Laser lighting device and laser lighting imaging system

Abstract

The invention discloses a laser lighting device and a laser lighting imaging system, and relates to the technical field of laser lighting, the laser lighting device comprises a laser light source, a spatial filtering module, a beam expanding module, a light beam homogenizing module, a decoherence module, a lighting lens, a spectroscope and a microscope objective, and the focus of the lighting lens coincides with the focus of the microscope objective; a laser beam emitted by the light source is filtered by the spatial filtering module, is sequentially expanded by the beam expanding module and homogenized by the beam homogenizing module, then enters the decoherence module, is subjected to phase modulation by the decoherence module, is emitted to the illumination lens, and is focused on a focus of the microscope objective through the illumination lens to obtain parallel uniform light for illumination. A high-order mode in laser is removed through the spatial filtering module to obtain a fundamental mode Gaussian beam, the beam expanding module expands the beam and further improves the collimation of the laser, the beam homogenizing module uniformly distributes the light intensity, and the decoherence module removes interference stray light and speckle noise to obtain parallel uniform light.

Description

Technical Field

[0001] The present invention relates to the field of laser lighting technology, and in particular to a laser lighting device and a laser lighting imaging system. Background Art

[0002] Laser illumination is a unique illumination method. Compared with traditional tungsten lamps or LED lamps, lasers have high peak light output power and power density, and can provide higher illumination brightness. In addition, the high monochromaticity and high collimation of lasers can improve the resolution of detection microscopes and provide higher-precision imaging detection. Compared with other illumination methods, coaxial illumination integrates the entire illumination light path into an optical detection system with a telecentric lens. Its illumination directionality is stronger, and the main illumination light is almost parallel to the optical axis, which can provide more uniform illumination than traditional illumination methods, thereby improving the signal-to-noise ratio of the detection image and improving the imaging quality.

[0003] Currently, due to the Gaussian distribution profile of the laser light intensity, directly coupling the laser output into the microscope objective lens will make the brightness distribution of the laser illumination field show the characteristics of strong light intensity in the middle and weak light intensity at the edge, thus failing to provide a highly uniform illumination beam, resulting in poor illumination effect and affecting the final imaging quality. In addition, the high coherence of the laser will also bring interference stray light and speckle noise, affecting the illumination effect and further reducing the imaging quality. Summary of the invention

[0004] The main purpose of the present invention is to provide a laser lighting device and a laser lighting imaging system, aiming to solve the technical problem of poor lighting effect of existing laser lighting.

[0005] To achieve the above-mentioned purpose, the present invention provides a laser lighting device, comprising a laser light source, a spatial filtering module, a beam expansion module, a beam homogenization module, a decoherence module, an illumination lens and a beam splitter, which are sequentially arranged along a first direction and on the same optical axis. The laser lighting device also comprises a microscope objective lens, wherein the beam splitter and the microscope objective lens are arranged at intervals along a second direction, wherein the first direction and the second direction are perpendicular to each other, and the focus of the illumination lens coincides with the focus of the microscope objective lens;

[0006] The laser beam emitted by the light source is filtered by the spatial filtering module, and then expanded by the beam expansion module and homogenized by the beam homogenization module. The obtained beam with uniform light intensity is emitted into the decoherence module, and then emitted toward the illumination lens after phase modulation by the decoherence module. Then, it is reflected by the illumination lens and the beam splitter and focused to the focus of the microscope objective lens, so as to illuminate the object surface through the microscope objective lens.

[0007] In one embodiment, the spatial filtering module includes a first lens, a second lens and a filter, wherein the first lens and the second lens are combined to form a 4f system, and the filter is arranged at a focal position of the 4f system.

[0008] In one embodiment, the filter is a pinhole aperture.

[0009] In one embodiment, the focal length of the second lens is greater than or equal to the focal length of the first lens.

[0010] In one embodiment, the focal length of the first lens is in a range of 20 mm to 40 mm, and the focal length of the second lens is in a range of 30 mm to 50 mm.

