CN101867709B - Spherical imaging device and imaging method thereof - Google Patents

Abstract

The invention discloses a spherical imaging device and an imaging method thereof and relates to an optical imaging device and an imaging method thereof, which solves the problem that the existing optical imaging system can not meet the technical requirements on light system weight, large viewing field and low cost in a satellite remote sensing imaging task under the premise of ensuring the imaging resolution. The spherical imaging device comprises a photoelectric conversion unit and a signal processing unit, wherein the photoelectric conversion unit comprises M photosensors with the planar light receiving surfaces, all the light receiving surfaces are uniformly arranged on one spherical surface, and the perpendicular line of each light receiving surface passes through the sphere center of the spherical surface. The imaging method of the spherical imaging device comprises the following steps: acquiring a point spread function, carrying out sampling, frequency domain transformation and inverse filtering for the light intensity distribution of a target image on the light receiving surfaces to obtain the distribution of the target image in the frequency domain space, and then carrying out frequency domain reverse transformation to obtain the light intensity distribution of the target image on the light receiving surfaces so as to finish imaging. The invention is applicable to visible light imaging as well as infrared imaging and microwave imaging process.

Description

Spherical imaging device and formation method thereof

Technical field

The present invention relates to a kind of optical imaging device and formation method.

Background technology

In typical optical imaging system, comprise imaging systems such as magnifying glass, telescope, microscope, all constitute, and obtain target image clearly through focus control through one group of optics.Its Design for optical system has determined the resolution of imaging system, and the size of optical lens is big more usually, and imaging resolution is high more; And highest resolution receives the constraint of optical diffraction limit, and the size of it and optical lens is inversely proportional to, and is directly proportional with wavelength; δ θ ∝ λ/D is promptly arranged; Wherein δ θ is an optical imaging system resolution, and λ is a wavelength, and D is the optical lens aperture.

In order to obtain high-resolution image, the Lens of optical system requires very big, and the weight of its camera also increases thereupon.For example in satellite remote sensing is used, optical camera is as payload, and general weight is more than 200kg, even carry out light-weight design, its weight is also about 100kg, so optical camera is one of key factor that influences the satellite overall objective.In addition, optical camera can only in less visual field, (generally be no more than 2 π) usually the imaging.

On the one hand the high-resolution imaging system of application requirements receives the constraint of physics realization but then, makes the consideration of having to compromise in the actual application.In satellite remote sensing was used, the index of optical camera confirmed it mainly is the product of compromises such as resolution, system weight, development cost.In addition; For improving image quality, camera electronics part has also adopted multinomial technology, improves the time of integration such as signal to noise ratio etc. as adopting TDI CCD device to increase; But also the control index of the attitude of satellite is had higher requirement simultaneously, improved the development cost of satellite indirectly.

Summary of the invention

The objective of the invention is to solve existing optical imaging system under the condition that guarantees imaging resolution, can not satisfy the problem that system weight is little, the visual field reaches the low Technology Need of cost greatly in the satellite remote sensing imaging task, a kind of spherical imaging device and formation method thereof are provided.

Spherical imaging device, it is made up of photoelectric conversion unit and signal processing unit, and the electrical signal of said photoelectric conversion unit connects the electric signal input end of signal processing unit; Said photoelectric conversion unit is made up of M light-sensitive device; The light receiving surface of each light-sensitive device is the plane; The light receiving surface of a said M light-sensitive device evenly is arranged on the same sphere, and the center vertical line of the light receiving surface of each light-sensitive device all passes through the centre of sphere of said sphere; Wherein, M is a positive integer.

Utilize the formation method of above-mentioned spherical imaging device, its process is following:

Step 1, according to target image, obtain the point spread function of spherical imaging device;

Step 2, utilize the light-sensitive device of photoelectric conversion unit, the light distribution on light receiving surface is sampled to target image, obtains the convolution of target image and point spread function;

Step 3, utilize processing unit,, obtain target image in the frequency domain spatial distributions through the frequency domain transform and the method for carrying out liftering in the frequency domain space; Pass through the frequency domain inverse transformation then, obtain the light distribution of target image on light receiving surface, accomplish imaging.

