Photon flux standard source and photon flux responsivity measurement method
By using a photon flux standard source composed of an integrating sphere light source and an aperture, the problem of calibrating the photon flux responsivity of a microscopic imaging system was solved, and high-precision measurement of photon flux responsivity was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NATIONAL INSTITUTE OF METROLOGY CHINA
- Filing Date
- 2022-05-25
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies struggle to accurately measure the photon flux responsivity of microscopic imaging systems, resulting in low calibration accuracy.
A photon flux standard source consisting of an integrating sphere light source and an aperture is used. The photon flux is determined by calculating the planar spacing, average brightness, and first and second areas, and then the photon flux responsivity of the detector under test is accurately calculated.
This improves the calibration accuracy of the photon flux responsivity of the microscopic imaging system, ensuring the accuracy of photon flux measurement.
Smart Images
Figure CN115077867B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of microscopic imaging radiation calibration technology, specifically to a photon flux standard source and a method for measuring photon flux responsivity. Background Technology
[0002] Measuring the photon flux responsivity of a microscopic imaging system is an extremely challenging problem. For a microscopic imaging system with an unknown photon flux responsivity, a standard brightness source of known luminance is typically required to image the system on the detector. By precisely measuring the solid angle of light collection of the microscopic imaging system, the photon flux entering the system can be calculated, thereby obtaining the photon flux responsivity.
[0003] However, the measurement of the solid angle of light collection in a current microscopic imaging system is difficult, making it hard to determine the photon flux entering the microscopic imaging system, which in turn leads to low accuracy of the photon flux responsivity of the calibrated microscopic imaging system. Summary of the Invention
[0004] This application provides a photon flux standard source and a photon flux responsivity measurement method to solve the technical problem that the accuracy of the calibrated photon flux responsivity of the microscopic imaging system is low due to the difficulty in determining the photon flux entering the microscopic imaging system.
[0005] In a first aspect, embodiments of this application provide a photon flux standard source, including an integrating sphere light source and an aperture; the outer side of the outlet of the integrating sphere light source includes a first flat surface with a first area, and the side of the aperture near the integrating sphere light source has a second flat surface with a second area, the first flat surface and the second flat surface are parallel and have a planar gap, and the outlet of the integrating sphere light source has an average brightness within the solid angle defined by the aperture; wherein, the planar gap, the average brightness, the first area and the second area are used to calculate the photon flux to determine the photon flux responsivity of the detector under test.
[0006] In one embodiment, the integrating sphere light source includes an integrating sphere and a light source:
[0007] The light source is embedded inside the integrating sphere; or
[0008] The light source is introduced into the integrating sphere via optical fiber, waveguide, or spatial coupling.
[0009] In one embodiment, the light source is any one of laser, light-emitting diode, monochromatic light with a spectral selection device, narrowband light source, tunable monochromatic / narrowband light source, and broadband light source.
[0010] In one embodiment, the shape of the integrating sphere light source outlet and the shape of the aperture include circular and square.
[0011] In one embodiment, both the outer side of the integrating sphere light source outlet and the side of the aperture near the integrating sphere light source are knife edges.
[0012] In one embodiment, the brightness of the integrating sphere light source has a spatial angular distribution, which is used to calculate the average brightness of the integrating sphere light source outlet within the solid angle defined by the aperture.
[0013] In one embodiment, the solid angle defined by the aperture is determined based on the interval between the second area and the plane.
[0014] Secondly, embodiments of this application provide a photon flux responsivity measurement method, applied to the aforementioned photon flux standard source, the photon flux responsivity measurement method comprising:
[0015] Based on the planar spacing, average brightness, first area, and second area in the photon flux standard source, determine the photon flux of the integrating sphere source passing through the aperture in the photon flux standard source;
[0016] The photon flux responsivity of the detector under test is determined based on the photon flux.
[0017] In one embodiment, after determining the photon flux of the integrating sphere source through the aperture in the photon flux standard source based on the planar spacing, average brightness, first area, and second area in the photon flux standard source, the method further includes:
[0018] When the photon flux is determined to be less than a preset flux threshold, the brightness field of the integrating sphere light source is spatially homogenized according to the reflective device or the spatial light modulator.
