CN104865686A - Off-axis three-mirror optical system based on main three-mirror integrated wide spectrum - Google Patents

Abstract

The invention discloses an off-axis three-mirror optical system based on the integration of three main mirrors and a broad spectrum. The secondary reflector is located on the reflection light path of the primary reflector, the third reflector is located on the reflection light path of the secondary reflector, the position of the aperture stop coincides with the position of the secondary reflector, and the light in the target area passes through the primary reflector, After reflection by the secondary reflector and the third reflector, an image is formed on the image plane. The reflectors used in the present invention are all quadratic surfaces, and the manufacturing and testing technologies for such surface-shaped reflectors are mature, which helps to reduce the manufacturing cost of the entire system while ensuring the imaging quality of the optical system. Moreover, the main reflector and the third reflector used in the present invention are designed in an integrated manner, which greatly reduces the difficulty of assembly and adjustment of the optical system, and is also of great significance to the lightening of the optical-mechanical system.

Description

An off-axis three-mirror optical system based on the integration of three main mirrors and a wide spectrum

technical field

The invention belongs to the field of optical technology and relates to an off-axis three-mirror optical system.

Background technique

With the continuous development of space earth observation technology, the off-axis three-mirror astigmatism optical system is gradually replacing the traditional coaxial optical system remote sensing camera, and has been widely used in the fields of aviation and aerospace. The reconnaissance camera on the US Quick Bird satellite, the Indian surveying and mapping camera CARTOSAT-1, the hyperspectral imager on the German environmental satellite EnMAP, and the visible light detector SBV on the US space target monitoring satellite MSX all use off-axis three-mirror systems.

In addition to the characteristics of a reflective optical system, the off-axis three-mirror optical system also has the advantages of a large field of view and no central obstruction, but it is difficult to assemble and adjust, and the cost is high, and the volume and mass of the optical-mechanical structural parts are large. Starting from the basic theory, reducing the difficulty of optical system installation and adjustment through optical design methods, and realizing the light-weight optical-mechanical structure of the off-axis three-mirror system will be of great significance to the design of space optical remote sensors.

Contents of the invention

In order to overcome the deficiencies of the existing technology, reduce the difficulty of installation and adjustment of the off-axis three-mirror optical system and the difficulty of surface processing of the mirror, the present invention provides an off-axis three-mirror optical system based on the integration of the main three mirrors and a wide spectrum. The off-axis three-mirror optical system has the advantages of large field of view and wide spectrum.

The purpose of the present invention is achieved through the following technical solutions:

An off-axis three-mirror optical system based on the integration of three primary mirrors with a broad spectrum, comprising a primary reflector, a secondary reflector, a third reflector and an aperture stop, the secondary reflector is located on the reflection optical path of the primary reflector, The third reflector is located on the reflection light path of the secondary reflector, the primary reflector and the third reflector are integrally formed, the position of the aperture stop coincides with the position of the secondary reflector, and the light in the target area passes through the primary reflector, the secondary reflector in sequence After reflection by the mirror and the third mirror, an image is formed on the image plane.

In the present invention, the primary reflector and the three reflectors are all hyperboloids, and the radius of curvature is the same as the quadratic coefficient of the aspheric surface, but each contains a different coefficient of the high-order term of the aspheric surface; the secondary reflector is a hyperboloid without Higher order coefficients.

The present invention has the following advantages:

1. The reflectors used in the present invention are all quadric surfaces. The manufacturing and testing technology of this surface-shaped reflector is mature, which helps to reduce the manufacturing cost of the entire system while ensuring the imaging quality of the optical system.

2. The main reflector and the third reflector used in the present invention are designed in an integrated manner, which greatly reduces the difficulty of assembly and adjustment of the optical system, and is also of great significance to the light-weight of the optical-mechanical system.

Description of drawings

Fig. 1 is the working principle diagram of the off-axis three-mirror optical system based on the integrated broad spectrum of the main three mirrors of the present invention;

Fig. 2 is a schematic structural diagram based on the integration of three primary mirrors provided by a specific embodiment of the present invention.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered by the present invention. within the scope of protection.

