CN103292980B - The measurement mechanism of photodetector linearity and cryogenic radiometry - Google Patents

Abstract

A measuring device for the straightness and surface response uniformity of a photodetector consists of three parts: a light source part, a device part and an instrument. The light source part is composed of a 1053nm pigtailed fiber laser, a fiber attenuator and a fiber collimator. The device part consists of an aperture, a 1/4 wave plate, a wedge mirror, a reflector, a power attenuator, a polarization beam splitter, an optical switch and a BNC-T head. The equipment part is composed of a chopper, a lock-in amplifier, a thermostat, a standard detector, a detector to be tested, a data acquisition card and a computer. The present invention adopts the principle of double optical path superposition method and utilizes the advantages of narrow line width of laser light source to realize accurate measurement of straightness and surface response uniformity of different photodetectors at specific wavelengths, and has the advantages of stable operation, strong anti-interference, It has the advantages of large dynamic range, convenient and quick measurement, etc., and the repeat measurement accuracy is better than 0.08%.

Description

Measuring device for photodetector straightness and surface response uniformity

technical field

The invention belongs to a detector characteristic parameter measuring device, in particular to a measuring device for the straightness and surface response uniformity of a photodetector.

Background technique

Linear measurement has always been an extremely important part of photoradiometric research and performance evaluation of photoelectric sensors, and straightness is one of the most basic characteristic parameters of detectors. However, in general, almost all detectors have linearity problems. Moreover, the calibration of these detectors or the measurement system composed of these detectors can only be carried out within a very limited range, and most of the areas outside the calibration point can only be estimated by the linearity of the system. The accuracy is very poor; at the same time, general detector manufacturers do not give the surface response uniformity of large-area detectors, which is very bad for users who need this indicator. At present, there is no mature instrument for measuring the straightness of photodetectors on the market. The straightness of detectors is generally measured by building a detection platform in a laboratory where necessary. The measurement results of these measuring devices are often affected by the stability of the light source, Limitations of factors such as temperature and external environmental noise, especially when the optical power is below 0.01 microwatts, the influence of noise is very large, which seriously affects the measurement results. Therefore, a high-precision device for measuring the straightness of the detector and the uniformity of the surface response is needed to measure the characteristic parameters of various photodetectors.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the above-mentioned existing technical problems and deficiencies, and provide a measuring device for the straightness and surface response uniformity of the photodetector, which should be able to realize the uniformity of the straightness and surface response of the photodetector. It should be able to measure the optical power within the dynamic range of 0.05nw to 0.5mw. It should be stable in operation, strong in anti-interference ability, and high in repeatable measurement accuracy.

The technical scheme that the present invention solves is as follows:

A measuring device for the straightness and surface response uniformity of a photodetector is characterized in that its composition includes: a light source, an optical fiber attenuator, an optical fiber collimator, an aperture, a chopper, a 1/4 wave plate, a wedge mirror, a second A reflector, a second reflector, a third reflector, a power attenuator, a first polarization beamsplitter, a second polarization beamsplitter, a first optical switch, a second optical switch and BNC-T head, a first phase lock Amplifier, second lock-in amplifier, standard photodetector, photodetector to be tested, data acquisition card, computer and incubator, the positional relationship of the above components is as follows:

The light source, fiber attenuator, fiber collimator, aperture, chopper, 1/4 wave plate, wedge mirror, first reflector, second reflector, third reflector, power attenuator, the first A polarization beam splitting prism, a second polarization beam splitting prism, a first optical switch, and a second optical switch are all placed in the incubator, along the direction of the single-mode linearly polarized light output by the light source, followed by the optical fiber Attenuator, fiber collimator, diaphragm, chopper, 1/4 wave plate and wedge mirror constitute the main optical path, the light source part provides laser output with narrow line width, the output power is adjusted through the fiber attenuator, and the output power from the fiber The optical path after the collimator is spatial light. The wedge mirror divides the main light path into a reference light path and a measurement light path. The composition of the measurement light path includes: a power attenuator, a first polarization beamsplitter prism and a second polarization beamsplitter prism with light splitting surfaces parallel to each other. A polarization beam splitting prism divides the incident light into a parallel polarization optical path and a vertical polarization optical path, and the parallel polarization optical path is sequentially composed of a first optical switch, a second reflector, a second polarization beam splitting prism and a photodetector to be tested, and the described The vertical polarization light path includes a third reflector, a second optical switch, a second polarization beam splitter and a photodetector to be tested, and the reference light path is sequentially formed by the first reflector and the standard in the direction of reflected light from the wedge mirror. The photodetector constitutes, the optical path from the wedge mirror to the reference optical path of the standard photodetector is equal to the optical path from the wedge mirror to the measuring optical path of the photodetector to be tested, and the output terminal of the standard photodetector is connected to the second lock-in amplifier The first input end of the photodetector to be tested is connected to the first input end of the described photodetector to be tested, and the first input end of the first lock-in amplifier is connected to the first input end of the described chopper. Be connected with the second input end of the first lock-in amplifier, the second input end of the second lock-in amplifier, the output end of the first lock-in amplifier and the output end of the second lock-in amplifier through the described The data acquisition card is connected to the input terminal of the computer, the photodetector to be tested is placed on the two-dimensional electromechanical mobile platform, and the output terminal of the computer is connected to the control terminal of the two-dimensional electromechanical mobile platform .

