CN101825516A - Device and method for testing infrared focal plane array device - Google Patents

Abstract

The invention discloses a device for testing an infrared focal plane array device, which comprises a radiation source and focal plane array module, a drive control module and a data acquisition processing module, wherein the radiation source and focal plane array module comprises an infrared radiation source, an optical system and a tested infrared focal plane array; the drive control module comprises a bias control module, a temperature control module and a time sequence control module; and the data acquisition processing module comprises an analog-to-digital signal converter, a video output module, a data acquisition card and a data analysis processing module. The device of the invention has the characteristics of low cost, high efficiency, accuracy, reliability and the like, is suitable for testing the large-scale infrared focal plane array device, and is of very important instructive significance to the designer of the device and the designer of an imaging system.

Description

A kind of proving installation of infrared focal plane array device and method of testing thereof

Technical field

The present invention relates to the infrared detection technique field, be specifically related to a kind of infrared focal plane array device proving installation and method of testing thereof of novel universal.

Background technology

Infrared imaging is the product of multidisciplinary, multi-field technological synthesis development, and its gordian technique comprises: infrared-sensitive material, semiconductor device technology, integrated circuit (IC) design, encapsulation technology, measuring technology and vacuum technique etc.In recent years, follow the fast development of each gate technique, infrared imagery technique has also obtained developing rapidly, has obtained using widely aspect civil and military.Infrared focal plane array (IRFPA) is the core devices of gazing type infra-red thermal imaging system, and its performance is directly connected to the performance evaluation of thermal infrared imager and the optimization of image processing algorithm.Building an effective infrared focal plane array device performance parameter test platform is the prerequisite that infrared focal plane array device is accurately estimated; Simultaneously, infrared focal plane array performance parameter and data statistics feature are the important evidence of carrying out the infrared imaging Flame Image Process, and the effect of image processing algorithm is except having certain relation with algorithm itself, also directly related with the data characteristics of image.Therefore, the infrared focal plane array device performance parameter test all has very important directive significance for the deviser of designs fabricator and thermal imaging system.

Different with the unit infrared eye, infrared focal plane array can not only be converted into heat radiation faint electric signal, but also has sensing circuit (ROIC), and the face battle array signal that can will obtain is exported through certain mode.Therefore the parameter evaluation of infrared focal plane array and parameter evaluation to the unit infrared eye are had a great difference, except will assessing the performance of each detector pixel, the performance of also tackling infrared focal plane array has whole evaluating.

Infrared focal plane array device characterisitic parameter testing standard is the 1998-07-18 issue, the State Standard of the People's Republic of China GB/T 17444-1998 that 1999-05-01 comes into effect " infrared focal plane array characterisitic parameter measuring technology standard ", the parameter-definition and the method for testing that are used to estimate infrared focal plane array have been provided, to the research of infrared imaging device with use highly significant this canonical system.Mainly the infrared focal plane array performance parameter is described by following index:

(1) pixel responsiveness: the focal plane output signal voltage that pixel per unit irradiation power produces in dynamic range under certain frame period or line period condition.

(2) invalid pixel comprises dead pixel and overheated pixel.Dead pixel: the pixel responsiveness is less than the pixel of average response rate 10%.Overheated pixel: the pixel noise voltage is greater than the pixel of 10 times of average noise voltages.

(3) pixel noise voltage: the root-mean-square value of focal plane pixel output signal voltage fluctuation under the background radiation parameter.

(4) noise equivalent temperature difference: this temperature difference was called noise equivalent temperature difference when average noise voltage equated with the signal voltage that the target temperature difference produces.

(5) pixel detecting rate: unit irradiation projects on the pixel of unit area, the signal to noise ratio (S/N ratio) that obtains in unit bandwidth.

(6) dynamic range: the ratio of saturation irradiation power and noise equivalent irradiation power.

(7) spectral response range: relative spectral response is 0.5 o'clock, the wavelength coverage between pairing incident irradiation minimal wave length and the long wavelength.

Summary of the invention

Problem to be solved by this invention is: proving installation and method of testing thereof that how a kind of infrared focal plane array device is provided, this proving installation and method of testing can directly be tested various infrared focal plane array devices, and various performance parameters are provided easily and fast, exactly.

Technical matters proposed by the invention is to solve like this: a kind of proving installation of infrared focal plane array device is provided, it is characterized in that, comprise radiation source and focal plane arrays (FPA) module, drive control module and digital sampling and processing, wherein:

1. radiation source and focal plane arrays (FPA) module comprise:

One infrared origin: provide have higher emissivity, the blackbody radiation source of good stability, homogeneity and low drift characteristic;

One optical system: mainly constitute, the infrared acquisition wave band of focal plane is had good transmitance, filter the wave band beyond the infrared acquisition wave band, the infrared radiation of infrared origin is focused on the infrared focal plane array by the infrared optics lens;

One tested infrared focal plane array;

2. drive control module comprises:

One bias voltage control module: provide work required low noise Dc bias to tested infrared focal plane array device;

One temperature control modules: provide temperature control to tested infrared focal plane array device, guarantee the homogeneity of temperature;

One sequential control module: control energy synchronous coordination work between each module;

3. digital sampling and processing comprises:

One Digital to Analog Converter: conversion digital signal or simulating signal;

One video output module: with simulating signal imaging on display;

One data collecting card: gather the digital signal after conversion and be transferred to computing machine;

One data analysis processing module: the signal that collects is carried out analyzing and processing;

4. described bias voltage control module connects tested infrared focal plane array device, provides work required low noise Dc bias; Described temperature control modules connects tested infrared focal plane array device, controls the homogeneity of its temperature; Described time-sequence control module connects tested infrared focal plane array device, Digital to Analog Converter and data collecting card simultaneously, provide sequential control to tested infrared focal plane array device, make its inner sensing circuit energy operate as normal, also provide synchronizing signal simultaneously, guarantee the work of three's energy synchronous coordination to Digital to Analog Converter and data collecting card; Described infrared origin focuses on the tested infrared focal plane array device after collimating by optical system, by Digital to Analog Converter simulating signal is flowed to the imaging on display of video output module, also simulating signal is flowed to data collecting card in addition, pass to computing machine by data collecting card, carry out data analysis by the data analysis processing module and handle, obtain the characterisitic parameter of tested infrared focus plane.

