CN102162739B - Method and device for testing in-orbit dynamic transfer function of space camera - Google Patents

Abstract

The invention provides a method and a device for testing an in-orbit dynamic transfer function of a space camera, and relates to the space optical field. By the invention, the problems that only a small partial area within image element ground resolution can be tested by the conventional camera during radiation brightness measurement of targets paved on the ground during in-orbit dynamic transfer function test, the test data has larger deviation due to the non-uniform targets, and the atmospheric transmissivity and the atmospheric back scattering which are calculated by adopting software are much different from actual values can be solved. In the invention, the test data of the in-orbit dynamic transfer function of the camera can be acquired directly by using the space camera as an optical remote sensor, adding a target of which the placement space frequency is 11p/mm on the ground and using an image shot by the space camera, so an error due to inaccurate ground measurement and atmospheric software calculation can be avoided, the modulation degree from the ground target comprising the atmospheric transmissivity and the atmospheric back scattering to the pupil of the camera is acquired directly, and the in-orbit dynamic transfer function of the camera can be obtained accurately and conveniently. The invention is applied to the in-orbit dynamic transfer test.

Description

Space camera dynamically passes letter method of testing and device at rail

Technical field

The present invention relates to the space optics field, be specifically related to a kind of space camera and dynamically pass letter method of testing and device at rail.

Background technology

The camera dynamic transfer function is the important parameter of check camera imaging quality; At present; It is through test land-based target target contrast that camera dynamically passes the letter test at rail; That is: through the degree of modulation of reflectance calculating target, adopt computed in software atmospheric transmittance and atmospheric backscatter, then the black and white target degree of modulation of computing camera entrance pupil.There is the problem of several aspects in this method, and one of which, ground test data are point measurement, is the part of measurement target drone, and test zone is the fraction in the resolving power of picture dot ground, because the inhomogeneous meeting of target causes bigger deviation.Its two, depart from greatlyyer with scattering behind computed in software atmospheric transmittance and the atmosphere and actual, software provides Utopian model, can not be just in time corresponding with weather conditions at that time, cause calculated value and actual value that bigger deviation is arranged.Thereby dynamically pass the letter test at rail for final camera and cause bigger deviation.Obtain accurate dynamic biography letter and just must obtain the degree of modulation of target (comprising atmospheric transmittance and atmospheric backscatter) accurately to the camera entrance pupil.

Summary of the invention

The present invention can only test the local zonule in the resolving power of picture dot ground for solution dynamically passes in the letter test at rail at existing camera in the target radiance measurement in floor pavement; And because the test data that causes such as inhomogeneous of target has bigger deviation; Adopt scattering and the big problem of actual value deviation behind computed in software atmospheric transmittance and the atmosphere simultaneously, provide a kind of land-based target target image that utilizes space camera to obtain to obtain dynamically to pass letter method of testing and device at rail.

Space camera dynamically passes the letter method of testing at rail, and this method may further comprise the steps:

The horizontal target pendulum of vertical target of step 1, the first right angle target, the second right angle target, nyquist frequency and nyquist frequency is on same level ground;

Step 2, adopt that the black target in the white target and the second right angle target in the described first right angle target of step 1 acquires camera entrance pupil place comprise atmospheric effect at interior degree of modulation M _Thing,

Concrete computation process is: the black target in the black target in the said first right angle target, white target and the second right angle target, white target have identical reflectivity and identical spoke brightness on the ground under the same sun angle of elevation;

Has identical reflectivity ρ on the ground _{W λ}White target have identical spoke brightness B _W,

$B_W={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{W\λ}}---\left(1\right)$

In the formula: B _WThe spoke brightness of-Bai target;

B _{W λ}The spectral radiance of-Bai target;

E _λ-the sun arrives the spectral irradiance on ground;

ρ _{W λ}The spectral reflectivity of-Bai target;

λ-wavelength, unit are nm;

Has identical reflectivity ρ on the ground _{D λ}Black target have identical spoke brightness B _D,

$B_D={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{D\λ}}}{\mathrm{\π}}={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{D\λ}}---\left(2\right)$

In the formula: B _DThe spoke brightness of-Hei target;

B _{D λ}The spectral radiance of-Hei target;

