Attenuating sheet, method of making, attenuating sheet wheel assembly, test system and test method

Abstract

The application relates to the fields of infrared optical film technology and precise photoelectric testing technology, and provides an attenuating piece, a preparation method, an attenuating piece wheel assembly, a testing system and a testing method. The application utilizes a first attenuating piece group and a second attenuating piece group to form an attenuating piece, each first attenuating piece in the first attenuating piece group adopts a zinc selenide base material and a nickel film and has high spectral transmittance; each second attenuating piece in the second attenuating piece group adopts a silicon base material, a gold film and a chromium adhesion layer and has high spectral transmittance; the attenuating piece is applied to an infrared detector nonlinearity testing system, different first attenuating pieces and second attenuating pieces can be combined to construct an attenuating assembly with a large dynamic range. The testing system using the attenuating piece can realize automatic scanning of incident photon flux density across more than four orders of magnitude, solves the problems of preparation and system integration of a mid-wave large dynamic range attenuating device, and improves the efficiency and reliability of infrared detector response nonlinearity testing.

Description

Technical Field

[0001] This application relates to the fields of infrared optical thin film technology and precision optoelectronic testing technology, and in particular to an attenuator, a preparation method, an attenuator wheel assembly, a testing system, and a testing method. Background Technology

[0002] In infrared detector nonlinearity testing, attenuators need to maintain spectral neutrality across a wide infrared spectral range (e.g., 3-17 micrometers (μm)) and provide accurate and stable attenuation values ​​over a large dynamic range (typically covering four orders of magnitude). Existing technologies suffer from the following problems:

[0003] 1) Difficulty in covering a wide infrared spectrum and a wide dynamic range: Traditional nickel (Ni) films have stable attenuation in the mid-infrared band, but under high attenuation conditions, excessive film thickness can lead to stress and shedding; while a single gold (Au) film requires extremely low thickness to achieve high transmittance, which is difficult to control in terms of process.

[0004] 2) Difficulty in controlling spectral neutrality across a wide spectrum: Within a wide spectrum, it is necessary to select a suitable substrate and metal film to improve the spectral flatness of the attenuation unit.

[0005] 3) Serialized fabrication issues: To achieve system strength adjustment, a series of attenuation plates with precisely known attenuation values ​​and suitable component devices are required. Traditional single-layer attenuation plate wheels cannot guarantee a series of attenuations over a large dynamic range and cannot be integrated with the control program of the nonlinearity testing system, making automated testing difficult.

[0006] Therefore, it is necessary to develop a combined preparation scheme, using the optimal film structure and substrate material for different attenuation ranges, in order to solve the problems of preparing attenuators with wide infrared spectrum, large dynamic range and serialization. Summary of the Invention

[0007] In view of this, embodiments of this application provide an attenuator, a preparation method, an attenuator wheel assembly, a testing system, and a testing method to solve the problems of preparing wide infrared spectral band, large dynamic range, and serialized attenuators in the prior art.

[0008] A first aspect of this application provides an attenuator for an infrared detector nonlinearity testing system, comprising: a first attenuator group and a second attenuator group.

[0009] Each of the first attenuators in the first attenuator group includes a first substrate and a first coating, wherein the first substrate material is zinc selenide and the first coating material is nickel;

[0010] The thickness of the first coating is 0~450 Å, and the attenuators in the first attenuator group have a first spectral transmittance for 3~17 μm infrared light;

[0011] Each of the second attenuators in the second attenuator group includes a second substrate, an adhesive layer, and a second coating, with the adhesive layer located between the second substrate and the second coating; the second substrate is made of silicon, the second coating is made of gold, and the adhesive layer is made of chromium.

[0012] The thickness of the second coating is 50 Å, and the thickness of the adhesion layer is 90~110 Å; the attenuators in the second attenuator group have a second spectral transmittance for 3~17 μm infrared light, and the second spectral transmittance is less than the first spectral transmittance.