A kind of method of testing of infrared focal plane array device is characterized in that, may further comprise the steps:

Gather focal plane arrays (FPA) raw data (F frame altogether);

Raw data is converted into analog voltage;

F frame magnitude of voltage is asked on average, obtained the F frame average response voltage of each pixel;

The computing array average voltage level;

Calculate the pixel responsiveness;

Computing array average response rate;

Calculate dead pixel number, and determine its coordinate;

Calculate the pixel noise voltage;

Computing array average noise voltage;

Calculate overheated pixel number, and determine its coordinate;

Calculate and revise the average corresponding rate of array and revise array average noise voltage;

The computer memory noise voltage;

Calculate the pixel detecting rate;

The average detectivity of computing array;

Nonuniformity correction;

The calculating noise equivalence temperature difference;

The calculating noise equivalent power;

Calculate dynamic range.

Method of testing according to infrared focal plane array device provided by the present invention is characterized in that, may further comprise the steps:

Step 101, beginning;

Step 102 is gathered raw data;

Step 103 from the Binary Conversion to the decimal system, obtains the analog voltage U ' [(i, j), f] of each pixel of focal plane arrays (FPA) with raw data, and f is the frame ordinal number, and i is the capable ordinal number of array, and j is array row ordinal numbers;

Step 104 is done on average the F frame voltage data that obtains in step 103, and computing formula is:

$U(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}^{\′}\[(i,j),f\];$

Step 105 is done on average to obtain the focal plane arrays (FPA) average voltage level to frame data of trying to achieve in step 104, and computing formula is as follows:

$\stackrel{\‾}{U}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}U(i,j)}{M\×N}$

In the formula, total M and N are respectively line number and total columns of focal plane arrays (FPA), M * N is exactly the pixel sum of array;

Step 106, the responsiveness of each pixel of focal plane arrays (FPA) is tested:

The isoparametric test of responsiveness, can be summed up as two kinds of response voltage tests under the radiation parameter, it is the test of background response voltage tester and black matrix response voltage, two different temperatures (T1 are used in background response voltage tester and the test of black matrix response voltage respectively, T2) voltage responsive under is represented, requiring the temperature range of black-body resource when testing usually is room temperature～1000K, and output does not add modulation; The blackbody radiation hole should be greater than 20 times of radiating aperture, with guarantee point light source irradiation to the distance of focal plane; The normal angle of blackbody radiation incident direction and focal plane photosurface is less than 5 °; The output voltage of focal plane must not surpass the dynamic range of follow-up system after amplifying, if tested detector is a pyroelectric detector, then, must there be optical chopper to realize AC coupling, respectively in temperature T for making detector detect temperature variation between object scene and certain reference temperature ₁And temperature T ₂Down, continuous acquisition F frame data are in temperature T ₁The F frame number group that records down is designated as U ' ₁[(i, j), f], in temperature T ₂The F frame number group that records down is designated as U ' ₂[(i, j), f], try to achieve two single frames pixel relevant voltage under the temperature respectively with the described method of step 104 then;

In temperature T ₁Down, the response voltage of pixel is:

$U_1(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}_1^{\′}[(i,j),f]$

In temperature T ₂Down, the response voltage of pixel is:

$U_2(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}_2^{\′}\[(i,j),f\]$

Then pixel is at T ₁, T ₂Response voltage difference under the two temperatures is:

ΔU(i，j)＝[U ₂(i，j)-U ₁(i，j)]

Responsiveness is:

$R(i,j)=\frac{\mathrm{\ΔU}(i,j)}{P_2-P_1}$

P ₁, P ₂For the focal plane receive from black matrix in temperature T ₁, T ₂Following corresponding intensity of illumination.

And have: $P=\frac{\mathrm{\σ}\×T^4\×d^2\×A_D}{\mathrm{\π}\×L^2}$

In the formula, σ is this Pan's constant of making a mistake, and its value is 5.673 * 10- ¹²(Wcm ^-2K ^-4); T is a temperature, and K, d are the blackbody radiation aperture, unit: cm; A _DBe focal plane pixel area, unit: cm ²L is that the black matrix perforation hole is to focal plane pixel face vertical range, unit: cm;

Step 107, the average response rate of calculating focal plane arrays (FPA):

Be the mean value of focal plane arrays (FPA) pixel responsiveness, unit is V/W, and its expression formula is as follows:

$\stackrel{\‾}{R}=\frac{1}{M\×N}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}R(i,j)$

In the formula, R (i, j) pixel responsiveness for being tried to achieve in the step 106;

Step 108 is calculated dead pixel number, and determines its coordinate:

The array average response rate that calculates according to step 107

Can judge dead pixel, promptly the pixel responsiveness is less than the pixel of average response rate 1/10, and dead pixel number scale is d.Can determine simultaneously the position coordinates of dead pixel;

Step 109, calculate the pixel noise voltage:

The pixel noise voltage is the root-mean-square value of focal plane pixel output signal voltage fluctuation under the background radiation parameter, and symbol is U _N(i, j), unit: volt (V),

