CN106840198B - A kind of low-light camera Calibration Method - Google Patents

A kind of low-light camera Calibration Method Download PDF

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Publication number
CN106840198B
CN106840198B CN201611194034.4A CN201611194034A CN106840198B CN 106840198 B CN106840198 B CN 106840198B CN 201611194034 A CN201611194034 A CN 201611194034A CN 106840198 B CN106840198 B CN 106840198B
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integrating sphere
light
low
calibration
radiation
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CN201611194034.4A
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CN106840198A (en
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李永强
王静怡
郝言慧
赵占平
郭永祥
柯君玉
张梦雨
刘君航
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北京空间机电研究所
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C25/00Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass

Abstract

A kind of low-light camera Calibration Method, the spectral radiance carry-over factor in tandem type low-light spectral radiometric calibration system between two neighboring cascade integral ball is calibrated using spectral radiometer first, obtains the spectral radiance in each spoke brightness level main integrating sphere radiation exit;Low-light camera to be measured is placed in thermal vacuum tank, and the component using low-light camera itself mechanical-optical setup component as vacuum environment in isolation thermal vacuum tank and the outer laboratory environment of tank;Adjustment thermal vacuum tank position makes low-light camera optical axis be directed at main integrating sphere export center;Thermal vacuum tank is vacuumized, and after the completion of vacuumizing, is taken temperature control measures to low-light camera optical machine main body and focal plane, is worked in low-light camera optical machine main body and focal plane at a temperature of its design work;Acquire the radiation calibration data of each spoke brightness level low-light camera;Camera rdaiation response characteristic is analyzed, calibration is completed.

Description

A kind of low-light camera Calibration Method

Technical field

The present invention relates to a kind of Calibration Method, especially a kind of height for the test of space flight low-light camera radiance Precision Experiment room Calibration Method.

Background technique

Space remote sensing camera needs to complete radiation calibration work, in system performance testing to determine the dynamic model of camera Enclose, respond linear, signal-to-noise ratio, absolute calibration coefficient and relative calibration coefficient etc..High-precision radiation calibration is remote sensing camera development Essential process in the process plays an important role in terms of camera system performance adjustment, detectivity judgement, and radiation is fixed Mark precision directly influences the quantification application level of the in-orbit image product of camera.It is micro- with the development of round-the-clock detection demand Light imaging detection technology starts to be applied to Field of Space Optical Remote Sensor, and demand of the user to low-light remote sensor quantification is applied is compeled It cuts, low-light radiation calibration technology becomes one of the Pinch technology for restricting the development of low-light optical sensor.

At present for the radiation calibration method of low-light optical sensor, it is fixed that radiation is generally directed pointing using spectral radiometer Mark source (such as integrating sphere) radiation outlet measures to obtain the spectral radiance in radiation calibration source, such as U.S. New The magnetosphere of Hampshire university-PROGRESS OF IONOSPHERIC RESEARCH IN laboratory (MIRL) F.Brent Sadler and Calgary university, Canada Leroy L.Cogger et al. combine " the Facility for optical calibration at low light delivered level(FOCAL3) " one described in the text using low-light Radiometric calibration facility to carry out radiation to quick aurora imager (FAI) fixed Calibration method.Radiation calibration can be carried out to optical sensor in laboratory environment environment in this way, but work as low-light When optical sensor focal plane temperature is lower than 0 DEG C, carrying out radiation calibration in laboratory environment will cause focal plane " moisture condensation " or " knot Frost " is lower than in-orbit focal plane operating temperature 0 DEG C of low-light optical sensor, cannot use and carry out spoke in laboratory environment It penetrates and determines calibration method;In addition, the FOCAL of New Hampshire university, the U.S.3Device is used places a thermoelectricity on integrating sphere Refrigeration mode silicon detector assists completing the calibration of low-light brightness, and spectral radiance stated accuracy is low under poor light condition, Wu Faman The requirement for the Larger Dynamic range low-light optical sensor radiation calibration precision that foot needs quantification to apply.