Use imaging device of the present invention and method and be carried out to picture; Can access the angular resolution identical with the traditional optical imaging system, but among the present invention not light requirement learn system, and the traditional optical imaging system must have optical system; Therefore, the present invention can realize lighter imaging system; In addition, the present invention can realize the imaging in 4 π spaces, and the traditional optical imaging system can only in less visual field, (generally be no more than 2 π) imaging, therefore, the present invention has wider imaging viewing field.And imaging device of the present invention mainly is made up of refacer spare, general relatively optical imaging system, and cost is lower.

Description of drawings

Fig. 1 is the general structure sketch map of spherical imaging device of the present invention; Fig. 2 is the structural representation of the photoelectric conversion unit in the spherical imaging device of the present invention; Fig. 3 is the flow chart of the formation method of spherical imaging device of the present invention; The light distribution sketch map that Fig. 4 produces on sphere for target; Fig. 5 is the coordinate system sketch map; The point spread function figure that Fig. 6 forms for sphere; Fig. 7 is the target image that is used to form images; Fig. 8 is the surface of intensity distribution of target image on light-sensitive device; Fig. 9 is for using the imaging results figure that the present invention obtains.

Embodiment

Embodiment one: combine Fig. 1 and Fig. 2 that this execution mode is described; The spherical imaging device of this execution mode; It is made up of photoelectric conversion unit 1 and signal processing unit 2, and the electrical signal of said photoelectric conversion unit 1 connects the electric signal input end of signal processing unit 2; Said photoelectric conversion unit 1 is made up of M light-sensitive device; The light receiving surface of each light-sensitive device is the plane; The light receiving surface of a said M light-sensitive device evenly is arranged on the same sphere, and the center vertical line of the light receiving surface of each light-sensitive device all passes through the centre of sphere of said sphere; Wherein, M is a positive integer, and it can be selected according to actual needs.

Embodiment two: the formation method of the spherical imaging device of this execution mode, it utilizes execution mode one described spherical imaging device to realize that its process is following:

Step 1, according to target image, obtain the point spread function of spherical imaging device;

Step 2, utilize the light-sensitive device of photoelectric conversion unit 1, the light distribution on light receiving surface is sampled to target image, obtains the convolution of target image and point spread function;

Step 3, utilize processing unit 2,, obtain target image in the frequency domain spatial distributions through the frequency domain transform and the method for carrying out liftering in the frequency domain space; Pass through the frequency domain inverse transformation then, obtain the light distribution of target image on light receiving surface, accomplish imaging.

The detailed process of the said content of step 1 can be:

Target image is a point target; The output of light-sensitive device is the point spread function of sphere imaging system on the sphere, and point target is enough far away from sphere, and then the light that sends of point target can be regarded parallel rays as at sphere; As shown in Figure 4, point spread function is described by following formula:

$\stackrel{\→}{p}\·\stackrel{\→}{n}=p\cos \left(\mathrm{\α}\right),$

In the following formula;

is the light intensity vector of point target; is sphere light-sensitive device plane earth unit vector; α is the angle of vector

and vector

, and p is the scalar form of vector

;

For obtaining the two-dimensional illumination intensity distribution of point target, need to set up the Mathematical Modeling of three-dimensional point spread function, its coordinate system definition is as shown in Figure 5, and in Fig. 5, definition is θ through the plane and the angle between the xoz plane (face face angle) of q point and x axle _x, the angle (face face angle) on plane and yoz plane through q point and y axle is θ _yWith the o point is the center of circle, and radius is on the sphere of r, and the light distribution of a point target generation enough far away can be used h (θ _x, θ _y) expression, q is the point on the sphere, represents the position at the light-sensitive device place on the sphere, each coordinate that q is ordered is expressed as with radius and direction cosines:

y＝rcos(β)，

z＝rcos(γ)，

Wherein,

Be radii vectors, r does

The scalar form,

It is radii vectors

With the angle of x axle, β is a radii vectors

With the angle of y axle, γ is a radii vectors

With the angle of z axle, θ _xAnd θ _yBe expressed as respectively with direction cosines:

tg(θ _x)＝y/z＝cos(β)/cos(γ)，

According to And sin ²(γ)+cos ²(γ)=1:

tg ²(θ _x)+tg ²(θ _y)＝tg ²(γ)＝1/cos ²(γ)-1，

Thus, can obtain at (θ _x, θ _y) under the coordinate system, the numerical solution of the point spread function that produces of point target, set up h (θ _x, θ _y) numerical value describe, can obtain at (θ _x, θ _y) point spread function in the coordinate system.