[0011] In one embodiment, the beam expansion module is a Galilean beam expander, and the Galilean beam expander includes a negative lens and a positive lens, and the focus of the negative lens coincides with the focus of the positive lens.

[0012] In one embodiment, the focal length of the negative lens ranges from -15 mm to -30 mm, and the focal length of the positive lens ranges from 60 mm to 70 mm.

[0013] In one embodiment, the beam homogenization module includes two aspheric lenses arranged on the same optical axis.

[0014] In one embodiment, the decoherence module is a random phase plate, and the random phase plate is driven by a driving member to rotate around a central axis of the random phase plate.

[0015] The present invention also proposes a laser illumination imaging system, comprising a tube lens and the above-mentioned laser illumination device, wherein the tube lens, the beam splitter and the objective lens are arranged in sequence along the second direction at intervals, and the light beam reflected by the object surface illuminated by the microscope passes through the objective lens, the beam splitter and the tube lens in sequence to obtain an image.

[0016] The technical solution of the present invention optimizes the laser beam step by step by adopting a spatial filtering module, a beam expansion module, a beam homogenization module, and a decoherence module. Specifically, after the light source passes through the spatial filtering module, some specific frequency components in the laser beam and the high-order modes of the laser are filtered out, thereby obtaining a fundamental mode Gaussian beam output to improve the lighting effect. The beam is then expanded by the beam expansion module to further improve the collimation of the laser. After beam expansion, the laser beam is shaped into a beam with uniform light intensity distribution by the beam homogenization module. The decoherence module is then used to phase modulate the beam to remove interference stray light and speckle noise, thereby obtaining a high-quality and uniform light intensity illumination beam to improve the lighting effect. The illumination beam is then directed to the microscope objective lens through an illumination lens and a beam splitter for illumination to improve the final imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of an embodiment of a laser illumination imaging system provided by the present invention;

[0019] Figure 2 An aspheric sag diagram of an aspheric lens in an embodiment of a laser lighting device provided by the present invention.

[0020] Description of Figure Numbers:

[0021] 100. Laser illumination device; 1. first lens; 2. pinhole aperture; 3. second lens; 4. negative lens; 5. positive lens; 6. first aspheric lens; 7. second aspheric lens; 8. random phase plate; 9. illumination lens; 10. beam splitter; 11. microscope objective lens; 12. object plane;

[0022] 200. Laser illumination imaging system; 13. Tube lens; 14. Image plane.

[0023] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0026] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] Laser illumination is a unique illumination method. Compared with traditional tungsten lamps or LED lamps, lasers have high peak light output power and power density, and can provide higher illumination brightness. In addition, the high monochromaticity and high collimation of lasers can improve the resolution of detection microscopes and provide higher-precision imaging detection. Compared with other illumination methods, coaxial illumination integrates the entire illumination light path into an optical detection system with a telecentric lens. Its illumination directionality is stronger, and the main illumination light is almost parallel to the optical axis, which can provide more uniform illumination than traditional illumination methods, thereby improving the signal-to-noise ratio of the detection image and improving the imaging quality.

[0028] Currently, due to the Gaussian distribution profile of the laser light intensity, directly coupling the laser output into the microscope objective will make the brightness distribution of the laser illumination field show the characteristics of strong light intensity in the middle and weak light intensity at the edge, thus failing to provide highly uniform illumination and affecting the final imaging quality. In addition, the high coherence of the laser will also bring interference stray light and speckle noise, further reducing the imaging quality of the microscope objective.

[0029] The present invention provides a laser lighting device 100 .