Summary of the invention

Technology of the invention solves the problems, such as: having overcome the deficiencies of the prior art and provide a kind of Spectral radiance measurement essence Degree height calibrates the high low-light Calibration Method of big dynamic range, analog camera operation on orbit temperature, calibration precision.

The technical solution of the invention is as follows: a kind of low-light camera Calibration Method, steps are as follows:

(1) it when light radiation is provided by secondary integrating sphere in the main integrating sphere of tandem type low-light spectral radiometric calibration system, uses Spectral radiometer tests the spectral radiance at main integrating sphere radiation outlet and secondary integrating sphere optical radiation measurement mouth, according to main product Spectral radiance at bulb separation radiation outlet and secondary integrating sphere optical radiation measurement mouth, is calculated tandem type low-light radiation calibration The spectral radiance carry-over factor of secondary integrating sphere in system to main integrating sphere;

At spectral radiometer test final stage integrating sphere optical radiation measurement mouth and secondary integrating sphere optical radiation measurement mouth Spectral radiance, according to the spectral radiance at final stage integrating sphere optical radiation measurement mouth and secondary integrating sphere optical radiation measurement mouth, Be calculated final stage integrating sphere in tandem type low-light spectral radiometric calibration system to secondary integrating sphere spectral radiance carry-over factor;

When the main integrating sphere radiation outlet output of tandem type low-light spectral radiometric calibration system is each low-light spoke brightness level, adopt It is declined at light radiation scaling system final stage integrating sphere optical radiation measurement mouth with spectral radiometer test cascade and secondary integrating sphere light Spectral radiance at actinometry mouth, the tandem type low-light spectral radiometric calibration system final stage integrating sphere optical radiation measurement mouth that will be measured Spectral radiance at place and secondary integrating sphere optical radiation measurement mouth, in conjunction with secondary integrating sphere to the spectral radiance of main integrating sphere Carry-over factor and final stage integrating sphere are calculated under each spoke brightness level to the spectral radiance carry-over factor of secondary integrating sphere, The spectral radiance in main integrating sphere radiation exit;

(2) low-light camera to be measured is placed in thermal vacuum tank, and using low-light camera itself mechanical-optical setup component be used as every Component from laboratory environment outside vacuum environment in thermal vacuum tank and tank;

(3) adjustment thermal vacuum tank position makes low-light camera optical axis be directed at main integrating sphere radiation export center;

(4) thermal vacuum tank is vacuumized, after the completion of vacuumizing, temperature control is taken to low-light camera optical machine main body and focal plane Measure works in low-light camera optical machine main body and focal plane under setting operating temperature, and camera focal plane may be set to different low temperature Operating condition;

(5) low-light under each spoke brightness level in the main integrating sphere radiation exit of tandem type low-light spectral radiometric calibration system is acquired The radiation calibration data of camera;

(6) according to the radiation calibration data of step (5), camera rdaiation response characteristic is determined, comprising: the dynamic model of camera It encloses, respond linear, signal-to-noise ratio, absolute calibration coefficient and relative calibration coefficient.

The main integrating sphere radiation outlet of tandem type low-light spectral radiometric calibration system can cover whole imaging views of low-light camera ?;Proportionate relationship between final stage integrating sphere inner diameter, secondary integrating sphere inner diameter and main integrating sphere ball inner diameter is 1:1:3.

After being vacuumized to vacuum tank, when air pressure is lower than 1 × 10 in tank-3When Pa, then temperature control is taken to arrange low-light camera focal plane It applies, and the low temperature for being set lower than in vacuum tank focal plane temperature is heat sink, is contaminated to avoid low-light camera focal plane.

The final stage integrating sphere optical radiation measurement mouth of tandem type low-light spectral radiometric calibration system is located at final stage integrating sphere and secondary product The horizontal side of bulb separation junction, be open coefficient, i.e. the ratio between integrating sphere optical radiation measurement open area and integrating sphere ball wall area, no Greater than 1%;Secondary integrating sphere optical radiation measurement mouth is located at the horizontal side of secondary integrating sphere and main integrating sphere junction, opening system Number is not more than 1%;Final stage integrating sphere optical radiation measurement mouth and secondary integrating sphere optical radiation measurement mouth are located at the radiation of tandem type low-light Scaling system it is ipsilateral.

