Efficient light collection system for resonance laser-induced fluorescence technology

Abstract

The invention discloses a high-efficiency light collection system for a resonance laser-induced fluorescence technology, and relates to the technical field of optics, and the system sequentially comprises a concave reflector, a cylindrical fluorescent light source, a first lens, a second lens, a narrow-band filter, a third lens and a fluorescence signal detector along a light path direction. A fluorescent signal on one side of the cylindrical fluorescent light source is reflected by the concave reflecting mirror, and then is received by the fluorescent signal detector after sequentially passing through the first lens, the second lens, the narrow-band optical filter and the third lens; a fluorescence signal on the other side is transmitted through the first lens and the second lens, and is received by the fluorescence signal detector after passing through the narrow-band optical filter and the third lens in sequence. According to the invention, the lens group with a large numerical aperture is used for collecting fluorescence, and the narrow-band optical filter is added for filtering scattered light and stray light, so that the microminiaturization design of the resonance laser-induced fluorescence high-efficiency light collection system is realized. And meanwhile, the concave reflecting mirror is added opposite to the detector, so that the collection efficiency of the fluorescence is improved.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to a high-efficiency light collection system for resonant laser-induced fluorescence technology. Background Technology

[0002] With the development of laser technology, detection technology, and microelectronics technology, resonant laser-induced fluorescence (LARF) technology is progressing towards higher sensitivity, higher accuracy, higher integration, and miniaturization. LARF is a key technology in atmospheric chemistry, combustion processes, and biomedical detection; therefore, achieving accurate and sensitive detection of LARF has significant scientific and applied value. The detection system discriminates and measures fluorescence signals within a specific narrow time frame, and the concentration of LARF is calculated based on the intensity of the received fluorescence signal and a calibration system. Stable excitation and collection of the fluorescence signal are crucial steps in LARF measurement. The fluorescence collection efficiency, which refers to the proportion of fluorescence detected by the photomultiplier tube, depends on the following parameters: Collection efficiency = , It is the solid angle fraction intercepted by the detection device. It is a function of the light collection system. This represents the quantum efficiency of a photomultiplier tube. This represents the total fluorescence count. Although laser-induced fluorescence technology has many advantages, technical bottlenecks still exist in practical applications. For example, the fluorescence signal overlaps with the laser wavelength, and the fluorescence scatters in all directions, making effective collection impossible, leading to loss of useful signal and decreased detection sensitivity. Therefore, to effectively collect weak fluorescence signals, it is necessary to design a corresponding, efficient fluorescence collection system. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a high-efficiency light collection system for resonant laser-induced fluorescence technology, which solves the problems of insufficient interference suppression, low collection efficiency, and decreased detection sensitivity in existing resonant laser-induced fluorescence technology.

[0004] To achieve the above objectives, the present invention adopts the following technical solution, including: A high-efficiency light collection system for resonant laser-induced fluorescence technology includes, in sequence along the optical path: a concave mirror, a cylindrical fluorescence source, a first lens, a second lens, a narrow-band filter, a third lens, and a fluorescence signal detector; The fluorescence signal from one side of the cylindrical fluorescent light source is reflected by a concave mirror, and then passes through a first lens, a second lens, a narrow-band filter, and a third lens in sequence before being received by a fluorescence signal detector; the fluorescence signal from the other side of the cylindrical fluorescent light source is transmitted through a first lens and a second lens, passes through a narrow-band filter, and a third lens in sequence before being received by a fluorescence signal detector.

[0005] Preferably, the first and second lenses are spherical lenses, and the third lens is an aspherical lens.

[0006] Preferably, the first lens is a concave-convex lens with negative optical power, the second lens is a biconvex lens with positive optical power, and the third lens is an aspherical lens with positive optical power.

[0007] Preferably, the concave mirror, the first lens, the second lens, the narrow-band filter, and the third lens are all made of N-BK7 material.

[0008] Preferably, the center wavelength of the narrowband filter corresponds to the fluorescence band and is used to filter out light in the non-fluorescent band.

[0009] Preferably, the first lens and the second lens are used to collimate the fluorescence signal, and the third lens is used to focus the fluorescence signal.

