A laser detection system for observing particulate matter or defects in a transparent sample

Abstract

The application relates to a laser detection system for observing transparent sample particles or defects, and belongs to the technical field of laser measuring instruments. The application is characterized in that a special structure light collecting lens is arranged between an excitation light source and a light collimation system, the sample is arranged between the excitation light source and the S2 surface of the light collecting lens, the refraction light generated by the excitation of the particles or defects on the sample by the excitation light source is collected by the light collecting lens with the special structure, the refraction light is reflected four times in the light collecting lens and then is emitted and converged, and the light collimation system is arranged to capture the light, so that the overall optical path system length is effectively shortened, the problems of large equipment volume and complex structure are solved, and large numerical aperture light energy collection can be realized.

Description

Technical Field

[0001] This invention relates to a laser detection system for observing particulate matter or defects in transparent samples, belonging to the field of laser measurement instrument technology. Background Technology

[0002] When a tiny object (such as sample particles or defects on a sample surface) is illuminated, its scattered light is emitted in all directions. The smaller the object, the lower the scattered energy, and the wider the scattering energy distribution angle; this is referred to as wide-channel scattered light. For a scattered light collection system, it is necessary to collect as much wide-channel scattered light as possible to acquire sufficient scattered signals from tiny objects in order to measure and identify the characteristics of the tiny objects or other information of interest.

[0003] In existing technologies, light energy harvesting devices with a large light-gathering range (i.e., large numerical aperture NA) are often used to collect scattered light energy, such as CN119804392A and CN110426326A. These devices use ellipsoidal reflectors to collect light energy. However, the amount of light energy collected by an ellipsoidal reflector is closely related to the distance between the two focal points of the ellipsoid. The longer the distance, the larger the angle that can be collected. Such a design inevitably results in a large structural size, making the equipment structure complex and unfavorable for equipment installation, debugging, stability, and cost control.

[0004] In addition, for example, CN118732248A and CN119620341A use two folded optical paths to shorten the overall length, and the reflex mirror assembly used to collect light energy consists of three separate optical elements, which also makes the equipment structure more complicated, which is not conducive to the installation, debugging, stability and cost control of the equipment.

[0005] Therefore, in order to address the above problems, there is an urgent need to find a laser measurement and detection device that can collect as much excitation light energy as possible while simplifying the size and structure of the device. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a laser detection system for observing particulate matter or defects in transparent samples. This laser detection system, constructed with a single lens structure, can achieve large numerical aperture light energy collection and significantly shorten the overall length of the optical system, resulting in a simple, compact, and reliable structure.

[0007] This invention provides a laser detection system for observing particulate matter or defects in transparent samples, comprising:

[0008] Excitation light source, capable of emitting an excitation beam;

[0009] A light collimation system having positive optical power and positioned on the path of the excitation beam;

[0010] The light-collecting lens has two optical surfaces arranged opposite to each other, namely surface S1 and surface S2; surface S1 has curvature and a first light-transmitting hole at the center, and the first light-transmitting hole is coated with a reflective film; surface S2 is flat and a second light-transmitting hole at the center, and the second light-transmitting hole is also coated with a reflective film.

[0011] The sample is placed on the side of the S2 surface of the light-collecting lens. When the sample is irradiated by the excitation beam, the particles or defects on the sample are excited to generate scattered light. The scattered light can enter the light-collecting lens through the second light-transmitting hole and is reflected four times between the two optical surfaces of the light-collecting lens before exiting from the first light-transmitting hole. The outgoing light rays will converge at a convergence point on the outer optical axis of the light-collecting lens, and the convergence point coincides with the focal point of the light collimation system. After passing through the light collimation system, the outgoing light rays will be emitted as parallel light rays.

[0012] Furthermore, a reflector with an inclination angle of 45 degrees is provided between the light-collecting lens and the light collimation system, and a light-blocking element is provided on one side of the emitted light. The reflector can convert the excess excitation beam after passing through the light-collecting lens into a vertical beam and direct it to the light-blocking element for collection.