[0013] A second aspect of this application provides a method for preparing an attenuator for an infrared detector nonlinearity testing system, characterized by comprising: preparing a first attenuator: depositing a nickel film 1-2 on a zinc selenide substrate 1-1 by an electron beam evaporation process, controlling the thickness of the Ni film 1-2 to a first preset target thickness, to obtain a first attenuator having a first spectral transmittance for 3~17μm infrared light; wherein the first spectral transmittance is 70%, 60%, 50%, 30%, 10%, or 1%;

[0014] Preparation of the second attenuator: On a double-sided polished silicon wafer substrate 1-3, a chromium film 1-4 of a second preset target thickness is deposited by electron beam evaporation as an adhesion layer, and a gold film 1-5 of a third preset target thickness is deposited to obtain a second attenuator with a second spectral transmittance for 3~17μm infrared light; wherein, the second spectral transmittance is 0.1%~0.2%.

[0015] A third aspect of this application provides an attenuator wheel assembly for an infrared detector nonlinearity testing system. The attenuator wheel assembly is used to mount the first attenuator and the second attenuator provided in the first aspect above, or to mount the first attenuator and the second attenuator prepared by the method provided in the second aspect above.

[0016] The attenuator wheel assembly includes a primary wheel 2-1 and a secondary wheel 2-2 arranged coaxially;

[0017] The first-stage roulette wheel 2-1 includes N first mounting positions; one of the N first mounting positions is used to install a second attenuator, at least one first mounting position is left empty, and the remaining first mounting positions are used to install first attenuators with different first spectral transmittances; N is a positive integer greater than or equal to 4;

[0018] The secondary wheel 2-2 includes M second mounting positions; at least one of the M second mounting positions is empty, and the remaining second mounting positions are used to install first attenuators with different first spectral transmittances; M is a positive integer greater than or equal to 6;

[0019] The first attenuator in the first installation position has a different first spectral transmittance level; the first attenuator in the second installation position has the same first spectral transmittance level.

[0020] A fourth aspect of the present application provides a mid-wave infrared detector response nonlinearity testing system, the testing system including the attenuator wheel assembly provided in the third aspect above;

[0021] The testing system also includes a dual aperture device, a blackbody light source, an off-axis parabolic mirror, a chopper, a pinhole aperture, a detector under test, and a control unit.

[0022] The attenuation wheel assembly is positioned at a preset tilt angle in front of the dual aperture device to prevent light path reflection;

[0023] The emitted light from the blackbody light source is divided into two parallel light paths and two focused light paths by an off-axis parabolic mirror;

[0024] The attenuator wheel assembly is set in the first parallel optical path, the dual aperture device is set in the second parallel optical path, the chopper and pinhole aperture are set at the intersection of the first focusing optical path, and the detector under test is set at the intersection of the second focusing optical path.

[0025] The control unit connects the attenuator wheel assembly and the dual aperture device. It is used to select the combination of attenuators on the two-stage wheel of the attenuator wheel assembly and to control the changes of the dual aperture device to obtain test data on the nonlinearity of the mid-wave infrared detector response.

[0026] A fifth aspect of this application provides a method for testing the response nonlinearity of a mid-wave infrared detector, characterized in that the testing method is used to test the testing system provided in the fourth aspect above;

[0027] The method includes:

[0028] The test sequence was determined; the test sequence covered different combinations of attenuators in the attenuator wheel assembly.

[0029] The test sequence is executed sequentially, and the attenuator wheel assembly and dual aperture device are controlled to obtain the acquired signal.

[0030] The incident photon number flux density and detector nonlinearity corresponding to each execution step are calculated based on the acquired signal using the stored spectral transmittance calibration data.

[0031] Determine the large dynamic range curve of output nonlinearity as a function of photon number flux density.

