CN1430048A - Method and device used for correcting heterogeneity of detector - Google Patents
Method and device used for correcting heterogeneity of detector Download PDFInfo
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- CN1430048A CN1430048A CN 01139289 CN01139289A CN1430048A CN 1430048 A CN1430048 A CN 1430048A CN 01139289 CN01139289 CN 01139289 CN 01139289 A CN01139289 A CN 01139289A CN 1430048 A CN1430048 A CN 1430048A
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- integration time
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Abstract
A method and equipment for correcting the heterogeneity of infrared focal plane detector features that a constant infrared source is only needed, the optical integration time of said focal plane detector is precisely controlled to control the incident energy on focal plane, and the response curves under different incident energy is measured for correcting the heterogeneity. In the system, a timing module programmed by microprocessor is additionally used for precisely regulating said integration time. Its advantages are simple structure and high effect.
Description
Technical field
The present invention relates to be used for the nonuniform measurement of infrared focal plane imaging system, the method and apparatus of correction.
Background technology
In the optics focal plane imaging system, because photodetector pixel responsiveness or the heterogeneity of spectral responsivity and the coupling factor of sensing circuit and detector etc. make the actual image that obtains that tangible heterogeneity be arranged, this in the infrared focus plane system particularly seriously (heterogeneity usually reaches more than 20%).Therefore, good measurement or imaging effect be reached, nonuniform measurement and correction must be in system, carried out.Because the heterogeneity of system exists the regular hour to change and drift, in the application that measuring accuracy is had relatively high expectations, must provide the function of straightened up in place calibration simultaneously.
Carry out Nonuniformity Correction, generally comprise following three steps: at first be the response characteristic of accurately measuring each probe unit; Determine correcting algorithm, calculation correction coefficient then on this basis; At last correction coefficient is offered hardware processing module, thereby finish real-time calibration function.
For measuring the infrared imaging system heterogeneity, usually use standard extend blackbody is as the measuring radiation source, by changing the radiation intensity of black-body resource, measure the signal output of infra-red thermal imaging system response, thereby obtain the heterogeneity curve of system responses, and to obtain good Nonuniformity Correction effect, need to gather system responses data at 2 above radiation intensity.The method that adopts in system realizes has at present: the one, and the chamber proving installation is measured by experiment, and it is difficult to satisfy the requirement that system for field is proofreaied and correct calibration; The 2nd, in system light path, settle the calibrated radiation source (hot and cold black matrix) of two varying strengths to be used for on-the-spot measurement demarcation, it has increased complex degree of system design.
Summary of the invention
The object of the present invention is to provide only needs a constant calibrated radiation source just can carry out the method for Nonuniformity Correction to infrared focal plane detector, thereby has simplified system design, and can satisfy the requirement that system for field is proofreaied and correct calibration.
Another object of the present invention provides a kind of heteropical device of detector of straightened up in place infrared focus plane.
For achieving the above object, the inventive method may further comprise the steps:
(1) provides single constant infrared area radiation source;
(2) response curve of measurement detector;
(3) determine correcting algorithm, and the calculation correction coefficient;
(4) proofread and correct.
According to feature of the present invention, the response curve of described measurement detector also comprises the step of the optical integration time of control detector; The optical integration time of described control detector may further comprise the steps:
(1) is set the minimum integration time;
(2) increase integral time by a fixed step size.
The present invention is used for the device of infrared focal plane detector Nonuniformity Correction, comprising:
Infrared origin;
Optical system is used for infrared origin at focal plane imaging;
Measuring and controlling is used to measure the response curve of infrared focal plane detector;
Data processing equipment;
It is characterized in that,
Described infrared origin includes only a constant infrared area radiation source;
Described measuring and controlling comprises the time block that can accurately adjust integral time, by systematic microprocessor control, thereby when measuring the response curve of detector the integral time of control detector.
Description of drawings
Fig. 1 is an infrared imaging system nonuniform measurement theory diagram.
Fig. 2 is an infrared focal plane imaging system Nonuniformity Correction theory diagram.
Fig. 3 is a Nonuniformity Correction device integration time block functional schematic of the present invention.
Fig. 4 is integration time block circuit theory diagrams.