Said h (the θ that sets up _x, θ _y) the detailed process described of numerical value can be:

At (θ _x, θ _y) in the coordinate system order computation at all angles tg ²(θ _x)+tg ²(θ _y) numerical value, calculate the corresponding cos of all angles (γ) then; Make h (θ _x, θ _y)=cos (γ); Traversal owns (θ at last _x, θ _y), θ wherein _x=-π～π, θ _y=-π～π can obtain at (θ _x, θ _y) point spread function in the coordinate system.

Fig. 6 has provided point target at (θ _x, θ _y) image of the point spread function that sphere produces in the coordinate system.

The convolution of described target image of step 2 and point spread function can be:

g(x，y)＝h(x，y)*f(x，y)，

Wherein, (x is the some set distribution function of target image y) to f, is used to describe target image; (x y) is the point spread function of sphere system to h; G (x, y) be f (x, y) and h (it is the result that the sampling of sphere light-sensitive device obtains for x, convolution y).

The detailed process of the said content of step 3 can be:

Utilize processing unit (2), to g (x, y)=h (x, y) * f (x y) carries out frequency domain transform, obtains:

G(u，v)＝H(u，v)F(u，v)，

Wherein, (u v) is that ((u v) is that ((u v) is f (x, y) result behind frequency domain transform to F to h for x, the y) result behind frequency domain transform to H to function g for x, the y) result behind frequency domain transform to G;

H (u, v) reach G (u under the v) known situation, obtains target image and in the frequency domain spatial distributions is:

F(u，v)＝G(u，v)/H(u，v)；

At last, (u, v) through the frequency domain inverse transformation, (x y), also promptly obtains target image promptly to obtain the some set distribution function f of target image with F again.

This execution mode has carried out emulation experiment, and in emulation, the pixel number of photoelectric conversion unit (1) is 256 * 256, and each pixel (being light-sensitive device) is of a size of 13 * 13 μ m ², the equivalent sphere area of photoelectric conversion unit (1) is 12mm ², the about 2mm of diameter of imaging spheroid.

Can obtain the experimental result of Fig. 7 to Fig. 9, wherein, Fig. 7 is the original object image, and it is the emulating image of a width of cloth natural scene figure, and Fig. 8 is the light distribution of target image on refacer spare, and Fig. 9 is for using the imaging results that this execution mode obtains.Can know that referring to Fig. 9 imaging effect of the present invention is fine, resolution is high, and the present invention can also satisfy the Technology Need that system weight is little and cost is low in the satellite remote sensing imaging task.

Use imaging device of the present invention and method and be carried out to picture; Can access the angular resolution identical with the traditional optical imaging system, but among the present invention not light requirement learn system, and the traditional optical imaging system must have optical system; Therefore, the present invention can realize lighter imaging system; In addition, the present invention can realize the imaging in 4 π spaces, and the traditional optical imaging system can only in less visual field, (generally be no more than 2 π) imaging, therefore, the present invention has wider imaging viewing field.And imaging device of the present invention mainly is made up of refacer spare, general relatively optical imaging system, and cost is lower.

The present invention adopts the light-sensitive device that distributes on the sphere that the luminous energy of target image on sphere is carried out Direct Sampling; And through analyzing the point spread function that obtains spherical imaging device; Utilize signal processing technology to obtain target image again, realized the imaging process of no optics system.The basic principle of spherical imaging device is; On the basis of linear shift invariant system; Through the point spread function (or impulse response of system) of sphere system, and the target image light distribution of sphere systematic sampling, and obtain target image through signal processing technology.

The present invention is applicable to the visual light imaging process, also is suitable for infrared imaging process and microwave imaging process.

Claims (6)

1. spherical imaging device is characterized in that it is made up of photoelectric conversion unit (1) and signal processing unit (2), and the electrical signal of said photoelectric conversion unit (1) connects the electric signal input end of signal processing unit (2); Said photoelectric conversion unit (1) is made up of M light-sensitive device; The light receiving surface of each light-sensitive device is the plane; The light receiving surface of a said M light-sensitive device evenly is arranged on the same sphere, and the center vertical line of the light receiving surface of each light-sensitive device all passes through the centre of sphere of said sphere; Wherein, M is a positive integer.