[0030] See also Figure 1In one embodiment of the present invention, the laser lighting device 100 includes a laser light source, a spatial filtering module, a beam expansion module, a beam homogenization module, a decoherence module, an illumination lens 9 and a beam splitter 10 which are sequentially arranged along a first direction and on the same optical axis. The laser lighting device 100 also includes a microscope objective lens 11. The beam splitter 10 and the microscope objective lens 11 are spaced apart along a second direction, wherein the first direction and the second direction are perpendicular to each other, and the focus of the illumination lens 9 coincides with the focus of the microscope objective lens 11. The laser beam emitted by the light source is filtered by the spatial filtering module, and then sequentially expanded by the beam expansion module and homogenized by the beam homogenization module to obtain a beam with uniform light intensity, which is then emitted into the decoherence module, and then phase-modulated by the decoherence module to be emitted to the illumination lens 9, and then reflected by the illumination lens 9 and the beam splitter 10 to be focused on the focus of the microscope objective lens 11, so as to illuminate the object surface 12 through the microscope objective lens 11.

[0031] The technical solution of the present invention optimizes the laser beam step by step by adopting a spatial filtering module, a beam expansion module, a beam homogenization module, and a decoherence module. Specifically, after the light source passes through the spatial filtering module, some specific frequency components in the laser beam and the high-order modes of the laser are filtered out, thereby obtaining a fundamental mode Gaussian beam output to improve the lighting effect. The beam is then expanded by the beam expansion module to further improve the collimation of the laser. After beam expansion, the laser beam is shaped into a beam with uniform light intensity distribution by the beam homogenization module. The decoherence module is then used to phase modulate the beam to remove interference stray light and speckle noise, thereby obtaining a high-quality and uniform light intensity illumination beam to improve the lighting effect. The illumination beam is then directed to the microscope objective 11 through the illumination lens 9 and the beam splitter 10 for illumination to improve the final imaging quality.

[0032] It should be noted that, in this embodiment, the light source emits a laser beam in the ultraviolet band, wherein the light source, the spatial filtering module, the beam expansion module, the beam homogenization module, and the decoherence module are arranged on the same optical axis to achieve laser coaxial illumination, and then the illumination lens 9 and the beam splitter 10 are used to integrate the light source into the microscope objective 11 for optical imaging.

[0033] The first direction is Figure 1 The front-to-back direction in the second direction is Figure 1 In the up and down directions, the focus of the illumination lens 9 coincides with the front focus of the microscope objective lens 11.

[0034] In one embodiment, the spatial filtering module includes a first lens 1, a second lens 3 and a filter, wherein the first lens 1 and the second lens 3 are combined to form a 4f system, and the filter is disposed at a focal position of the 4f system.

[0035] It can be understood that the focal lengths of the first lens 1 and the second lens 3 are f1 and f2 respectively, and the placement distance between the first lens 1 and the second lens 3 is f1+f2, thereby forming a 4f system, wherein the laser beam first passes through the first lens 1 for a first Fourier transform to form a spectrum diagram at the rear focal plane of the first lens 1, and the filter is placed at the position of the spectrum diagram, that is, the focal position of the first lens 1, to selectively block certain frequency components, and then the second lens 3 performs a second Fourier transform on the light field passing through the filter, thereby obtaining a fundamental mode Gaussian beam with the laser high-order mode removed.

[0036] In one embodiment, the filter is a pinhole aperture 2 .

[0037] It can be understood that the use of the pinhole aperture 2 can effectively reduce the high-order modes of the laser, and the principle of the pinhole aperture 2 to achieve spatial filtering is pinhole imaging, which is simple in principle and does not require complex optical elements, and can effectively reduce costs and structural complexity.

[0038] Specifically, in the present embodiment, the aperture of the pinhole aperture 2 is 40 μm; it can be understood that the 40 μm pinhole can help reduce the high-order modes in the laser beam in the ultraviolet band and improve the quality and purity of the beam, and for the ultraviolet band, the aperture of 40 μm is relatively large, and the diffraction effect caused by it is smaller, which means that compared with visible light or infrared light, the diffraction effect produced by the 40 μm pinhole in the ultraviolet band is more controllable, thereby having less impact on the shape and intensity distribution of the beam.