Low-light radiation calibration carries out in close luminous environment, and vacuum tank is placed in calibration dark room conditions, calibrates and removes grade in darkroom Joining the light radiation scaling system that declines main integrating sphere radiation exit has outside light radiation, introduces stray light without other light sources;To keep away Exempt from environment stray light and enter calibration darkroom, the laboratory environment illumination calibrated outside darkroom is lower than 1 × 10-4lx。

The different worst cold cases of camera focal plane, preferably -30 DEG C of worst cold case.

The advantages of the present invention over the prior art are that:

(1) present invention calibrates two neighboring cascade integral in tandem type low-light spectral radiometric calibration system using spectral radiometer Spectral radiance carry-over factor between ball realizes under poor light condition to main integrating sphere radiation exit spectral radiance Accurate Calibration.

(2) the method for the present invention using low-light camera itself mechanical-optical setup component as isolation thermal vacuum tank in vacuum environment and The component of the outer laboratory environment of tank, solves and introduces itself light of non-camera in general calibrating method in low-light camera Calibration optical path Learning part will cause the problem of calibration precision reduces, and can be realized high-precision low-light radiation calibration.

(3) the method for the present invention takes temperature control measures to low-light camera by the way that low-light camera to be placed in thermal vacuum tank, can be with It works in low-light camera optical machine main body and focal plane at a temperature of design work, it is equal different low at -30 DEG C that camera focal plane may be implemented Radiation calibration under warm operating condition, with in-orbit state consistency, calibration precision is high.

(4) present invention can be realized 108: the radiation calibration of 1 or more dynamic range.

Detailed description of the invention

Fig. 1 is the flow diagram of Calibration Method of the present invention;

Fig. 2 is the structure composition figure of robot scaling equipment used in Calibration Method of the present invention.

Specific embodiment

Basic ideas of the invention are as follows: propose a kind of low-light camera Calibration Method, use spectral radiometer mark first The spectral radiance carry-over factor in tandem type low-light spectral radiometric calibration system between two neighboring cascade integral ball is made, is obtained each The spectral radiance in spoke brightness level main integrating sphere radiation exit;Low-light camera to be measured is placed in thermal vacuum tank, and is used Component of low-light camera itself the mechanical-optical setup component as vacuum environment in isolation thermal vacuum tank and the outer laboratory environment of tank;Adjustment Thermal vacuum tank position makes low-light camera optical axis be directed at main integrating sphere export center;Thermal vacuum tank is vacuumized, and completion is vacuumized Afterwards, temperature control measures are taken to low-light camera optical machine main body and focal plane, low-light camera optical machine main body and focal plane is made to work in its design Under operating temperature;Acquire the radiation calibration data of each spoke brightness level low-light camera;Camera rdaiation response characteristic is analyzed, it is fixed to complete Mark.

This method is substantially increased micro- by improving the precision to low-light spectral radiometric calibration system output spectrum spoke luminance test Light radiation scaling precision;Method is using low-light camera itself mechanical-optical setup component as vacuum environment and tank in isolation thermal vacuum tank The component of outer laboratory environment avoids and introduces the optical element of non-camera itself in calibration optical path and easily cause radiation calibration precision The case where reduction, and radiation calibration of the camera in vacuum environment under different temperatures may be implemented.

Preferred specific embodiment are as follows: a kind of low-light camera Calibration Method, steps are as follows:

(1) it when light radiation is provided by secondary integrating sphere in the main integrating sphere of tandem type low-light spectral radiometric calibration system, uses Spectral radiometer tests the spectral radiance at main integrating sphere radiation outlet and secondary integrating sphere optical radiation measurement mouth, according to main product Spectral radiance at bulb separation radiation outlet and secondary integrating sphere optical radiation measurement mouth, is calculated tandem type low-light radiation calibration The spectral radiance carry-over factor of secondary integrating sphere in system to main integrating sphere;

