CN204359512U - Wavefront and image surface position calibration device for large-diameter collimator - Google Patents

Abstract

The utility model belongs to the field of photoelectric testing and relates to a wave front and image plane position calibration device of a large-caliber parallel light tube. The device includes a fiber laser, a two-dimensional precision long guide rail, a CCD camera and a control unit; the CCD camera is installed on the two-dimensional precision long guide rail; the two-dimensional precision long guide rail includes a horizontal guide rail and a vertical guide rail installed on the horizontal guide rail; the CCD camera can Move along the two-dimensional precision long guide rail in the horizontal direction and vertical direction; the fiber laser is located directly in front of the CCD camera; the control unit is respectively connected with the two-dimensional precision long guide rail and the CCD camera. Accurate testing of face position.

Description

A device for calibrating the wavefront and image plane position of a large aperture collimator

technical field

The utility model belongs to the field of photoelectric testing and relates to a wave front and image plane position calibration device of a large-caliber parallel light tube.

Background technique

The collimator is an optical precision measurement device used to simulate an infinite target in the laboratory, emit parallel light beams, and measure the imaging quality and performance parameters of an optical system or camera.

In recent years, due to the rapid development of my country's aerospace and aviation technology, especially the implementation of high-resolution projects, the imaging quality and ground resolution of space cameras have become higher and higher, and the focal length and aperture of cameras have also become larger and larger. Therefore, it is required to detect the optical precision measurement equipment of long focal length, large-aperture camera imaging quality and performance parameters-the aperture and focal length of the collimator will also become longer and larger, and its imaging quality requirements will also be greatly improved. Therefore, the collimator itself Higher requirements are placed on the detection of the image quality, that is, the accuracy of the exit wavefront and focal plane position (ie, the parallelism of the exit beam).

The commonly used method for collimator is to use self-collimation test method, using large-diameter flat mirror and interferometer to measure the wavefront of the light tube, and using a pentaprism and theodolite to measure the beam collimation. The existing problem is that when the aperture of the light pipe increases, the aperture of the reflector also increases accordingly, and the surface shape of the reflector itself cannot be accurately measured. In addition, the material and processing costs of the reflector are also doubled, and the measurement method is affected by the environment and human subjectivity. Sexual influences lead to large measurement errors.

Utility model content

In order to solve the problems existing in the background technology, the utility model proposes a device for calibrating the wavefront and image plane position of a large-diameter collimated light tube, which can realize accurate testing of the wavefront and focal plane position of the light tube.

The technical solution of the utility model is:

A large-aperture collimator wavefront and image plane position calibration device is characterized in that it includes a fiber laser, a two-dimensional precision long guide rail, a CCD camera and a control unit;

The CCD camera is installed on the two-dimensional precision long guide rail; the two-dimensional precision long guide rail includes a horizontal guide rail and a vertical guide rail installed on the horizontal guide rail; moving; the fiber laser is located directly in front of the CCD camera; the control unit is connected to the two-dimensional precision long guide rail and the CCD camera respectively.

The above-mentioned control unit is a computer.

The above-mentioned CCD camera is composed of an optical lens connected with a CCD detector.

The above-mentioned optical lens includes two lenses, one is a spherical mirror and the other is an aspherical mirror.

The fiber head of the above-mentioned fiber laser is a single-mode fiber head.

The utility model advantage is as follows:

1. The utility model utilizes the multi-point scanning technology of a small-diameter CCD camera to simultaneously realize the measurement of the wavefront and focal plane positions of a large-diameter collimator;

2. The utility model adopts the relative position positioning splicing technology, and completes the high-precision splicing of the target coordinate positions of multiple images at different positions in the same plane. The data in this plane adopts the two-dimensional linear least square method to fit and calculate the linear items , remove the linear term, and restore the wavefront of the collimated light pipe by using the partition gradient integration algorithm or the Southwell algorithm or the wavefront polynomial fitting algorithm; using the center image position as the reference, through the nonlinear polynomial fitting algorithm, different light pipes can be realized. Aperture beam parallelism measurement.