[0019] In one embodiment, after the step of determining the photon flux responsivity of the detector under test based on the photon flux, the method further includes:
[0020] The photon flux of the light source under test is determined based on the photon flux responsivity.
[0021] The photon flux standard source and photon flux responsivity measurement method provided in this application embodiment include an integrating sphere light source and an aperture. The integrating sphere light source outlet has a first flat surface with a first area on its outer side, and the aperture near the integrating sphere light source has a second flat surface with a second area. The first and second flat surfaces are parallel and have a planar gap. The integrating sphere light source outlet has an average brightness within the solid angle defined by the aperture. Therefore, the photon flux can be accurately calculated based on the planar gap, average brightness, first area, and second area, facilitating the accurate determination of the photon flux responsivity of the detector under test. Since the photon flux entering the microscopic imaging system can be accurately determined, the accuracy of the photon flux responsivity of the microscopic imaging system calibrated based on the photon flux can be improved. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of the structure of the photon flux standard source provided in the embodiments of this application;
[0024] Figure 2 This is a schematic diagram of a scene using the photon flux standard source provided in an embodiment of this application;
[0025] Figure 3 This is a schematic flowchart of the photon flux responsivity measurement method provided in the embodiments of this application. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] Figure 1 A schematic diagram of the structure of a photon flux standard source provided in an embodiment of this application. (Refer to...) Figure 1 This application provides a photon flux standard source, which may include an integrating sphere light source 10 and an aperture 20.
[0028] It should be noted that the outer side of the integrating sphere light source 10 has a flat surface. In this embodiment, the flat surface on the outer side of the integrating sphere light source 10 is defined as the first flat surface, and the area of the first flat surface is defined as the first area A1. The side of the aperture 20 near the integrating sphere light source 10 is a flat surface. In this embodiment, the flat surface on the side of the aperture 20 near the integrating sphere light source 10 is defined as the second flat surface, and the area of the second flat surface is defined as the second area A2. Furthermore, the first flat surface and the second flat surface are parallel and have a certain interval, that is, there is a planar interval d between the first flat surface and the second flat surface.
[0029] It should be further noted that the outlet of the integrating sphere light source 10 has an average brightness within the solid angle defined by the aperture 20. In this embodiment, the average brightness of the outlet of the integrating sphere light source 10 within the solid angle defined by the aperture 20 is L.
[0030] Furthermore, it should be noted that the aforementioned first area A1, second area A2, average brightness L, and planar spacing d can be used to calculate the photon flux of the integrating sphere light source 10 through the aperture 20. This allows for the determination of the photon flux responsivity of the detector under test based on the photon flux of the integrating sphere light source 10 through the aperture 20. The specific determination process can be found in the subsequent photon flux responsivity measurement method, which will not be elaborated upon here. The detector under test can be a microscopic imaging system that requires photon flux responsivity testing.
[0031] Furthermore, in this embodiment, the integrating sphere light source 10 may include an integrating sphere and a light source. The light source may be embedded inside the integrating sphere, or it may be introduced into the integrating sphere via optical fiber, waveguide, or spatial coupling.
[0032] Furthermore, the light source can be one of the following: laser, LED (light-emitting diode), monochromatic light through a spectral selection device, narrowband light source, tunable monochromatic / narrowband light source, broadband light source, etc. For example, it can be a laser, an LED, or a narrowband light source.
[0033] Furthermore, after multiple reflections inside the integrating sphere, the light emitted from the light source can form a luminance field with good spatial uniformity at the exit of the integrating sphere, whose normal luminance L N The luminance distribution L(Ω) within a certain spatial solid angle can be measured using a standard luminance measuring device, thereby allowing the calculation of the average luminance L within that spatial solid angle.