The noise voltage of pixel calculates formula:

$U_N(i,j)=\sqrt{\frac{1}{F-1}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}\{U(i,j)-U^{\′}\[(i,j),f\]{\}}^2}$

The noise of focal plane device can be divided into average noise and spatial noise two classes;

Step 110, computing array average noise voltage:

Array average noise voltage is exactly the mean value of each effective pixel noise voltage of focal plane arrays (FPA), and symbol is

Unit is V, and its expression formula is:

$\stackrel{\‾}{U_N}=\frac{1}{M\×N}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_N(i,j)$

In the formula, U _N(i j) is the pixel noise voltage;

Step 111 is calculated overheated pixel number, and determines its coordinate:

The array average noise voltage that calculates according to step 110 can judge overheated pixel, and promptly the pixel noise voltage is greater than the pixel of 10 times of array average noise voltages, and overheated pixel number scale is h, can determine the position coordinates of overheated pixel simultaneously;

Step 112, calculate and revise array average response rate and revise array average noise voltage:

In step 108 and step 111, obtained respectively that dead pixel is counted d and overheated pixel is counted h, based on this, utilize formula

$\stackrel{\‾}{R}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}R(i,j)$

Can obtain revising array average response rate; Utilize formula

$\stackrel{\‾}{U_N}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_N(i,j)$

Can obtain revising array average noise voltage;

Step 113, the computer memory noise voltage:

Spatial noise voltage is responsiveness unevenness U _RWith average black matrix response voltage

Product, symbol is U _SP, unit is V, its expression formula is:

$U_{\mathrm{SP}}=U_R\×\stackrel{\‾}{U_s}$

In the following formula, $U_R=\frac{1}{R}\sqrt{\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{[R(i,j)-\stackrel{\‾}{R}]}^2}\×100\%$

Calculate the formula of spatial noise voltage in this method:

$U_{\mathrm{sp}}=\sqrt{\underset{i,j=1}{\overset{M,N}{\mathrm{\Σ}}}\[U(i,j)-\stackrel{\‾}{U}{\]}^2/(M\×N)};$

Step 114, calculate the pixel detecting rate:

Projecting area when the irradiation of 1W is 1cm ²Pixel on, the signal to noise ratio (S/N ratio) that in the 1Hz bandwidth, obtains, promptly pixel responsiveness R (i, j) with pixel noise voltage U _NRatio, and the long-pending square root of converting unit bandwidth and unit pixel area, its symbol is D ^*(i, j), unit is cmHz ^1/2W ^-1, its expression formula is:

$D^{*}(i,j)=\sqrt{\frac{A_P}{{2t}_{\mathrm{int}}}}\×\frac{R(i,j)}{U_N(i,j)}$

In the formula, A _DBe the pixel area, unit is cm ²t _IntBe the integral time of detector;

Step 115, the average detectivity of computing array:

The mean value of the pixel detecting rate of each effective pixel is exactly the average detectivity of focal plane device in the focal plane device, is designated as

Unit also is cmHz ^1/2W ^-1, its expression formula is:

$\stackrel{\‾}{D^{*}}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{D}^{*}(i,j);$

Step 116, nonuniformity correction:

In temperature T ₁Down, array average response voltage is:

$\stackrel{\‾}{U_1}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_1(i,j)}{M\×N}$

Temperature T ₂Down, array average response voltage is:

$\stackrel{\‾}{U_2}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_2(i,j)}{M\×N}$

For each pixel, two correction parameters are arranged, be respectively α (i, j) and β (i, j):

$\mathrm{\α}(i,j)=\frac{\stackrel{\‾}{U_2}-\stackrel{\‾}{U_1}}{U_2(i,j)-U_1(i,j)}$

$\mathrm{\β}(i,j)=\stackrel{\‾}{U_1}-\mathrm{\α}(i,j)\×U_1(i,j)$

Pixel response voltage U after the correction _CShould be:

U _C(i，j)＝α(i，j)×U(i，j)+β(i，j)；

Step 117, the calculating noise equivalence temperature difference:

If when the signal voltage of average noise voltage and target temperature difference generation equated, defining this temperature difference was noise equivalent temperature difference, i.e. the ratio of the target temperature difference and signal to noise ratio (S/N ratio), unit is K, its expression formula is:

$\mathrm{NETD}=\frac{T_2-T_1}{U_s/\stackrel{\‾}{U_N}}$

In the formula, T is the extend blackbody temperature, and unit is K; T ₀Be ambient temperature, unit is K; Us is the poor of the response voltage of focal plane under T2 and two temperature of T1,

Be array average noise voltage;

Step 118, the calculating noise equivalent power:

When signal to noise ratio (S/N ratio) is 1, the irradiation power that the focal plane pixel is accepted, i.e. the ratio of the average noise voltage of focal plane device and average response rate, symbol is NEP, and unit is W, and its expression formula is:

$\mathrm{NEP}=\frac{\stackrel{\‾}{U_N}}{\stackrel{\‾}{R}};$

Step 119, calculate dynamic range:

So-called dynamic range is the saturation irradiation power P _SatWith the ratio of noise equivalent power NEP, symbol is DR, then can get:

$\mathrm{DR}=\frac{P_{\mathrm{sat}}}{\mathrm{NEP}}$

In the formula, $\mathrm{DR}=20\×\log \left(\frac{U_{\max }-U_{\min }}{U_N}\right)$

U _MaxBe the maximal value of response voltage, U _MinIt is the minimum value of response voltage.

Beneficial effect of the present invention: this platform has that cost is low, and the efficient height waits characteristics accurately and reliably, is fit to the test of extensive infrared focal plane array device.Very important directive significance is all arranged for the deviser of designs fabricator and thermal imaging system.