[0032] The beneficial effects of this application embodiment compared with the prior art are as follows: This application embodiment utilizes a first attenuator group and a second attenuator group to construct an attenuator for an infrared detector nonlinearity testing system. Each first attenuator in the first attenuator group uses a zinc selenide substrate and a nickel film, exhibiting high spectral transmittance. Each second attenuator in the second attenuator group uses a silicon substrate, a gold film, and a chromium adhesion layer, also exhibiting high spectral transmittance. Applying this attenuator to an infrared detector nonlinearity testing system allows for the construction of attenuation components with a large dynamic range by combining different first and second attenuators. The testing system using this attenuator can achieve automatic scanning of incident photon number flux density spanning more than four orders of magnitude, solving the problems of fabrication and system integration of mid-wave large dynamic range attenuation devices, and improving the efficiency and reliability of infrared detector response nonlinearity testing. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of an attenuator for an infrared detector nonlinearity testing system provided in an embodiment of this application.

[0035] Figure 2 This is a schematic diagram of the attenuator wheel assembly for an infrared detector nonlinearity testing system provided in an embodiment of this application.

[0036] Figure 3 This is the optical path diagram of the mid-wave infrared detector response nonlinearity testing system provided in the embodiments of this application.

[0037] Figure 4 The curve is a wide dynamic nonlinearity obtained by testing using the testing system provided in the embodiments of this application.

[0038] Figure 5 This is a spectral curve obtained by performing a spectral test on the prepared attenuator using the test method provided in the embodiments of this application.

[0039] Among them, 1-1: Zinc selenide substrate; 1-2: Nickel film; 1-3: Silicon wafer substrate; 1-4: Chromium film; 1-5: Gold film; 2-1: First-stage wheel; 2-2: Second-stage wheel; 2-3: Stepper motor; 2-4: Stepper motor; 2-5: DP9 interface; 2-6: DP9 interface; 2-7: First mounting position; 2-8: First mounting position; 2-9: First mounting position; 2-10: First mounting position; 2-11: First mounting position; 2-12: First mounting position; 3-1: Blackbody; 3-2: First off-axis parabolic mirror; 3-3: Second off-axis parabolic mirror; 3-4: Third off-axis parabolic mirror; 3-5: Fourth off-axis parabolic mirror; 3-6: Double-layer filter wheel; 3-7: Chopper; 3-8: Pinhole; 3-9: Double aperture device; 3-10: Detector. Detailed Implementation

[0040] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0041] The following will describe in detail, with reference to the accompanying drawings, an attenuator, an attenuator preparation method, an attenuator wheel assembly, and a mid-wave infrared detector response nonlinearity testing system and method according to embodiments of this application.

[0042] Example 1

[0043] Figure 1 An attenuator for an infrared detector nonlinearity testing system, as provided in an embodiment of this application, is illustrated. Figure 1 As shown, the attenuator includes a first attenuator group and a second attenuator group. Each first attenuator in the first attenuator group includes a first substrate and a first coating. The first substrate material is zinc selenide (SeZn), i.e., the first substrate is a zinc selenide substrate 1-1; the first coating material is nickel, i.e., the first coating is a Ni film 1-2.

[0044] In some embodiments of this application, the thickness of the first coating can be 0~450Å, and the attenuators in the first attenuator group have a first spectral transmittance for 3~17μm infrared light.

[0045] Meanwhile, each of the second attenuators in the second attenuator group includes a second substrate, an adhesive layer, and a second coating. The adhesive layer is located between the second substrate and the second coating. The material of the second substrate is silicon (Si), that is, the second substrate is a silicon wafer substrate 1-3. The material of the second coating is gold (Au), that is, the second coating is a gold film 1-5. The material of the adhesive layer is chromium (Cr), that is, the adhesive layer is a chromium film 1-4.

[0046] The thickness of the second coating can be 50 Å, and the thickness of the adhesion layer can be 90~110 Å; the attenuators in the second attenuator group have a second spectral transmittance for 3~17 μm infrared light, and the second spectral transmittance is less than the first spectral transmittance.

[0047] In some embodiments of this application, the thickness of the first coating can be selected as 0 Å, 50 Å, 75 Å, 100 Å, 300 Å, or 400 Å, corresponding to first spectral transmittances of 70%, 60%, 50%, 30%, 10%, and 1%, respectively. That is, the first spectral transmittance is 70% when the first coating thickness is 0 Å, 60% when the first coating thickness is 50 Å, 50% when the first coating thickness is 75 Å, 30% when the first coating thickness is 100 Å, 10% when the first coating thickness is 300 Å, and 1% when the first coating thickness is 400 Å.