[0034] Furthermore, the outer surface of the integrating sphere outlet in the integrating sphere light source 10 is flat, and the opening, i.e., the outer side of the outlet of the integrating sphere light source 10, is a knife edge, such as... Figure 2 As shown, Figure 2This is a schematic diagram of a photon flux standard source provided in an embodiment of this application. Specifically, the light rays emitted from the integrating sphere are not blocked by anything other than the blade edge; the area of the integrating sphere outlet 30, i.e., the first area, is A1. An aperture 20 is installed at a distance d from the outer surface of the integrating sphere outlet 30. The centerline of the aperture 20 coincides with the centerline of the integrating sphere opening. The surface of the aperture 20 facing the integrating sphere outlet 30 is a flat surface, and the opening of the aperture 20 is also a blade edge. The area of the aperture 20 is A2. The distance d between the two surfaces can be adjusted within a certain range. Based on the area of the surface of the aperture 20 facing the integrating sphere outlet 30, i.e., the second area, A2, and based on the second area and the distance d between the two flat surfaces (i.e., the planar spacing, which can be adjusted according to actual needs), the solid angle Ω = A2 / d of the aperture 20 opening relative to the integrating sphere opening 30 can be calculated. 2 Based on the measured spatial brightness distribution of the integrating sphere light source, the average brightness L within that solid angle can be calculated. Furthermore, the photon flux Φ = LA1A2 / d2 emitted by the integrating sphere light source 10 through the aperture 20 can be calculated using the flux calculation formula. The spectrum of the integrating sphere light source 10 can be measured using a standard spectral measuring device, and the aforementioned photon flux can also be converted into photons per second using the spectral wavelength. In addition, the shape of the outlet of the integrating sphere light source 10 and the aperture 20 can be circular, square, etc., and can be replaced as needed; for example, they can also be rhomboid, triangular, etc.
[0035] Understandably, the size of the integrating sphere light source 10 can be customized according to actual needs. A typical application is to calibrate the photon flux responsivity of a microscopic imaging system. In this case, the overall size of the integrating sphere can be 5-10 mm, for example, 5 mm, 7 mm, 8 mm, 10 mm, etc., and it is embedded in a rectangular carrier of standard commercial slide size to facilitate use on the sample stage of the microscopic imaging system.
[0036] Furthermore, when the brightness of the integrating sphere light source 10 is very weak (e.g., the calculated photon flux Φ is below 1 pW), due to the sparse number of photons, the randomness of the photon reflection process inside the integrating sphere is insufficient, resulting in significant spatial non-uniformity of the brightness field formed at the outlet of the integrating sphere, which will introduce certain measurement errors. In this case, a rapidly rotating or vibrating reflective device (e.g., a diffuse reflector or a micromirror array) or a spatial light modulator that rapidly modulates the intensity can be used to spatially homogenize the brightness field of the integrating sphere light source 10. For example, a controllable micromirror array can be installed inside the integrating sphere, and the reflection angle of the micromirror array can be randomly changed within a certain time. After integration over a certain time, the light reflected by the micromirror array at different reflection angles forms a brightness field at the outlet of the integrating sphere, and its uniformity can be significantly improved.
[0037] The photon flux standard source provided in this embodiment includes an integrating sphere light source and an aperture. The outer side of the integrating sphere light source outlet includes a first flat surface with a first area, and the side of the aperture near the integrating sphere light source has a second flat surface with a second area. The first and second flat surfaces are parallel and have a planar gap. The integrating sphere light source outlet has an average brightness within the solid angle defined by the aperture. Therefore, the photon flux can be accurately calculated based on the planar gap, average brightness, first area, and second area, facilitating the accurate determination of the photon flux responsivity of the detector under test. Since the photon flux entering the microscopic imaging system can be accurately determined, the accuracy of the photon flux responsivity of the microscopic imaging system calibrated based on the photon flux can be improved.
[0038] Accordingly, this application also provides a method for measuring the photon flux responsivity of the aforementioned photon flux standard source, referring to... Figure 3 , Figure 3 This is a flowchart illustrating the photon flux responsivity measurement method provided in an embodiment of this application. The photon flux responsivity measurement method includes:
[0039] Step S100: Determine the photon flux of the integrating sphere source through the aperture in the photon flux standard source based on the planar spacing, average brightness, first area and second area in the photon flux standard source.
[0040] Since the area of the first flat surface in the photon flux standard source is defined as the first area A1, the area of the second flat surface is defined as the second area A2, and the planar interval between the first and second flat surfaces is d, and the average brightness of the integrating sphere light source 10 exiting within the solid angle defined by the aperture 20 is L, the photon flux Φ of the integrating sphere light source 10 through the aperture 20 in this embodiment can be calculated using the following photon flux calculation formula:
[0041] Φ=LA1A2 / d 2 ;
[0042] Where Φ is the photon flux of the integrating sphere source 10 through the aperture 20 in the photon flux standard source, and the unit is W (watts). It can also be converted into the number of photons per second (s) by the wavelength of the light source. -1 L is the average brightness of the integrating sphere light source 10 within the solid angle defined by the aperture 20, A1 is the area of the first flat surface, A2 is the area of the second flat surface, and d is the planar spacing between the first flat surface and the second flat surface.
