CN1776450A - Sparse aperture pupil structure and its design optimizing method - Google Patents

Abstract

The invention is applicable to optical sensor in high resolution in space remote sensing area. The structure of sparse aperture pupils is composed of 9 pieces of sub mirror with identical diameter. The distribution structure is as following: connecting line passing through center of each sub mirror forms a equilateral triangle; a sub mirror located at each vertex of the equilateral triangle, and together with centers of the adjacent sub mirrors constitutes a small equilateral triangle. Thus, there are three pieces of identical small equilateral triangle. Space between sub mirrors and fill factor are adopted and controlled by the optimized method. Features are: flexible structure of sparse aperture pupils, easy of installation and adjustment, better improving imaging quality of optical system.

Description

The method of a kind of sparse aperture pupil structure and design optimization thereof

Technical field

The present invention relates to the method for a kind of sparse aperture pupil structure in the high-resolution optical remote sensing device of space remote sensing field and design optimization thereof.

Background technology

The spatial resolution of star-loaded optical remote sensing system is one of leading indicator of weighing its performance.The angular resolution of remote sensor optical system is operation wavelength λ and the ratio of entrance pupil bore D, and promptly δ=λ/D shows that heavy-caliber optical system just has high spatial resolution.But the difficulty of making and detect large caliber reflecting mirror is big, cost is high, and will cause the volume of remote sensor big, quality is heavy, brings great difficulty for the development and the emission of remote sensor, can't realize even at all.Therefore, the sparse aperture systematic research develops thereupon.Sparse aperture pupil structure is one of wherein more rising scheme.So-called sparse aperture be with several less optical apertures with necessarily regularly arranged, constitute a big optical aperture.According to bibliographical information, the arrangement architecture of sparse aperture has anchor ring structure, loop configuration, Golay structure, three arm configurations etc.

As the optical system of routine, angular resolution and sensitivity are two leading indicators of sparse aperture system, they all are subjected to the influence of the fill factor, curve factor of sparse aperture system, the arrangement in sub-aperture (pupil structure), and sparse aperture is with respect to the logical light area fill factor, curve factor of D

Represent.Reaching under the condition of request for utilization, reasonably pupil structure can make system have the lightest weight and minimum volume.So pupil structure optimization becomes a key component of sparse aperture design.

Summary of the invention

The purpose of this invention is to provide a kind of spatial resolution height, structure flexibly, the sparse aperture pupil structure that is easy to debug and the method for design optimization thereof.

Realize that the object of the invention technical scheme is: provide a kind of sparse aperture pupil structure, it is characterized in that: it is made of 9 identical sub-mirrors of diameter, its distributed architecture is: wherein the line of centres of 3 sub-mirrors constitutes an equilateral triangle, the center of other 6 sub-mirrors is distributed in respectively on three limits of this equilateral triangle, the sub-mirror line of centres that 2 on every limit, the sub-mirror on each summit of described equilateral triangle are adjacent constitutes three identical little equilateral triangles.

A kind of design optimization method of sparse aperture pupil structure is provided, it is characterized in that: in the described sparse aperture pupil structure, satisfying condition between the sub-mirror center that the sub-mirror on each summit of equilateral triangle is adjacent apart from s:

$s=\sqrt{3}d-\mathrm{\ϵ}$

And the fill factor, curve factor F of sparse aperture pupil structure satisfies condition:

$F\≥0.1837+0.0906\frac{\mathrm{\ϵ}}{d}$

Wherein: d is the diameter of sub-mirror, and ε is a correction factor, and its span is 0＜ε≤0.15d.

