CN103439791A - Method for correcting wavefront errors with changeable correcting field range - Google Patents

Abstract

The invention relates to the field of remote sensing, in particular to a method for correcting wavefront errors with a changeable correcting field range. The method comprises the steps of collecting a full field remote sensing image, dividing the full field remote sensing image into M sub-field images, using Lukosz polynomial linear superposition for expressing wavefront errors, using the integral of image power spectrum density low-frequency space as the image quality assessment function of the tth sub-field image, using the relation between the coefficient of the ith order of the Lukosz polynomial and the image quality assessment function for solving all the coefficients of the ith order of the Lukosz polynomial, obtaining the coefficient correcting value of the ith order of the Lukosz polynomial according to all the solved coefficients of the ith order of the Lukosz polynomial, and carrying out calibration on the wavefront errors by using a deformable mirror according to the coefficient correcting value of the ith order of the Lukosz polynomial. According to the method for correcting the wavefront errors with the changeable correcting field range, wavefront sensors do not need to be arranged on all field of a remote sensor to measure the wavefront errors, the system is simple in structure, the arithmetic does not need repeated iteration, and the method for correcting the wavefront errors with the changeable correcting field range is good in instantaneity.

Description

A kind ofly proofread and correct the variable wavefront error bearing calibration of field range

Technical field

The present invention relates to the remote sensing field, be specifically related to a kind of variable wavefront error bearing calibration of field range of proofreading and correct.

Background technology

The many aspects such as space optical remote can be used for territory planning, environmental monitoring, resource investigation, prevents and reduces natural disasters, military surveillance, have significant economic and social benefit.High-resolution space optical remote sensor is due to characteristics such as its heavy caliber, long-focus, and imaging performance easily is subject to the impact of inside and outside factor and can't realizes high-resolution imaging.These influence factors comprise the mirror finish error, and space temperature and gravity environment change the surface deformation caused, optical system is debug error in-orbit, the optical jitter that the satellite platform flutter causes etc.These influence factors are that optical system is brought the wavefront error of can not ignore, and cause imaging resolution to descend.Based on adaptive optical technique, wavefront error is measured and proofreaied and correct is one of Major Technology of implementation space optical sensor high-resolution imaging.

The working field of view of space optical remote sensor is generally larger, adopt ADAPTIVE OPTICS SYSTEMS to carry out timing to its wavefront error, normally for the wavefront error of visual field on axle, proofreaied and correct, the aberration of the outer visual field of axle can not, by full remuneration, cause the picture element of the outer visual field of axle relatively to descend.

In order to enlarge the correction field range for the ADAPTIVE OPTICS SYSTEMS of space optical remote sensor, a Wavefront sensor can be set respectively in each visual field to survey the wavefront error of respective field of vision, utilize distorting lens to be proofreaied and correct one by one the wavefront error of each visual field, this method needs a plurality of Wavefront sensors, and structure is very complicated.Another kind method is the wide visual field adaptive optics bearing calibration adopted based on random paralleling gradient descent algorithm, and the method need to be carried out repeatedly iteration, and computation process is very loaded down with trivial details, consuming time long, is unfavorable for applying in-orbit.

Summary of the invention

In view of this, the invention provides a kind of variable wavefront error bearing calibration of field range of proofreading and correct, there are without iterative computation repeatedly the characteristics that real-time is good.

This scheme is achieved in that

A kind ofly proofread and correct the variable wavefront error bearing calibration of field range, comprising:

Step 1, gather the full visual field of width remote sensing images;

Step 2, described full visual field remote sensing images are divided into to M sub-view field image by the uniform grid form, make every sub-view field image meet approximate wait dizzy;

Step 3, the polynomial linear superposition of use Lukosz mean wavefront error φ,

wherein, a _ithe polynomial coefficient of the described Lukosz in i rank, L _i(r, θ) is the described Lukosz polynomial expressions in i rank, and N is the polynomial total exponent number of described Lukosz;

The integration of step 4, use image power spectrum density low frequency space is as the image quality evaluation function J of t sub-view field image _t,

wherein, S _tthe image power spectrum density that (u, v) is t sub-visual field, (u, v) is the frequency domain coordinate, R is corresponding to the annular region m on frequency domain ₁≤ (u ²+ v ²) ^1/2≤ m ₂, m wherein ₁and m ₂it is the default value that is less than the cutoff frequency of the detector that gathers full visual field remote sensing images in frequency domain.