3. The optical lens in the utility model adopts two lenses, one spherical surface and one aspherical surface, in the form of large F number (diameter 5-110mm, focal length 300-500mm) and large focal depth, which eliminates chromatic aberration and realizes the super Diffraction phenomenon, which solves the influence of camera defocus and aberration on the diffuse spots at different positions of the guide rail, and improves the accuracy of interpretation;

4. The utility model uses the single-mode optical fiber head as a point light source to generate standard spherical waves. By using different distance simulations, the calibration of the wavefront and focal plane positions of collimator tubes with arbitrary apertures and focal lengths can be realized.

Description of drawings

Fig. 1 is a schematic structural diagram of the calibration device of the present invention.

1—fiber laser, 2—optical lens, 3—CCD detector, 4—two-dimensional precision long guide rail, 5—computer.

Fig. 2 is a structural schematic diagram of wavefront calibration and focal plane position measurement of the collimated light tube to be treated by the utility model.

1—collimator to be calibrated, 2—optical lens, 3—CCD detector, 4—two-dimensional precision long guide rail, 5—computer, 6—fiber laser.

Detailed ways

This paper proposes a new detection device and method to solve the detection of the accuracy of the wavefront and focal plane position of the large aperture collimator.

As shown in Figure 1: the device includes a fiber laser 1, a two-dimensional precision long guide rail 4, an optical lens 2, a CCD detector 3 and a computer 5;

The optical lens 2 and the CCD detector 3 are precisely connected to form a CCD camera.

The CCD camera is installed on the two-dimensional precision long guide rail 4; the two-dimensional precision long guide rail 4 includes a horizontal guide rail and a vertical guide rail installed on the horizontal guide rail; the CCD camera can move horizontally and vertically along the two-dimensional precision long guide rail 4; The laser 1 is located directly in front of the CCD camera; the control unit is respectively connected with the two-dimensional precision long guide rail 4 and the CCD camera.

The control unit used in this device is the computer 5; the function of the computer 5 is to control the movement of the two-dimensional precision long guide rail 4, store the image collected by the CCD camera and extract the center position of the image point for data interpretation processing and calculation.

The optical lens 2 is in the form of a large F number (diameter 5-110mm, focal length 300-500mm) and a large depth of focus. The optical lens 2 includes a superdiffraction optical lens, including two lenses, one is a spherical mirror and the other is an aspherical mirror, eliminating Chromatic aberration, which realizes the super-diffraction phenomenon of the target; solves the influence of camera defocus and aberration on the diffuse spots at different positions of the guide rail, and improves the accuracy of interpretation;

CCD detector 3 is used for collecting the image by optical lens 2;

Among them, the fiber laser 1 is used to emit standard spherical waves at different positions, and is used to calibrate the reference of the wavefront and focal plane position calibration device; the fiber head of the fiber laser uses a single-mode fiber head as a point light source to generate standard spherical waves. The simulation of different distances can realize the calibration of collimator wavefront devices with arbitrary apertures.

According to the description of the structure of the above-mentioned device, the calibration method of the wavefront and image plane position calibration device of the large-aperture collimator is now described, which specifically includes the following steps:

Step 1) Fix the CCD camera on the two-dimensional precision long guide rail, and adjust the optical axis of the CCD camera to be perpendicular to the movement axis of the horizontal guide rail and the vertical guide rail;

Step 2) Place the fiber laser in front of the CCD camera, and align the fiber head of the fiber laser with the CCD camera, and adjust the power of the laser until the CCD camera can receive the light intensity of the fiber laser;

Step 3) The CCD camera obtains the centroid coordinates (x _i , y _j ) of the image points emitted by the fiber laser at different positions on the two-dimensional precision long guide rail;