[0013] Furthermore, the relationship between the diameter D1 of the first light-transmitting hole and the diameter D2 of the second light-transmitting hole is 0.8≤D1 / D2≤1.2.

[0014] Furthermore, the diameter D3 of the light-collecting lens is related to the diameter D1 of the first light-transmitting hole and the diameter D2 of the second light-transmitting hole in the following relationship: D1 / D3≤1 / 3, D2 / D3≤1 / 3.

[0015] Furthermore, the scattered light can enter the light-receiving lens through the second light-transmitting hole at a scattering angle of α to β, wherein the minimum scattering angle α = 5° and the maximum scattering angle β = 64°.

[0016] Furthermore, the scattered light undergoes sequential reflections of r1, r2, r3, and r4 on surfaces S1 and S2 within the light-receiving lens, with r1 and r3 on surface S1 and r2 and r4 on surface S2. In other words, the scattered light is reflected four times within the light-receiving lens before exiting through the first light-transmitting hole.

[0017] Furthermore, in the four reflections of the light-receiving lens entering from the S2 surface with the minimum scattering angle α, the distance L2 from the fourth reflection point r4b to the optical axis O of the light-receiving lens is greater than 0.5*D2.

[0018] Furthermore, when the light enters the receiving lens from the S2 surface at the maximum scattering angle β, the distance L1 between the transmission position from the S1 surface after the fourth reflection and the optical axis O of the receiving lens is less than 0.5*D1.

[0019] Furthermore, the emitted rays will converge at a point F1 on the outer optical axis of the receiving lens.

[0020] The beneficial effects of this invention are:

[0021] This invention utilizes a specially structured light-collecting lens placed between the excitation source and the light collimation system. The sample is placed between the S2 plane of the excitation source and the light-collecting lens. The excitation source excites particles or defects on the sample, generating refracted light. The refracted light is reflected four times within the light-collecting lens and then converged. The light collimation system captures the refracted light, thereby effectively shortening the overall optical path length. This solves the problems of large device size and complex structure, while also enabling large numerical aperture light energy collection. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure in one embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the light-collecting lens in one embodiment of the present invention.

[0024] Figure 3 This is a dot matrix diagram of light rays converged by a light-collecting lens in one embodiment of the present invention.

[0025] In the figure, 1 is the excitation source; 2 is the light-collecting lens; 3 is the light collimation system; 4 is the mirror; 5 is the sample; and 6 is the light-blocking element. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] In this invention, the terms "first" and "second" are used only to distinguish similar components / parts in different positions or with different characteristics, and have no other limiting meaning; "upper" refers to the direction in which each component is away from the ground, and "lower" refers to the direction in which each component is away from the ground.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] This invention proposes a laser detection system for observing particulate matter or defects in transparent samples. The laser detection system, constructed with a single lens structure, can achieve large numerical aperture light energy collection and significantly shorten the overall length of the optical system, resulting in a simple, compact, and reliable structure.

[0031] This invention provides a laser detection system for observing particulate matter or defects in transparent samples, such as... Figure 1 As shown, the array includes, from left to right, an excitation light source 1, a sample 5, a light-collecting lens 2, a reflector 4, and a light collimation system 3. Among these:

[0032] Excitation source 1 is a light source assembly capable of emitting an excitation beam, which is emitted horizontally from left to right;

[0033] The light collimation system 3 has positive optical power and is positioned on the path of the excitation beam. It can collect and converge light from the left end and emit parallel light from the right end to achieve the light collimation effect, so as to facilitate the subsequent processing and analysis of the collected signal using various optical elements.