(2) when light radiation is only provided by final stage integrating sphere in secondary integrating sphere, using spectral radiometer test final stage product Spectral radiance at bulb separation optical radiation measurement mouth and secondary integrating sphere optical radiation measurement mouth, is surveyed according to final stage integrating sphere light radiation The spectral radiance at mouth and secondary integrating sphere optical radiation measurement mouth is measured, is calculated in tandem type low-light spectral radiometric calibration system Spectral radiance carry-over factor of the final stage integrating sphere to secondary integrating sphere;

It (3) is each low-light spoke brightness level in the main integrating sphere radiation outlet output of tandem type low-light spectral radiometric calibration system When, it is cascaded at the light radiation scaling system final stage integrating sphere optical radiation measurement mouth that declines using spectral radiometer test and secondary integrates Spectral radiance at ball optical radiation measurement mouth surveys the tandem type low-light spectral radiometric calibration system final stage integrating sphere light radiation measured The spectral radiance at mouth and at secondary integrating sphere optical radiation measurement mouth is measured, in conjunction with the spectrum spoke of secondary integrating sphere to main integrating sphere Each spoke brightness level is calculated to the spectral radiance carry-over factor of secondary integrating sphere in brightness carry-over factor and final stage integrating sphere Under, the spectral radiance in main integrating sphere radiation exit;

(4) low-light camera to be measured is placed in thermal vacuum tank;

(5) using low-light camera itself mechanical-optical setup component as vacuum environment in isolation thermal vacuum tank and the outer laboratory of tank The component of environment;

(6) adjustment thermal vacuum tank position makes low-light camera optical axis be directed at main integrating sphere radiation export center;

(7) thermal vacuum tank is vacuumized;

(8) after the completion of thermal vacuum tank vacuumizes, temperature control measures is taken to low-light camera optical machine main body and focal plane, make low-light Camera optical machine main body and focal plane work at a temperature of design work;

(9) radiation calibration data of each spoke brightness level low-light camera is acquired;

(10) camera rdaiation response characteristic is analyzed, calibration is completed.

The calculation formula of spectral radiance carry-over factor of the secondary integrating sphere to main integrating sphere in the step (1) are as follows: ρ1-2 (λ)=L1(λ)/L2(λ), in formula, ρ1-2(λ) is spectral radiance carry-over factor of the secondary integrating sphere to main integrating sphere, L1(λ)、 L2(λ) is respectively the output of tandem type low-light spectral radiometric calibration system when being same spoke brightness level, the master that is measured with spectral radiometer Integrating sphere radiates the spectral radiance at the spectral radiance and secondary integrating sphere optical radiation measurement mouth in exit.

In the step (2) final stage integrating sphere to secondary integrating sphere spectral radiance carry-over factor calculation formula are as follows: ρ2-3(λ)=L2(λ)/L3(λ), in formula, ρ2-3(λ) is the spectral radiance carry-over factor of final stage integrating sphere and secondary integrating sphere, L2 (λ)、L3(λ) be respectively tandem type low-light spectral radiometric calibration system output be same spoke brightness level when, measured with spectral radiometer Secondary integrating sphere optical radiation measurement mouth at spectral radiance and secondary integrating sphere optical radiation measurement mouth at spectral radiance.

In the step (3) when light radiation is provided by secondary integrating sphere inner light source in main integrating sphere, by secondary integrating sphere Spectral radiance at optical radiation measurement mouth calculates the preferred calculation formula of the spectral radiance in main integrating sphere radiation exit are as follows: L'1i(λ)=L'2i(λ)×ρ1-2(λ), in formula, L'1i(λ) is that tandem type low-light spectral radiometric calibration system output spoke brightness level is i When main integrating sphere radiation exit spectral radiance, L'2i(λ) is that tandem type low-light spectral radiometric calibration system exports spoke brightness level Spectral radiance when for i at secondary integrating sphere optical radiation measurement mouth.When in secondary integrating sphere light radiation only by final stage integrating sphere When offer, calculate that the spectrum spoke in main integrating sphere radiation exit is bright by the spectral radiance of final stage integrating sphere optical radiation measurement mouth The calculation formula of degree are as follows: L'1i(λ)=L'3i(λ)×ρ2-3(λ)×ρ1-2(λ), in formula, L'3i(λ) is that the radiation of tandem type low-light is fixed Mark system exports spectral radiance when spoke brightness level is i at final stage integrating sphere optical radiation measurement mouth.