Taking the center of the two-dimensional precision long guide rail (x ₀ , y ₀ ) as the reference, control the two-dimensional precision long guide rail to drive the CCD camera to move in both horizontal and vertical directions; the moving range is the aperture of the collimator to be calibrated, and the moving step Divide the movement range by the number of points to be sampled, and the computer records the coordinates (M, N) of different positions of the two-dimensional guide rail; at the same time, the CCD camera collects images at each position and interprets the coordinates of the center of mass of each image point (x _i , y _j ); The center of the two-dimensional precision long guide rail is the intersection of the center of the horizontal guide rail and the center of the vertical guide rail;

Step 4) The CCD camera obtains the centroid coordinates (x _i ', y _j ') of the image points emitted by the collimator to be calibrated at different positions on the two-dimensional precision long guide rail;

Step 4.1) Install the collimator to be calibrated in front of the CCD camera, and adjust the position of the fiber laser so that the fiber head of the fiber laser is located on the focal plane of the collimator;

Step 4.2) Based on the center of the two-dimensional precision long guide rail, control the two-dimensional precision long guide rail to drive the CCD camera to move in both horizontal and vertical directions. According to step 3) the same position as the guide rail moves is used to calibrate the full aperture of the collimator Sampling is carried out, while the CCD camera collects images at each position and interprets the centroid coordinate position (xi _' , y _j ') of each image point;

Step 5) Determine the wavefront position of the collimator to be calibrated;

Step 5.1) Calculate the difference coordinates (Δx i , Δy j ) of the centroid coordinate positions (x _i , y _j ) and (x _{i ′} , y _{j ′} ) of the image points in the two interpretations of step 3) and step 4.2);

Step 5.2) The difference coordinates (Δx _i , Δy _j ) of each position of the guide rail obtained in step 5.1) within the full aperture of the collimator to be calibrated; plan in a plane, and use the two-dimensional linear least squares method to fit Calculate the linear term and remove the linear term;

Step 5.3) Calculate the wavefront position of the collimator to be calibrated by using the partition gradient integration method or the Southwell algorithm or the wavefront polynomial fitting algorithm;

Step 6) Determine the position of the image plane of the collimator to be calibrated;

Step 6.1) Make a difference between the image centroid coordinates (x _i ′, y _j ′) obtained in step 4.2) and the image centroid coordinates (x ₀ , y ₀ ) obtained when the two-dimensional precision long guide rail is at the center, and obtain the difference coordinates (Δx _i ', Δy _j ');

Step 6.2) Fit the obtained difference coordinates (Δx _i ′, Δy _j ′) with a two-dimensional polynomial to obtain the parallelism error of the beam within the full aperture of the collimator to be calibrated, and use the Gaussian formula to calculate the image plane position error.

Step 6.3) Using the image plane position error obtained in step 6.2), determine the image plane position of the collimator to be calibrated.

Claims (5)

1. heavy caliber parallel light tube wavefront and an image planes position label means, is characterized in that: comprise fiber laser, two-dimentional accurate long guideway, CCD camera and control module;

Described CCD camera is arranged on two-dimentional accurate long guideway; The accurate long guideway of described two dimension comprises horizontal guide rail and is arranged on the vertical guide rail on horizontal guide rail; Described CCD camera can move with vertical direction in the horizontal direction along the accurate long guideway of two dimension; Described fiber laser is positioned at the dead ahead of CCD camera; Described control module respectively long guideway accurate with two dimension and CCD camera is connected.

2. heavy caliber parallel light tube wavefront according to claim 1 and image planes position label means, is characterized in that: described control module is computing machine.

3. heavy caliber parallel light tube wavefront according to claim 2 and image planes position label means, is characterized in that: described CCD camera is connected to form by optical lens and ccd detector.

4. heavy caliber parallel light tube wavefront according to claim 3 and image planes position label means, it is characterized in that: described optical lens comprises two panels lens, a slice is spherical mirror, a slice is aspheric mirror.

5. heavy caliber parallel light tube wavefront and image planes position label means according to claim 4, is characterized in that: the optical fiber head of described fiber laser is single-mode fiber head.