[0034] like Figure 2 As shown, the light-collecting lens 2 has two opposing optical surfaces, namely surface S1 and surface S2. Surface S1 has curvature (aspherical) and a first light-transmitting hole at its center, with a reflective film coated on the outside. Surface S2 is planar and has a second light-transmitting hole at its center, also coated with a reflective film. Preferably, the diameter of the first light-transmitting hole is D1 = 10 mm, and the diameter of the second light-transmitting hole is D2 = 11 mm. The light-collecting lens has a diameter D3 = 42 mm, a thickness of 17.723 mm, and a working wavelength of 0.266 μm.

[0035] The specific parameters of the light-collecting lens 2 are shown in Table 1:

[0036] Table 1

[0037]

[0038] The sample is placed on the side of the light-collecting lens 2 where the S2 surface is located. If there is a small object (particle or defect) at the light spot, the sample is irradiated by the excitation beam, which excites the particles or defects on the sample to generate scattered light. The scattered light can enter the light-collecting lens 2 through the second light-transmitting hole and is reflected four times between the two optical surfaces of the light-collecting lens before exiting through the first light-transmitting hole. The outgoing light rays will converge at a convergence point on the outer optical axis of the light-collecting lens 2, and the convergence point coincides with the focal point of the light collimation system 3. After passing through the light collimation system 3, the outgoing light rays will be emitted as parallel light rays. Furthermore, the scattered light can enter the collecting lens through the second aperture at scattering angles of α to β, where the minimum scattering angle α = 30° and the maximum scattering angle β = 64°. Light rays between α and β are collected by the collecting lens 2. After refraction from the collecting lens 2, the outgoing light rays converge at a converging point F1 on the outer optical axis of the collecting lens. The RMS radius of the converging spot is 0.112, close to the diffraction limit, resulting in good focusing effect. Figure 3 As shown.

[0039] Preferably, further, in the four reflections of the light-receiving lens 2 entering from the S2 surface with the minimum scattering angle α, the distance L2 = 6.3 mm from the fourth reflection point r4b to the optical axis O of the light-receiving lens. When entering the light-receiving lens from the S2 surface with the maximum scattering angle β, the distance L1 = 6 mm from the transmission position from the S1 surface after the fourth reflection to the optical axis O of the light-receiving lens.

[0040] Furthermore, in order to prevent the excitation light from entering the light collimation system, a reflector 4 with an inclination angle of 45 degrees is provided in the area between the light-collecting lens and the light collimation system where no light is collected. The reflector 4 can reflect the excess laser emitted from the light-collecting lens 2 on the left side downward in a direction perpendicular to the optical axis. A light-blocking element 6 is provided below the side of the emitted light and away from the optical axis. The reflected excess laser can be collected by the light-blocking element 6, thereby avoiding interference with the detection signal.

[0041] Furthermore, the scattered light undergoes sequential reflections of r1, r2, r3, and r4 on surfaces S1 and S2 within the light-receiving lens 2, with r1 and r3 on surface S1 and r2 and r4 on surface S2. This means that the scattered light is reflected four times within the light-receiving lens 2 before exiting through the first light-transmitting hole. This is equivalent to the scattered light being reflected four times between surfaces S1 and S2 of the light-receiving lens 2, effectively shortening the overall optical path system length.

[0042] This invention relates to a method for detecting and measuring sample defects using lasers:

[0043] Step 1: Place the surface of the transparent sample 5 to be tested at the focal point on one side of the light-collecting lens 2, and use the excitation light source 1 to emit a laser and focus it on the surface of the sample to be tested;

[0044] Step 2: Move sample 5 along a certain path. For example, for a circular sample, move it outward in a spiral shape starting from the center of the sample, or for a square sample, move it along an "arch" path.

[0045] Step 3: During the movement, if there are particles or defects on the sample surface, the incident laser will be scattered. The smaller the size of the particles or defects, the wider the angle of the scattered light energy distribution. This scattered light energy enters the light-collecting lens with a large numerical aperture through the second light-transmitting hole and is collected into the lens. After four reflections between the S1 and S2 surfaces in front of and behind the lens, it is transmitted out of the light-collecting lens 2 through the first light-transmitting hole and converges at a convergence point F1 on the outer optical axis of the light-collecting lens.