ρ _{D λ}The spectral reflectivity of-Hei target;

Atmospheric spectral transmittance is τ _λ, the atmospheric scattering spectral radiance is B _{SCAT λ}, said white target arrives the spoke brightness L of camera entrance pupil _WFor

$L_W=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}(\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT\λ}})$

$=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}{B}_{\mathrm{SCAT\λ}}=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}$

$={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{W\λ}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}---\left(3\right)$

In the formula: B _SCATThe brightness of-atmospheric backscatter integration spoke;

Black target arrives the spoke brightness L of camera entrance pupil _DFor

$L_D=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{D\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}$

$={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{D\λ}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}---\left(4\right)$

Camera is through the laboratory radiation calibration, and the radiance relation that draws camera output DN value and camera entrance pupil place is:

DN＝R×L

In the formula, DN-gradation of image value;

The R-responsiveness;

The brightness of L-camera entrance pupil spoke;

The mean value of the white target DN value of said camera output is DN _W, the mean value of the black target DN value of camera output is DN _D, can get:

DN _W＝R×L _W

That is: L _W=DN _W/ R

Can get equally:

L _D＝DN _D/R

Obtain:

M _Thing-camera entrance pupil place comprises atmospheric effect in interior degree of modulation;

Horizontal target (4) the test camera of step 3, the employing vertical target of the described nyquist frequency of step 1 and nyquist frequency is the degree of modulation M of the picture at nyquist frequency place in spatial frequency _Picture, obtain camera and dynamically pass letter at rail;

Concrete computation process is: the vertical target of said nyquist frequency and the horizontal target of nyquist frequency are to the degree of modulation M of camera entrance pupil _ThingDegree of modulation M with the first right angle target in the step 2 and the second right angle target acquisition to the camera entrance pupil _ThingEquate; That is:

The degree of modulation M of the picture of the vertical satellite flight orbital direction of computing camera _{Picture V}With degree of modulation M along the picture of rail direction _{Picture H}For:

In the formula: DN _VmaxGradation of image value maximal value for the vertical satellite flight orbital direction of camera;

DN _VminGradation of image value minimum value for the vertical satellite flight orbital direction of camera;

DN _HmaxBe the gradation of image value maximal value of camera along the rail direction;

DN _HminBe the gradation of image value minimum value of camera along the rail direction;

Obtain camera and dynamically pass letter at rail; Dynamically the passing letter at rail and be respectively the dynamic biography letter MTF of camera of said camera in vertical satellite flight orbital direction _VWith dynamic biography letter MTF along the rail direction _H:

Space camera dynamically passes the letter proving installation at rail, and this device comprises the vertical target of the first right angle target, the second right angle target, nyquist frequency and the horizontal target of nyquist frequency; Vertical target of said nyquist frequency and satellite flight parallel track; The horizontal target of nyquist frequency is vertical with the satellite flight track, and the vertical target of the said first right angle target, the second right angle target, nyquist frequency and the horizontal target of nyquist frequency are made up of white target and black target respectively; Said black target is identical with the contrast of white target; The horizontal target pendulum of vertical target of the said first right angle target, the second right angle target, nyquist frequency and nyquist frequency is on same level ground; The described first right angle target is corresponding with the spatial frequency 1lp/mm in the space camera with the spatial frequency that the second right angle target constitutes on the locus; The white target of high diffuse reflectance that all white targets all are made of the same material, the black target of low diffuse reflectance that all black targets are processed by other a kind of identical materials.