2. utilize the formation method of the described spherical imaging device of claim 1, it is characterized in that its process is following:

Step 1, according to target image, obtain the point spread function of spherical imaging device;

Step 2, utilize the light-sensitive device of photoelectric conversion unit (1), the light distribution on light receiving surface is sampled to target image, obtains the convolution of target image and point spread function;

Step 3, utilize processing unit (2),, obtain target image in the frequency domain spatial distributions through the frequency domain transform and the method for carrying out liftering in the frequency domain space; Pass through the frequency domain inverse transformation then, obtain the light distribution of target image on light receiving surface, accomplish imaging.

3. the formation method of spherical imaging device according to claim 2 is characterized in that the detailed process of the said content of step 1 is:

Target image is a point target, and point spread function is described by following formula:

$\stackrel{\→}{p}\·\stackrel{\→}{n}=p\cos \left(\mathrm{\α}\right),$

In the following formula;

is the light intensity vector of point target;

is the unit vector on sphere light-sensitive device plane; α is the angle of vector and vector

, and p is the scalar form of vector ;

Set up the Mathematical Modeling of three-dimensional point spread function, definition is θ through the plane and the angle between the xoz plane of q point and x axle _x, be θ through the plane of q point and y axle and the angle on yoz plane _yWith the o point is the center of circle, and radius is on the sphere of r, and the light distribution of a point target generation enough far away is with h (θ _x, θ _y) expression, q is the point on the sphere, represents the position at the light-sensitive device place on the sphere, each coordinate that q is ordered is expressed as with radius and direction cosines:

y＝rcos(β)，

z＝rcos(γ)，

Wherein,

Be radii vectors, r does

The scalar form,

It is radii vectors

With the angle of x axle, β is a radii vectors

With the angle of y axle, γ is a radii vectors

With the angle of z axle, θ _xAnd θ _yBe expressed as respectively with direction cosines:

tg(θ _x)＝y/z＝cos(β)/cos(γ)，

According to And sin ²(γ)+cos ²(γ)=1:

tg ²(θ _x)+tg ²(θ _y)＝tg ²(γ)＝1/cos ²(γ)-1，

Thus, obtain at (θ _x, θ _y) under the coordinate system, the numerical solution of the point spread function that produces of point target, set up h (θ _x, θ _y) numerical value describe, obtain at (θ _x, θ _y) point spread function in the coordinate system.

4. the formation method of spherical imaging device according to claim 3 is characterized in that the said h of foundation (θ _x, θ _y) the detailed process described of numerical value be:

At (θ _x, θ _y) in the coordinate system order computation at all angles tg ²(θ _x)+tg ²(θ _y) numerical value, calculate corresponding cos (γ) then; Make h (θ _x, θ _y)=cos (γ); Traversal owns (θ at last _x, θ _y), θ wherein _x=-π～π, θ _y=-π～π promptly obtains at (θ _x, θ _y) point spread function in the coordinate system.

5. the formation method of spherical imaging device according to claim 2 is characterized in that the convolution of described target image of step 2 and point spread function is:

g(x，y)＝h(x，y)*f(x，y)，

Wherein, (x is the some set distribution function of target image y) to f, is used to describe target image; (x y) is the point spread function of sphere system to h; G (x, y) be f (x, y) and h (it is the result that the sampling of sphere light-sensitive device obtains for x, convolution y).

6. the formation method of spherical imaging device according to claim 5 is characterized in that the detailed process of the said content of step 3 is:

Utilize processing unit (2), to g (x, y)=h (x, y) * f (x y) carries out frequency domain transform, obtains:

G(u，v)＝H(u，v)F(u，v)，

Wherein, (u v) is that ((u v) is that ((u v) is f (x, y) result behind frequency domain transform to F to h for x, the y) result behind frequency domain transform to H to function g for x, the y) result behind frequency domain transform to G;

H (u, v) reach G (u under the v) known situation, obtains target image and in the frequency domain spatial distributions is:

F(u，v)＝G(u，v)/H(u，v)；

At last, (u, v) through the frequency domain inverse transformation, (x y), also promptly obtains target image promptly to obtain the some set distribution function f of target image with F again.

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