Low-light camera itself mechanical-optical setup component includes the components such as the optical window of camera itself, lens in step (5).

The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.

It is as shown in Figure 1 the structure composition figure of robot scaling equipment used in the method for the present invention, wherein 1,2 and 3 be respectively final stage product Bulb separation, secondary bulb separation and main integrating sphere, 1,2 and 3 constitute tandem type low-light spectral radiometric calibration system, and final stage integrating sphere inner wall is straight Proportionate relationship preferred embodiment between diameter, secondary integrating sphere inner diameter and main integrating sphere ball inner diameter is 1:1:3,4,5 points Not Wei final stage integrating sphere, secondary bulb separation optical radiation measurement mouth;Final stage integrating sphere optical radiation measurement mouth 4 is located at final stage integrating sphere 1 With the horizontal side of secondary 2 junction of integrating sphere, the opening of final stage integrating sphere optical radiation measurement mouth 4 coefficient (optical radiation measurement mouth face The ratio between long-pending and integrating sphere ball wall area) it is not more than 1%;Secondary integrating sphere optical radiation measurement mouth 5 is located at secondary integrating sphere 2 and main product The horizontal side of 3 junction of bulb separation, secondary integrating sphere optical radiation measurement mouth 5 are open coefficient no more than 1%;Final stage integrating sphere light spoke It penetrates measuring mouth 4 and secondary integrating sphere optical radiation measurement mouth 5 is located at the ipsilateral of tandem type low-light spectral radiometric calibration system;It is integrated based on 6 The radiation of ball exports, and main integrating sphere radiation outlet can cover whole imaging viewing fields of low-light camera;7 be spectral radiometer, and 8 are Low-light camera, 9 be thermal vacuum tank.

It is illustrated in figure 2 the flow diagram of Calibration Method of the present invention, low-light radiation calibration carries out in close luminous environment, Vacuum tank is placed in calibration dark room conditions, is calibrated in darkroom except the main integrating sphere of tandem type low-light spectral radiometric calibration system radiates exit Have outside light radiation, introduces stray light without other light sources;To avoid environment stray light from entering calibration darkroom, preferred embodiment are as follows: fixed The laboratory environment illumination marked outside darkroom is lower than 1 × 10-4lx.When light in the main integrating sphere 3 of tandem type low-light spectral radiometric calibration system When radiation is provided by secondary integrating sphere 2, main integrating sphere radiation outlet 6 and secondary integrating sphere light spoke are tested using spectral radiometer 7 The spectral radiance at measuring mouth 5 is penetrated, according to the light at main integrating sphere radiation outlet 6 and secondary integrating sphere optical radiation measurement mouth 5 Spoke brightness is composed, the secondary integrating sphere 2 being calculated in tandem type low-light spectral radiometric calibration system arrives the spectral radiance of main integrating sphere 3 Carry-over factor;Final stage integrating sphere optical radiation measurement mouth 4 and secondary integrating sphere optical radiation measurement mouth 5 are tested using spectral radiometer 7 The spectral radiance at place, according to the spectrum spoke at final stage integrating sphere optical radiation measurement mouth 4 and secondary integrating sphere optical radiation measurement mouth 5 The spectral radiance transmitting of the final stage integrating sphere in tandem type low-light spectral radiometric calibration system to secondary integrating sphere is calculated in brightness Coefficient;When 6 output of main integrating sphere radiation outlet of tandem type low-light spectral radiometric calibration system is each low-light spoke brightness level, use The test of spectral radiometer 7 cascades at the light radiation scaling system final stage integrating sphere optical radiation measurement mouth 4 that declines and secondary integrating sphere light Spectral radiance at actinometry mouth 5, the tandem type low-light spectral radiometric calibration system final stage integrating sphere optical radiation measurement that will be measured Spectral radiance at mouth 4 and at secondary integrating sphere optical radiation measurement mouth 5, in conjunction with the spectrum spoke of secondary integrating sphere to main integrating sphere Each spoke brightness level is calculated to the spectral radiance carry-over factor of secondary integrating sphere in brightness carry-over factor and final stage integrating sphere Under, the spectral radiance at main integrating sphere radiation outlet 6.The calibration of tandem type low-light spectral radiometric calibration system spectral radiance is completed Afterwards, low-light camera 8 to be measured is placed in thermal vacuum tank 9, and true as isolation heat using low-light camera itself mechanical-optical setup component The component of vacuum environment and the outer laboratory environment of tank in slack tank;Adjustment thermal vacuum tank position makes low-light camera optical axis be directed at main integral Spherical radiation export center;Thermal vacuum tank is vacuumized, preferred embodiment are as follows: when air pressure is lower than 1 × 10 in tank-3When Pa, to low-light phase Machine optical machine main body and focal plane take temperature control measures, and the low temperature for being set lower than in vacuum tank focal plane temperature is heat sink, makes low-light phase Machine optical machine main body and focal plane work at a temperature of its design work, camera focal plane temperature can be set as -30 according to scaling requirements DEG C etc. different worst cold cases.