[0048] The transmittance of the second spectrum is approximately 0.1% to 0.2%.

[0049] According to the technical solution provided in the embodiments of this application, an attenuator is constructed using a first attenuator group and a second attenuator group to form an attenuator for an infrared detector nonlinearity testing system. Each first attenuator in the first attenuator group uses a zinc selenide substrate and a nickel film, exhibiting high spectral transmittance. Each second attenuator in the second attenuator group uses a silicon substrate, a gold film, and a chromium adhesion layer, also exhibiting high spectral transmittance. By applying this attenuator to the infrared detector nonlinearity testing system, a large dynamic range attenuation component can be constructed by combining different first and second attenuators. The testing system using this attenuator can achieve automatic scanning of incident photon number flux density spanning more than four orders of magnitude, solving the problems of fabrication and system integration of mid-wave large dynamic range attenuation devices, and improving the efficiency and reliability of infrared detector response nonlinearity testing.

[0050] Example 2

[0051] This application also provides a method for preparing an attenuator for an infrared detector nonlinearity testing system, comprising the following steps:

[0052] Preparation of the first attenuator: On the zinc selenide substrate 1-1, a nickel film 1-2 is deposited by electron beam evaporation process. The thickness of the Ni film 1-2 is controlled to a first preset target thickness to obtain a first attenuator with a first spectral transmittance for 3~17μm infrared light; wherein the first spectral transmittance is 70%, 60%, 50%, 30%, 10% or 1%.

[0053] Preparation of the second attenuator: On a double-sided polished silicon wafer substrate 1-3, a chromium film 1-4 of a second preset target thickness is deposited by electron beam evaporation as an adhesion layer, and a gold film 1-5 of a third preset target thickness is deposited to obtain a second attenuator with a second spectral transmittance for 3~17μm infrared light; wherein, the second spectral transmittance is 0.1%~0.2%.

[0054] In some implementations, the first preset target thickness is 0~450 Å; the second preset target thickness is 100 Å; and the third preset target thickness is 50 Å.

[0055] In other words, two different schemes adapted to different attenuation ranges can be used to prepare two types of attenuators, and these two types of attenuators can be combined to form an attenuator for an infrared detector nonlinearity testing system.

[0056] The first scheme involves depositing a nickel film 1-2 on a zinc selenide substrate 1-1 using an electron beam evaporation process, precisely controlling the thickness of the nickel film 1-2 to a preset target thickness. The preset target thickness can be selected within the range of 0 to 450 Å based on the required optical density, thus preparing neutral density attenuators with transmittances of 70%, 60%, 50%, 30%, 10%, and 1% within a range of 3 to 17 μm.

[0057] The zinc selenide substrate has low absorption in this band, and the nickel film has relatively small dispersion, ensuring that this series of attenuators has good spectral neutrality over a wide range.

[0058] The second approach involves using a double-sided polished silicon wafer as the substrate to achieve lower transmittance while ensuring film adhesion and spectral neutrality. A 100 Å chromium (Cr) film 1-4 can be deposited as an adhesion layer on the double-sided polished silicon substrate 1-3 via electron beam evaporation, followed by the deposition of a gold (Au) film 1-5, to prepare an attenuator with a transmittance of approximately 0.1% to 0.5% within the 3–17 μm range.

[0059] This structure utilizes the high reflectivity of gold in the infrared band to achieve extremely low spectral transmittance (approximately 0.1%~0.2%) with a relatively thin overall film thickness. Meanwhile, the silicon substrate has good mechanical stability in the infrared band, and the chromium adhesion layer enhances the adhesion of the gold film.

[0060] All attenuators prepared by the two schemes need to be calibrated by measuring their spectral transmittance in the mid-infrared band using a Fourier spectrometer, and their spectral transmittance curve data should be obtained.

