CN103528680A - Multispectral optical splitting system based on close range co-focal surface linear array detector - Google Patents

Abstract

The invention provides a multispectral optical splitting system based on a close range co-focal surface linear array detector. The multispectral optical splitting system comprises three layers of prism groups in stacked arrangement, wherein the first layer of main body is a first parallelogram prism, a second layer of main body is a second parallelogram prism, and the third layer of main body is a rectangular prism, the inclined surface angle of the first parallelogram prism is 45 degrees, a reflecting film is plated on the left-side inclined surface, and a dichromatic optical splitting film is plated at the right-side inclined surface; the inclined surface angle of the second parallelogram prism is theta, and a dichromatic optical splitting film is plated at the right-side inclined surface. The multispectral optical splitting system solves the problem of RGB (red, green and blue) multispectral optical splitting of the close range co-focal surface linear array detector.

Description

A kind of based on the multispectral beam splitting system of confocal upper thread array detector closely

Technical field

The invention belongs to aviation/spacer remote sensing and field of measuring technique, relate to a kind of R(red), G(is green), B(is blue) multispectral beam splitting system.

Background technology

In remote sensing field, in view of different atural object has different reflectance signature spectrum, the atural object obtaining according to remote sensing camera, at the Reflectivity curve of spectrum at different wave length place, just can make a distinction different atural object.R(is red), G(is green), B(is blue) as conventional multispectral passage, they have different effects aspect atural object detection, B(is blue) passage is mainly used to survey shallow water landform, distinguishes soil and vegetation; G(is green) passage is used for distinguishing vegetation pattern and monitoring crop growing way; R(is red) for plant classification.

At present, the multispectral method that realizes light splitting such as R, G, B mainly contains:

1) many camera lenses light splitting, utilizes a plurality of identical or very approaching camera lenses to same Scenery Imaging, and color filter limits the spectral coverage of each camera lens representative, a corresponding multispectral spectral coverage of camera lens.The light splitting of many camera lenses requires during with registration each camera lens optical axis parallel to a rad precision, and after assembling, precision can keep.Therefore, be only applicable to the small-sized Multi-spectral CCD Camera that ground resolution is low, focal length is short.

2) many line array CCDs multispectral imaging, has 3 or several CCD linear arrays that are arranged in parallel exactly on a device, their apart from each others plate respectively corresponding filter coating and obtain a plurality of spectral coverages on this device cover glass.Advantage: simple in structure, be suitable for apart from each other between multispectral sensing device, otherwise it is extremely narrow that multispectral interference light filtering film is coated with width, coating process cannot be realized.Shortcoming: the multispectral image of terrain object does not obtain simultaneously, during to same target registration, because there is difference the multispectral CCD photograph time of difference, platform stance variation can cause registration error.

3) single-lens light splitting arranges beam splitting system exactly after camera lens, and the light receiving is resolved into a plurality of spectrum segment.Generally by be coated with spectro-film on Amici prism, by the incident beam of same visual field separately.Advantage: the R that this method obtains, G, B image strict corresponding be the multispectral image of Same Scene.

Summary of the invention

The present invention proposes a kind of based on the multispectral beam splitting system of confocal upper thread array detector closely, has solved close proximity and confocal 's the multispectral light splitting difficult problem of linear array detector RGB.

Basic technical scheme of the present invention is as follows:

Based on the multispectral beam splitting system of confocal upper thread array detector closely, comprise three layers of prism group of stacked setting, the main body of ground floor is the first parallelogram prism, and the main body of the second layer is the second parallelogram prism, and the main body of the 3rd layer is rectangular prism; Wherein, the bevel angle of the first parallelogram prism is 45 degree, and inclined-plane, left side is coated with reflectance coating, and inclined-plane, right side is coated with dichromatism spectro-film; The bevel angle of the second parallelogram prism is θ, and inclined-plane, right side is coated with dichromatism spectro-film;

Light is by the bottom surface incident of the first parallelogram prism, through the inclined-plane, right side of the first parallelogram prism reflection B wave band, transmission R, G-band; A road wherein, the B band of light of reflection is secondary reflection again through the inclined-plane, left side of the first parallelogram prism, successively through upper bottom surface, the inclined-plane, left side of the second parallelogram prism, the upper bottom surface of the second parallelogram prism, the described rectangular prism outgoing of the first parallelogram prism; Another road, the R of transmission, G-band light are through the bottom surface of the second parallelogram prism, in the color separation again of the inclined-plane, right side of the second parallelogram prism, reflection G-band, transmission R wave band, the G-band light of reflection is secondary reflection again through the inclined-plane, left side of the second parallelogram prism, successively through the upper bottom surface of the second parallelogram prism, described rectangular prism outgoing; The final rgb light spectral component that produces, each prism thickness in three layers of prism group is suitable, to guarantee that each wave band image planes are aplanatism, all coplanar;