By the output spoke brightness level of order modification tandem type low-light spectral radiometric calibration system from high to low, in each spoke brightness The radiation calibration data collecting work of level progress low-light camera;According to radiation calibration data, determine that the rdaiation response of camera is special Property, it obtains the dynamic range of camera, respond linear, signal-to-noise ratio, absolute calibration coefficient and relative calibration coefficient.

Low-light camera Calibration Method of the invention, radiation calibration precision depend on spectral radiometer spectral radiance The influence and low-light camera self performance of measurement accuracy, tandem type low-light spectral radiometric calibration system performance to calibration precision are to radiation The influence of calibration precision.If the calibration error that Spectral radiance measurement introduces is δ1, the calibration mistake of radiation calibration source performance introducing Difference is δ2, the calibration error that low-light camera self performance introduces is δ3, radiation calibration precision is δ, excellent according to calibration error principle Select relational expression

Spectral radiometer calibration accuracy is better than 5%, preferred embodiment are as follows: under poor light condition, such as 1 × 10-4W/(m2·sr· μm) when Spectral radiance measurement precision be better than 10%;Influence of the tandem type low-light spectral radiometric calibration system performance to calibration precision is small In 5%;The calibration error that low-light camera self performance introduces is less than 10%;So the radiation calibration precision that the present invention may be implemented Better than 15%, and it can be realized 108: the radiation calibration of 1 or more dynamic range.

The present invention may be implemented that Spectral radiance measurement precision is high, calibration dynamic range is big, analog camera operation on orbit The high low-light radiation calibration of temperature, calibration precision, may be applied not only to radiation calibration and the performance test of low-light optical sensor, Such as dynamic range and signal-to-noise ratio test etc., and can be applied to other optical sensors under weak spoke brightness input condition Performance test.

The content that description in the present invention is not described in detail belongs to the well-known technique of those skilled in the art.

Claims (6)