The optical signature function of optimal evaluation sparse aperture image quality is a modulation transfer function (MTF), and the ability that it has reflected optical system transmission information has also reflected the contrast of variant spatial frequency on the image planes.Even under D and all identical situation of F, the planform in sub-aperture, queueing discipline difference, its corresponding MTF is also different.Studies show that when mtf value was zero, the image information of corresponding space frequency was lost, and can't recover.Accompanying drawing 1 is the biography letter curve synoptic diagram that MTF has zero point in the sparse aperture pupil structure cutoff frequency zone, referring to Fig. 1, as frequency ρ 〉=ρ _RThe time, the information of corresponding frequencies is nonsensical.Pairing spatial frequency was real space cutoff frequency ρ when therefore, definition MTF occurred zero for the first time _R, the criterion of sparse aperture optimization is ρ _RBig as far as possible, corresponding simultaneously fill factor, curve factor F is as far as possible little.

Accompanying drawing 2 is for the synoptic diagram of a kind of sparse aperture pupil structure of providing according to technical solution of the present invention, according to designing requirement, under the situation that D determines, can regulate between the sub-mirror apart from s, promptly regulates the relative position of nine sub-mirrors, makes ρ _RBig as far as possible.The enlarged diagram that dimensional MTF distributes as shown in Figure 3, each roundlet is represented sub-transport function MTF among the figure _d, its radius i.e. son passes the letter cutoff frequency ${\mathrm{\ρ}}_{\mathrm{dc}}=\frac{d}{\mathrm{\λf}}.$ Desire to make the interior MTF of frequency plane the frequency ρ at zero point to occur _RAs far as possible big, at first each son passes letter and must intersect, and, be that the intersection point decentering of sub-transport function at center is far away as far as possible with A and B point among Fig. 3.If the distance that intersection point decentering O is ordered is x, equation is arranged

According to the relation of spatial frequency and bore, wavelength, focal length as can be known, in the formula $l_4=\frac{s}{\mathrm{\λf}}.$

Equation is asked extreme value, ${\left(x_2\right)}_{\max }=\frac{2d}{\mathrm{\λf}},$ At this moment, another intersection point $x_1=\frac{d}{\mathrm{\λf}},$ Distance between the sub-mirror $s=\sqrt{3}d.$ But owing to the sub-transport function radius that with the O point is the center is similarly At distance x ₁A zero point just appears in the place.Therefore, must get $s=\sqrt{3}d-\mathrm{\ϵ},$ ε is a very little correction factor, and 0＜ε≤0.15d so just can be at x ₁The place avoids occur zero point.At this moment, ${\mathrm{\ρ}}_R=\frac{2d-\frac{{6\mathrm{\ϵ}}^2}{16}}{\mathrm{\λf}}\≈\frac{2d}{\mathrm{\λf}}.$

Further as can be seen, as long as make $x_2+x_3\≥\sqrt{3}\·l_2/2,$ Do not appear in the frequency plane shown in Figure 3 zero point.Find the solution following formula, fill factor, curve factor must satisfy: $F\≥F_{\min }=0.1837+0.0906\frac{\mathrm{\ϵ}}{d}.$

When $s=\sqrt{3}d-\mathrm{\ϵ}$ With $F\≥F_{\min }=0.1837+0.0906\frac{\mathrm{\ϵ}}{d}$ The time, the MTF inferred-zero occurs in whole cutoff frequency scope.

By above-mentioned principle analysis as can be seen, the present invention has following significant advantage:

1, the present invention has adopted the structure that each sub-mirror center becomes equilateral triangle to distribute, and therefore, this sparse aperture pupil structure is flexible, is easy to debug.

2, adopt the design optimization method of sub-mirror spacing s of control and fill factor, curve factor F that sparse aperture pupil structure of the present invention is carried out reasonable optimizing, make the image quality of the optical system of its formation obtain improving preferably.