Description of drawings

The process flow diagram of the method for the test infrared focal plane array device characterisitic parameter that Fig. 1 provides for an embodiment of the present invention.

The system chart of the device of the test infrared focal plane array device characterisitic parameter that Fig. 2 provides for an embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described:

The object of the present invention is to provide a kind of analysis calculation method, hardware unit and software program of test infrared focal plane array device characterisitic parameter general, that can directly apply to hardware, with easily and fast, test the performance parameter of infrared focal plane array device exactly.

As shown in Figure 1, to achieve these goals, the invention provides a kind of analysis calculation method of test infrared focal plane array device characterisitic parameter general, that can directly apply to hardware, it is characterized in that, may further comprise the steps:

Gather focal plane arrays (FPA) raw data (F frame altogether);

Raw data is converted into analog voltage;

F frame magnitude of voltage is asked on average, obtained the F frame average response voltage of each pixel;

The computing array average voltage level;

Calculate the pixel responsiveness;

Computing array average response rate;

Calculate dead pixel number, and determine its coordinate;

Calculate the pixel noise voltage;

Computing array average noise voltage;

Calculate overheated pixel number, and determine its coordinate;

Calculate and revise the average corresponding rate of array and revise array average noise voltage;

The computer memory noise voltage;

Calculate the pixel detecting rate;

The average detectivity of computing array;

Nonuniformity correction;

The calculating noise equivalence temperature difference;

The calculating noise equivalent power;

Calculate dynamic range.

As shown in Figure 2, the present invention also provides a kind of device of testing the infrared focal plane array device characterisitic parameter, comprises with the lower part:

This device is made up of three big modules, is respectively radiation source and focal plane arrays (FPA) module, drive control module and digital sampling and processing.

First is radiation source and focal plane arrays (FPA) module.Comprise blackbody radiation source, optical system and infrared focal plane array.

Second portion is a drive control module.Comprise bias voltage control module, time-sequence control module and temperature control modules.

Third part is a digital sampling and processing.Comprise analog to digital conversion of signals (A/D), video output module, data collecting card and software processes.

Based on provided by the invention a kind of general, can directly apply to the analysis calculation method of the test infrared focal plane array device characterisitic parameter of hardware, the present invention also provides a cover to be used to test the software program of infrared focal plane array device characterisitic parameter, comprises the computer program code of execution according to step 101 in the embodiment～120 described methods.

To be elaborated to embodiments of the present invention below.Fig. 1 is the process flow diagram according to an embodiment of the present invention test infrared focal plane array characterisitic parameter.This flow process starts from step 101.

Step 102 is gathered raw data (a total F frame).

Step 103, because raw data is 16 bits, this step from the Binary Conversion to the decimal system, obtains the analog voltage U ' [(i, j), f] of each pixel of focal plane arrays (FPA) with raw data.(f is the frame ordinal number, and i is the capable ordinal number of array, and j is array row ordinal numbers).

Step 104 is done on average the F frame voltage data that obtains in step 103, and computing formula is:

$U(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}^{\′}\[(i,j),f\]$

Obtain the F frame average response voltage of each pixel.Single frames data after average have alleviated the random noise, response unevenness of indivedual pixels etc. to a certain extent.

Step 105 is done on average to obtain the focal plane arrays (FPA) average voltage level to frame data of trying to achieve in step 104.Computing formula is as follows:

$\stackrel{\‾}{U}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}U(i,j)}{M\×N}$

In the formula, total M and N are respectively line number and total columns of focal plane arrays (FPA), M * N is exactly the pixel sum of array.

Step 106 is tested the responsiveness of each pixel of focal plane arrays (FPA).

The isoparametric test of responsiveness can be summed up as two kinds of response voltage tests under the radiation parameter, i.e. background response voltage tester and black matrix response voltage test.The irradiation of these two kinds of tests all must be constant uniform.After recording background response voltage and black matrix response voltage, each characterisitic parameter such as responsiveness can calculate according to definition.

In this method of testing, two different temperatures are used in the test of background response voltage tester and black matrix response voltage respectively, and (T1, T2) voltage responsive under is represented.

Requiring the temperature range of black-body resource when testing usually is room temperature～1000K, and output does not add modulation; The blackbody radiation hole should be greater than 20 times of radiating aperture, with guarantee point light source irradiation to the distance of focal plane; The normal angle of blackbody radiation incident direction and focal plane photosurface is less than 5 °; The output voltage of focal plane must not surpass the dynamic range of follow-up system after amplifying.

If tested detector is pyroelectric detector, then, must there be optical chopper to realize AC coupling for making detector detect temperature variation between object scene and certain reference temperature.

This method of testing is, respectively in temperature T ₁And temperature T ₂Down, continuous acquisition F frame data are in temperature T ₁The F frame number group that records down is designated as U ' ₁[(i, j), f], in temperature T ₂The F frame number group that records down is designated as U ' ₂[(i, j), f].Try to achieve two single frames pixel relevant voltage under the temperature respectively with the described method of step 104 then.

In temperature T ₁Down, the response voltage of pixel is:

$U_1(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}_1^{\′}\[(i,j),f\]$

In temperature T ₂Down, the response voltage of pixel is:

$U_2(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}_2^{\′}\[(i,j),f\]$

Then pixel is at T ₁, T ₂Response voltage difference under the two temperatures is:

ΔU(i，j)＝[U ₂(i，j)-U ₁(i，j)]

Responsiveness is:

$R(i,j)=\frac{\mathrm{\ΔU}(i,j)}{P_2-P_1}$

P ₁, P ₂For the focal plane receive from black matrix in temperature T ₁, T ₂Following corresponding intensity of illumination.