Principle of work of the present invention: the present invention proposes a kind of camera image that utilizes can accurately obtain camera dynamically passes letter at rail method; That is: be the method that the target image of 1lp/mm obtains to comprise the degree of modulation that arrives the camera entrance pupil of atmospheric transmittance and atmospheric backscatter through the camera spatial frequency; Through the camera spatial frequency is the method that the target image of nyquist frequency obtains the degree of modulation of picture; Thereby accurately obtain camera and dynamically pass the method for testing of letter, and invent corresponding testing device at rail.The present invention is two kinds of targets of ornaments on ground; The spatial frequency that comprises corresponding space camera is that target and the spatial frequency of 1lp/mm is the target of nyquist frequency, and spatial frequency is that the target of 1lp/mm is used to test that target (comprising influences such as atmospheric transmittance and atmospheric backscatter interior) arrives camera entrance pupil place comprises atmospheric effect at interior degree of modulation M _Thing, spatial frequency is that to be used to test camera be the degree of modulation M of the picture at nyquist frequency place in spatial frequency to the target of nyquist frequency _PictureThereby, obtain camera and dynamically pass letter, that is: MTF=M at rail _Picture/ M _ThingIn the method, use spatial frequency to obtain the degree of modulation M of camera entrance pupil as the target image of 1lp/mm _ThingBe that this target radiance arrives the camera entrance pupil through propagation in atmosphere (promptly receiving atmospheric transmittance and atmospheric backscatter etc. to influence the back); Be converted into image output after being received by camera; The gradation of image value of camera output and the spoke brightness of camera entrance pupil are linear response relationships, and promptly the gradation of image value is proportional to the brightness of camera entrance pupil spoke, thereby use spatial frequency can try to achieve the degree of modulation M at camera entrance pupil place as the corresponding gradation of image value (this image is influenced by spatial frequency hardly) of the target of 1lp/mm _Thing, this M _ThingComprising at that time, atmospheric transmittance and atmospheric backscatter are the actual values that directly records through space camera interior.With spatial frequency is that the target of nyquist frequency arrives the camera entrance pupil behind atmospheric transmittance and atmospheric backscatter state is consistent; The identical sun angle of elevation, identical reflectivity, identical atmospheric transmittance; Identical atmospheric backscatter spoke brightness; Just spatial frequency is different, thereby this method has avoided inaccurate and with the error of atmosphere computed in software introducing because of ground survey.Can obtain camera more accurately and conveniently and dynamically pass letter at rail.

Beneficial effect of the present invention: the spatial frequency that the present invention furnishes corresponding space camera through ground is the target of 1lp/mm; With furnishing corresponding camera spatial frequency is the nyquist frequency target; Target image through the acquisition of analysis space camera; What directly obtain camera dynamically passes the letter test data at rail, and this method accurately, simply and is conveniently avoided the error of introducing because of ground survey sum of errors estimation atmospheric transmittance and atmospheric backscatter etc.

Description of drawings

Fig. 1 puts synoptic diagram for space camera of the present invention dynamically passes the letter proving installation at rail.

Among the figure: 1, the first right angle target, 2, vertical target of nyquist frequency, 3 nyquist frequency target unit, 4, the horizontal target of nyquist frequency, 5, the second right angle target.

Embodiment

Embodiment one, combination Fig. 1 explain this embodiment, and space camera dynamically passes the letter method of testing at rail, and this method is realized by following steps:

The vertical target 2 of step 1, the first right angle target 1, the second right angle target 5, nyquist frequency and the horizontal target pendulum of nyquist frequency are on same level ground;

Step 2, adopt that white target and the black target in the second right angle target 5 in the described first right angle target 1 of step 1 acquire camera entrance pupil place comprise atmospheric effect at interior degree of modulation M _Thing,

Concrete computation process is: the black target in the black target in the said first right angle target 1, white target and the second right angle target 5, target has identical reflectivity and identical spoke brightness on the ground in vain; At camera imaging constantly, combine all targets among Fig. 1 all under the identical sun angle of elevation, pass through identical atmospheric transmittance; After influenced by identical atmospheric backscatter; Arrive the camera entrance pupil, through after having the camera of linear response, obtain the target image of camera output again.

Has identical reflectivity ρ on the ground _{W λ}White target have identical spoke brightness B _W,

$B_W={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}\frac{E_{\mathrm{\λ}}{\×\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{W\λ}}---\left(1\right)$

In the formula: B _WThe spoke brightness of-Bai target;

B _{W λ}The spectral radiance of-Bai target;

E _λ-the sun arrives the spectral irradiance on ground;

ρ _{W λ}The spectral reflectivity of-Bai target;

λ-wavelength unit is nm.

Has identical reflectivity ρ on the ground _{D λ}Black target have identical spoke brightness B _D,

$B_D={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}\frac{E_{\mathrm{\λ}}{\×\mathrm{\ρ}}_{\mathrm{D\λ}}}{\mathrm{\π}}={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{D\λ}}---\left(2\right)$

In the formula: B _DThe spoke brightness of-Hei target.