The bevel angle θ of the second parallelogram prism meets following formula:

$(t_2-t_1)\frac{1+\sin (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}{\cos (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}={\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000391394580000012.png"\; state="\{\{state\}\}">t</figure-callout>}}_2$

Wherein: t ₁the distance of separating for R wave band image planes and G-band image planes along continuous straight runs;

T ₂it is the bottom surface length of side of the second parallelogram prism.

Based on above-mentioned basic scheme, the present invention also does following optimization and limits and improve:

The arranged on left and right sides of above-mentioned the first parallelogram prism is glued together respectively the first right-angled trapezium prism, the first Tp, the arranged on left and right sides of the second parallelogram prism is glued together respectively the second right-angled trapezium prism, the second Tp, makes ground floor and second layer prism group profile smooth.

Right side at the first Tp is also provided with another rectangular prism, corresponding to the image planes of panchromatic detector.

All prisms all adopt optical quartz glass JGS1 above.

The bottom surface length of side t2 of above-mentioned the second parallelogram prism is 2.24mm, and the bevel angle θ of the second parallelogram prism is 44.6 °.

The present invention is based on single-lens, adopt Amici prism color separation, it has overcome traditional single-lens minute light time, and R, G, tri-detectors of B can not confocal and needed the problem of apart from each other in view of the size of Amici prism, has solved at a distance of multispectral minute optical issue of two linear array detectors of 4 pixels only.Specifically there is following advantage:

1, multi-spectral linear array detector can confocal.

2, can close proximity between RGB multi-spectral linear array detector, be only several pixels.This is more practical for the interior individual devices that is packaged with many linear array detectors.

3, this beam splitting system can make R, G, detector that B is corresponding obtain R, G, the B multispectral image of the same target in ground simultaneously.

4, multispectral dichromatism spectro-film range line array detector is far away, for film surface defect, requires to decrease.

5, beam splitting system structure is simpler, compact.

Accompanying drawing explanation

Fig. 1 beam splitting system figure of the present invention.

Fig. 2 is the dimensional drawing of beam splitting system of the present invention.

Fig. 3 is beam splitting system partial enlarged drawing of the present invention.

Embodiment

The present embodiment carries out based on detector layout, is packaged with the linear array detectors of 3 groups of sub-pixel splicings between two in single detector, between every group of detector at a distance of 2.2mm.During design, select wherein 4 as R, G, B and panchromatic detector, need be by incident be divided into three beams to produce R, G, B and panchromatic image.

This multispectral beam splitting system comprises that 8 little prisms form, and wherein comprises two rectangular prisms, two Tps, two right-angled trapezium prisms, two parallelogram prisms (hypotenuse angle 45 degree, 44.6 °).Prism material is the optical quartz glass JGS1 that physicochemical characteristics is fine and expansion coefficient is very low, choose reasonable optical quartz slab-thickness and parallel quadrant prism hypotenuse angle in design, guarantee that incident light is after beam splitting system, each component imaging surface of multispectral R, G, B and PAN is aplanatism, and coplanar.

Article 6, linear array detector lays respectively in same image planes, and its direction is perpendicular to paper.B represents for receiving the linear array detector of blue component, and G represents for receiving the linear array detector of green component, and R represents that PAN represents panchromatic detector for receiving the linear array detector of red component, for receiving the linear array detector of whole spectral coverage.

B and G image planes need meet certain horizontally separated distance and coplanar, should meet following formula:

$(t_2-t_1)\&times;\mathrm{tg}(\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})=t_1\&times;\mathrm{tg\&theta;}$ (horizontally separated distance)

$t_1\&times;\mathrm{tg\&theta;}+\frac{t_2-t_1}{\cos (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}=t_2$ (aplanatism)

That is: $(t_2-t_1)\frac{1+\sin (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}{\cos (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}={\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000391394580000012.png"\; state="\{\{state\}\}">t</figure-callout>}}_2$

Wherein: t ₁it is the distance that two image planes along continuous straight runs separate.

T ₂for the horizontal length of side of parallelogram prism (face 3,4 of take is hypotenuse).

θ is parallelogram prism 3,4 face tilt angles.