[0039] In one embodiment, the focal length of the second lens 3 is greater than or equal to the focal length of the first lens 1 .

[0040] It can be understood that when the focal length of the second lens 3 is equal to the focal length of the first lens 1, the spatial filtering module is only used to perform spatial filtering on the laser beam, and by adjusting the focal length of the second lens 3 to be larger than the focal length of the first lens 1, the spatial filtering module can have a certain beam expansion effect on the laser beam.

[0041] In one embodiment, the focal length of the first lens 1 is in a range of 20 mm to 40 mm, and the focal length of the second lens 3 is in a range of 30 mm to 50 mm.

[0042] It can be understood that the focal length range of the first lens 1 is 20 mm to 40 mm, which is a moderate focal length. This focal length can provide better resolution on the Fourier transform plane, so as to more accurately select and filter out specific spatial frequency components, thereby facilitating the acquisition of a better quality light beam, and the focal length range of the second lens 3 is slightly larger than that of the first lens 1, so as to facilitate a primary beam expansion process of the laser beam; and the small focal lengths of the first lens 1 and the second lens 3 are conducive to layout and reduce occupied space.

[0043] In one embodiment, the beam expansion module is a Galilean beam expander, which includes a negative lens 4 and a positive lens 5 , and the focus of the negative lens 4 coincides with the focus of the positive lens 5 .

[0044] It can be understood that the beam expansion module can improve the collimation of the light beam and expand the light beam to the target size. In the present embodiment, a Galileo beam expander is used for beam expansion, which is mainly composed of a negative lens 4 (i.e., a concave lens) with a negative focal length and a positive lens 5 (i.e., a convex lens) with a positive focal length. The laser beam first passes through the negative lens 4 to form a divergent light beam, and then passes through the positive lens 5 to focus the divergent light beam into a larger light beam. In addition, the Galileo beam expander has a simple structure, low cost, and is easy to arrange.

[0045] In other embodiments, the beam expansion module can also use a Kepler beam expander, which is composed of two convex lenses with positive focal lengths. The light beam first passes through the first convex lens to form an intermediate image on its rear focal plane; then it passes through the second convex lens to magnify the intermediate image into a larger light beam; the Kepler beam expander has a higher magnification and smaller aberration.

[0046] In one embodiment, the focal length of the negative lens 4 ranges from -15 mm to -30 mm, and the focal length of the positive lens 5 ranges from 60 mm to 70 mm.

[0047] It can be understood that, through the above focal length range, the Galilean beam expander can achieve a magnification of 2 to 4.67 times, and within this range, the divergence angle of the light beam can be limitedly reduced to improve the collimation of the light beam. According to actual needs, a Galilean beam expander with a corresponding magnification is selected.

[0048] In one embodiment, the beam homogenization module includes two aspheric lenses arranged on the same optical axis.

[0049] It can be understood that an aspheric lens is a lens whose surface profile does not completely follow the spherical geometry; by changing the curvature, an aspheric lens allows light at different positions to be focused on the same plane, thereby reducing spherical aberration, and, through a specifically designed aspheric shape, the light beam can be distributed more evenly in a specific area.

[0050] like Figure 2 As shown, the sagittal height distribution of the two aspheric lenses in this embodiment is shown. The two aspheric lenses are respectively a first aspheric lens 6 and a second aspheric lens 7. The first aspheric lens 6 and the second aspheric lens 7 are used to stretch the central light of the laser beam with a larger intensity to both sides, and compress the edge light of the laser beam with a smaller intensity toward the middle, thereby obtaining a light beam with uniform intensity distribution.

[0051] In one embodiment, the decoherence module is a random phase plate 8, and the random phase plate 8 is driven by a driving member to rotate around the central axis of the phase plate.