B _{D λ}The spectral radiance of-Hei target

ρ _{D λ}The spectral reflectivity of-Hei target;

The atmospheric spectral transmittance of this moment is τ _λ, the atmospheric scattering spectral radiance is B _{SCAT λ}, then white target arrives the spoke brightness L of camera entrance pupil _WFor

$L_W=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}(\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT\λ}})$

$=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}{B}_{\mathrm{SCAT\λ}}=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{W\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}$

$={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{W\λ}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}---\left(3\right)$

In the formula: B _SCATThe brightness of-atmospheric backscatter integration spoke;

Black target arrives the spoke brightness L of camera entrance pupil _DFor

$L_D=\underset{\mathrm{\λ}=500}{\overset{900}{\mathrm{\Σ}}}\frac{E_{\mathrm{\λ}}\×{\mathrm{\ρ}}_{\mathrm{D\λ}}}{\mathrm{\π}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}$

$={\mathrm{\Σ}}_{\mathrm{\λ}=500}^{900}{B}_{\mathrm{D\λ}}\×{\mathrm{\τ}}_{\mathrm{\λ}}+B_{\mathrm{SCAT}}---\left(4\right)$

In target shown in Figure 1, the reflectivity of all white targets is identical, thereby arrives the spoke brightness L of camera entrance pupil _WEquate that the emissivity of all black targets is identical, arrives the spoke brightness L of camera entrance pupil equally _DEquate.

Radiance L for camera output DN value and entrance pupil place has following relation:

DN＝R×L

In the formula, DN-camera output DN value;

The R-responsiveness;

The brightness of L-camera entrance pupil spoke.

In Fig. 1, white target is chosen a-quadrant in 1, and the average of output DN value is DN _W, black target is chosen the B zone in 5, and the average of output DN value is DN _D, a-quadrant and B zone constitute the target that the camera spatial frequency is 1lp/mm on the locus, and this moment, the biography letter of camera was 0.9999, thereby the DN value of on two zones, exporting camera subject biography letter influence hardly, so

DN _W＝R×L _W

Promptly try to achieve: L _W=DN _W/ R

Can get equally:

L _D＝DN _D/R

Can try to achieve

M _Thing-camera entrance pupil degree of modulation;

The horizontal target 4 test cameras of step 3, the employing vertical target of the described nyquist frequency of step 1 and nyquist frequency are the degree of modulation M of the picture at nyquist frequency place in spatial frequency _Picture, obtain camera and dynamically pass letter at rail;

Concrete computation process is: the vertical target 2 of said nyquist frequency and the horizontal target 4 of nyquist frequency are to the degree of modulation M of camera entrance pupil _ThingAcquire the degree of modulation M of camera entrance pupil with the first right angle target 1 in the step 2 and the second right angle target 5 _ThingEquate; Image is influenced by the nyquist frequency spatial frequency; The target material is consistent in vain because in the material of the white target on the horizontal target 4 of vertical target 2 of nyquist frequency and nyquist frequency and the first right angle target 1 and the second right angle target 5; The material of the black target on the vertical target 2 of this nyquist frequency and the horizontal target 4 of nyquist frequency is consistent with the black target material in the first right angle target 1 and the second right angle target 5; Promptly have identical reflectivity respectively, thereby arrive the M of camera entrance pupil _ThingFor

Utilize the target image in the horizontal target 4 of vertical target 2 and nyquist frequency of nyquist frequency, can calculate the degree of modulation M of the picture of camera vertical track direction _{Picture V}With degree of modulation M along the picture of rail direction _{Picture H}

So try to achieve the dynamic biography letter MTF in the vertical track direction of camera _VWith dynamic biography letter MTF along the rail direction _H