Description of drawings

Accompanying drawing 1 has the biography letter curve synoptic diagram at zero point for MTF in the sparse aperture pupil structure cutoff frequency zone;

A kind of sparse aperture pupil structure synoptic diagram of accompanying drawing 2 for providing according to technical solution of the present invention;

The MTF synoptic diagram of a kind of sparse aperture pupil structure of providing according to technical solution of the present invention is provided accompanying drawing 3;

Accompanying drawing 4 is the correlation curve figure of sparse aperture pupil structure design optimization front and back MTF in the embodiment of the invention;

Accompanying drawing 5 is the image pattern that is modeled to of the preceding resolving power test target of sparse aperture pupil structure design optimization in the embodiment of the invention;

Accompanying drawing 6 for sparse aperture pupil structure design optimization in the embodiment of the invention after resolving power test target be modeled to image pattern.

Embodiment

Below in conjunction with drawings and Examples the present invention is further described:

Embodiment one:

Referring to accompanying drawing 2, the described a kind of sparse aperture pupil structure of present embodiment is that the identical sub-mirror of d constitutes by 9 diameters, its distributed architecture is: the line of centres of each sub-mirror constitutes an equilateral triangle, the sub-mirror line of centres that sub-mirror on each summit of this equilateral triangle is adjacent constitutes three identical little equilateral triangles, the diameter D of this sparse aperture pupil is the circumscribed diameter of the sub-mirror on each summit of equilateral triangle, according to designing requirement, D=500mm, design optimization method by sparse aperture pupil structure of the present invention, the design fill factor, curve factor is F=20%, diameter d=the 74.5mm of sub-mirror then, in the sparse aperture pupil structure, satisfying condition in the heart in the sub-mirror that the sub-mirror on each summit of equilateral triangle is adjacent apart from s: $s=\sqrt{3}d-\mathrm{\ϵ},$ Get ε=0.1d, then determine s=121.6mm.

Fig. 4 is the correlation curve figure of sparse aperture pupil structure design optimization front and back MTF in the embodiment of the invention, referring to accompanying drawing 4, as seen MTF before and after relatively optimizing distributes, when fill factor, curve factor is 20%, in the cutoff frequency zone, zero point do not appear in the structure MTF after the optimization, the structure MTF of You Huaing not is zero point promptly to occur near 0.3 in normalized frequency, this explanation: the structure after design optimization method of the present invention is handled, the information that more helps the corresponding space frequency is recovered, and has improved the sharpness of image that optical system becomes.

Accompanying drawing 5 for sparse aperture pupil structure design optimization in the embodiment of the invention before resolving power test target be modeled to image pattern, accompanying drawing 6 for sparse aperture pupil structure design optimization in the embodiment of the invention after resolving power test target be modeled to image pattern.Referring to Fig. 5 and Fig. 6, by figure intermediate-resolution printed line to finding out significantly, the photofit picture radio-frequency head separated time of optimizing structure is more clear to differentiating, and the photofit picture radio-frequency head separated time of not optimizing structure is to differentiating unclear or can not differentiating fully, optimize structure become image definition apparently higher than not optimizing structure one-tenth figure sharpness.

Claims (2)

1. sparse aperture pupil structure, it is characterized in that: it is made of 9 identical sub-mirrors of diameter, its distributed architecture is: wherein the line of centres of 3 sub-mirrors constitutes an equilateral triangle, the center of other 6 sub-mirrors is distributed in respectively on three limits of this equilateral triangle, the sub-mirror line of centres that 2 on every limit, the sub-mirror on each summit of described equilateral triangle are adjacent constitutes three identical little equilateral triangles.

2. the design optimization method of a sparse aperture pupil structure as claimed in claim 1 is characterized in that: in the described sparse aperture pupil structure, and satisfying condition between the sub-mirror center that the sub-mirror on each summit of equilateral triangle is adjacent apart from s:

$s=\sqrt{3}d-\mathrm{\ϵ}$

And the fill factor, curve factor F of sparse aperture pupil structure satisfies condition:

$F\≥0.1837+0.0906\frac{\mathrm{\ϵ}}{d}$

Wherein: d is the diameter of sub-mirror, and ε is a correction factor, and its span is 0＜ε≤0.15d.

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