[0061] Example 3

[0062] Figure 2 The structure of an attenuator wheel assembly for an infrared detector nonlinearity testing system provided in this application embodiment is shown. The attenuator wheel assembly is used to install the first attenuator and the second attenuator in Embodiment 1, or to install the first attenuator and the second attenuator prepared by the method provided in Embodiment 2.

[0063] like Figure 2 As shown, the attenuator wheel assembly includes a primary wheel 2-1 and a secondary wheel 2-2 arranged coaxially. The primary wheel 2-1 includes N first mounting positions; one of the N first mounting positions is used to install a second attenuator, at least one first mounting position is left empty, and the remaining first mounting positions are used to install first attenuators with different first spectral transmittances; N is a positive integer greater than or equal to 4.

[0064] The secondary wheel 2-2 includes M second mounting positions; at least one of the M second mounting positions is vacant, and the remaining second mounting positions are used to install first attenuators with different first spectral transmittances; M is a positive integer greater than or equal to 6.

[0065] Each first attenuator in the first installation position has a different first spectral transmittance level; each first attenuator in the second installation position has the same first spectral transmittance level.

[0066] In one example, the first-level roulette wheel 2-1 may include six first mounting positions: 2-7, 2-8, 2-9, 2-10, 2-11, and 2-12. The second-level roulette wheel 2-2 may also include six second mounting positions.

[0067] Multiple first attenuators with different first spectral transmittance levels can be installed in the first installation position, and multiple first attenuators with the same first spectral transmittance level can be installed in the second installation position of the secondary disk 2-2. By installing the first attenuators in this way, the combination of the two-stage disks can achieve attenuation rates spanning multiple orders of magnitude, with a large attenuation amplitude and a relatively uniform distribution of the combined attenuation rate.

[0068] That is, the first and second attenuators, prepared using the two methods described above and covering different attenuation ranges respectively, can be integrated into an automated double-layer wheel assembly: the first attenuators with transmittances of approximately 0.1%, 1%, and 10% are placed in the first-stage wheel 2-1 to achieve order-of-magnitude adjustment of incident radiation; the first attenuators with transmittances of approximately 70%, 60%, 50%, 30%, and 10% are placed in the second-stage wheel 2-2 to achieve fine adjustment. One position in each wheel is reserved without an attenuator to achieve 100% transmittance.

[0069] The primary and secondary photon wheel 2-1 are driven by independent stepper motors 2-3 and 2-4, respectively, and are connected to the host computer via RS485 protocol through DP9 interfaces 2-5 and 2-6, respectively, and are coordinated by the system's main control software. By combining primary coarse adjustment with secondary fine adjustment, and in conjunction with the opening and closing measurement of dual apertures, high-density scanning of incident photon flux density spanning four orders of magnitude can be achieved in the automated nonlinearity testing process.

[0070] In some embodiments, the first spectral transmittance of the first attenuator installed at the first mounting position includes 10% and 1%, and the second spectral transmittance of the second attenuator installed at the first mounting position is 0.1%; the first spectral transmittance of the first attenuator installed at the second mounting position includes 70%, 60%, 50%, 30%, and 10%.

[0071] In other words, the first mounting position of the first-stage wheel 2-1 can be equipped with first attenuators with first spectral transmittances of 10%, 1%, and 0.1%, respectively. Meanwhile, the empty first mounting position can be considered as having a first attenuator with a first spectral transmittance of 100%. Therefore, the first-stage wheel 2-1 can be considered to have four different orders of magnitude of first attenuators: 100%, 10%, 1%, and 0.1%. Here, "order of magnitude" refers to the order of magnitude of the first spectral transmittance.

[0072] The second mounting position of the secondary wheel 2-2 can be used to install first attenuators with first spectral transmittance of 70%, 60%, 50%, 30% and 10% respectively, and these first attenuators have the same order of magnitude of first spectral transmittance.