The power of the reference optical path and the measurement optical path is adjusted through the optical fiber attenuator. The optical power of the reference optical path on the standard photodetector is guaranteed to be between 0.1 microwatts and 200 microwatts. In actual operation, a fixed power is selected , the reference optical path will not change after the entire optical path is adjusted.

The advantages of the present invention are:

1. The double optical path method is adopted to reduce the influence of light source shaking, and the thermostat is used to reduce the influence of temperature and stray light, so the device operates stably and has strong anti-interference ability.

2. Use chopper and lock-in amplifier to measure weaker signals, use fiber attenuator and power attenuator to achieve higher dynamic range, so the device has a large dynamic range and can achieve straightness and surface response Accurate measurement of uniformity.

3. Under the requirement that the optical power is greater than 0.1 microwatts, the lock-in amplifier may not be used to reduce costs, and different light sources may be used to measure specific optical wavelengths, so the device is simple and flexible.

Description of drawings

Fig. 1 is the structural representation of the measurement device of the straightness of the photodetector and the uniformity of the surface response of the present invention

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the protection scope of the present invention should not be limited thereby.

Please refer to Fig. 1, Fig. 1 is a schematic structural diagram of the measuring device of the straightness of the photodetector and the uniformity of the surface response of the present invention, as can be seen from Fig. 1, the composition of the measuring device of the straightness of the photodetector of the present invention and the uniformity of the surface response Including: light source 1, fiber attenuator 2 and fiber collimator 3, aperture 4, chopper 5, 1/4 wave plate 6, wedge mirror 8, first mirror 7, second mirror 14, third Mirror 13, power attenuator 9, first polarization splitter prism 10, second polarization splitter prism 15, first optical switch 11, second optical switch 12 and BNC-T type head 19, first lock-in amplifier 20, the second Two lock-in amplifiers 21, standard photodetector 16, photodetector 17 to be measured, data acquisition card 22, computer 23 and incubator 18, the positional relationship of above-mentioned components is as follows:

The light source 1, the fiber attenuator 2, the fiber collimator 3, the diaphragm 4, the chopper 5, the 1/4 wave plate 6, the wedge mirror 8, the first reflector 7, the second reflector 14, the first Three reflection mirrors 13, power attenuator 9, first polarization beam splitter prism 10, second polarization beam splitter prism 15, first optical switch 11, second optical switch 12 are all placed in the described constant temperature box 18, along the described The direction of the single-mode linearly polarized light output by the light source 1 is followed by the fiber attenuator 2, the fiber collimator 3, the diaphragm 4, the chopper 5, the 1/4 wave plate 6 and the wedge mirror 8 to form the main optical path, The wedge mirror 8 divides the main light path into a reference light path and a measurement light path. The composition of the measurement light path includes: a power attenuator 9, a first polarization beamsplitter prism 10 and a second polarization beamsplitter prism 15 whose beam splitting surfaces are placed parallel to each other. The first polarization beam splitter 10 described above divides the incident light into a parallel polarization optical path and a vertical polarization optical path. Photodetector 17, described vertical polarization optical path comprises the 3rd reflecting mirror 13, the second optical switch 12, the second polarization beam splitter prism 15 and the photodetector 17 to be measured, and described reference optical path is in described wedge mirror The reflected light direction of 8 is constituted successively by the first reflecting mirror 7 and the standard photodetector 16, the reference light path from the wedge mirror 8 to the standard photodetector 16 and the light from the measuring light path from the wedge mirror 8 to the photodetector 17 to be measured The process is equal, the output of the standard photodetector 16 is connected with the first input of the second lock-in amplifier 21, the output of the photodetector 17 to be tested is connected with the first lock-in amplifier 20 The first input end of the described chopper 5 is respectively connected with the second input end of the first lock-in amplifier 20 and the second lock-in amplifier 21 of the second lock-in amplifier 21 through the BNC-T type head 19. Input end is connected, and the output end of described first lock-in amplifier 20 and the output end of second lock-in amplifier 21 are connected through described data acquisition card 22 and the input end of computer 23, described photodetector to be tested 17 is placed on the two-dimensional electromechanical mobile platform, and the output terminal of the computer 23 is connected with the control terminal of the two-dimensional electromechanical mobile platform.