Step 5, according to the user, to the interest level of described full visual field remote sensing images internal object, be each described sub-view field image value of assigning weight, calculate corresponding image quality evaluation function J,

the number that wherein M is sub-view field image, η _tbe t the weight that visual field is corresponding;

Each rank coefficient of described Lukosz polynomial expression meets

wherein, i=1,2 ... N, q ₀and q ₁for the constant relevant with picture structure;

Step 6, utilize each rank coefficient of Lukosz polynomial expression to meet

with described image quality evaluation function

between relation of equality solve each rank coefficient of Lukosz polynomial expression;

Step 7, according to each rank of coefficient calculations Lukosz polynomial expression, each rank of tried to achieve Lukosz polynomial expression coefficient correction amount a _{i, corr};

Step 8, according to each rank of Lukosz polynomial expression coefficient correction amount a _{i, corr}, utilize distorting lens to be proofreaied and correct described wavefront error.

Beneficial effect:

The first, the present invention adopts Lukosz fitting of a polynomial wavefront error, calculates the correcting value of each rank Lukosz mode coefficient in conjunction with the image quality evaluation function, and computation process, without iteration repeatedly, needs repeatedly the optimized algorithm of iteration to compare real-time with tradition and greatly improves.

The second, wavefront error bearing calibration of the present invention utilizes the image quality evaluation function of remote sensing images to obtain the wavefront error correcting value, does not need that each visual field is arranged to Wavefront sensor and measures wavefront error, simple in structure, has reduced the complicacy of system, has reduced cost.

Three, wavefront error bearing calibration of the present invention adopts the method to the image quality evaluation function weighting that in every sub-visual field, image is corresponding, obtains the image quality evaluation function used in the wavefront error correcting algorithm.Distribute identical weighted value can to when ADAPTIVE OPTICS SYSTEMS works in the generaI investigation pattern each visual field, adopt full visual field balance correction, now can in the full field range of remote sensor, obtain comparatively balanced picture element.Can strengthen the weighted value in field of view of interest zone when ADAPTIVE OPTICS SYSTEMS works in the detailed survey pattern, even all the other visual field weighted values can be made as to zero, adopt emphasis to proofread and correct, now can obtain the more details information of interesting target.

The accompanying drawing explanation

The process flow diagram that Fig. 1 is the variable wavefront error bearing calibration of correction field range of the present invention.

Embodiment

The invention provides a kind of variable wavefront error bearing calibration of field range of proofreading and correct, as shown in Figure 1, comprising:

Step 1, gather the full visual field of width remote sensing images;

Step 2, described full visual field remote sensing images are divided into to M sub-view field image by the uniform grid form, make every sub-view field image meet approximate wait dizzy;

Step 3, the polynomial linear superposition of use Lukosz mean wavefront error φ,

$\mathrm{\φ}=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{a}_i{L}_i(r,\mathrm{\θ})$

Wherein, a _ithe polynomial coefficient of the described Lukosz in i rank, L _i(r, θ) is the described Lukosz polynomial expressions in i rank, and N is the polynomial total exponent number of described Lukosz;

The integration of step 4, use image power spectrum density low frequency space is as the image quality evaluation function J of t sub-view field image _t,

wherein, S _tthe image power spectrum density that (u, v) is t sub-visual field, (u, v) is the frequency domain coordinate, R is corresponding to the annular region m on frequency domain ₁≤ (u ²+ v ²) ^1/2≤ m ₂, m wherein ₁and m ₂it is the default value that is less than the cutoff frequency of the detector that gathers full view field image in frequency domain.While calculating evaluation function, can determine m according to emulation experiment ₁and m ₂concrete numerical value, value is with each rank coefficient of described Lukosz polynomial expression and described image quality evaluation function J _tbetween relation meet parabolic relation be as the criterion, wherein, i=1,2 ... N, q ₀and q ₁for the constant relevant with picture structure;

Step 5, according to the user, to the interest level of described full visual field remote sensing images internal object, be each described sub-view field image value of assigning weight, calculate corresponding image quality evaluation function J,

the number that wherein M is sub-view field image, η _tbe t the weight that visual field is corresponding;

Employing, to the method for the image quality evaluation function weighting that in every sub-visual field, image is corresponding, obtains the image quality evaluation function used in the wavefront error correcting algorithm.Distribute identical weighted value can to when ADAPTIVE OPTICS SYSTEMS works in the generaI investigation pattern each visual field, adopt full visual field balance correction.Can strengthen the weighted value in field of view of interest zone when ADAPTIVE OPTICS SYSTEMS works in the detailed survey pattern, even all the other visual field weighted values can be made as to zero, adopt emphasis to proofread and correct.