And have: $P=\frac{\mathrm{\σ}\×T^4\×d^2{A}_D}{\mathrm{\π}\×L^2}$

In the formula, σ is this Pan's constant of making a mistake, and its value is 5.673 * 10- ¹²(Wcm ^-2K ^-4); T is a temperature, and K, d are the blackbody radiation aperture, unit: cm; A _DBe focal plane pixel area, unit: cm ²L is that the black matrix perforation hole is to focal plane pixel face vertical range, unit: cm.

Step 107, the average response rate of calculating focal plane arrays (FPA).

Be the mean value of focal plane arrays (FPA) pixel responsiveness, unit is V/W.Its expression formula is as follows:

$\stackrel{\‾}{R}=\frac{1}{M\×N}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}R(i,j)$

In the formula, R (i, j) pixel responsiveness for being tried to achieve in the step 106.

Step 108 is calculated dead pixel number, and determines its coordinate.

The array average response rate that calculates according to step 107

Can judge dead pixel, promptly the pixel responsiveness is less than the pixel of average response rate 1/10 (this value derives from standard GB/T 17444-1998, also can be set up on their own by the user), and dead pixel number scale is d.Can determine simultaneously the position coordinates of dead pixel.

Step 109 is calculated the pixel noise voltage.

The pixel noise voltage is the root-mean-square value of focal plane pixel output signal voltage fluctuation under the background radiation parameter.Symbol is U _N(i, j), unit: volt (V).

The noise voltage of pixel calculates formula:

$U_N(i,j)=\sqrt{\frac{1}{F-1}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}\{U(i,j)-U^{\′}\[(i,j),f\]{\}}^2}$

The noise of focal plane device can be divided into average noise and spatial noise two classes.

Step 110, computing array average noise voltage.

Array average noise voltage is exactly the mean value of each effective pixel noise voltage of focal plane arrays (FPA), and symbol is

Unit is V.Its expression formula is:

$\stackrel{\‾}{U_N}=\frac{1}{M\×N}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_N(i,j)$

In the formula, U _N(i j) is the pixel noise voltage.

Step 111 is calculated overheated pixel number, and determines its coordinate.

The array average noise voltage that calculates according to step 110 can judge overheated pixel, be that (this value derives from standard GB/T 17444-1998 to the pixel noise voltage greater than 10 times of array average noise voltages, also can set up on their own by the user) pixel, overheated pixel number scale is h.Can determine simultaneously the position coordinates of overheated pixel.

Step 112 is calculated and is revised array average response rate and revise array average noise voltage.

In step 108 and step 111, obtained respectively that dead pixel is counted d and overheated pixel is counted h, based on this, utilize formula

$\stackrel{\‾}{R}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}R(i,j)$

Can obtain revising array average response rate; Utilize formula

$\stackrel{\‾}{U_N}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_N(i,j)$

Can obtain revising array average noise voltage.

Step 113, the computer memory noise voltage.

Spatial noise voltage is responsiveness unevenness U _RWith average black matrix response voltage

Product, symbol is U _SP, unit is V, its expression formula is:

$U_{\mathrm{SP}}=U_R\·\stackrel{\‾}{U_s}$

In the following formula, $U_R=\frac{1}{R}\sqrt{\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{[R(i,j)-\stackrel{\‾}{R}]}^2}\×100\%$

Calculate the formula of spatial noise voltage in this method:

$U_{\mathrm{sp}}=\sqrt{\underset{i,j=1}{\overset{M,N}{\mathrm{\Σ}}}\[U(i,j)-\stackrel{\‾}{U}{\]}^2/(M\×N)}$

Step 114 is calculated the pixel detecting rate.

Projecting area when the irradiation of 1W is 1cm ²Pixel on, the signal to noise ratio (S/N ratio) that in the 1Hz bandwidth, obtains, promptly pixel responsiveness R (i, j) with pixel noise voltage U _NRatio, and the long-pending square root of converting unit bandwidth and unit pixel area, its symbol is D ^*(i, j), unit is cmHz ^1/2W ^-1, its expression formula is:

$D^{*}(i,j)=\sqrt{\frac{A_P}{{2t}_{\mathrm{int}}}}\×\frac{R(i,j)}{U_N(i,j)}$

In the formula, A _DBe the pixel area, unit is cm ²t _IntBe the integral time of detector.

Step 115, the average detectivity of computing array.

The mean value of the pixel detecting rate of each effective pixel is exactly the average detectivity of focal plane device in the focal plane device, is designated as

Unit also is cmHz ^1/2W ^-1, its expression formula is:

$\stackrel{\‾}{D^{*}}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{D}^{*}(i,j)$

Step 116, nonuniformity correction.

Owing to reasons such as infrared focal plane device manufacture crafts, the responsiveness of each pixel is inconsistent, therefore need proofread and correct raw data when imaging.

In temperature T ₁Down, array average response voltage is:

$\stackrel{\‾}{U_1}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_1(i,j)}{M\×N}$

Temperature T ₂Down, array average response voltage is:

$\stackrel{\‾}{U_2}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_2(i,j)}{M\×N}$

For each pixel, two correction parameters are arranged, be respectively α (i, j) and β (i, j):

$\mathrm{\α}(i,j)=\frac{\stackrel{\‾}{U_2}-\stackrel{\‾}{U_1}}{U_2(i,j)-U_1(i,j)}$

$\mathrm{\β}(i,j)=\stackrel{\‾}{U_1}-\mathrm{\α}(i,j)\×U_1(i,j)$

Pixel response voltage U after the correction _CShould be:

U _C(i，j)＝α(i，j)×U(i，j)+β(i，j)

Step 117, the calculating noise equivalence temperature difference.