[0073] When combining two-stage attenuators, taking the first attenuator with a first spectral transmittance of 10% in the first-stage attenuator 2-1 as an example, when combined with the first attenuator with a first spectral transmittance of 100% in the second-stage attenuator 2-2, the total attenuation rate is 10%×100%; when combined with the first attenuator with a first spectral transmittance of 70% in the second-stage attenuator 2-2, the total attenuation rate is 10%×70%; when combined with the first attenuator with a first spectral transmittance of 60% in the second-stage attenuator 2-2, the total attenuation rate is 10%×60%; when combined with the first attenuator with a first spectral transmittance of 50% in the second-stage attenuator 2-2, the total attenuation rate is 10%×50%; when combined with the first attenuator with a first spectral transmittance of 30% in the second-stage attenuator 2-2, the total attenuation rate is 10%×30%; ​​and when combined with the first attenuator with a first spectral transmittance of 10% in the second-stage attenuator 2-2, the total attenuation rate is 10%×10%. This results in an overall attenuation range of 100%×100% to 0.1%×10%. This attenuation range spans four orders of magnitude, and the resulting combined attenuation rates are relatively uniform, with 5 to 6 combined attenuation rates in each order of magnitude, thus constructing an attenuation component with a large dynamic range.

[0074] Example 4

[0075] This application also provides a mid-wave infrared detector response nonlinearity testing system. The system includes the attenuator wheel assembly described in Embodiment 3, and further includes a dual-aperture device, a blackbody light source, an off-axis parabolic mirror, a chopper, a pinhole aperture, the detector under test, and a control unit.

[0076] The attenuator wheel assembly is positioned at a preset tilt angle in front of the dual aperture device to prevent light path reflection. The emitted light from the blackbody light source forms two parallel light paths and two focused light paths through an off-axis parabolic reflector. The attenuator wheel assembly is positioned in the first parallel light path, the dual aperture device is positioned in the second parallel light path, the chopper and pinhole aperture are positioned at the intersection of the first focused light path, and the detector under test is positioned at the intersection of the second focused light path. The control unit connects the attenuator wheel assembly and the dual aperture device, and is used to select the combination of attenuators on the two-stage wheel of the attenuator wheel assembly, and control the changes of the dual aperture device to obtain the test data of the nonlinearity of the mid-wave infrared detector response.

[0077] In some implementations, the control unit may store spectral transmittance calibration data of each attenuator in the attenuator wheel assembly in the 3~17μm band, which is used to integrate the spectral transmittance calibration data according to the response band of the detector when calculating the number flux density of photons incident on the detector.

[0078] Figure 3 The optical path of a mid-wave infrared detector response nonlinearity testing system, also provided in an embodiment of this application, is illustrated. For example... Figure 3 As shown, the optical path includes at least a blackbody 3-1, a first off-axis parabolic mirror 3-2, a second off-axis parabolic mirror 3-3, a third off-axis parabolic mirror 3-4, a fourth off-axis parabolic mirror 3-5, a double-layer filter wheel 3-6, a chopper 3-7, a pinhole 3-8, a double aperture device 3-9, and a detector 3-10.

[0079] The attenuator wheel assembly 3-6 can be integrated into the dual-aperture test optical path. Parallel light is initially positioned through the attenuator mounting holes with 100% transmittance. The stepper motors 2-3 and 2-4 of the dual-layer attenuator wheels are controlled by a program to rotate, positioning different combinations of attenuators within the optical path.

[0080] Simultaneously, the dual-aperture device (3-9) is controlled by a program to obtain nonlinearity test data. Repeating the above process and changing the combination of the dual-layer attenuator, a complete automated test can collect approximately 20 high-precision data points, ultimately yielding... Figure 4 The curves showing the variation of nonlinearity within a dynamic range of approximately four orders of magnitude of photon number flux density are shown.

[0081] Depend on Figure 4 It can be seen that by adjusting the combination of attenuators, the light intensity can be changed. Figure 3 The nonlinear testing system yielded a curve showing the change in detector nonlinearity with photon flux density. The nonlinearity of the response increased with increasing photon flux density.

