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JP-7856755-B2 - Apparatus for measuring the performance of an optical detector, and related measurement methods.

JP7856755B2JP 7856755 B2JP7856755 B2JP 7856755B2JP-7856755-B2

Inventors

  • リリアン・マルチノー

Assignees

  • リンレッド

Dates

Publication Date
20260511
Application Date
20221005
Priority Date
20211029

Claims (10)

  1. An apparatus (10) for measuring the performance of an optical detector (20), - A cryostat (17) capable of placing the optical detector (20) under its expected operating conditions, comprising means for placing it under vacuum and cooling it, - A holder (19) that is fixed inside the cryostat (17) and capable of receiving the optical detector (20), - Means for measuring the performance of the optical detector (20), - A measuring device (10) comprising shielding bodies (12a to 12b) arranged around the retainer (19) that are capable of limiting radiation that may reach the retainer in the wavelength range of the optical detector (20), - A single-mode optical fiber (16) in the wavelength range of the optical detector (20), wherein the optical fiber (16) is inserted into the aperture (15) of the cryostat (17) and fixed to the aperture of the shielding body (12a to 12b), and has a first end (14) that projects a light beam onto all or part of the optical detector (20), The second end (22) on the outside of the cryostat (17), which is intended to receive the light beam, An optical fiber (16) and - At least two modules (50-52) for generating the light beam, each incorporating a fiber light source (23, 33, 43) capable of generating a light beam at the second end (22) of the optical fiber (16), Equipped with, An apparatus for measuring the performance of an optical detector (20), characterized in that the means for measuring the performance of the optical detector (20) is capable of measuring the performance according to the light beam received at the second end (22), and a plurality of separate measurements can be performed by replacing the modules (50-52) connected to the second end (22).
  2. An apparatus for measuring the performance of an optical detector (20) according to claim 1, wherein the fiber light sources (23, 33, 43) are formed from light-emitting diodes, supercontinuum light sources, or lasers.
  3. An apparatus for measuring the performance of an optical detector (20) according to claim 1 , wherein a core made of fluorinated glass, chalcogenide glass, or polycrystalline material is formed on the optical fiber (16).
  4. A first luminous flux generating module (50), which is one of the modules, is intended to be connected to the second end (22) of the optical fiber (16) in order to perform radiation measurements. - A fiber light source (23) intended to generate a light beam inside the first feeder optical fiber (28), - An optical attenuator (24) capable of limiting the light beam, the attenuator (24) being connected between the first feeder optical fiber (28) and the second feeder optical fiber (29), - An optical splitter (25) connected to the second feeder optical fiber (29) capable of splitting the optical beam of the second feeder optical fiber (29) into a third feeder optical fiber (30) and a fourth feeder optical fiber (31), wherein the third feeder optical fiber (30) is connected to the second end (22) of the optical fiber (16) inserted into the cryostat (17), - A reference detector (26) connected to the fourth feeder optical fiber (31), and capable of measuring the luminous flux at the output of the optical splitter (25) in order to obtain a predicted luminous intensity by controlling the power of the fiber light source (23) and the optical attenuator (24), An apparatus for measuring the performance of the optical detector (20) according to claim 1 , comprising the above.
  5. A second light beam generation module (51), which is one of the modules, is intended to be connected to the second end (22) of the optical fiber (16) in order to perform residual magnetism measurements. - A fiber light source (33) intended to generate a light beam inside the first feeder optical fiber (28), - An optical shutter (35) capable of blocking the light beam is connected between the first feeder optical fiber (28) and the second feeder optical fiber (29), - An optical splitter (25) connected to the second feeder optical fiber (29) capable of splitting the optical beam of the second feeder optical fiber (29) into a third feeder optical fiber (30) and a fourth feeder optical fiber (31), wherein the third feeder optical fiber (30) is connected to the second end (22) of the optical fiber (16) inserted into the cryostat (17), - A reference detector (34) connected to the fourth feeder optical fiber (31) is capable of controlling the light beam at the output of the optical splitter (25), An apparatus for measuring the performance of the optical detector (20) according to claim 1 , comprising the above.
  6. An apparatus for measuring the performance of an optical detector (20) according to claim 5, wherein the second light beam generation module (51), which is intended to be connected to the second end (22) of the optical fiber (16) for performing residual magnetism measurements, is also implemented for performing dark current measurements by cutting off the power supply to the fiber light source (33).
  7. An apparatus for measuring the performance of an optical detector (20) according to claim 1 , wherein the optical fiber (16) has a normalized frequency (V) in the range of 1.2 to 3.8 in the wavelength range of interest.
  8. A third beam generation module (52), which is one of the modules , is intended to be connected to the second end (22) of the optical fiber (16) in order to perform spectral response measurements. - A fiber light source (43) intended to generate a light beam inside the first feeder optical fiber (44), - A diffraction grating (46) connected to the first feeder optical fiber (44), - A filter (47) connected to the output of the diffraction grating (46), - A second feeder optical fiber (48) connected to the output of the filter (47), An apparatus for measuring the performance of the optical detector (20) according to claim 1 , comprising the above.
  9. A method for measuring the performance of an optical detector (20) using an apparatus for measuring the performance of an optical detector (20) according to any one of claims 1 to 8, - Step (60) of assembling the optical detector (20) to the holder (19) of the cryostat (17), - Step (61) of placing the cryostat (17) under vacuum until the optical detector (20) reaches a desired operating vacuum level, - Step (62) of cooling the cryostat (17) until the optical detector (20) reaches a desired operating temperature, - Step (63) of connecting the first optical beam generation module (50-52) to the second end (22) of the optical fiber (16), - A step (64) to measure the performance of the optical detector (20), - A step (65) of separating the first light beam generation module (50-52) from the second end (22) of the optical fiber (16), - Step (66) of connecting the second optical fiber (16) to the second end (22) of the optical fiber (16), - A step (67) to measure the performance of the optical detector (20), - A step (72) of heating the cryostat (17) until it reaches room temperature, - Step (73) of returning the cryostat (17) to ambient pressure and removing the optical detector (20), Methods that include...
  10. - A step (63) of connecting a first light beam generation module (50) for performing radiation measurement to the second end (22) of the optical fiber (16), - The radiation measurement step (64) of the optical detector (20), - A step (65) of separating the first light beam generation module (50) from the second end (22) of the optical fiber (16), - A step (66) of connecting a second optical beam generation module (51) for performing residual magnetism measurement to the second end (22) of the optical fiber (16), - A step (67) of measuring the residual magnetism of the optical detector (20), - A step (68) of measuring the dark current of the optical detector (20), - A step (69) of separating the second optical fiber (16) from the second end (22) of the optical fiber (16), - Step (70) of connecting a third optical beam generation module (52) for performing spectral response measurement to the second end (22) of the optical fiber (16), - A step (71) of measuring the spectral response of the optical detector (20), The method according to claim 9, including the method described in claim 9.

