Optical fiber spectrometer with adjustable spectrum

Abstract

The spectrum-adjustable optical fiber spectrometer comprises an optical fiber interface module, a grating module, a detector module and a shell, and the optical fiber interface module, the grating module and the detector module are all inserted from the outside and fixed to the shell; the grating module comprises a grating mounting seat, a grating is mounted on the inner side of the grating mounting seat, an adjusting groove is formed in the outer side of the grating mounting seat, a strip-shaped hole is formed in the grating mounting seat, a grating mounting seat groove is formed in the shell, and a grating mounting hole is formed in the bottom of the grating mounting seat groove. And the grating mounting seat is fixed on the shell through a screw in the strip-shaped hole. According to the invention, the optical fiber interface module, the grating module and the detector module are modularly designed and are installed and fixed on the shell from the outside, so that when a user needs to adjust the wavelength range, the resolution ratio, the sensitivity and other performance parameters of the spectrograph due to different use scenes, the corresponding modules can be directly adjusted or replaced from the outside, and the operation is convenient and fast.

Description

Technical Field

[0001] This invention belongs to the field of spectrometer technology, and particularly relates to a fiber optic spectrometer with adjustable spectrum. Background Technology

[0002] Miniature spectrometers have the advantages of small size, high portability, and simple operation, and can be applied to a variety of scenarios such as environmental monitoring, food safety monitoring, industrial production monitoring, medical and health care, and jewelry testing.

[0003] Existing spectrometers typically include a fiber optic interface, grating, detector, circuit board, and mirror. During assembly, these components are first securely installed inside the spectrometer housing. Next, the circuit board is assembled, and finally, the top cover is fastened to the housing. To ensure the spectrometer's airtightness, potting compound is usually applied between the circuit board and the housing, or between the circuit board and the top cover, for sealing.

[0004] When a spectrometer is used in different scenarios, the wavelength range, resolution, and sensitivity required by the user will vary. Since the internal optical components of most spectrometers on the market are encapsulated inside a casing, users cannot adjust parameters such as wavelength range, resolution, and sensitivity themselves and must return the spectrometer to the factory for replacement. However, even when the manufacturer replaces parts, they must first remove the potting adhesive, then disassemble the top cover and circuit board to replace the internal components. This disassembly process is time-consuming and laborious, and can easily scratch the circuit board and optical components during adhesive removal. Furthermore, there is a risk of introducing dust and foreign matter, which can affect the return rate. Summary of the Invention

[0005] This invention addresses the technical problem that adjusting parameters such as wavelength range, resolution, and sensitivity of existing spectrometers is inconvenient when used in different application scenarios. It proposes a fiber optic spectrometer with modular assembly of components, which allows users to easily adjust performance parameters themselves.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A spectrally tunable fiber optic spectrometer includes a fiber optic interface module, a grating module, a detector module, and a housing. The fiber optic interface module, grating module, and detector module are all externally inserted into and fixed to the housing. The grating module includes a grating mounting base, with a grating mounted inside the grating mounting base and an adjustment groove on the outside of the grating mounting base. The grating mounting base has a strip-shaped hole. The housing has a grating mounting slot, with a grating mounting hole at the bottom of the grating mounting slot. The grating mounting base is fixed to the housing by screws inside the strip-shaped hole.

[0007] Preferably, the fiber optic interface module includes a fiber optic interface box, a slit, and an aperture. The fiber optic interface box includes a fiber optic connector, a fixing flange, and an inner housing. The slit and aperture are mounted on the inner housing.

[0008] Preferably, the housing is provided with an interface box mounting hole, and the fixing flange is fixed to the housing by screws.

[0009] Preferably, the detector module includes a detector mounting base, on the inner side of which a detector and a detector circuit board are mounted. The outer casing is provided with a detector mounting slot, and the detector mounting base is installed in the detector mounting slot.

[0010] Preferably, the detector mounting base is provided with a strip-shaped hole, and the detector mounting base is fixed by screws inside the strip-shaped hole.

[0011] Preferably, the system also includes a filter module, which includes a filter mounting base, a filter is disposed inside the filter mounting base, a screw hole is disposed at the center of the filter mounting base, and a filter mounting groove is disposed on the outer shell. The filter mounting base is mounted in the filter mounting groove by screws in the screw hole.

[0012] Preferably, a reflector and a circuit board are installed inside the housing.