Embodiment
What Fig. 1 showed is to measure the heteropical schematic diagram of infrared imaging system, as shown in the figure, the radiation that send in black matrix face source is through optical system imaging, the data that record on infrared focus plane are recorded and handle, and just can draw the response curve of system under different projectile energy situations.
A distinguishing feature of the present invention is exactly in the infrared imaging system nonuniform measurement, only need provide a constant infrared origin.Accomplish this point, the present invention controls the emittance that incides on the focal plane by the optical integration time of accurate control focus planardetector, and the response curve of measuring system under different projectile energy situations, thus the Nonuniformity Correction of the system of realization.
For this reason, in infrared imaging system of the present invention design, adopt microprocessor control circuit, and in circuit, increase by the time block that can accurately adjust the detector integrates time, control integral time by microprocessor, thereby measure the response curve of each probe unit of system.
Fig. 2 shows infrared focal plane imaging system Nonuniformity Correction block diagram of the present invention.As seen from the figure, the infrared radiation in one black matrix face source is also received by detector on the focal plane through optical system imaging, and the signal of reception enters correcting circuit through analog to digital conversion, as 2 linear correcting digital circuits, the data after the correction are stored as image hardwood data.In addition, Fig. 2 also shows, detector is subjected to the control of accurate timing control module integral time to the reception of infrared radiation, the monitoring of total system and processing are then finished by microprocessor, also be that its control time block is measured control, the control correcting circuit carries out the coefficient correction, and the image frame data of storage is done data analysis.
Key of the present invention is the design of accurate timing integration module, and Fig. 3 has provided its schematic block diagram.One crystal oscillator clock, produce for example clock signal of 20MHz, and through frequency counter, for example finally produce the output clock of 5MHz behind 4 frequency divisions, in addition, by frame frequency counter timer and integral counting timer generation formation integrated pulse, this integrated pulse is subjected to the output control of clock division counter respectively in view of frame frequency counter timer and integral counting timer, obviously be associated with the clock of above-mentioned output, and be sent to device on the infrared radiation focal plane together, in addition, above-mentioned frame frequency counter timer is controlled with the Microprocessor Interface buffer cell that the integral counting timer also is subjected to linking to each other with microprocessor via bus, therefore, finally can realize control by microprocessor to integral time.
Fig. 4 has provided the circuit embodiments figure of accurate timing module of the present invention, wherein adopt 8253 timers, 8253 provide 3 16 counter, the present invention designs and has adopted wherein 2, T0 is used for the frame frequency counting, T1 is used for counting integral time, and the counting initial value all can be made amendment by Microprocessor Interface.
Above-mentioned controls integral time with microprocessor, particularly, can realize by the software programming of microprocessor.As an example, below provide the software flow of nonuniform measurement of the present invention and correction factor calculation:
A. initialization process hardware;
B. be set integral time is detector minimum integration time (～20 μ s);
C. gather N frame (N＞5) view data, the line data of going forward side by side is level and smooth;
D. progressively increase integral time, the desirable 100 μ s of step-length～500 μ s;
E. repeating step C, D are saturated until view data;
F. according to the response curve of the view data calculating detector that writes down, adopt linear fit or polynomial expression correcting algorithm usually.Linear fit promptly adopts the relation of response measurement value V that linear representation comes the match detector cells and corresponding incident radiation
V(i，j，)＝R
i，j+O
i，j
Wherein coefficients R, O adopt least square method to determine that establishing integral time is T
k(k=1 ..., K), corresponding response data is V
k, then
The response straight line of each pixel is done on average, regularly gone out the normal response straight line, promptly
V()＝ R+ O
G. calculate the linearity correction COEFFICIENT K of each unit
Ij, B
IjAs follows, and with the K that calculates
I, j, B
I, jWrite in the coefficient storage district of correcting circuit.
Y(i，j)＝K
i，jV(i，j)+B
i，j
B
i，j＝ O-K
i，j·O
i，j
One embodiment of the present of invention are as follows:
Adopt the infrared imaging system of 256 * 256 yuan of medium wave HgCdTe focus planardetectors, its optical focal length 50mm, relative aperture are 1: 1.2.