Description

This invention relates to an apparatus for measuring the performance of an optical detector, and related measurement methods. More specifically, the invention relates to a low-temperature quantum phenomenon-implementing detector, which must be cooled to ultra-low temperatures, typically in the range of 50 to 200 K. This invention is intended to be applied to measuring the performance of detectors in the visible range, specifically in the near-infrared region, i.e., infrared with wavelengths in the range of 1 to 2.5 micrometers (also known as SWIR, or "Short-Wavelength Infrared"), the mid-infrared region with wavelengths in the range of 3 to 8 micrometers (also known as MWIR, or "Mid-Wavelength Infrared"), and the far-infrared region with wavelengths in the range of 8 to 14 micrometers (also known as LWIR, or "Long-Wavelength Infrared"). Therefore, the present invention may be applied to multiple detectors and multiple distinct regions. More specifically, the present invention is intended to provide high-precision measurements to characterize the performance of detectors intended for highly demanding applications, such as space applications. To characterize the performance of quantum detectors, especially before they are deployed on satellites, - Radiometric measurements, - Residual magnetism measurement, - Multiple different measurements may be performed, such as dark current measurement and - spectral response measurement. Radiation measurements are intended to measure the output level response of the detector 20 in response to the beam of photons incident on the detector 20. For this purpose, as illustrated in Figure 1a, the radiation testbench 100 conventionally includes a light source 101 that enables the acquisition of a pseudo-blackbody emission law with an emission peak of approximately 1 micrometer. Typically, this light source 101 may have a color temperature of approximately 2,700 Kelvin and a light intensity of several tens of watts. In the sense of the present invention, "color temperature" characterizes the light source by comparison with an ideal material that emits light only through thermal action. Such a light source 101 conventionally comprises a winding that forms a resistor. However, the light L11 generated by this type of light source 101 is extremely non-uniform, and at long-field views, it is possible to observe light variations due to the shape of the resistor winding of the light source 101. To correct this drawback, an integrating sphere 102 is used at the output of the light source 101 to obtain a more uniform luminous flux L12. More precisely, this integrating sphere 102 is driven by the light source 101 through an adjustable aperture 103. In fact, the adjustable aperture 103 allows for adjustment of the amount of photons while maintaining a constant current for the light source 101, in order to ensure the stability of the light source 101. Furthermore, the adjustable aperture 103 does not alter the distribution of light rays at the output of the integrating sphere 102. To control the amount of photons entering the integrating sphere 102, a reference detector 104 is provided on the integrating sphere 102 to measure the amount of photons present in the integrating sphere 102. The controller 110 controls the power of the light source 101 and the aperture ratio of the aperture 103 according to the amount of photons searched and measured by the reference detector 104. The luminous flux L12 at the output of the integrating sphere 102 penetrates a thermal enclosure 105, whose inner walls are intended to absorb radiation in the wavelength range of interest. This thermal enclosure 105 incorporates a shielding element 106, which allows for limiting the viewing angle of the detector 20. More precisely, stray light is captured by the shielding element 106 and absorbed by the walls of the thermal enclosure 105, so that only the luminous flux directly transmitted by the integrating sphere 102 reaches the detector 20. The thermalization of the thermalized enclosure 105 allows for limiting the luminescence capacitance of the walls. For example, the enclosure can be maintained at a temperature of 12°C while the room temperature is substantially 22°C. Therefore, the luminous flux L13 at the output of the thermal enclosure 105 reaches the detector 20 directly. The detector 20 is embedded in a cryostat 107, which is intended to replicate the operating conditions of the detector 20. For example, for space applications, the detector 20 may operate at extremely low temperatures and under vacuum. More precisely, the vacuum level in cryostat 107 can be 10⁻⁵ mbar, while the temperature of cryostat 107 can be around 180 K for short-wavelength infrared detectors, between 150 K and 110 K for mid-wavelength infrared detectors, and between 60 K and 100 K for long-wavelength infrared detectors. To limit the propagation of the light beam L13 within the cryostat 107, a shielding element 112 may also be provided