If when the signal voltage of average noise voltage and target temperature difference generation equated, defining this temperature difference was noise equivalent temperature difference (NETD), i.e. the ratio of the target temperature difference and signal to noise ratio (S/N ratio), unit is K, its expression formula is:

$\mathrm{NETD}=\frac{T_2-T_1}{U_s/\stackrel{\‾}{U_N}}$

In the formula, T is the extend blackbody temperature, and unit is K; T ₀Be ambient temperature, unit is K; Us is the poor of the response voltage of focal plane under T2 and two temperature of T1,

Be array average noise voltage.

Step 118, the calculating noise equivalent power.

When signal to noise ratio (S/N ratio) is 1, the irradiation power that the focal plane pixel is accepted, i.e. the ratio of the average noise voltage of focal plane device and average response rate, symbol is NEP, and unit is W, and its expression formula is:

$\mathrm{NEP}=\frac{\stackrel{\‾}{U_N}}{\stackrel{\‾}{R}}$

Step 119 is calculated dynamic range.

So-called dynamic range is the saturation irradiation power P _SatWith the ratio of noise equivalent power NEP, symbol is DR.

By the test and the calculating of front, can obtain the equivalent power NEP of device, therefore, its main difficulty of test is the test to saturation irradiation power.Adopt the test macro of test response rate, by changing the distance of black matrix and focal plane, or change black matrix outgoing aperture, change black matrix and be incident upon irradiation power P on the pixel of focal plane; Measure the average black matrix response voltage under each P value condition Adopt least square fitting to go out two straight lines of linear zone and saturation region, then the horizontal ordinate P of the pairing point of the intersection point of two straight lines again _Sat, be exactly the measured value of its saturation irradiation power.Then can get:

$\mathrm{DR}=\frac{P_{\mathrm{sat}}}{\mathrm{NEP}}$

In the formula, $\mathrm{DR}=20\×\log \left(\frac{U_{\max }-U_{\min }}{U_N}\right)$

U _MaxBe the maximal value of response voltage, U _MinIt is the minimum value of response voltage.

Fig. 2 is the system chart according to the device of embodiment of the present invention test infrared focal plane array characterisitic parameter.This device is made up of three big modules, is respectively radiation source and focal plane arrays (FPA) module, drive control module and digital sampling and processing.

First is radiation source and focal plane arrays (FPA) module.Comprise blackbody radiation source, optical system and infrared focal plane array.Blackbody radiation source has good stable, homogeneity and low drift characteristic, has higher emissivity simultaneously, and temperature control precision can reach 0.01 ℃.Infrared optical system mainly is made up of the infrared optics lens, and the infrared acquisition wave band in the focal plane has good transmitance, and its all band does not then see through, and the infrared radiation of finishing radiation source focuses on the function on the focal plane.Blackbody radiation focuses on the infrared focus plane after collimating by infrared optical system, by sensing circuit simulating signal is exported.

Second portion is a drive control module.Comprise bias voltage control module, time-sequence control module and temperature control modules.Provide work required low noise Dc bias by the high precision dc signal source to infrared focal plane array.(FPGA) provides sequential control to infrared focal plane array by field programmable gate array, makes the sensing circuit energy operate as normal of infrared focal plane array inside.FPGA also provides synchronizing signal to analogue-to-digital converters and data collecting card simultaneously, guarantees the work of whole module synchronous coordination.During non-refrigerating infrared focal plane work, the fluctuation of environment temperature increases the noise in output signal of focal plane, this device uses thermoelectric controller (TEC) that infrared focal plane array is carried out temperature control, guarantees the homogeneity of whole focal plane arrays (FPA) temperature as far as possible, and temperature-controlled precision is 0.01 ℃.

Third part is a digital sampling and processing.Comprise Digital to Analog Converter (ADC), video output module, data collecting card and software processes.Here adopt 14 Digital to Analog Converter, speed can reach 10MHz, can satisfy the requirement to precision and speed.Digital signal after conversion can imaging on display via the video output module, is convenient to the naked eyes Direct observation.Digital signal after conversion also passes to computing machine by the high-speed collection card of PCIE interface, carries out data analysis by software program provided by the invention at last and handles, and obtains the characterisitic parameter of focal plane arrays (FPA).

Claims (3)

1. the proving installation of an infrared focal plane array device is characterized in that, comprises radiation source and focal plane arrays (FPA) module, drive control module and digital sampling and processing, wherein:

1. radiation source and focal plane arrays (FPA) module comprise:

One infrared origin: provide have higher emissivity, the blackbody radiation source of good stability, homogeneity and low drift characteristic;

One optical system: mainly constitute, the infrared acquisition wave band of focal plane is had good transmitance, filter the wave band beyond the infrared acquisition wave band, the infrared radiation of infrared origin is focused on the infrared focal plane array by the infrared optics lens;

One tested infrared focal plane array;

2. drive control module comprises:

One bias voltage control module: provide work required low noise Dc bias to tested infrared focal plane array device;

One temperature control modules: provide temperature control to tested infrared focal plane array device, guarantee the homogeneity of temperature;

One sequential control module: control energy synchronous coordination work between each module;

3. digital sampling and processing comprises:

One Digital to Analog Converter: conversion digital signal or simulating signal;

One video output module: with simulating signal imaging on display;

One data collecting card: gather the digital signal after conversion and be transferred to computing machine;

One data analysis processing module: the signal that collects is carried out analyzing and processing;

4. described bias voltage control module connects tested infrared focal plane array device, provides work required low noise Dc bias; Described temperature control modules connects tested infrared focal plane array device, controls the homogeneity of its temperature; Described time-sequence control module connects tested infrared focal plane array device, Digital to Analog Converter and data collecting card simultaneously, provide sequential control to tested infrared focal plane array device, make its inner sensing circuit energy operate as normal, also provide synchronizing signal simultaneously, guarantee the work of three's energy synchronous coordination to Digital to Analog Converter and data collecting card; Described infrared origin focuses on the tested infrared focal plane array device after collimating by optical system, by Digital to Analog Converter simulating signal is flowed to the imaging on display of video output module, also simulating signal is flowed to data collecting card in addition, pass to computing machine by data collecting card, carry out data analysis by the data analysis processing module and handle, obtain the characterisitic parameter of tested infrared focus plane.

