Testing device for diffraction efficiency of grating
The grating diffraction efficiency testing device addresses the limitation of single-grating testing by using a system with adjustable components to ensure consistent light incidence and detection, enabling accurate and comprehensive testing of multiple gratings, simulating their actual use state in a spectrometer.
Patent Information
- Application Number
- CN202421213461.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-30
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2034-05-30
AI Technical Summary
Current convex grating diffraction efficiency test systems are only applicable to a single grating and cannot meet the test requirements for multiple gratings in the same system.
A grating diffraction efficiency testing device comprising a light source, beam expansion and collimation system, a beam splitter, variable apertures, and detection systems, with adjustable components to ensure consistent light incidence and detection, allowing for the measurement of the average diffraction efficiency across the entire grating surface.
Enables accurate and comprehensive testing of multiple gratings by ensuring consistent light incidence and detection, simulating the actual use state of the gratings in a spectrometer, thereby improving the accuracy and practicality of the test results.
Smart Images
Figure CN222212198U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of high-precision optical element performance testing, in particular to a device and method for testing the diffraction efficiency of a convex grating. Background Art
[0002] Gratings are the core components of imaging spectrometers in remote sensing technology. Among them, the Offner spectroscopic imaging system using convex reflection gratings has the advantages of compact structure, small spectral curvature and high image quality, making it the first choice for imaging spectrometer spectroscopic systems. Gratings can separate monochromatic light or target spectrum from polychromatic light, and can diffract incident light of different wavelengths to different directions. Each direction corresponds to an order, and each order corresponds to a different diffraction efficiency. Therefore, diffraction efficiency is an important parameter among all the performance of gratings. It reflects the utilization rate of light energy by the grating. When the diffraction efficiency of the target order meets the performance requirements, the grating performance can be considered to be optimal. The pixels at each position on the photosensitive surface of the detector of the spectral detection system will receive the diffracted light of the grating. Therefore, it is also crucial to test the average diffraction efficiency of the entire grating surface and determine whether the energy of each row and column position meets the requirements.
[0003] At present, the convex grating diffraction efficiency test system is only applicable to a single grating, and cannot meet the test requirements of multiple gratings in the same system. Therefore, technicians in this field are committed to developing a test device and method suitable for testing the average diffraction efficiency of multiple gratings. Summary of the invention
[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the current convex grating diffraction efficiency test system is only applicable to a single grating and cannot meet the test requirements of the same system for multiple gratings.
[0005] In order to solve the above technical problems, the utility model provides a grating diffraction efficiency testing device, comprising a light source, a beam expansion collimation system, and a beam splitter which are arranged in sequence; the beam splitter is a 5:5 semi-reflective and semi-transmissive beam splitter, a first variable aperture and a first detection system are arranged in sequence in the reflection direction of the beam splitter, a second variable aperture and a grating to be measured are arranged in sequence in the transmission direction of the beam splitter, and a second detection system is arranged in sequence in the reflection direction of the grating to be measured, and the technical point is that the second variable aperture is used to adjust its aperture so that the incident light beam aperture of the grating to be measured is consistent with the effective aperture of the grating to be measured. The aperture is consistent; the first variable iris is consistent with the second variable iris in aperture; the first detection system includes a first non-detachable focusing lens and a first power meter for focusing; the second detection system includes a second focusing lens that can be disassembled and replaced according to the grating curvature radius, and a second power meter for receiving diffracted light energy; an adjustment mechanism is arranged under the second detection system, and the adjustment mechanism includes a support rod fixedly connected to the second detection system at one end, a track hole is opened at the other end, and a guide rail passes through the track hole, and an angle adjustment device is arranged between the support rod and the second detection system.
[0006] The light beam emitted by the light source outputs parallel light after passing through the beam expansion and collimation system, and the parallel light is divided into a first light beam and a second light beam of equal intensity after passing through the beam splitter, and the first light beam passes through the first variable aperture and then passes through the photosensitive surface of the first detection system; the second light beam passes through the second variable aperture and then enters the surface of the grating to be measured, and is reflected by the grating to be measured to the photosensitive surface of the second detection system; the diffraction efficiency of the grating to be measured is determined according to the numerical values of the first detection system and the second detection system.
[0007] Furthermore, the tilt angle of the grating to be measured is adjustable, and the grating to be measured is used to adjust its tilt angle so that the incident angle of the incident light on the surface of the grating to be measured is consistent with the actual incident angle of the grating to be measured in the spectrometer.
[0008] Furthermore, the first variable iris is used to make the incident light energy in the first variable iris and the incident light energy in the second variable iris consistent by adjusting its aperture.