In conjunction with Fig. 1, described all white portions of this embodiment all are the white targets of high diffuse reflectance that has commaterial to process, the black target of the low diffuse reflectance that all black regions have other a kind of identical materials to process, and black, white target has identical contrast; Wherein white portion and black region size are the square of 20 times ground picture dot resolving power in the first right angle target 1 and the second right angle target 5; The first right angle target 1 and the second right angle target 5 constitute the target of corresponding space camera 1lp/mm spatial frequency, and what be used to obtain camera entrance pupil place comprises atmospheric effect at interior degree of modulation M _ThingThe 3rd, vertical target unit; The 2nd, vertical target of forming by N Nai Kuisi frequency target unit 3 with 1/N dislocation; Be the target bar width of the distance of two adjacent vertical target unit 3 between when on the locus, putting for (N-1)/N; Said each target bar width is 1 times of ground picture dot resolving power, and each target bar length is 8 times of ground picture dot resolving powers, is used for the dynamic transfer function of measuring vertical orbital direction; The 4th, by the horizontal target that the target unit 3 of N Nai Kuisi frequency is formed, be about to the target identical and turn 90 degrees placement with 2 with 1/N dislocation, become horizontal target, be used to measure the dynamic transfer function of direction along ng a path; Said N is the positive integer more than or equal to 5.

Embodiment two, space camera dynamically pass the letter proving installation at rail, and this device comprises the first right angle target 1, the second right angle target 5, vertical target 2 of nyquist frequency and the horizontal target 4 of nyquist frequency; The vertical target 2 and the satellite flight parallel track of said nyquist frequency; The horizontal target 4 of nyquist frequency is vertical with the satellite flight track, and the said first right angle target 1, the second right angle target 5, vertical target 2 of nyquist frequency and the horizontal target 4 of nyquist frequency are made up of white target and black target respectively; Said black target is identical with the contrast of white target.

The described first right angle target 1 of this embodiment and the second right angle target 5 constitute the target of corresponding space camera 1lp/mm spatial frequency.

The horizontal target unit with 1/N dislocation that the vertical target unit with 1/N dislocation that vertical target 2 of the described nyquist frequency of this embodiment and the horizontal target of nyquist frequency are made up of N nyquist frequency target unit 3 respectively and N Nai Kuisi frequency target unit 3 are formed is formed, and said N is the positive integer more than or equal to 5.

The present invention, directly obtains to comprise atmospheric transmittance and atmospheric backscatter and comprises atmospheric effect at interior degree of modulation M at interior ground target arrival camera entrance pupil place as optical sensor through space camera _Thing, avoided error inaccurate and that introduce with the atmosphere computed in software because of ground survey, can obtain the target image through camera and obtain camera more accurately and conveniently and dynamically pass letter at rail.

Claims (7)

1. space camera dynamically passes the letter method of testing at rail, it is characterized in that, this method may further comprise the steps:

Vertical target (2) of step 1, the first right angle target (1), the second right angle target (5), nyquist frequency and the horizontal target (4) of nyquist frequency pendulum are on same level ground;

Step 2, adopt that the described first right angle target (1) of step 1 and the second right angle target (5) acquire camera entrance pupil place comprise atmospheric effect at interior degree of modulation M _Thing,

Concrete computation process is: the black target in the black target in the said first right angle target (1), white target and the second right angle target (5), white target have identical reflectivity and identical spoke brightness on the ground under the same sun angle of elevation;

Has identical reflectivity ρ on the ground _{W λ}White target have identical spoke brightness B _W,

In the formula: B _WThe spoke brightness of-Bai target;

B _{W λ}The spectral radiance of-Bai target;

E _λ-the sun arrives the spectral irradiance on ground;

ρ _{W λ}The spectral reflectivity of-Bai target;

λ-wavelength, unit are nm;

Has identical reflectivity ρ on the ground _{D λ}Black target have identical spoke brightness B _D,

In the formula: B _DThe spoke brightness of-Hei target;

B _{D λ}The spectral radiance of-Hei target;

ρ _{D λ}The spectral reflectivity of-Hei target;

Atmospheric spectral transmittance is τ _λ, the atmospheric scattering spectral radiance is B _{SCAT λ}, said white target arrives the spoke brightness L of camera entrance pupil _WFor

In the formula: B _SCATThe brightness of-atmospheric backscatter integration spoke; Black target arrives the spoke brightness L of camera entrance pupil _DFor

Camera output DN value is:

DN＝R×L

In the formula, DN-gradation of image value;

The R-responsiveness;

The brightness of L-camera entrance pupil spoke;

The average of the white target DN value of said camera output is DN _W, the average of the black target DN value of camera output is DN _D, can get:

DN _W＝R×L _W

That is: L _W=DN _W/ R

Can get equally:

L _D＝DN _D/R

Obtain:

M _Thing-camera entrance pupil place comprises atmospheric effect in interior degree of modulation;

Horizontal target (4) the test camera of step 3, the employing vertical target of the described nyquist frequency of step 1 (2) and nyquist frequency is the degree of modulation M of the picture at nyquist frequency place in spatial frequency _Picture, obtain camera and dynamically pass letter at rail;

Concrete computation process is: the vertical target (2) of said nyquist frequency and the horizontal target (4) of nyquist frequency are to the degree of modulation M of camera entrance pupil _ThingComprise atmospheric effect at interior degree of modulation M with the first right angle target (1) in the step 2 and the second right angle target (5) obtain to camera entrance pupil place _ThingEquate; That is:

The degree of modulation M of the picture of the vertical satellite flight orbital direction of computing camera _{Picture V}With degree of modulation M along the picture of rail direction _{Picture H}For:

In the formula: DN _VmaxGradation of image maximal value for the vertical satellite flight orbital direction of camera;

DN _VminGradation of image minimum value for the vertical satellite flight orbital direction of camera;

DN _HmaxBe the gradation of image maximal value of camera along the rail direction;

DN _HminBe the gradation of image minimum value of camera along the rail direction;

Obtain camera and dynamically pass letter at rail; Dynamically the passing letter at rail and be respectively the dynamic biography letter MTF of camera of said camera in vertical satellite flight orbital direction _VWith dynamic biography letter MTF along the rail direction _H:

2. space camera according to claim 1 dynamically passes the letter method of testing at rail; It is characterized in that; The horizontal target with 1/N dislocation that vertical target with 1/N dislocation that the vertical target (2) of the said nyquist frequency of step 1 and the horizontal target (4) of nyquist frequency are made up of N nyquist frequency target unit (3) respectively and N nyquist frequency target unit (3) are formed is formed, and said N is the positive integer more than or equal to 5.

3. space camera according to claim 2 dynamically passes the letter method of testing at rail, it is characterized in that, the distance of adjacent target unit is the target bar width of (N-1)/N in the vertical target of said 1/N dislocation and the horizontal target of 1/N dislocation.

4. space camera according to claim 1 dynamically passes the letter method of testing at rail; It is characterized in that the spatial frequency that black target constitutes in white target and the second right angle target (5) in the described first right angle target (1) of step 1 is corresponding with the spatial frequency 1lp/mm in the space camera on the locus.

5. space camera dynamically passes the letter proving installation at rail, and this device comprises the vertical target (2) of the first right angle target (1), the second right angle target (5), nyquist frequency and the horizontal target (4) of nyquist frequency; Vertical target (2) of said nyquist frequency and satellite flight parallel track; The horizontal target (4) of nyquist frequency is vertical with the satellite flight track, and the vertical target (2) of the said first right angle target (1), the second right angle target (5), nyquist frequency and the horizontal target (4) of nyquist frequency are made up of white target and black target respectively; Said black target is identical with the contrast of white target; Vertical target (2) of the said first right angle target (1), the second right angle target (5), nyquist frequency and the horizontal target (4) of nyquist frequency pendulum are on same level ground; The described first right angle target (1) is corresponding with the spatial frequency 1lp/mm in the space camera with the spatial frequency that the second right angle target (5) constitutes on the locus; The white target of high diffuse reflectance that all white targets all are made of the same material, the black target of low diffuse reflectance that all black targets are processed by other a kind of identical materials.

6. space camera according to claim 5 dynamically passes the letter proving installation at rail; It is characterized in that the spatial frequency that black target constitutes in white target and the second right angle target (5) in the described first right angle target (1) is corresponding with the spatial frequency 1lp/mm in the space camera on the locus.

7. space camera according to claim 5 dynamically passes the letter proving installation at rail; It is characterized in that; The horizontal target unit with 1/N dislocation that the vertical target unit with 1/N dislocation that the vertical target (2) of said nyquist frequency and the horizontal target (4) of nyquist frequency are made up of N nyquist frequency unit respectively and N Nai Kuisi frequency cells are formed is formed, and said N is the positive integer more than or equal to 5.

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