[0010] Preferably, the concave reflector has a radius of curvature of 23 mm, a net aperture of 23 mm, and a refractive index of 1.5168.

[0011] Preferably, the first lens has a radius of curvature of -200mm on the side facing the cylindrical fluorescent light source, a radius of curvature of -46.781mm on the side facing the fluorescent signal detector, a net aperture of 25mm, a thickness of 7.543mm, and a refractive index of 1.5168.

[0012] Preferably, the second lens has a radius of curvature of 120 mm on the side facing the cylindrical fluorescent light source and a radius of curvature of -200 mm on the side facing the fluorescent signal detector, a net aperture of 30 mm, a thickness of 14.4 mm, and a refractive index of 1.5168.

[0013] Preferably, the third lens has a radius of curvature of 31.384 mm, a conic coefficient of -1.911, and a fourth-order aspherical coefficient of 5 × 10⁻⁶. -6 It has a net aperture of 32mm, a thickness of 24mm, and a refractive index of 1.5168.

[0014] The advantages of this invention are: The high-efficiency light-collecting system for resonant laser-induced fluorescence technology of this invention enables efficient collection of fluorescence emitted from all directions. Adding a concave reflector opposite the detector effectively improves the fluorescence collection efficiency. A narrow-band filter with a center wavelength corresponding to the fluorescence band is added behind the second lens to filter out non-fluorescent light, suppressing scattered and stray light and effectively eliminating spectral interference from other molecules. A large numerical aperture collection lens group is arranged perpendicular to the column fluorescence direction to achieve effective collection of fluorescence emitted from all directions. The first and second lenses collimate the fluorescence signal, and the third lens focuses the fluorescence signal. This optical system design reduces stray light interference and efficiently collects fluorescence signals, thereby increasing the system's sensitivity. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the high-efficiency light collection system according to the present invention.

[0016] Figure 2 This is a schematic diagram of the optical path of the high-efficiency light collection system according to the present invention.

[0017] Explanation of reference numerals in the attached figures: E1 - Concave mirror; E2 - Cylindrical fluorescence; E3 - First lens; E4 - Second lens; E5 - Narrow-band filter; E6 - Third lens; E7 - Fluorescence signal detector. Detailed Implementation

[0018] 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 embodiments of the present invention, and not all embodiments. 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.

[0019] Depend on Figure 1 As shown, the present invention provides a high-efficiency light collection system for resonant laser-induced fluorescence technology, which includes, in sequence along the optical path: a concave mirror E1, a cylindrical fluorescence light source E2, a first lens E3, a second lens E4, a narrowband filter E5, a third lens E6, and a fluorescence signal detector E7.

[0020] The concave mirror E1 is located to the left of the cylindrical fluorescent light source E2; the first lens E3, the second lens E4, the narrow-band filter E5, the third lens E6, and the fluorescent signal detector E7 are located to the right of the cylindrical fluorescent light source E2. Figure 2As shown, the fluorescence signal from one side of the cylindrical fluorescence light source E2 is reflected by the concave mirror E1, then sequentially passes through the first lens E3, the second lens E4, the narrowband filter E5, and the third lens E6 before being received by the fluorescence signal detector E7. The fluorescence signal from the other side is transmitted through the first lens E3 and the second lens E4, filtered by the narrowband filter E5, and then received by the fluorescence signal detector E7. The fluorescence signal is collected by the large numerical aperture spherical lens (i.e., the first lens E3 and the second lens E4) and the concave mirror E1, and then reaches the fluorescence signal detector after passing through the narrowband filter E5 and the focusing lens (i.e., the third lens E6).

[0021] Adding a concave mirror E1 opposite the fluorescence signal detector E7 improves fluorescence collection efficiency. Adding a narrowband filter E5 behind the second lens E4, with its center wavelength corresponding to the fluorescence band, filters out light in non-fluorescent bands. The first lens E3 and the second lens E4 collimate the fluorescence signal, while the third lens E6 focuses the fluorescence signal.