[0043] Step 200: Determine the photon flux responsivity of the detector under test based on the photon flux.
[0044] After obtaining the photon flux Φ of the integrating sphere light source 10 through the aperture 20 in the photon flux standard source, this embodiment can directly treat the photon flux standard source as a whole, that is, including the integrating sphere light source 10 and the aperture 20, and install it in front of the detector under test. The solid angle of the integrating sphere light source 10 through the aperture 20 is controlled to be smaller than the solid angle of the detector under test, so that the light passing through the aperture 20 can be completely received by the detector under test. Based on the photon flux of the integrating sphere light source 10 through the aperture 20 and the reading of the detector under test (specifically, a photocurrent reading or a photoelectron reading), the photon flux responsivity of the detector under test is determined. Specifically, the reading of the detector under test can be compared with the photon flux of the integrating sphere light source 10 through the aperture 20, and the result of the ratio calculation is determined as the photon flux responsivity of the detector under test.
[0045] Understandably, in this embodiment, the integrating sphere source 10 and the aperture 20 of the photon flux standard source can be separated and installed sequentially in front of the detector under test. Specifically, the center of the aperture 20 can be adjusted to a determinable position Z at the center of the field of view in front of the detector under test, where Z is a distance z from the detector, and z > d. The aperture 20 is moved closer to the detector by a distance d, and the integrating sphere source 10 is moved to the center of the exit plane of the integrating sphere source 10 and located at the determinable position Z, while ensuring that the solid angle of the aperture 20 opening to the light source is smaller than the light-receiving solid angle of the detector under test. The reading of the detector under test at this time is I. Further, the integrating sphere source 10 is removed, and the background reading of the detector under test at this time is I0. Then, based on the photon flux of the integrating sphere source 10 through the aperture 20 and the readings I and I0, the photon flux responsivity of the detector under test can be determined. Specifically, the difference between readings I and I0 can be calculated, and the result of the difference calculation can be compared with the photon flux of the integrating sphere light source 10 through the aperture 20. The result of the ratio calculation is determined as the photon flux responsivity of the detector under test. The calculation process can be achieved using the following formula:
[0046] s=(I-I0) / Φ.
[0047] Further, after determining the photon flux of the integrating sphere source through the aperture in the photon flux standard source based on the planar spacing, average brightness, first area, and second area in the photon flux standard source, the method further includes:
[0048] Step A: When the photon flux is determined to be less than a preset flux threshold, the brightness field of the integrating sphere light source is spatially homogenized according to the reflective device or spatial light modulator.
[0049] It should be noted that after determining the photon flux of the integrating sphere light source 10 through the aperture 20 in the photon flux standard source, this embodiment can also determine the brightness of the integrating sphere light source 10, which can be specifically determined by the calculated photon flux Φ. When the brightness of the integrating sphere light source is very weak, for example, when the calculated photon flux Φ is below a preset flux threshold (e.g., 1 pW), due to the sparse number of photons, the randomness of the photon reflection process inside the integrating sphere is insufficient, resulting in a large spatial non-uniformity of the brightness field formed from the outlet of the integrating sphere, which will bring certain measurement errors. Therefore, this embodiment can use a rapidly rotating or vibrating reflective device (e.g., a diffuse reflector or a micromirror array), or a spatial light modulator that rapidly modulates the intensity, to spatially homogenize the brightness field of the integrating sphere light source 10. For example, a controllable micromirror array can be installed inside the integrating sphere, and the reflection angle of the micromirror array can be randomly changed within a certain time. Through integration over a certain time, the light reflected by the micromirror array at different reflection angles forms a brightness field at the outlet of the integrating sphere, so that the uniformity of the brightness field formed from the outlet of the integrating sphere can be significantly improved.