The Nonuniformity Correction of this system adopts linear Mathematical Correction Method, realizes that by 1 16 multiplier and 16 totalizers correction coefficient K, B are stored in electric erasable E with the 16bits fixed-point representation
2Among the RPOM (4M bits).The accurate timing module such as Fig. 4 integral time of hardware circuit adopts the 5MHz crystal oscillator as readout clock, and the integrated pulse signal is produced by 8253 timers, and pulse width range is 32 μ s～20ms, and the minimal adjustment step-length is 3.2 μ s, and timing accuracy is better than 1 ‰.
When carrying out the non-homogeneous measurement in scene, cover system's camera lens as constant radiation source with the blackout crown cap, the microprocessor Control Software is uniformly-spaced chosen 15～20 measurement points of integral time from 32 μ s (approximate zero incident) to 4ms (saturated incident), the output data of each unit of record detector, adopt least square method to carry out linear fit, determine fitting coefficient, calculate the correction coefficient of each unit in view of the above, and refresh coefficient E after being translated into 16 fixed-point values
2RPOM.
Test result shows, adopt this bearing calibration after, the heterogeneity of imaging system from initial 15% reduce to＜0.1%.Further calculate demonstration,, heterogeneity can be reduced to below 0.5 ‰ if adopt the multiple spot curve fitting.
Claims (8)
1. a method that is used for the infrared focal plane detector Nonuniformity Correction is characterized in that, may further comprise the steps:
(1) provides single constant infrared area radiation source;
(2) response curve of measurement detector;
(3) determine correcting algorithm, and the calculation correction coefficient;
(4) proofread and correct.
2. method according to claim 1 is characterized in that, the response curve of described measurement detector also comprises the step of the optical integration time of control detector.
3. method according to claim 2 is characterized in that, the optical integration time of described control detector may further comprise the steps:
(1) is set the minimum integration time;
(2) increase integral time by a fixed step size.
4. method according to claim 1 is characterized in that, described correcting algorithm comprises linear fit or polynomial expression correcting algorithm.
5. device that is used for the infrared focal plane detector Nonuniformity Correction comprises:
Infrared origin;
Optical system is used for infrared origin at focal plane imaging;
Measuring and controlling is used to measure the response curve of infrared focal plane detector;
Data processing equipment;
It is characterized in that,
Described infrared origin includes only a constant infrared area radiation source;
Described measuring and controlling comprises the time block that can accurately adjust integral time, by systematic microprocessor control, thereby when measuring the response curve of detector the integral time of control detector.
6. the device that is used for the infrared focal plane detector Nonuniformity Correction according to claim 5 is characterized in that, described integration time block comprises the frequency counter of crystal oscillator clock division and frame frequency counter timer and integral counting timer.
7. the device that is used for the infrared focal plane detector Nonuniformity Correction according to claim 5, it is characterized in that described integration time block comprises the device that detector is provided with the minimum integration time, and the device that progressively increases integral time by a fixed step size.
8. the device that is used for the infrared focal plane detector Nonuniformity Correction according to claim 5 is characterized in that also comprising the digital circuit that adopts linear fit or polynomial expression to proofread and correct.