[0046] Step 4: After passing through point F1, the light rays enter the collimation system 3 and will exit in a collimated state;

[0047] Step 5: The beam collimated by the collimation system 3 is parallel light, providing ample space for various optical devices and processing. For example, filters can be used to obtain wavelengths of interest, and polarizers can be used to obtain polarized light of interest. Finally, these rays are incident on a photoelectric conversion device and converted into electrical signals. The presence, strength, corresponding wavelength, and occurrence time of the electrical signals characterize the presence, size, composition, and location of particles, thus enabling the detection of particles or defects using laser technology.

[0048] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A laser detection system for observing particulate matter or defects in transparent samples, characterized in that, include: Excitation light source, capable of emitting an excitation beam; A light collimation system having positive optical power and positioned on the path of the excitation beam; The light-collecting lens has two optical surfaces arranged opposite to each other, namely surface S1 and surface S2; surface S1 has curvature and a first light-transmitting hole at the center, and the first light-transmitting hole is coated with a reflective film; surface S2 is flat and a second light-transmitting hole at the center, and the second light-transmitting hole is also coated with a reflective film. The sample is placed on the side of the S2 surface of the light-collecting lens. When the sample is irradiated by the excitation beam, the particles or defects on the sample are excited to generate scattered light. The scattered light can enter the light-collecting lens through the second light-transmitting hole and undergo four reflections between the two optical surfaces of the light-collecting lens before exiting from the first light-transmitting hole. The outgoing light rays will converge at a convergence point on the outer optical axis of the light-collecting lens, and the convergence point coincides with the focal point of the light collimation system. After passing through the light collimation system, the outgoing light rays will be emitted as parallel rays.

2. The laser detection system according to claim 1, characterized in that, A reflector with an inclination angle of 45 degrees is provided between the light-collecting lens and the light collimation system. A light-blocking element is provided on one side of the emitted light. The reflector can convert the excess excitation beam after passing through the light-collecting lens into a vertical beam and direct it to the light-blocking element for collection.

3. The laser detection system according to claim 2, characterized in that, The relationship between the diameter D1 of the first light-transmitting hole and the diameter D2 of the second light-transmitting hole is 0.8≤D1 / D2≤1.

2.

4. The laser detection system according to claim 3, characterized in that, The diameter D3 of the light-collecting lens is related to the diameter D1 of the first light-transmitting hole and the diameter D2 of the second light-transmitting hole in the following relationship: D1 / D3≤1 / 3, D2 / D3≤1 / 3.

5. The laser detection system according to claim 4, characterized in that, The scattered light can enter the light-receiving lens through the second light-transmitting hole at a scattering angle of α to β, wherein the minimum scattering angle α = 5° and the maximum scattering angle β = 64°.

6. The laser detection system according to claim 5, characterized in that, The scattered light undergoes sequential reflections of r1, r2, r3, and r4 on surfaces S1 and S2 within the light-receiving lens, with r1 and r3 on surface S1 and r2 and r4 on surface S2. In other words, the scattered light is reflected four times within the light-receiving lens before exiting through the first light-transmitting hole.

7. The laser detection system according to claim 6, characterized in that, In the four reflections of the light-collecting lens entering the light-collecting lens from the S2 surface with the minimum scattering angle α, the distance L2 from the fourth reflection point r4b to the optical axis O of the light-collecting lens is greater than 0.5*D2.

8. The laser detection system according to claim 6, characterized in that, When the light enters the receiving lens from the S2 surface at the maximum scattering angle β, the distance L1 from the transmission position from the S1 surface after the fourth reflection to the optical axis O of the receiving lens is less than 0.5*D1.

9. The laser detection system according to claim 6, characterized in that, The outgoing light rays converge at a point F1 on the outer optical axis of the receiving lens.

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