[0022] In this embodiment, the first lens E3 and the second lens E4 are spherical lenses, and the third lens E6 is an aspherical lens. The first lens E3 is a concave-convex lens with negative optical power, the second lens E4 is a biconvex lens with positive optical power, and the third lens E6 is an aspherical lens with positive optical power. All three lenses—E3, E4, and E6—are made of N-BK7 material with a refractive index of 1.51680. The fluorescence wavelength is set to 308 nm, which is within the effective range of the dispersion formula for N-BK7 glass.

[0023] In this embodiment, the physical parameters of each component are listed in Table 1 below, and the parameters of the aspherical lens (third lens E6) are listed in Table 2 below.

[0024] Table 1 Physical parameters of each component

[0025] Table 2 Aspherical lens parameters

[0026] The parameters of an aspherical lens satisfy the equation:

[0027] in, z For aspherical sag, c For aspherical paraxial curvature, y For lens diameter, k The conic coefficient, a 4 represents the fourth order aspheric coefficient. a 6 represents the 6th order aspheric coefficient. a 8 represents the 8th order aspheric coefficient. a10 It is the 10th order aspheric coefficient.

[0028] Specifically, the R-values ​​(radius of curvature), thicknesses, and refractive indices of each lens surface in this embodiment are shown in Table 1, and the parameters of the aspherical lens are shown in Table 2. In the tables, R1 represents the radius of curvature on the left side of the lens, and R2 represents the radius of curvature on the right side of the lens.

[0029] In this embodiment, the fluorescence spot and fluorescence power detected by ray tracing are shown in Table 3 below. Since the fluorescence power is set to 0.001w at the emitting end, the calculated collection efficiency is 4.028%.

[0030] Table 3. Fluorescent spots detected by the detector

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency light collection system for resonant laser-induced fluorescence technology, characterized in that, Along the optical path, it includes, in sequence: a concave mirror, a cylindrical fluorescent light source, a first lens, a second lens, a narrowband filter, a third lens, and a fluorescent signal detector; The fluorescence signal from one side of the cylindrical fluorescent light source is reflected by a concave mirror, and then passes through a first lens, a second lens, a narrow-band filter, and a third lens in sequence before being received by a fluorescence signal detector; the fluorescence signal from the other side of the cylindrical fluorescent light source is transmitted through a first lens and a second lens, passes through a narrow-band filter, and a third lens in sequence before being received by a fluorescence signal detector.

2. The high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 1, characterized in that, The first and second lenses are spherical lenses, and the third lens is an aspherical lens.

3. The high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 2, characterized in that, The first lens is a concave-convex lens with negative optical power, the second lens is a biconvex lens with positive optical power, and the third lens is an aspherical lens with positive optical power.

4. The high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 1, characterized in that, The concave mirror, the first lens, the second lens, the narrow-band filter, and the third lens are all made of N-BK7 material.

5. A high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 1, characterized in that, The center wavelength of the narrowband filter corresponds to the fluorescence band and is used to filter out light in the non-fluorescent band.

6. A high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 1, 2, or 3, characterized in that, The first and second lenses are used to collimate the fluorescence signal, and the third lens is used to focus the fluorescence signal.

7. A high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 1, characterized in that, The concave mirror has a radius of curvature of 23 mm, a net aperture of 23 mm, and a refractive index of 1.5168.

8. A high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 2 or 3, characterized in that, The first lens has a radius of curvature of -200mm on the side facing the cylindrical fluorescent light source and a radius of curvature of -46.781mm on the side facing the fluorescent signal detector. It has a net aperture of 25mm, a thickness of 7.543mm, and a refractive index of 1.5168.

9. A high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 2 or 3, characterized in that, The second lens has a radius of curvature of 120 mm on the side facing the cylindrical fluorescent light source and a radius of curvature of -200 mm on the side facing the fluorescent signal detector. It has a net aperture of 30 mm, a thickness of 14.4 mm, and a refractive index of 1.5168.

10. A high-efficiency light collection system for resonant laser-induced fluorescence technology according to claim 2 or 3, characterized in that, The third lens has a radius of curvature of 31.384 mm, a conic coefficient of -1.911, and a fourth-order aspherical coefficient of 5 × 10⁻⁶. -6 It has a net aperture of 32mm, a thickness of 24mm, and a refractive index of 1.5168.

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