The present invention designs an off-axis three-mirror optical system with a focal length of 1200mm, relative aperture D/f'=1/12, field of view (rectangular field of view): 10°×1°, and working band: 0.55μm-15μm.

As shown in Figure 1, the optical system includes a primary reflector 1, a secondary reflector 2, a third reflector 3 and an aperture stop 4, the secondary reflector 2 is located on the reflection optical path of the primary reflector 1, and the third reflector 3 Located on the reflected optical path of the secondary reflector 2 , the position of the aperture stop 4 coincides with that of the secondary reflector 2 , and the primary reflector 1 and the third reflector 3 are integrally formed.

The structural parameters of the optical system are shown in Table 1.

Table 1

the Radius of curvature/mm Interval/mm Aspheric Quadratic Coefficients Aspherical Higher Order Off axis/mm primary mirror -1265.044 -278.039 -10.809 10th order 70 secondary mirror -669.173 278.039 -4.470 - 10 third mirror -1265.044 -970.525 -10.809 10th order -39

The primary reflector 1 and the third reflector 3 are hyperboloids, the radius of curvature is the same as the quadratic coefficient of the aspheric surface, but each contains a different aspheric high-order coefficient; the secondary reflector 3 is also a hyperboloid, but does not contain a high Subterm coefficient.

In actual manufacturing, the main reflector 1 and the third reflector 3 mill out the same spherical surface on the same substrate, and then according to the design results of the aspheric surface, mill different high-order aspheric surface shapes in different regions of the spherical surface to form the main three-dimensional The mirror realizes the integrated design of the main reflector 1 and the third reflector 3 of the optical system, as shown in FIG. 2 , both have the same radius of curvature.

Claims (8)

1. An off-axis three-reflection optical system based on the integrated broad spectrum of the main three mirrors, characterized in that the off-axis three-reflection optical system is composed of a main reflector, a secondary reflector, the third reflector and an aperture stop, The secondary reflector is located on the reflection light path of the primary reflector, the third reflector is located on the reflection light path of the secondary reflector, the position of the aperture stop coincides with the position of the secondary reflector, and the light in the target area passes through the primary reflector in sequence , the secondary reflector and the third reflector are reflected and imaged at the image plane. 2. The off-axis three-mirror optical system based on the integration of three main mirrors and a broad spectrum according to claim 1, wherein the main mirror and the third mirror are integrally formed. 3. The off-axis three-mirror optical system based on the integrated broad spectrum of the main three mirrors according to claim 1 or 2, wherein the main reflector and the third reflector are both hyperboloids, and the radius of curvature and the aspheric surface The quadratic coefficients are the same, but each contains different aspherical higher-order coefficients. 4. The off-axis three-mirror optical system based on the integration of main three mirrors and wide spectrum according to claim 3, characterized in that the radius of curvature of the main mirror: -1265.044mm, interval: -278.039mm, aspheric two Sub-term coefficient: -10.809, aspheric high-order term order: 10th order, off-axis distance: 70mm. 5. The off-axis three-mirror optical system based on the integration of main three mirrors and wide spectrum according to claim 3, characterized in that the radius of curvature of the third mirror: -1265.044mm, interval: -970.525mm, aspherical Quadratic coefficient: -10.809, aspheric high-order term: 10th order, off-axis amount: -39mm. 6. The off-axis three-mirror optical system based on the integration of three main mirrors and wide spectrum according to claim 1, characterized in that the secondary reflector is a hyperboloid and does not contain high-order coefficients. 7. The off-axis three-mirror optical system based on the integration of main three mirrors and wide spectrum according to claim 6, characterized in that the radius of curvature of the secondary reflector: -669.173mm, interval: 278.039mm, aspheric secondary Item coefficient: -4.470, off-axis amount: 10mm. 8. The off-axis three-mirror optical system based on the integration of main three mirrors and wide spectrum according to claim 1, characterized in that the focal length of the off-axis three-mirror optical system is 1200mm, and the relative aperture D/f'=1/12 , Field of view: 10°×1°, working band: 0.55μm-15μm.