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| CNB011392894A CN1187589C (en) | 2001-12-29 | 2001-12-29 | Method and device used for correcting heterogeneity of detector |
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| CNB011392894A CN1187589C (en) | 2001-12-29 | 2001-12-29 | Method and device used for correcting heterogeneity of detector |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102289788A (en) * | 2011-06-17 | 2011-12-21 | 中国电子科技集团公司第二十八研究所 | Strip non-uniformity real-time correction method in multi-channel infrared detector |
| CN102494784A (en) * | 2011-12-15 | 2012-06-13 | 电子科技大学 | Readout circuit and readout method for point-by-point bias correction data of infrared focal plane array image element |
| CN102768107A (en) * | 2012-07-10 | 2012-11-07 | 武汉高德红外股份有限公司 | Nonuniformity correcting device and method by aiming at detector pixel response rate |
| CN102779332A (en) * | 2012-07-09 | 2012-11-14 | 中国人民解放军国防科学技术大学 | Nonlinear-fitting infrared non-uniform correction method based on time-domain Kalman filtering correction |
| CN103095963A (en) * | 2011-12-17 | 2013-05-08 | 中国航空工业集团公司洛阳电光设备研究所 | Infrared linear detector inhomogeneous correction method and infrared linear detector inhomogeneous correction device based on field programmable gate array (FPGA) |
| CN103219997A (en) * | 2013-02-06 | 2013-07-24 | 北京空间机电研究所 | Multispectral multi-focal-plane splicing infrared detector control and signal sampling circuit |
| CN103335716A (en) * | 2013-06-21 | 2013-10-02 | 中国科学院西安光学精密机械研究所 | Area array infrared camera calibration and non-uniformity correction method based on variable integration time |
| CN104268870A (en) * | 2014-09-24 | 2015-01-07 | 北京津同利华科技有限公司 | Short-wave infrared focal plane non-uniformity correction algorithm based on wavelet transformation histogram |
| CN105869129A (en) * | 2015-12-01 | 2016-08-17 | 中国科学院上海技术物理研究所 | Residual heterogeneous noise elimination method for aiming at thermal infrared image after heterogeneous correction |
| CN107941331A (en) * | 2017-12-27 | 2018-04-20 | 四川大学 | The energy-probe design method of ArF excimer laser Light Energies uniformity detection |
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2001
- 2001-12-29 CN CNB011392894A patent/CN1187589C/en not_active Expired - Fee Related
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102289788B (en) * | 2011-06-17 | 2013-05-01 | 中国电子科技集团公司第二十八研究所 | Strip non-uniformity real-time correction method in multi-channel infrared detector |
| CN102289788A (en) * | 2011-06-17 | 2011-12-21 | 中国电子科技集团公司第二十八研究所 | Strip non-uniformity real-time correction method in multi-channel infrared detector |
| CN102494784B (en) * | 2011-12-15 | 2013-11-13 | 电子科技大学 | Readout circuit and readout method for point-by-point bias correction data of infrared focal plane array image element |
| CN102494784A (en) * | 2011-12-15 | 2012-06-13 | 电子科技大学 | Readout circuit and readout method for point-by-point bias correction data of infrared focal plane array image element |
| CN103095963A (en) * | 2011-12-17 | 2013-05-08 | 中国航空工业集团公司洛阳电光设备研究所 | Infrared linear detector inhomogeneous correction method and infrared linear detector inhomogeneous correction device based on field programmable gate array (FPGA) |
| CN102779332A (en) * | 2012-07-09 | 2012-11-14 | 中国人民解放军国防科学技术大学 | Nonlinear-fitting infrared non-uniform correction method based on time-domain Kalman filtering correction |
| CN102768107A (en) * | 2012-07-10 | 2012-11-07 | 武汉高德红外股份有限公司 | Nonuniformity correcting device and method by aiming at detector pixel response rate |
| CN103219997A (en) * | 2013-02-06 | 2013-07-24 | 北京空间机电研究所 | Multispectral multi-focal-plane splicing infrared detector control and signal sampling circuit |
| CN103219997B (en) * | 2013-02-06 | 2016-08-10 | 北京空间机电研究所 | Many spectral coverages multi-focal-plane splicing Infrared Detectors controls and signal sample circuit |
| CN103335716A (en) * | 2013-06-21 | 2013-10-02 | 中国科学院西安光学精密机械研究所 | Area array infrared camera calibration and non-uniformity correction method based on variable integration time |
| CN103335716B (en) * | 2013-06-21 | 2016-06-08 | 中国科学院西安光学精密机械研究所 | Area array infrared camera calibration and non-uniformity correction method based on variable integration time |
| CN104268870A (en) * | 2014-09-24 | 2015-01-07 | 北京津同利华科技有限公司 | Short-wave infrared focal plane non-uniformity correction algorithm based on wavelet transformation histogram |
| CN105869129A (en) * | 2015-12-01 | 2016-08-17 | 中国科学院上海技术物理研究所 | Residual heterogeneous noise elimination method for aiming at thermal infrared image after heterogeneous correction |
| CN105869129B (en) * | 2015-12-01 | 2019-04-02 | 中国科学院上海技术物理研究所 | For the thermal infrared images residue non-uniform noise minimizing technology after nonuniformity correction |
| CN107941331A (en) * | 2017-12-27 | 2018-04-20 | 四川大学 | The energy-probe design method of ArF excimer laser Light Energies uniformity detection |
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