[0082] Figure 5 The Fourier Transform Infrared (FTIR) spectroscopic test results of the prepared neutral density attenuator are presented. It can be seen that neutral density attenuation of approximately 70%, 60%, 50%, 30%, 10%, 1%, and 0.1% can be achieved in the range of 3 to 17 μm.

[0083] Example 5

[0084] This application also provides a method for testing the response nonlinearity of a mid-wave infrared detector, used in the testing system described in Example 4. The method includes the following steps:

[0085] The test sequence was determined; the test sequence covered different combinations of attenuators in the attenuator wheel assembly.

[0086] The test sequence is executed sequentially, and the attenuator wheel assembly and dual aperture device are controlled to obtain the acquired signal.

[0087] The incident photon number flux density and detector nonlinearity corresponding to each execution step are calculated based on the acquired signal using the stored spectral transmittance calibration data.

[0088] Determine the large dynamic range curve of output nonlinearity as a function of photon number flux density.

[0089] In other words, the embodiments of this application provide a method for preparing and applying a broadband neutral density attenuator suitable for infrared detector response nonlinearity testing systems.

[0090] In terms of fabrication, a segmented approach was proposed: for the transmittance range of 1% to 70%, a nickel film was deposited using electron beam evaporation or electron beam sputtering on a zinc selenide substrate; for the low transmittance range of approximately 0.1% to 0.2%, a chromium / gold composite film was deposited on a silicon substrate, successfully fabricating a series of attenuators covering the 3 to 17 μm band with neutral density attenuation.

[0091] In terms of application, the calibrated series of attenuators are configured in a double-layered disk connected to a host computer to construct a large dynamic range attenuation component, which is then integrated into a mid-infrared detector dual-aperture response nonlinearity testing system. Utilizing the spectral calibration data of the attenuators, the system can achieve automatic scanning of incident photon flux density across four orders of magnitude or more, thus solving the problems of fabrication and system integration of mid-wave large dynamic range attenuation devices and improving the efficiency and reliability of infrared detector response nonlinearity testing.

[0092] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0093] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0094] 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, and should all be included within the protection scope of this application.

Claims

1. An attenuator for an infrared detector nonlinearity testing system, characterized in that, The attenuator includes a first attenuator group and a second attenuator group; Each first attenuator in the first attenuator group comprises a first substrate and a first coating, wherein the first substrate material is zinc selenide and the first coating material is nickel; The thickness of the first coating is 0~450Å, and the attenuators in the first attenuator group have a first spectral transmittance for 3~17μm infrared light; Each of the second attenuators in the second attenuator assembly comprises a second substrate, an adhesive layer, and a second coating, with the adhesive layer located between the second substrate and the second coating; the second substrate is made of silicon, the second coating is made of gold, and the adhesive layer is made of chromium; The thickness of the second coating is 50 Å, and the thickness of the adhesion layer is 90~110 Å; the attenuator in the second attenuator group has a second spectral transmittance for 3~17 μm infrared light, and the second spectral transmittance is less than the first spectral transmittance.

2. The attenuator for an infrared detector nonlinearity testing system according to claim 1, characterized in that, The thickness of the first coating is 0 Å, 50 Å, 75 Å, 100 Å, 300 Å, or 400 Å, corresponding to first spectral transmittances of 70%, 60%, 50%, 30%, 10%, and 1%, respectively. The transmittance of the second spectrum is 0.1%~0.2%.

3. A method for preparing an attenuator for an infrared detector nonlinearity testing system, characterized in that, include: Preparation of the first attenuator: On a zinc selenide substrate (1-1), a nickel film (1-2) is deposited by electron beam evaporation. The thickness of the Ni film (1-2) is controlled to a first preset target thickness to obtain a first attenuator with a first spectral transmittance for 3~17μm infrared light; wherein the first spectral transmittance is 70%, 60%, 50%, 30%, 10%, or 1%. Preparation of the second attenuator: On a double-sided polished silicon wafer substrate (1-3), a chromium film (1-4) of a second preset target thickness is deposited by electron beam evaporation as an adhesion layer, and a gold film (1-5) of a third preset target thickness is deposited to obtain a second attenuator with a second spectral transmittance for 3~17μm infrared light; wherein, the second spectral transmittance is 0.1%~0.2%.