[0009] Furthermore, the second focusing lens can be disassembled and replaced according to the grating curvature radius, and the replacement principle is 0<grating F number-lens F number<0.5.
[0010] Furthermore, both the first power meter and the second power meter are optical power meters, and the measurement accuracy of the optical power meters is 0.1mw.
[0011] Furthermore, the light source is a continuously tunable laser, the power of the continuously tunable laser is 8W, the wavelength range is 400nm~2400nm, the spectrum width is 7nm, and the power stability is less than 1%.
[0012] The utility model uses a continuously tunable laser to output a light source, outputs parallel light after a beam expansion and collimation system, and then is divided into two light beams with the same intensity by a beam splitter, and adjusts a second variable iris so that the aperture of the light beam incident on the grating surface is consistent with the effective aperture of the grating, thereby realizing the test of the average diffraction efficiency of the entire surface of the grating to be tested, and solving the problem that the current grating diffraction efficiency test is a small area test and cannot represent the diffraction efficiency of the entire grating.
[0013] The utility model makes the inclination angle of the grating to be measured adjustable so that the incident angle of the incident light on the surface of the grating to be measured is consistent with the incident angle of the grating actually used in the spectrometer, simulates the actual use state of the grating to be measured in the spectrometer, realizes the test of the average diffraction efficiency of the whole surface of the grating to be measured in the actual use state, and improves the practicality of the utility model.
[0014] The utility model firstly ensures that the incident light energy of the first detection system and the grating surface is consistent by adjusting the aperture of the variable aperture, and makes the light incident on the first detection system by adjusting the aperture of the variable aperture, thereby ensuring the accuracy of the first detection system and further ensuring the accuracy of the test result of the utility model.
[0015] The utility model sets an angle adjustment device, a guide rail, and a track hole, and adjusts their positions and angles to obtain the reflected light angle and accuracy of the target level of the grating to be tested, thereby realizing the test of the ideal level of the grating to be tested, such as +1 level, 0 level, and -1 level, while ensuring the accuracy of the test result of the utility model.
[0016] The utility model realizes the testing of various gratings by arranging a detachable and replaceable second focusing lens and replacing the second focusing lens.
[0017] The utility model sets a continuously tunable laser to output light of different wavelengths and performs multi-point wavelength output measurement, which greatly reduces the inaccuracy of grating diffraction efficiency curve fitting and further improves the accuracy of the test results of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a structural schematic diagram of the testing device of the utility model;
[0019] Figure 2 is a structural schematic diagram of a first detection system;
[0020] Figure 3 is a structural schematic diagram of a second detection system;
[0021] Figure 4 It is a front view schematic diagram of the adjustment mechanism;
[0022] Figure 5 is a side schematic diagram of the adjustment mechanism;
[0023] Figure 6 This is a grating diffraction efficiency curve diagram of Example 1 of the utility model;
[0024] Figure 7 This is a grating diffraction efficiency curve diagram of Example 2 of the utility model.
[0025] Attached photos
[0026] 1-light source; 2-beam expansion and collimation system; 3-beam splitter; 4-first variable aperture; 5-first detection system; 6-second variable aperture; 7-grating to be measured; 8-second detection system; 51-first focusing lens; 52-first power meter; 81-second focusing lens; 82-second power meter; 83-support rod; 84-angle adjustment device; 85-track hole; 86-guide rail. DETAILED DESCRIPTION
[0027] The utility model is further described below in conjunction with embodiments and drawings.
[0028] like Figure 1 The grating diffraction efficiency testing device provided by the utility model comprises a light source 1, a beam expansion and collimation system 2, and a beam splitter 3 which are arranged in sequence; the beam splitter 3 is a 5:5 semi-reflective and semi-transmissive beam splitter 3, a first variable iris 4 and a first detection system 5 are arranged in sequence in the reflection direction of the beam splitter 3, a second variable iris 6 and a grating to be measured 7 are arranged in sequence in the transmission direction of the beam splitter 3, and a second detection system 8 is arranged in sequence in the reflection direction of the grating to be measured 7, and the second variable iris 6 is used to adjust its aperture so that the incident light beam aperture of the grating to be measured 7 is consistent with the effective use aperture of the grating to be measured 7; the aperture of the first variable iris 4 is consistent with that of the second variable iris 6; Figure 2 As shown, the first detection system 5 includes a non-detachable first detection system 51 for focusing and a first power meter 52; Figure 3 As shown, the second detection system 8 includes a second focusing lens 81 that can be disassembled and replaced according to the grating curvature radius, and a second power meter 82 for receiving diffracted light energy; Figure 5 , 6As shown, an adjustment mechanism is arranged below the second detection system 8, and the adjustment mechanism includes a support rod 83 fixedly connected to the second detection system 8 at one end, a track hole 85 is opened at the other end, and a guide rail 86 passes through the track hole 85, and an angle adjustment device 84 is arranged between the support rod 83 and the second detection system 8. Its working principle is that the light beam emitted by the light source 1 outputs parallel light after passing through the beam expansion and collimation system 2, and the parallel light is divided into a first light beam and a second light beam with the same intensity after passing through the beam splitter 3, and the first light beam passes through the first variable diaphragm 4 and is focused to the photosensitive surface of the first power meter 52 in the first detection system 5 by the first focusing lens 51; the second light beam passes through the second variable diaphragm 6 and is incident on the surface of the grating 7 to be measured, and is reflected by the grating 7 to be measured and focused by the second focusing lens 81 in the second detection system 8 and then to the photosensitive surface of the second power meter 82 in the second detection system 8; the diffraction efficiency of the grating 7 to be measured is determined according to the numerical calculation of the first power meter 52 and the second power meter 82.