1. a kind of low-light camera Calibration Method, it is characterised in that steps are as follows:
(1) when light radiation is provided by secondary integrating sphere in the main integrating sphere of tandem type low-light spectral radiometric calibration system, using spectrum Radiometer tests the spectral radiance at main integrating sphere radiation outlet and secondary integrating sphere optical radiation measurement mouth, according to main integrating sphere Spectral radiance at radiation outlet and secondary integrating sphere optical radiation measurement mouth, is calculated tandem type low-light spectral radiometric calibration system In secondary integrating sphere to main integrating sphere spectral radiance carry-over factor;
Using the spectrum at spectral radiometer test final stage integrating sphere optical radiation measurement mouth and secondary integrating sphere optical radiation measurement mouth Spoke brightness is calculated according to the spectral radiance at final stage integrating sphere optical radiation measurement mouth and secondary integrating sphere optical radiation measurement mouth Obtain final stage integrating sphere in tandem type low-light spectral radiometric calibration system to secondary integrating sphere spectral radiance carry-over factor;
When the main integrating sphere radiation outlet output of tandem type low-light spectral radiometric calibration system is each low-light spoke brightness level, using light Spectrum radiometer test cascades at the light radiation scaling system final stage integrating sphere optical radiation measurement mouth that declines and secondary integrating sphere light radiation Spectral radiance at measuring mouth, by the tandem type low-light spectral radiometric calibration system final stage integrating sphere optical radiation measurement mouth measured and Spectral radiance at secondary integrating sphere optical radiation measurement mouth is transmitted in conjunction with the spectral radiance of secondary integrating sphere to main integrating sphere Coefficient and final stage integrating sphere are calculated under each spoke brightness level, main product to the spectral radiance carry-over factor of secondary integrating sphere The spectral radiance in bulb separation radiation exit;
(2) low-light camera to be measured is placed in thermal vacuum tank, and using low-light camera itself mechanical-optical setup component as isolation heat The component of vacuum environment and the outer laboratory environment of tank in vacuum tank;
(3) adjustment thermal vacuum tank position makes low-light camera optical axis be directed at main integrating sphere radiation export center;
(4) thermal vacuum tank is vacuumized, after the completion of vacuumizing, takes temperature control to arrange low-light camera optical machine main body and focal plane It applies, works in low-light camera optical machine main body and focal plane under setting operating temperature, camera focal plane may be set to different low temperature works Condition;
(5) low-light camera under each spoke brightness level in the main integrating sphere radiation exit of tandem type low-light spectral radiometric calibration system is acquired Radiation calibration data;
(6) according to the radiation calibration data of step (5), camera rdaiation response characteristic is determined, comprising: the dynamic range of camera, sound It should linear, signal-to-noise ratio, absolute calibration coefficient and relative calibration coefficient.
2. a kind of low-light camera Calibration Method according to claim 1, it is characterised in that:
Whole imaging viewing fields of the main integrating sphere radiation outlet covering low-light camera of tandem type low-light spectral radiometric calibration system;Final stage product Proportionate relationship between bulb separation inner diameter, secondary integrating sphere inner diameter and main integrating sphere ball inner diameter is 1:1:3.
3. a kind of low-light camera Calibration Method according to claim 1, it is characterised in that: vacuumized to vacuum tank Afterwards, when in tank air pressure be lower than 1 × 10-3When Pa, then temperature control measures are taken to low-light camera focal plane, and be set lower than in vacuum tank The low temperature of focal plane temperature is heat sink, is contaminated to avoid low-light camera focal plane.
4. a kind of low-light camera Calibration Method according to claim 1, it is characterised in that: the radiation of tandem type low-light is fixed The final stage integrating sphere optical radiation measurement mouth of mark system is located at the horizontal side of final stage integrating sphere and secondary integrating sphere junction, opening The ratio between coefficient, i.e. integrating sphere optical radiation measurement open area and integrating sphere ball wall area are not more than 1%;Secondary integrating sphere light radiation Measuring mouth is located at the horizontal side of secondary integrating sphere and main integrating sphere junction, and opening coefficient is not more than 1%;Final stage integrating sphere light Actinometry mouth and secondary integrating sphere optical radiation measurement mouth are located at the ipsilateral of tandem type low-light spectral radiometric calibration system.
5. a kind of low-light camera Calibration Method according to claim 1, it is characterised in that: low-light radiation calibration is close It is carried out in luminous environment, vacuum tank is placed in calibration dark room conditions, is calibrated and is removed the main product of tandem type low-light spectral radiometric calibration system in darkroom Bulb separation radiation exit has outside light radiation, introduces stray light without other light sources;To avoid environment stray light from entering calibration darkroom, The laboratory environment illumination calibrated outside darkroom is lower than 1 × 10-4lx。
6. a kind of low-light camera Calibration Method according to claim 1, it is characterised in that: the low temperature work of camera focal plane The worst cold case that condition is -30 DEG C.
CN201611194034.4A 2016-12-21 2016-12-21 A kind of low-light camera Calibration Method CN106840198B (en)

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