The multispectral R of the present embodiment and the horizontally separated distance of G image planes are only 0.033mm, and coplanar; Multispectral B and the horizontally separated distance of R image planes are only 2.2mm, and coplanar; R and the horizontally separated distance of PAN image planes are also 2.2mm, and coplanar.

As shown in Figure 1, each reflecting surface of colour splitting prism is coated with dichroic film, and light incides after colour splitting prism, first through 1 reflection B wave band, transmission R, G-band, then the R of transmission, G-band light are by 3 separation of color separation face, reflect G-band, thereby finally produce rgb light spectral component.In four reflectings surface, 1,3 faces are coated with dichromatism spectro-film, and 2 are coated with reflectance coating.R, G, B and panchromatic detector are coplanar, and B, G-band are used wherein one group of detector that sub-pixel splices between two, and two detector pitch are 4 pixels.

For the dichroic coating of 1,3, can be respectively with reference to table 1, the listed plated film requirement of table 2.Reflecting surface 2 guarantees reflectivity R >=90% in corresponding passband.

The 1 plated film requirement of table 1 color separation face

The 3 plated film requirements of table 2 color separation face

The beam splitting system project organization of this uniqueness of the present invention, successfully solved close proximity (between B and G only at a distance of 4 pixels, 2.2mm between G and R) and the R of many coplanar linear array detectors, G, multispectral minute optical issue of B, whole beam splitting system is simple in structure, compact.Be particularly suitable for Aeronautics and Astronautics multispectral remote sensing field, for solving the closely multispectral light splitting of linear array detector, be extremely important.

Claims (5)

1. one kind based on the multispectral beam splitting system of confocal upper thread array detector closely, it is characterized in that: three layers of prism group that comprise stacked setting, the main body of ground floor is the first parallelogram prism, and the main body of the second layer is the second parallelogram prism, and the main body of the 3rd layer is rectangular prism; Wherein, the bevel angle of the first parallelogram prism is 45 degree, and inclined-plane, left side is coated with reflectance coating, and inclined-plane, right side is coated with dichromatism spectro-film; The bevel angle of the second parallelogram prism is θ, and inclined-plane, right side is coated with dichromatism spectro-film;

Light is by the bottom surface incident of the first parallelogram prism, through the inclined-plane, right side of the first parallelogram prism reflection B wave band, transmission R, G-band; A road wherein, the B band of light of reflection is secondary reflection again through the inclined-plane, left side of the first parallelogram prism, successively through upper bottom surface, the inclined-plane, left side of the second parallelogram prism, the upper bottom surface of the second parallelogram prism, the described rectangular prism outgoing of the first parallelogram prism; Another road, the R of transmission, G-band light are through the bottom surface of the second parallelogram prism, in the color separation again of the inclined-plane, right side of the second parallelogram prism, reflection G-band, transmission R wave band, the G-band light of reflection is secondary reflection again through the inclined-plane, left side of the second parallelogram prism, successively through the upper bottom surface of the second parallelogram prism, described rectangular prism outgoing; The final rgb light spectral component that produces, each prism thickness in three layers of prism group is suitable, to guarantee that each wave band image planes are aplanatism, all coplanar;

The bevel angle θ of the second parallelogram prism meets following formula:

$(t_2-t_1)\frac{1+\sin (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}{\cos (\frac{\mathrm{\&pi;}}{2}-2\mathrm{\&theta;})}=t_2$

Wherein: t ₁the distance of separating for R wave band image planes and G-band image planes along continuous straight runs;

T ₂it is the bottom surface length of side of the second parallelogram prism.

2. according to claim 1 based on the multispectral beam splitting system of confocal upper thread array detector closely, it is characterized in that: the arranged on left and right sides of the first parallelogram prism is glued together respectively the first right-angled trapezium prism, the first Tp, the arranged on left and right sides of the second parallelogram prism is glued together respectively the second right-angled trapezium prism, the second Tp, makes ground floor and second layer prism group profile smooth.

3. according to claim 2 based on the multispectral beam splitting system of confocal upper thread array detector closely, it is characterized in that: the right side at the first Tp is also provided with another rectangular prism, corresponding to the image planes of panchromatic detector.

According to described in claim 2 or 3 based on the multispectral beam splitting system of confocal upper thread array detector closely, it is characterized in that: all prisms all adopt optical quartz glass JGS1.

According to described in claim 2 or 3 based on the multispectral beam splitting system of confocal upper thread array detector closely, it is characterized in that: the bottom surface length of side t2 of the second parallelogram prism is 2.24mm, and the bevel angle θ of the second parallelogram prism is 44.6 °.

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