[0029] The second focusing lens 81 can be disassembled and replaced according to the grating curvature radius to ensure that the grating diffraction light can be focused. The second focusing lens (81) can be disassembled and replaced according to the grating curvature radius, and the replacement principle is 0 < grating F number - lens F number < 0.5.
[0030] The second variable aperture 6 is used to adjust its aperture so that the incident light beam aperture of the grating 7 to be measured is consistent with the effective use aperture of the grating 7 to be measured, thereby realizing the test of the average diffraction efficiency of the entire surface of the grating 7 to be measured.
[0031] Preferably, the inclination angle of the grating 7 to be measured is adjustable, and the grating 7 to be measured is used to adjust its inclination angle so that the incident angle of the incident light on the surface of the grating 7 to be measured is consistent with the actual grating use angle of the grating 7 to be measured in the spectrometer; thereby simulating the actual use state of the grating 7 to be measured in the spectrometer, and realizing the test of the whole-surface average diffraction efficiency of the grating 7 to be measured in the actual use state.
[0032] Preferably, the first variable aperture 4 is used to adjust its aperture so that the incident light energy in the first variable aperture 4 and the second variable aperture 6 is consistent; the positions and angles of the first detection system 5, the second detection system 8, the first power meter 52, and the second power meter 82 are all adjustable; the first detection system 5 is used to focus the split light to a size that can be fully received by the first power meter 52 by adjusting its position and angle, and the first power meter 52 is used to ensure that the light focused by the first detection system 5 is incident on the center of the photosensitive surface of the first power meter 52 by adjusting its position and angle; the position and angle of the second detection system 8 and the position and angle of the second power meter 82 are adjusted to obtain the angle of reflected light of the ideal order of the grating to be measured; thereby, the measurement result of the first power meter 52 is the optical power value of the first light beam after focusing, and the measurement result of the second power meter 82 is the optical power value of the second light beam after reflection and focusing by the grating, thereby realizing the test of the ideal order +1, 0 or -1 of the grating to be measured.
[0033] Preferably, the first power meter 52 and the second power meter 82 are both optical power meters, and the measurement accuracy of the optical power meter is 0.1 mw.
[0034] Preferably, the light source 1 is a continuously tunable laser, the laser power of the continuously tunable laser is 8 W, the wavelength range is 400 nm to 2400 nm, the spectrum width is 7 nm, and the power stability is less than 1%. Example
[0035] Using the above test device, the diffraction efficiency of the first convex grating is tested:
[0036] First, the size of the first convex grating is measured to be 30mm, and the effective aperture of the first convex grating is 29mm. The aperture of the second variable aperture 6 is adjusted to 29mm to ensure the consistency of the incident light beam aperture and the effective aperture of the first convex grating; the aperture of the first variable aperture is adjusted to 29mm to ensure the consistency of the incident light energy in the first variable aperture and the second variable aperture; the incident angle of the light on the surface of the first convex grating is determined to be 22°, and the inclination angle of the first convex grating is adjusted to 22° to ensure that the incident light angle on the surface of the first convex grating is consistent with the design angle of the first convex grating in the application scenario; the diffraction angles of the first convex grating -1 order corresponding to different wavelengths are calculated to be 19.1~21.3°, and the angles of the second focusing lens and the second power meter are adjusted to ensure that the second power meter can receive the light intensity of the beam focus point after the complete spot is focused; the angles of the first focusing lens and the first power meter are adjusted to ensure that the first power meter can receive the light intensity of the beam focus point after the complete spot is focused.