[0013] Preferably, a grating bracket is provided on the inner side of the grating mounting base, and the grating is fixed on the grating bracket.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: The spectrally tunable fiber optic spectrometer of this invention features a modular design of fiber optic interface module, grating module, and detector module, which are externally installed and fixed to the housing. When users need to adjust the wavelength range, resolution, sensitivity, and other performance parameters of the spectrometer due to different usage scenarios, they can directly adjust or replace the corresponding modules from the outside without having to return the equipment to the factory for adjustment or replacement of internal components. This expands the scope of application of the equipment and reduces the cost of using the equipment.

[0015] It also features an adjustable filter module, which can be adjusted to shift the slightly larger indentation starting position to the ideal position, thus solving the problem of large manufacturing tolerances in notch filters. By replacing other filter modules from the outside, filtering functions for other bands can be achieved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the fiber optic spectrometer of the present invention; Figure 2 This is a schematic diagram of the internal structure of the fiber optic spectrometer of the present invention; Figure 3This is a schematic diagram of the outer casing structure of the fiber optic spectrometer of the present invention; Figure 4 This is a schematic diagram of the fiber optic interface module structure of the fiber optic spectrometer of the present invention; Figure 5 This is a schematic diagram of the grating module structure of the fiber optic spectrometer of the present invention; Figure 6 This is an assembly diagram of the grating module of the fiber optic spectrometer of the present invention; Figure 7 This is a schematic diagram of the detector module structure of the fiber optic spectrometer of the present invention; Figure 8 This is an assembly diagram of the detector module and filter module of the fiber optic spectrometer of the present invention; Figure 9 This is a spectrum of a xenon lamp. In the above figures: 1. Outer shell; 11. Interface box mounting hole; 12. Grating mounting slot; 13. Grating mounting hole; 14. Detector mounting slot; 15. Filter mounting slot; 2. Reflector; 3. Fiber optic interface module; 31. Fiber optic interface box; 311. Fiber optic connector; 312. Fixing flange; 313. Inner box; 32. Slit; 33. Aperture; 4. Grating module; 41. Grating mounting base; 42. Grating; 43. Grating bracket; 44. Adjustment groove; 45. Grating fixing slot; 5. Detector module; 51. Detector mounting base; 52. Detector; 53. Detector circuit board; 54. Detector fixing slot; 6. Filter module; 61. Filter mounting base; 62. Filter; 63. Filter bracket; 64. Screw hole; 7. Screw. Detailed Implementation

[0017] To better understand the present invention, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0018] Example: Figures 1-3 As shown, a spectrally tunable fiber optic spectrometer includes a fiber optic interface module 3, a grating module 4, a detector module 5, a filter module 6, a reflector 2, a circuit board, and a housing 1. The reflector 2 and the circuit board are installed inside the housing 1. The fiber optic interface module 3, the grating module 4, the detector module 5, and the filter module 6 are all inserted into and fixed to the housing 1 from the outside, and can be adjusted or replaced from the outside, making it convenient for users or distributors to adjust the performance parameters of the spectrometer themselves.

[0019] like Figure 4As shown, the fiber optic interface module 3 includes a fiber optic interface box 31, a slit 32, and an aperture 33. The width of the slit 32 mainly determines the resolution of the spectrometer, while the diameter of the aperture 33 mainly affects the amount of stray light. The fiber optic interface box 31 includes a fiber optic connector 311, a fixing flange 312, and an inner housing 313. The slit 32 and the aperture 33 are mounted on the inner housing 313 by adhesive or screws 7, forming an integrated and detachable fiber optic interface module 3. The outer shell 1 is provided with an interface box mounting hole 11. During installation, the interface box is inserted into the interface box mounting hole 11 from the outside, and then the fixing flange 312 is fixed to the outer shell 1 with screws 7 to complete the assembly. When the user needs to adjust the resolution of the spectrometer, the original fiber optic interface module 3 can be replaced with the fiber optic interface module 3 of the required resolution, which is simple and convenient to operate.