The light source 1 is a laser with fiber pigtail output.

First, the optical path is adjusted, and the optical path is adjusted as shown in Figure 1. The light source part includes a pigtailed fiber laser 1, a fiber attenuator 2 and a fiber collimator 3, and the three are directly connected through a polarization-maintaining fiber. The pigtailed fiber laser 1 Output single-mode linearly polarized light, wavelength 1053nm, fiber attenuator 2 has an attenuation range of at least 3 orders of magnitude, fiber collimator 3 has an output spot size of 0.45mm; adjust the output power of the laser to 3 milliwatts, and then adjust the fiber The attenuator 2 is until the output power of the fiber collimator 3 is 2.5 milliwatts, and now the light reaches the wedge mirror 8 through the diaphragm 4, the chopper 5 and the 1/4 wave plate 6, and the reflectivity of the wedge mirror 8 is 4.6%. The power of the reference optical path is 0.112 milliwatts, and the light of the reference optical path reaches the power of the standard photodetector 16 through the reflector 7 (the reflectivity is 90%) to be 0.1 milliwatts, ensuring that the power is in the linear interval of the standard photodetector 16, and the wedge mirror The transmittance of 8 is 92%, and the optical power of the measuring optical path is 1.85 milliwatts. The power attenuator 9 has an attenuation range of 6 orders of magnitude, which can attenuate the light of the measuring optical path to a minimum of 2 nanowatts, and the light passes through The minimum power reaching the photodetector 17 to be tested by the two polarization beam splitters 10 and 15 is 1 nanowatt. After the fiber attenuator 2 and the power attenuator 9 are combined, the actual dynamic range is 0.05nw-0.5mw.

The chopper 5 modulates the light into a square wave of a specific frequency. It is advisable to select the frequency value away from the AC frequency of 50Hz and its multiples, such as choosing 80Hz, 120Hz, 230Hz or the like; Wave frequency is connected with lock-in amplifier 20,21 through BNC-T type head 19; The output of standard photodetector 16 is connected with lock-in amplifier 21, and the output of photodetector 17 to be tested is connected with lock-in amplifier 20; Data acquisition card 22 is a dual-channel input, the A channel is connected to the lock-in amplifier 20, and the B channel is connected to the lock-in amplifier 21, and finally the computer 23 is used to control and collect; Control the motion of the 2D electromechanical stage for mobile scanning.

Before described computer 23 is processed, following assumption is arranged:

Make the power of the light that passes through the polarization beam splitter 10 parallel-polarized to arrive at the photodetector 17 to be tested separately be _PA , then the output of the first lock-in amplifier 20 is V( _PA ), and the output of the second lock-in amplifier 21 is V (P _AR ); the power that the light that makes the vertically polarized light of the polarization beam splitter prism 10 arrive independently at the photodetector 17 to be measured is P _B , then the output of the first lock-in amplifier 20 is V (P _B ), and the second lock-in amplifier The output of 21 is V(P _BR ); the power that makes the light of parallel polarization and vertical polarization reach the photodetector 17 under test together is P _A +P _B , then the output of the first lock-in amplifier 20 is V(P _A + P _B ), the output of the second lock-in amplifier 21 is V(P _(A+B)R ), and the straightness is defined as formula:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; AR</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; BR</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

Adjust the power attenuator 9 to attenuate with an attenuation coefficient less than or equal to 50% each time, and the coefficient can be set (here, the attenuation with a coefficient of 50% is used as an example). Since the dynamic range is 0.05nw-0.5mw, there are 7 The order of magnitude is attenuated 24 times, and 24 data can be obtained. Calculate the straightness under the corresponding power (P _A +P _B ) _i (i=1,2,3,...,24):

${\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; AR</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; BR</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2,3</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; twenty\; four</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; II</span>}<span\; class="notranslate">\; )</span>$

After the assumption is completed, at first carry out the straightness measurement of the photodetector 17 to be tested, and the computer 23 carries out the following processing:

When the power attenuator 9 does not attenuate, and when the optical switches 11 and 12 of the optical path of the parallel polarization and vertical polarization through the polarization beam splitter 10 are all opened, the power entering the photodetector to be tested is 1mw, and the following operations are performed on this basis:

Attenuate the power attenuator 9 by 50%, first open the optical switch 11 of the optical path of parallel polarization, close the optical switch 12 of the optical path of vertical polarization, and the computer 23 controls the data acquisition card 22 to collect data, and the A and B channels collect 1000 data respectively , A channel calculates the average value of 1000 collected data to obtain V(P _A ) ₁ , B channel obtains the average value of 1000 collected data to obtain V(P _AR ) ₁ ; then turn on the vertical polarization The optical switch 12 of the optical path closes the optical switch 11 of the parallel polarization optical path, the computer 23 controls the data acquisition card 22 to collect data, the A and B channels collect 1000 data respectively, and the A channel calculates the average value of the collected 1000 data , get V(P _B ) ₁ , calculate the average value of 1000 collected data in channel B, get V(P _BR ) ₁ ; then open the optical switches 11 and 12 of the optical paths of parallel polarization and vertical polarization at the same time, and the computer 23 Control the data acquisition card 22 for data acquisition, the A and B channels collect 1000 data respectively, the A channel obtains the average value of the collected 1000 data, and obtains V( _PA +P _B ) ₁ , and the B channel obtains the collected data The average value of the 1000 data, get V(P _(A+B)R ) ₁ ; finally calculate the straightness when the power is at 0.5mw:

${\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; AR</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; BR</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; V</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

$\left(\mathrm{III}\right)$

Next, the power attenuator is attenuated by 50%, the above operation is repeated, and the power attenuator and the fiber attenuator are used in combination, and so on, the straightness _Δi ( i=1,2,3,...,24), as shown in formula (II), there are 24 data in total, and among these 24 data, choose the one whose straightness is closest to 1 (if there are more than one, choose any a), for example, Δ _n (1≤n≤24) is closest to 1, then the straightness correction coefficient θ _n of the nth point = 1, then the straightness correction coefficient of any other point m is (IV) formula:

$\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ></span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; IV</span>}<span\; class="notranslate">\; )</span>$

From the obtained straightness correction coefficient θ _m (m=1,2,3,...,24), the corresponding linear interval and its quality can be judged as follows:

In the corresponding power interval of |θ _m -1|>0.01 (m=1, 2, 3,...,24), it is considered that the straightness of the photodetector 17 to be tested is relatively poor, and when 0.01<|θ _m -1| <0.001 (m=1,2,3,...,24) of the corresponding power range, it is considered that the straightness of the photodetector 17 to be tested is relatively good, at |θ _m -1|<0.001 (m=1,2, 3,...,24), the straightness of the photodetector 17 to be tested is considered to be very good; so far, the straightness and required linear range of the photodetector 17 to be tested at different powers can be obtained.

Carry out the surface response uniformity measurement of photodetector 17 to be tested then, at this moment photoswitch 11,12 are opened all the time, the spot diameter of beam incident on standard photodetector 16 and photodetector 17 to be measured is 1mm, by computer 26 pair The two-dimensional electromechanical stage of clamping photodetector 17 to be tested carries out scanning control, and the spacing of scanning control is 1mm, and the contour of scanning is a square, and the square size is the peripheral maximum length of detection surface of photodetector 17 to be measured (assuming that measured The maximum length is S millimeters, then the points that need to be scanned are N, N=S*S), to include the whole detection surface of the photodetector 17 to be tested, the starting point of scanning is the bottom left when facing the photodetector 17 to be measured The corner is a coordinate point, assuming that the coordinates are (X, Y) (0≤X≤S, 0≤Y≤S).

Regulate the power attenuator 9, make the power P _OSR of the reference light incident on the standard photodetector (16) as close as possible to the power P _OSR of the measurement light incident on the photodetector 17 to be measured = 0.1 milliwatts, the standard of adjustment is the A channel The collected data should be as equal as possible to the data collected by channel B; after adjustment, ensure that the position and optical power of the measurement optical path remain unchanged, assuming that the actual incident power after adjustment is P _OS (P _OS ≈ P _OSR ).

The computer 23 controls the two-dimensional mechanical and electric stage to scan the detection surface of the photoelectric detector 17 to be tested. Starting from the coordinate origin, the scanning coordinates are (X, Y) (0≤X≤S, 0≤Y≤S), and the photoelectric to be tested The detector 17 first moves toward the negative axis of the X axis, and performs one-dimensional horizontal scanning. There are S points in the horizontal scanning. Move in the positive direction to perform one-dimensional horizontal scanning, and the number of horizontal scanning points is S, and so on to scan the entire surface.