[0050] Furthermore, after the step of determining the photon flux responsivity of the detector under test based on the photon flux, the method further includes:
[0051] Step B: Determine the photon flux of the light source under test based on the photon flux responsivity.
[0052] After calibrating the photon flux responsivity of a detector in a microscopic imaging system based on a photon flux standard source and the above method, this application can also calibrate the photon flux of an unknown brightness source (hereinafter referred to as the test source) within a defined solid angle by replacing the light source in the integrating sphere. Specifically, if there is a test source with a spectrum similar to the photon flux standard source and a luminous area smaller than or equal to the aperture area of the integrating sphere light source 10, then after calibrating the photon flux responsivity of the test detector, the integrating sphere light source 10 is removed and replaced with the test source, and the reading of the test detector at this time is determined to be I'. Further, the test source is removed, and the background reading of the test detector at this time is determined to be I0'. Then, the photon flux of the test source within the solid angle defined by the aperture 20 is Φ' = (I' - I0') / s.
[0053] The photon flux responsivity measurement method provided in this application includes an integrating sphere light source and an aperture, with the outer side of the integrating sphere light source outlet comprising a first flat surface with a first area, and the aperture near the integrating sphere light source comprising a second flat surface with a second area. The first and second flat surfaces are parallel and have a planar gap, and the integrating sphere light source outlet has an average brightness within a solid angle defined by the aperture. Therefore, the photon flux can be accurately calculated based on the planar gap, average brightness, first area, and second area, and the photon flux responsivity of the detector under test can be accurately determined based on the photon flux. Since the photon flux entering the microscopic imaging system can be accurately determined, the accuracy of the photon flux responsivity of the microscopic imaging system calibrated based on the photon flux can be improved.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A method for measuring photon flux responsivity, characterized in that, A photon flux standard source with adjustable photon flux and photon flux solid angle; The photon flux responsivity measurement method includes: Determine the magnitude and solid angle of the photon flux of the detector under test; Adjust the photon flux magnitude and solid angle of the photon flux standard source; Measure the photon flux responsivity of the detector under test; The photon flux standard source includes an integrating sphere light source and an aperture. The outer side of the integrating sphere light source outlet includes a first flat surface with a first area, and the side of the aperture near the integrating sphere light source has a second flat surface with a second area. The first flat surface and the second flat surface are parallel and have a planar gap, which is adjustable. The solid angle of the second area of the aperture relative to the outlet of the integrating sphere light source varies with the planar gap. The integrating sphere light source has an average brightness within the solid angle defined by it and the aperture. Based on the planar gap, the average brightness, the first area, and the second area, the photon flux of the integrating sphere light source through the aperture in the photon flux standard source can be calculated. The photon flux standard source can be used to calibrate detectors that measure photon flux, and to determine the photon flux responsivity of the detector based on the photon flux. Both the first area and the second area are light-transmitting areas. When the photon flux is less than a preset flux threshold, resulting in uneven brightness at the outlet of the integrating sphere light source, a reflective device or a spatial light modulator is used to spatially homogenize the brightness field of the integrating sphere light source.
2. The photon flux responsivity measurement method according to claim 1, characterized in that, The integrating sphere light source includes an integrating sphere and a light source: The light source is embedded inside the integrating sphere; or The light source is introduced into the integrating sphere via optical fiber, waveguide, or spatial coupling.
3. The photon flux responsivity measurement method according to claim 2, characterized in that, The light source is any one of the following: laser, light-emitting diode, monochromatic light with a spectral selection device, narrowband light source, tunable monochromatic / narrowband light source, and broadband light source.
4. The photon flux responsivity measurement method according to claim 1, characterized in that, The shape of the integrating sphere light source outlet and the shape of the aperture include circular and square.
5. The photon flux responsivity measurement method according to claim 1, characterized in that, Both the outer side of the integrating sphere light source outlet and the side of the aperture near the integrating sphere light source are knife-edges.
6. The photon flux responsivity measurement method according to claim 1, characterized in that, The brightness of the integrating sphere light source has a spatial angular distribution, which is used to calculate the average brightness of the integrating sphere light source outlet within the solid angle defined by the aperture.
7. The photon flux responsivity measurement method according to claim 1, characterized in that, The solid angle defined by the aperture is determined based on the interval between the second area and the plane.