[0020] like Figure 5 , Figure 6 As shown, the grating module 4 includes a grating mounting base 41 and a grating 42. A grating support 43 is provided on the inner side of the grating mounting base 41, and the grating 42 is fixed on the grating support 43. An adjustment groove 44 is provided on the outer side of the grating mounting base 41, and multiple grating fixing strip holes 45 are provided on the edge of the grating mounting base 41 for fixing. In this embodiment, two strip holes are provided, symmetrically arranged on both sides of the grating mounting base 41. A grating mounting slot 12 is provided on the outer shell 1, and a grating mounting hole 13 is provided at the bottom of the grating mounting slot 12. During installation, the grating 42 is inserted into the outer shell 1 through the grating mounting hole 13, and the grating mounting base 41 is inserted into the grating mounting slot 12. In this embodiment, the grating mounting slot 12 matches the grating mounting base 41, and the grating mounting base 41 can be quickly positioned and smoothly installed in the grating mounting slot 12. Both the grating mounting slot 12 and the grating mounting base 41 are circular, and the grating mounting base 41 is fixed in the grating mounting slot 12 by screws 7 in the grating fixing slot 45. The line pair number specification of the grating 42 determines the resolution of the spectrometer and the size of the detection spectral range, while its blaze wavelength determines the sensitivity of the spectrometer's spectrum.

[0021] During the assembly of the spectrometer, a tool can be inserted into the adjustment groove 44 to rotate the grating mounting base 41, changing the angle of the grating 42 in the grating mounting base groove 12, thereby adjusting the detection range of the spectrum. After adjusting the angle, it is tightened by the screw 7 in the strip hole. When using the instrument or when fine-tuning the spectral range is required, the user can remove the screw 7 and rotate it to check, which is very convenient. If the resolution needs to be adjusted, the original grating module 4 can be directly replaced with the grating module 4 of the required resolution.

[0022] like Figure 7 , Figure 8As shown, the detector module 5 includes a detector mounting base 51, on the inner side of which a detector 52 and a detector circuit board 53 are mounted. The outer casing 1 has a detector mounting slot 14, with a through hole at the bottom for the detector 52 and detector circuit board 53 to pass through. When installing the detector module 5, the detector mounting base 51 is installed in the detector mounting slot 14 to quickly position it. The detector mounting base 51 has a detector fixing slot 54, which is fixed by screws 7 within the slot 54. Before tightening the screws 7, the focal length can be adjusted by fine-tuning the position of the detector mounting base 51 relative to the outer casing 1, placing the photosensitive surface at the focal point of the light beam. This improves spectral resolution. After adjusting the position, the screws 7 are tightened. The pixel size of the detector 52 determines the resolution, while the number of pixels in the detector 52 determines the size of the detection spectral range. If it is necessary to adjust the resolution or the size of the detection spectral range, the existing detector module 5 can be directly replaced with a detector module 5 of the required specifications.

[0023] Spectrometers often require spectral processing during use, especially in DOAS (Differential Ultraviolet Gas Analysis) systems, where xenon lamps are commonly used as the light source. However, pulsed xenon lamps exhibit highly uneven spectral power distribution and contain very high-intensity spikes near the 230nm wavelength (e.g., Figure 9 As shown, within the detectable range of the spectrometer detector 52, high-intensity spectral peaks are easily saturated. To avoid saturation, the light intensity is usually reduced, resulting in some spectral bands having excessively low energy and poor absorbance signal-to-noise ratio. To address the problem of the excessively high 230nm peak in the xenon lamp spectrum, the existing solution is to add a notch filter 62 with a concave center wavelength of 230nm and a concave starting wavelength of 222nm to the spectrometer to balance the spectrum. However, since the falling edge position of this filter 62 needs strict control, if the starting wavelength of the falling edge is too short, the power of the lower-power band (180-220nm) will be damaged, affecting the measurement range of NH3, SO2, and NO. If the starting wavelength is too long, the attenuation effect of the 230nm peak will be reduced, or the concave position may even exceed the peak tip of 230nm. Due to limitations in the manufacturing process of filter 62, it is difficult to accurately manufacture the starting position of the recess. Therefore, the starting position of each batch of filter 62 will have deviations. As a result, in order to control the 230nm peak of the xenon lamp spectrum, it is necessary to select filter 62. Purchasing multiple sets of filter 62 will increase the cost of purchasing equipment.

[0024] To address the issue of large manufacturing tolerances in the notch filter 62, the spectrometer described in this embodiment is equipped with a filter module 6. For example... Figure 8As shown, the filter module 6 includes a filter mounting base 61 and a filter 62. A filter support 63 is provided inside the filter mounting base 61, and the filter 62 is mounted on the filter support 63 by adhesive or screws 7. The outer shell 1 is provided with a filter mounting groove 15, and a screw hole 64 is provided at the center of the filter mounting base 61. The filter mounting base 61 is mounted in the filter mounting groove 15 by screws 7 in the screw hole 64.