Step 6, utilize each rank coefficient of Lukosz polynomial expression to meet

with described image quality evaluation function

between relation of equality solve each rank coefficient of Lukosz polynomial expression;

Particularly, solve certain single order Lukosz multinomial coefficient a _ithe time, introduce the side-play amount b of this rank pattern thereby make it produce certain deformation by distorting lens is transmitted control signal in wavefront error _i, b _iselection by experiment, determined, the principle of choosing is to guarantee

relation exist all the time.

Image quality evaluation function while not adding side-play amount is J ₀, add positive displacement errors+b _il _ithe time the image quality evaluation function be J ₊, system is added negative displacement errors-b _il _ithe time the image quality evaluation function be J _-.

According to

image quality evaluation function and a by these three times measurement gained _isimultaneous Equations has:

$\left\{\begin{array}{c}{J}_0=q_0-q_1\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{a}_k^2-q_1{a}_i^2\\ J_{+}=q_0-q_1\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{a}_k^2-q_1{(a_i+b_i)}^2\\ J_{-}=q_0-q_1\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{a}_k^2-q_1{(a_i-b_i)}^2\end{array}\right.$ Wherein, i=1,2 ... N.Solve i rank Lukosz multinomial coefficient a _ifor:

$a_i=\frac{b_i(J_{+}-J_{-})}{{2J}_{+}-{4J}_0+{2J}_{-}}$

Step 7, according to each rank of coefficient calculations Lukosz polynomial expression, each rank of tried to achieve Lukosz polynomial expression coefficient correction amount a _{i, corr};

From the phase conjugation principle, produce the correcting value a of i rank Lukosz mode coefficient _{i, corr}for:

$a_{i,\mathrm{corr}}={-a}_i=-\frac{b_i(J_{+}-J_{-})}{{2J}_{+}-{4J}_0+{2J}_{-}}$

Be wavefront error to be corrected by mean, be proofreaied and correct it, only need to produce with the wavefront of this wavefront error conjugation and get final product with distorting lens.

Step 8, according to the polynomial coefficient correction amount of described i rank Lukosz, utilize distorting lens to be proofreaied and correct described wavefront error.

If the influence function matrix of distorting lens is F, each column vector of F is the wavefront corresponding Lukosz coefficient vector of each actuator to distorting lens while adding unit voltage, and F can be measured in advance by interferometer or other Wavefront sensors.In trimming process, F is constant.The voltage vector that the voltage that wavefront error is carried out to apply on each actuator of timing with distorting lens forms is V.Wavefront error vector to be corrected is A, and wherein each element of A is Lukosz mode coefficient a to be corrected _{i, corr}, have

A＝F·V

Solve the correction voltage V that above-mentioned system of equations can obtain each actuator of distorting lens:

V＝F ⁺·A

F wherein ⁺the generalized inverse matrix of representing matrix F.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (1)

1. proofread and correct the variable wavefront error bearing calibration of field range for one kind, it is characterized in that, comprising:

Step 1, gather the full visual field of width remote sensing images;

Step 2, described full visual field remote sensing images are divided into to M sub-view field image by the uniform grid form, make every sub-view field image meet approximate wait dizzy;

Step 3, the polynomial linear superposition of use Lukosz mean wavefront error φ,

wherein, a _ithe polynomial coefficient of the described Lukosz in i rank, L _i(r, θ) is the described Lukosz polynomial expressions in i rank, and N is the polynomial total exponent number of described Lukosz;

The integration of step 4, use image power spectrum density low frequency space is as the image quality evaluation function J of t sub-view field image _t,

wherein, S _tthe image power spectrum density that (u, v) is t sub-visual field, (u, v) is the frequency domain coordinate, R is corresponding to the annular region m on frequency domain ₁≤ (u ²+ v ²) ^1/2≤ m ₂, m wherein ₁and m ₂it is the default value that is less than the cutoff frequency of the detector that gathers remote sensing images in frequency domain;

Step 5, according to the user, to the interest level of described full visual field remote sensing images internal object, be each described sub-view field image value of assigning weight, calculate corresponding image quality evaluation function J,

the number that wherein M is sub-view field image, η _tbe t weight corresponding to sub-visual field;

Each rank coefficient of described Lukosz polynomial expression meets

q wherein ₀and q ₁for the constant relevant with picture structure;

Step 6, utilize each rank coefficient of Lukosz polynomial expression to meet

with described image quality evaluation function between relation of equality solve each rank coefficient of Lukosz polynomial expression;

Step 7, according to each rank of coefficient calculations Lukosz polynomial expression, each rank of tried to achieve Lukosz polynomial expression coefficient correction amount a _{i, corr};

Step 8, according to each rank of Lukosz polynomial expression coefficient correction amount a _{i, corr}utilize distorting lens to be proofreaied and correct described wavefront error.