4. The method for preparing an attenuator for an infrared detector nonlinearity testing system according to claim 3, characterized in that, The first preset target thickness is 0~450Å; the second preset target thickness is 100Å; and the third preset target thickness is 50Å.

5. An attenuation wheel assembly for an infrared detector nonlinearity testing system, characterized in that, The attenuator wheel assembly is used to install the first attenuator and the second attenuator as described in claim 1 or 2, or to install the first attenuator and the second attenuator prepared by the method described in claim 3 or 4. The attenuation wheel assembly includes a primary wheel (2-1) and a secondary wheel (2-2) arranged coaxially. The first-stage wheel (2-1) includes N first mounting positions; one of the N first mounting positions is used to install a second attenuator, at least one first mounting position is left empty, and the remaining first mounting positions are used to install first attenuators with different first spectral transmittances; N is a positive integer greater than or equal to 4; The secondary wheel (2-2) includes M second mounting positions; at least one of the M second mounting positions is vacant, and the remaining second mounting positions are used to install first attenuators with different first spectral transmittances; M is a positive integer greater than or equal to 6; The first attenuator in the first installation position has a different first spectral transmittance level; the first attenuator in the second installation position has the same first spectral transmittance level.

6. The attenuation wheel assembly for an infrared detector nonlinearity testing system according to claim 5, characterized in that, The first spectral transmittance of the first attenuator installed at the first mounting position includes 10% and 1%, and the second spectral transmittance of the second attenuator installed at the first mounting position is 0.1%. The first spectral transmittance of the first attenuator installed in the second mounting position includes 70%, 60%, 50%, 30%, and 10%.

7. The attenuation wheel assembly for an infrared detector nonlinearity testing system according to claim 5, characterized in that, Both the primary wheel (2-1) and the secondary wheel (2-2) are equipped with stepper motors; The stepper motor drives at least one of the first-stage wheel (2-1) and the second-stage wheel (2-2) to rotate, thereby obtaining the target attenuator combination.

8. A system for testing the nonlinearity of a mid-wave infrared detector response, characterized in that, The testing system includes the attenuation wheel assembly as described in any one of claims 5 to 7; The testing system also includes a dual aperture device, a blackbody light source, an off-axis parabolic mirror, a chopper, a pinhole aperture, a detector under test, and a control unit. The attenuation wheel assembly is positioned at a preset tilt angle in front of the dual aperture device to prevent light path reflection; The emitted light from the blackbody light source is divided into two parallel light paths and two focused light paths by an off-axis parabolic mirror; The attenuator wheel assembly is set in the first parallel optical path, the dual aperture device is set in the second parallel optical path, the chopper and pinhole aperture are set at the intersection of the first focusing optical path, and the detector under test is set at the intersection of the second focusing optical path. The control unit connects the attenuator wheel assembly and the dual aperture device. It is used to select the combination of attenuators on the two-stage wheel of the attenuator wheel assembly and to control the changes of the dual aperture device to obtain test data on the nonlinearity of the mid-wave infrared detector response.

9. The mid-wave infrared detector response nonlinearity testing system according to claim 8, wherein the control unit stores spectral transmittance calibration data of each attenuator in the attenuator wheel assembly in the 3~17μm band, and is used to integrate the spectral transmittance calibration data according to the response band of the detector when calculating the photon number flux density incident on the detector.

10. A method for testing the nonlinearity of the response of a mid-wave infrared detector, characterized in that, The testing method is used to perform testing using the testing system described in claim 8 or 9; The method includes: The test sequence is determined; the test sequence covers different combinations of attenuators in the attenuator wheel assembly; The test sequence is executed sequentially, and the attenuator wheel assembly and dual aperture device are controlled to obtain the acquired signal. Using the stored spectral transmittance calibration data, the incident photon number flux density and detector nonlinearity corresponding to each execution step are calculated based on the acquired signal. Determine the large dynamic range curve of output nonlinearity as a function of photon number flux density.

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