2. the method for testing of an infrared focal plane array device is characterized in that, may further comprise the steps:

Gather the focal plane arrays (FPA) raw data;

Raw data is converted into analog voltage;

F frame magnitude of voltage is asked on average, obtained the F frame average response voltage of each pixel;

The computing array average voltage level;

Calculate the pixel responsiveness;

Computing array average response rate;

Calculate dead pixel number, and determine its coordinate;

Calculate the pixel noise voltage;

Computing array average noise voltage;

Calculate overheated pixel number, and determine its coordinate;

Calculate and revise the average corresponding rate of array and revise array average noise voltage;

The computer memory noise voltage;

Calculate the pixel detecting rate;

The average detectivity of computing array;

Nonuniformity correction;

The calculating noise equivalence temperature difference;

The calculating noise equivalent power;

Calculate dynamic range.

3. the method for testing of infrared focal plane array device according to claim 2 is characterized in that, may further comprise the steps:

Step 101, beginning;

Step 102 is gathered raw data;

Step 103 from the Binary Conversion to the decimal system, obtains the analog voltage U ' [(i, j), f] of each pixel of focal plane arrays (FPA) with raw data, and f is the frame ordinal number, and i is the capable ordinal number of array, and j is array row ordinal numbers;

Step 104 is done on average the F frame voltage data that obtains in step 103, and computing formula is:

$U(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}^{\′}[(i,j),f];$

Step 105 is done on average to obtain the focal plane arrays (FPA) average voltage level to frame data of trying to achieve in step 104, and computing formula is as follows:

$\stackrel{\‾}{U}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}U(i,j)}{M\×N}$

In the formula, total M and N are respectively line number and total columns of focal plane arrays (FPA), M * N is exactly the pixel sum of array;

Step 106, the responsiveness of each pixel of focal plane arrays (FPA) is tested:

The isoparametric test of responsiveness, can be summed up as two kinds of response voltage tests under the radiation parameter, it is the test of background response voltage tester and black matrix response voltage, two different temperatures (T1 are used in background response voltage tester and the test of black matrix response voltage respectively, T2) voltage responsive under is represented, requiring the temperature range of black-body resource when testing usually is room temperature～1000K, and output does not add modulation; The blackbody radiation hole should be greater than 20 times of radiating aperture, with guarantee point light source irradiation to the distance of focal plane; The normal angle of blackbody radiation incident direction and focal plane photosurface is less than 5 °; The output voltage of focal plane must not surpass the dynamic range of follow-up system after amplifying, if tested detector is a pyroelectric detector, then, must there be optical chopper to realize AC coupling, respectively in temperature T for making detector detect temperature variation between object scene and certain reference temperature ₁And temperature T ₂Down, continuous acquisition F frame data are in temperature T ₁The F frame number group that records down is designated as U ' ₁[(i, j), f], in temperature T ₂The F frame number group that records down is designated as U ' ₂[(i, j), f], try to achieve two single frames pixel relevant voltage under the temperature respectively with the described method of step 104 then;

In temperature T ₁Down, the response voltage of pixel is:

$U_1(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}_1^{\′}[(i,j),f]$

In temperature T ₂Down, the response voltage of pixel is:

$U_2(i,j)=\frac{1}{F}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{U}_2^{\′}[(i,j),f]$

Then pixel is at T ₁, T ₂Response voltage difference under the two temperatures is:

ΔU(i，j)＝[U ₂(i，j)-U _I(i，j)]

Responsiveness is:

$R(i,j)=\frac{\mathrm{\ΔU}(i,j)}{P_2-P_1}$

P ₁, P ₂For the focal plane receive from black matrix in temperature T ₁, T ₂Following corresponding intensity of illumination.

And have: $P=\frac{\mathrm{\σ}\×T^4\×d^2\×A_D}{\mathrm{\π}\×L^2}$

In the formula, σ is this Pan's constant of making a mistake, and its value is 5.673 * 10 ^-12(Wcm ^-2K ^-4); T is a temperature, and K, d are the blackbody radiation aperture, unit: cm; A _DBe focal plane pixel area, unit: cm ²L is that the black matrix perforation hole is to focal plane pixel face vertical range, unit: cm;

Step 107, the average response rate of calculating focal plane arrays (FPA):

Be the mean value of focal plane arrays (FPA) pixel responsiveness, unit is V/W, and its expression formula is as follows:

$\stackrel{\‾}{R}=\frac{1}{M\×N}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}R(i,j)$

In the formula, R (i, j) pixel responsiveness for being tried to achieve in the step 106;

Step 108 is calculated dead pixel number, and determines its coordinate:

The array average response rate that calculates according to step 107

Can judge dead pixel, promptly the pixel responsiveness is less than the pixel of average response rate 1/10, and dead pixel number scale is d.Can determine simultaneously the position coordinates of dead pixel;

Step 109, calculate the pixel noise voltage:

The pixel noise voltage is the root-mean-square value of focal plane pixel output signal voltage fluctuation under the background radiation parameter, and symbol is U _N(i, j), unit: volt (V),

