medium 2;

[0049] Move the first three-dimensional translation stage 4 and the second three-dimensional translation stage 8 so that the CCD camera 11 detects a petal-shaped transverse mode laser beam having 18 “petals”;

[0050] If the effective distance between the zone plate 9 and the focusing lens 10 is adjusted to 120 mm, the output beam at this time is a petal-shaped laser pulse with 24 "petals" (such as Figure 6 shown).

[0051] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific implementation case of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A structured light laser with a built-in diffraction lens, characterized in that: The invention comprises an optical resonant cavity (7), a pump light source (1), a pump light plane reflector (3), a first three-dimensional translation stage (4), a second three-dimensional translation stage (8), an imaging detector (11), a third three-dimensional translation stage (12) and a computer (13); the optical resonant cavity (7) is composed of a plane total reflector (5), a diffraction lens (9), a laser gain medium (2), a focusing lens (10) and a concave partial reflector (6) which are placed in sequence on the same optical axis; the plane total reflector (5) is fixed on the first three-dimensional translation stage (4), the concave partial reflector (6) is fixed on the second three-dimensional translation stage (8), the imaging detector (11) is fixed on the third three-dimensional translation stage (12), and the output end of the imaging detector (11) is connected to the input end of the computer (13); The pump light source (1) is vertically incident on the laser gain medium (2), and the transmitted light transmitted through the laser gain medium (2) is incident on the pump light plane reflector (3), and is reflected back into the laser gain medium (2) by the pump light plane reflector (3); The laser gain medium (2) is stimulated to emit, generating laser oscillation in the optical resonant cavity (7), and after the oscillating laser beams are coherently superimposed by the diffraction effect of the diffraction lens (9), the concave partial reflection mirror (6) outputs laser beams of different transverse modes; By moving the first three-dimensional translation stage (4) and the second three-dimensional translation stage (8), the imaging detector (11) detects laser beams with different transverse modes.

2. The structured light laser with built-in diffraction lens according to claim 1, characterized in that: The pump light plane reflector (3) is plated with a total reflection film for the wavelength of the pump light source (1).

3. The structured light laser with built-in diffraction lens according to claim 1, characterized in that: The light-transmitting surface of the focusing lens (10) is coated with a transmission-enhancing film for the emission wavelength of the laser gain medium (2).

4. The structured light laser with a built-in diffraction lens according to claim 1, characterized in that: The diffraction lens (9) is a zone plate, a photon sieve or other modulation devices having a lens function.

5. The structured light laser with built-in diffraction lens according to claim 1, characterized in that: The imaging detector (11) is a CCD camera, a CMOS image sensor or a thermoelectric array camera.

Images