[0037] Then turn on the laser to emit a beam, output light of different wavelengths, and measure the light intensity of the first beam and the second beam corresponding to each wavelength. The light intensity of the first beam is 1.935-1.962W, and the light intensity of the second beam is 1.102W-1.567W. Calculate the average diffraction efficiency curve of the first convex grating as follows: Figure 6 As shown, the first convex grating uses a wavelength range of 380nm to 750nm, wherein the range of 380nm to 400nm is a fitting value. Example
[0038] Using the above test device, the diffraction efficiency of the second convex grating is tested:
[0039] First, the size of the second convex grating is measured to be 21mm, and the effective aperture of the second convex grating is 19mm. The aperture of the second variable iris 6 is adjusted to 19mm to ensure the consistency between the incident light beam aperture and the effective aperture of the second convex grating; the aperture of the first variable iris is adjusted to 19mm to ensure the consistency of the incident light energy in the first variable iris and the second variable iris; the incident angle of the light on the surface of the second convex grating is determined to be 27°, and the inclination angle of the second convex grating is adjusted to 27° to ensure that the incident light angle on the surface of the second convex grating is consistent with the design angle of the second convex grating in the application scenario; the diffraction angles of the second convex grating -1 order corresponding to different wavelengths are calculated to be 24.9~26.1°, and the second focusing lens angle and the second power meter angle are adjusted to ensure that the second power meter can receive the light intensity of the beam focus point after the complete spot is focused; the first focusing lens angle and the first power meter angle are adjusted to ensure that the first power meter can receive the light intensity of the beam focus point after the complete spot is focused.
[0040] Then turn on the laser to emit a beam, output light of different wavelengths, and measure the light intensity of the first beam and the second beam corresponding to each wavelength, where the light intensity of the first beam at 740nm~1000nm is 1.280~1.291W, and the light intensity range of the second beam of different wavelengths-1st diffraction at 740nm~1000nm is 0.652W~1.035W; the light intensity of the first beam at 1000nm~1440nm is 1.260~1.295W, and the light intensity range of the second beam of different wavelengths-1st diffraction at 1000nm~1440nm is 0.813W~1.041W; calculate the average diffraction efficiency value of the second convex grating as follows Figure 7 As shown, the second convex grating uses a wavelength range of 740nm to 1440nm.
[0041] The above convex grating test results are consistent with the grating design results, which verifies the rationality of the convex grating diffraction efficiency test method and provides a reasonable basis for the performance evaluation of the spectrometer system.
Claims
1. A device for testing grating diffraction efficiency, comprising a light source (1), a beam expansion and collimation system (2), and a beam splitter (3) arranged in sequence; the beam splitter (3) is a 5:5 semi-reflective semi-transmissive beam splitter (3); a first variable aperture (4) and a first detection system (5) are arranged in sequence in the reflection direction of the beam splitter (3); a second variable aperture (6) and a grating to be measured (7) are arranged in sequence in the transmission direction of the beam splitter (3); and a second detection system (8) is arranged in sequence in the reflection direction of the grating to be measured (7), characterized in that: The second variable iris (6) is used to adjust its aperture so that the incident light beam aperture of the grating to be measured (7) is consistent with the effective use aperture of the grating to be measured (7); the first variable iris (4) and the second variable iris (6) have the same aperture; the first detection system (5) comprises a first non-detachable focusing lens (51) and a first power meter (52) for focusing; the second detection system (8) comprises a second focusing lens (81) that can be removed and replaced according to the grating curvature radius, and a second power meter (82) for receiving diffracted light energy; an adjustment mechanism is arranged below the second detection system (8), the adjustment mechanism comprising a support rod (83) fixedly connected to the second detection system (8) at one end, a track hole (85) at the other end, a guide rail (86) passing through the track hole (85), and an angle adjustment device (84) is arranged between the support rod (83) and the second detection system (8).
2. The grating diffraction efficiency testing device according to claim 1, characterized in that: The tilt angle of the grating to be measured (7) is adjustable, and the grating to be measured (7) is used to adjust its tilt angle so that the incident angle of the incident light on the surface of the grating to be measured (7) is consistent with the actual incident angle of the grating to be measured (7) in the spectrometer.
3. The grating diffraction efficiency testing device according to claim 1, characterized in that: The first variable iris (4) is used to make the incident light energy in the first variable iris (4) and the incident light energy in the second variable iris (6) consistent by adjusting its aperture.
4. The grating diffraction efficiency testing device according to claim 1, characterized in that: The light source (1) is a continuously tunable laser.
5. The grating diffraction efficiency testing device according to claim 1, characterized in that: The second focusing lens (81) can be disassembled and replaced according to the grating curvature radius, and the replacement principle is 0<grating F number-lens F number<0.5.