[0025] When screw 7 is not tightened, the filter mounting base 61 can rotate around screw 7. Utilizing the angle-sensitive characteristic of the dielectric film filter 62, when the filter 62 rotates from 0° (including clockwise and counterclockwise), its recessed wavelength position (including the top and bottom edges) will undergo a blue shift. The principle of the blue shift due to the tilt of the filter 62 is as follows: When the filter 62 is tilted, the incident angle of light increases, and the optical path length propagating in the filter 62 medium shortens. According to the principle of interference, the optical path difference and wavelength satisfy the formula: 2ndcosθ = mλ (where n is the refractive index of the medium, d is the film thickness, θ is the angle of refraction, m is the interference order, and λ is the wavelength). Increasing the incident angle increases θ and decreases cosθ. To maintain the balance of the equation, the wavelength λ needs to decrease, i.e., a blue shift occurs (the wavelength shifts towards shorter wavelengths). When rotated to 45° (a larger rotation angle would affect the spectrometer's resolution due to errors caused by the tilted glass), the measured wavelength exhibits a blue shift of approximately 10 nm. Therefore, when designing the notch filter 62, the notch initiation position can be set larger, for example, to 225±3 nm. By rotating the filter 62, the slightly larger notch initiation position can be blue-shifted to the ideal position. After finding the appropriate angle, tighten the screw 7. Alternatively, this method can be used to replace other filter modules 6 externally to filter other wavelengths, with the same adjustable angle.

[0026] The spectrally tunable fiber optic spectrometer described in this embodiment features a modular design of fiber optic interface module 3, grating module 4, and detector module 5, which are externally installed and fixed to the housing 1. When users need to adjust the wavelength range, resolution, sensitivity, and other performance parameters of the spectrometer due to different usage scenarios, they can directly adjust or replace the corresponding modules from the outside without having to return the equipment to the factory for adjustment or replacement of internal components. This expands the scope of application of the equipment and reduces the cost of using the equipment.

[0027] It also features an adjustable filter module 6, which can be used to adjust the angle of the filter module 6 to shift the slightly larger indentation starting position to the ideal position, thus solving the problem of large manufacturing process tolerance of the notch filter 62. By replacing other filter modules 6 from the outside, other band filtering functions can be achieved.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A spectrally tunable fiber optic spectrometer, characterized in that: The device includes a fiber optic interface module, a grating module, a detector module, and a housing. The fiber optic interface module, grating module, and detector module are all inserted into and fixed to the housing from the outside. The grating module includes a grating mounting base, on the inner side of which a grating is installed. An adjustment groove is provided on the outer side of the grating mounting base, and a strip-shaped hole is provided on the grating mounting base. The housing has a grating mounting slot, and a grating mounting hole is provided at the bottom of the grating mounting slot. The grating mounting base is fixed to the housing by screws in the strip-shaped hole.

2. The spectrally tunable fiber optic spectrometer according to claim 1, characterized in that: The fiber optic interface module includes a fiber optic interface box, a slit, and an aperture. The fiber optic interface box includes a fiber optic connector, a fixed flange, and an inner housing. The slit and aperture are mounted on the inner housing.

3. The spectrally tunable fiber optic spectrometer according to claim 2, characterized in that: The outer casing is provided with interface box mounting holes, and the fixing flange is fixed to the outer casing with screws.

4. The spectrally tunable fiber optic spectrometer according to claim 1, characterized in that: The detector module includes a detector mounting base, on the inner side of which a detector and a detector circuit board are mounted. The outer casing has a detector mounting slot, and the detector mounting base is installed in the detector mounting slot.

5. The spectrally tunable fiber optic spectrometer according to claim 4, characterized in that: The detector mounting base has a slotted hole, and the detector mounting base is fixed by screws inside the slotted hole.

6. The spectrally tunable fiber optic spectrometer according to claim 1, characterized in that: It also includes a filter module, which includes a filter mounting base, a filter is disposed inside the filter mounting base, a screw hole is disposed at the center of the filter mounting base, and a filter mounting groove is disposed on the outer shell. The filter mounting base is installed in the filter mounting groove by screws in the screw hole.

7. The spectrally tunable fiber optic spectrometer according to claim 1, characterized in that: The housing contains a reflector and a circuit board.

8. The spectrally tunable fiber optic spectrometer according to claim 1, characterized in that: A grating bracket is provided on the inner side of the grating mounting base, and the grating is fixed on the grating bracket.

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