The noise voltage of pixel calculates formula:

$U_N(i,j)=\sqrt{\frac{1}{F-1}\underset{f=1}{\overset{F}{\mathrm{\Σ}}}{\{U(i,j)-U^{\′}[(i,j),f\left]\right\}}^2}$

The noise of focal plane device can be divided into average noise and spatial noise two classes;

Step 110, computing array average noise voltage:

Array average noise voltage is exactly the mean value of each effective pixel noise voltage of focal plane arrays (FPA), and symbol is

Unit is V, and its expression formula is:

$\stackrel{\‾}{U_N}=\frac{1}{M\×N}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_N(i,j)$

In the formula, U _N(i j) is the pixel noise voltage;

Step 111 is calculated overheated pixel number, and determines its coordinate:

The array average noise voltage that calculates according to step 110 can judge overheated pixel, and promptly the pixel noise voltage is greater than the pixel of 10 times of array average noise voltages, and overheated pixel number scale is h, can determine the position coordinates of overheated pixel simultaneously;

Step 112, calculate and revise array average response rate and revise array average noise voltage:

In step 108 and step 111, obtained respectively that dead pixel is counted d and overheated pixel is counted h, based on this, utilize formula

$\stackrel{\‾}{R}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}R(i,j)$

Can obtain revising array average response rate; Utilize formula

$\stackrel{\‾}{U_N}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_N(i,j)$

Can obtain revising array average noise voltage;

Step 113, the computer memory noise voltage:

Spatial noise voltage is responsiveness unevenness U _RWith average black matrix response voltage

Product, symbol is U _SP, unit is V, its expression formula is:

$U_{\mathrm{SP}}=U_R\×\stackrel{\‾}{U_s}$

In the following formula, $U_R=\frac{1}{R}\sqrt{\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{[R(i,j)-\stackrel{\‾}{R}]}^2}\×100\%$

Calculate the formula of spatial noise voltage in this method:

$U_{\mathrm{sp}}=\sqrt{\underset{i,j=1}{\overset{M,N}{\mathrm{\Σ}}}{[U(i,j)-\stackrel{\‾}{U}]}^2/(M\×N)};$

Step 114, calculate the pixel detecting rate:

Projecting area when the irradiation of 1W is 1cm ²Pixel on, the signal to noise ratio (S/N ratio) that in the 1Hz bandwidth, obtains, promptly pixel responsiveness R (i, j) with pixel noise voltage U _NRatio, and the long-pending square root of converting unit bandwidth and unit pixel area, its symbol is D ^*(i, j), unit is cmHz ^1/2W ^-1, its expression formula is:

$D^{*}(i,j)=\sqrt{\frac{A_D}{2t_{\mathrm{int}}}}\×\frac{R(i,j)}{U_N(i,j)}$

In the formula, A _DBe the pixel area, unit is cm ²t _IntBe the integral time of detector;

Step 115, the average detectivity of computing array:

The mean value of the pixel detecting rate of each effective pixel is exactly the average detectivity of focal plane device in the focal plane device, is designated as Unit also is cmHz ^1/2W ^-1, its expression formula is:

$\stackrel{\‾}{D^{*}}=\frac{1}{M\×N-(d+h)}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{D}^{*}(i,j);$

Step 116, nonuniformity correction:

In temperature T ₁Down, array average response voltage is:

$\stackrel{\‾}{U_1}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_1(i,j)}{M\×N}$

Temperature T ₂Down, array average response voltage is:

$\stackrel{\‾}{U_2}=\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{U}_2(i,j)}{M\×N}$

For each pixel, two correction parameters are arranged, be respectively α (i, j) and β (i, j):

$\mathrm{\α}(i,j)=\frac{\stackrel{\‾}{U_2}-\stackrel{\‾}{U_1}}{U_2(i,j)-U_1(i,j)}$

$\mathrm{\β}(i,j)=\stackrel{\‾}{U_1}-\mathrm{\α}(i,j)\×U_1(i,j)$

Pixel response voltage U after the correction _CShould be:

U _C(i，j)＝α(i，j)×U(i，j)+β(i，j)；

Step 117, the calculating noise equivalence temperature difference:

If when the signal voltage of average noise voltage and target temperature difference generation equated, defining this temperature difference was noise equivalent temperature difference, i.e. the ratio of the target temperature difference and signal to noise ratio (S/N ratio), unit is K, its expression formula is:

$\mathrm{NETD}=\frac{T_2-T_1}{U_s/\stackrel{\‾}{U_N}}$

In the formula, T is the extend blackbody temperature, and unit is K; T ₀Be ambient temperature, unit is K; Us is the poor of the response voltage of focal plane under T2 and two temperature of T1,

Be array average noise voltage;

Step 118, the calculating noise equivalent power:

When signal to noise ratio (S/N ratio) is 1, the irradiation power that the focal plane pixel is accepted, i.e. the ratio of the average noise voltage of focal plane device and average response rate, symbol is NEP, and unit is W, and its expression formula is:

$\mathrm{NEP}=\frac{\stackrel{\‾}{U_N}}{\stackrel{\‾}{R}};$

Step 119, calculate dynamic range:

So-called dynamic range is the saturation irradiation power P _SatWith the ratio of noise equivalent power NEP, symbol is DR, then can get:

$\mathrm{DR}=\frac{P_{\mathrm{sat}}}{\mathrm{NEP}}$

In the formula, $\mathrm{DR}=20\×\log \left(\frac{U_{\max }-U_{\min }}{U_N}\right)$

U _MaxBe the maximal value of response voltage, U _MinIt is the minimum value of response voltage.

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