[0052] It can be understood that each pixel on the random phase plate 8 realizes random phase modulation of 0 or π. Since the surface of the random phase plate 8 is a random phase delay, the coherence between the light waves is destroyed when the light beam passes through, thereby suppressing the interference light and speckle effect. In specific applications, the random phase plate 8 is driven in a rotating state by a driving member to achieve the above effect.

[0053] Specifically, during the actual arrangement process, a servo motor may be used to drive the random phase plate 8 to rotate.

[0054] The present invention also proposes a laser illumination imaging system 200, which includes a tube lens 13 and the above-mentioned laser illumination device 100. The specific structure of the laser illumination imaging system 200 refers to the above-mentioned embodiment. Since the laser illumination imaging system 200 adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0055] Among them, the laser lighting device 100 is used to irradiate a laser beam to the object plane 12 to illuminate the object plane 12, and the tube lens 13, the beam splitter 10 and the objective lens are arranged in sequence along the second direction. The light beam reflected by the object plane 12 illuminated by the microscope passes through the objective lens, the beam splitter 10 and the tube lens 13 in sequence to obtain an image.

[0056] It should be noted that the microscope objective lens 11 and the object plane 12 are placed in parallel, so as to illuminate the object plane 12 with parallel light and facilitate subsequent imaging on the image plane 14 through the tube lens 13 .

[0057] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A laser lighting device, characterized in that: The laser illumination device comprises a laser light source, a spatial filtering module, a beam expansion module, a beam homogenization module, a decoherence module, an illumination lens and a beam splitter which are sequentially arranged along a first direction and on the same optical axis. The laser illumination device also comprises a microscope objective lens. The beam splitter and the microscope objective lens are arranged at intervals along a second direction. The first direction and the second direction are perpendicular to each other, and the focus of the illumination lens coincides with the focus of the microscope objective lens. The laser beam emitted by the light source is filtered by the spatial filtering module, and then expanded by the beam expansion module and homogenized by the beam homogenization module. The obtained beam with uniform light intensity is emitted into the decoherence module, and then emitted toward the illumination lens after phase modulation by the decoherence module. Then, it is reflected by the illumination lens and the beam splitter and focused to the focus of the microscope objective lens, so as to illuminate the object surface through the microscope objective lens.

2. The laser lighting device according to claim 1, characterized in that: The spatial filtering module includes a first lens, a second lens and a filter, wherein the first lens and the second lens are combined to form a 4f system, and the filter is arranged at a focal position of the 4f system.

3. The laser lighting device according to claim 1, characterized in that: The filter is a pinhole aperture.

4. The laser lighting device according to claim 1, characterized in that: The focal length of the second lens is greater than or equal to the focal length of the first lens.

5. The laser lighting device according to claim 4, characterized in that: The focal length of the first lens ranges from 20 mm to 40 mm, and the focal length of the second lens ranges from 30 mm to 50 mm.

6. The laser lighting device according to any one of claims 1 to 5, characterized in that: The beam expansion module is a Galilean beam expander, which includes a negative lens and a positive lens, and the focus of the negative lens coincides with the focus of the positive lens.

7. The laser lighting device according to claim 6, characterized in that: The focal length of the negative lens ranges from -15 mm to -30 mm, and the focal length of the positive lens ranges from 60 mm to 70 mm.

8. The laser lighting device according to any one of claims 1 to 5, characterized in that: The beam homogenization module comprises two aspheric lenses arranged on the same optical axis.

9. The laser lighting device according to any one of claims 1 to 5, characterized in that: The decoherence module is a random phase plate, and the random phase plate is driven by a driving member to rotate around the central axis of the random phase plate.

10. A laser illumination imaging system, characterized in that: It comprises a tube lens and the laser lighting device as described in any one of claims 1 to 9, wherein the tube lens, the beam splitter and the objective lens are arranged in sequence along the second direction at intervals, and the light beam reflected by the object surface illuminated by the microscope passes through the objective lens, the beam splitter and the tube lens in sequence to obtain an image.

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