During the scanning process, the computer 23 controls the data acquisition card 22 to carry out data acquisition and processing as follows:

Whenever a point (X, Y) (0≤X≤S, 0≤Y≤S) is scanned, the A channel collects 1000 data and calculates the average value. The result obtained by the A channel is V(P _OS ) _{(X, Y)} ; B channel collects 1000 data, calculates the average value, the result obtained by B channel is V(P _OSR ) _(X,Y) , and then calculates the ratio of A channel and B channel As the response value of the coordinate point, such as formula (V):

After getting the response value of each point (X, Y) (0≤X≤S, 0≤Y≤S) (0≤X≤S,0≤Y≤S), discard the response value point, keep the response value , find all remaining response values The standard deviation σ of , using 3σ to represent the measurement uncertainty, using the measurement uncertainty to characterize the surface response uniformity of the photodetector 17 to be tested, so far the surface response uniformity of the photodetector 17 to be tested is obtained.

In summary, the device of the present invention can realize accurate measurement of photodetector straightness and surface response uniformity, has the advantages of stable operation, strong anti-interference, large dynamic range, convenient and quick measurement, etc., and the repeated measurement accuracy is better than 0.08% .

Claims (2)

1. the measurement mechanism of a photodetector linearity and cryogenic radiometry, be characterised in that its formation comprises: light source (1), fibre optic attenuator (2) and optical fiber collimator (3), diaphragm (4), chopper (5), quarter wave plate (6), wedge mirror (8), first catoptron (7), second catoptron (14), 3rd catoptron (13), power attenuator (9), first polarization splitting prism (10), second polarization splitting prism (15), first photoswitch (11), second photoswitch (12) and BNC-T type head (19), first lock-in amplifier (20), second lock-in amplifier (21), standard light electric explorer (16), photodetector to be measured (17), data collecting card (22), computing machine (23) and constant temperature oven (18), the position relationship of above-mentioned component is as follows:

Described light source (1), fibre optic attenuator (2), optical fiber collimator (3), diaphragm (4), chopper (5), quarter wave plate (6), wedge mirror (8), first catoptron (7), second catoptron (14), 3rd catoptron (13), power attenuator (9), first polarization splitting prism (10), second polarization splitting prism (15), first photoswitch (11), second photoswitch (12) is all placed in described constant temperature oven (18), along the single mode linearly polarized light direction that described light source (1) exports, described fibre optic attenuator (2) successively, optical fiber collimator (3), diaphragm (4), chopper (5), quarter wave plate (6) and wedge mirror (8) form main optical path, main optical path is divided into reference path and optical path by this wedge mirror (8), the formation of described optical path comprises: power attenuator (9), light splitting surface be parallel to each other place the first polarization splitting prism (10) and the second polarization splitting prism (15), incident light is divided into parallel polarization light path and vertical polarization light path by described the first polarization splitting prism (10), described parallel polarization light path is the first photoswitch (11) successively, second catoptron (14), second polarization splitting prism (15) and photodetector to be measured (17), described vertical polarization light path comprises the 3rd catoptron (13), second photoswitch (12), second polarization splitting prism (15) and photodetector to be measured (17), described reference path is made up of the first catoptron (7) and standard light electric explorer (16) successively the reflected light direction at described wedge mirror (8), from wedge mirror (8) to the reference path of standard light electric explorer (16) with from wedge mirror (8) to the equivalent optical path of the optical path of photodetector to be measured (17), the output terminal of described standard light electric explorer (16) is connected with the first input end of the second lock-in amplifier (21), the output terminal of described photodetector to be measured (17) is connected with the first input end of described the first lock-in amplifier (20), described chopper (5) through described BNC-T type head (19) respectively with the second input end of described the first lock-in amplifier (20), second input end of the second lock-in amplifier (21) is connected, the output terminal of described the first lock-in amplifier (20) is connected with the input end of computing machine (23) through described data collecting card (22) with the output terminal of the second lock-in amplifier (21), described photodetector to be measured (17) is placed on two dimensional motor tool mobile platform, the output terminal of described computing machine (23) is connected with the control end of described two dimensional motor tool mobile platform.

2. the measurement mechanism of photodetector linearity according to claim 1 and cryogenic radiometry, is characterized in that: described light source (1) is the laser instrument that band optical fiber pigtail exports.