CN112378427B - Method for establishing reference optical axis of large-caliber optical system - Google Patents

Abstract

The invention discloses a method for establishing a reference optical axis of a large-caliber optical system. The method comprises the following steps: the laser tracker scans the primary mirror to model and calculate the virtual central axis; adjusting the position of the target ball to meet the virtual central axis space equation; the interferometer marks the central position of the target ball; adjusting the center of the reticle to coincide with the center of a converged light spot of the interferometer to complete the marking of a space point on the virtual central axis; repeating the above operations to finish marking another space point on the virtual central axis; the theodolite is aligned with the centers of the two reticles to determine a reference optical axis. The method can quickly and accurately establish the installation and adjustment reference optical axis for the optical system, provides a reliable and accurate installation and adjustment reference for subsequent installation and adjustment detection work, and is suitable for various optical systems.

Description

Method for establishing reference optical axis of large-caliber optical system

Technical Field

The invention belongs to the technical field of optical detection, relates to an optical telescope adjustment technical method, and particularly relates to a large-caliber optical system reference optical axis establishing method adopting laser tracker-interferometer combined measurement.

Background

In the field of large optical system development, after parts required in devices such as a large-aperture telescope, a large-aperture collimator and the like are processed, a specific optical assembly and adjustment technology is required to carry out system assembly and adjustment, and the optical system after assembly and adjustment can normally work. The telescope is adjusted to install each optical element to a specific spatial position according to the optical design requirement, so that the system achieves the optical performance required by the design. If the telescope has a misalignment amount, the conditions of aberration increase, imaging quality reduction, target detail loss and the like can be caused, so that the optical system can reach the design standard through a reasonable installation and adjustment process.

In the common optical system installation and adjustment schemes such as a telescope and the like, the main mirror and mechanical positioning are relied on, and the optical axis marking process is avoided. The method uses the primary mirror as a system to establish the whole adjusting reference, uses the wave aberration of the system as a judgment basis, and realizes the adjustment of the optical system by adjusting the secondary mirror. In the other scheme, two cross lines are drawn by taking the edge of the primary mirror as a reference, and a cross wire is used as the center of the vertex of the primary mirror to establish the reference. The two schemes can not accurately find the main optical axis of the main mirror, so that the pointing direction of the optical system, the off-axis visual field image quality and the design are deviated.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a large-caliber optical system reference optical axis establishing method based on laser tracker-interferometer combined measurement, which can quickly establish the installation and adjustment reference optical axes of optical systems such as a telescope. The method has strong universality, is suitable for the adjustment of various types of main mirrors, and particularly has good applicability to the annular main mirror which cannot be adjusted by the traditional method.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for establishing a reference optical axis of a large-caliber optical system comprises the following steps:

step 1: placing the target ball at the edge of the main mirror, recording the spatial position of the target ball, moving the target ball at the edge of the main mirror to obtain n target ball coordinates

；

Step 2: establishing the outer contour of the primary mirror according to the coordinates obtained in thestep 1

And calculating to obtain a space linear equation of the virtual central axis

；

And step 3: moving the target ball, and monitoring the position coordinates of the target ball in real time until the coordinates of the target ball

Satisfy the space linear equation

The central point of the target ball is positioned on the central shaft;

and 4, step 4: aligning the measuring target ball by using an interferometer, and adjusting the position of the interferometer along the direction of the virtual central axis until the interferometer obtains interference fringes which are close to 0 fringe in a view field, wherein the interference fringes show that the focus of a lens of the interferometer is superposed with the center of the target ball;

and 5: moving the target ball away, finely adjusting the position of the first reticle until the intersection point of the converged light spot of the interferometer and the cross line of the first reticle coincides, namely, the first reticle is adjusted in place, and fixing the first reticle in space

；

Step 6: changing the position of the target ball, repeating the steps 3-5, and determining the position of another point on the central shaft

And using the second reticle identification;

and 7: using theodolites to align the first reticles respectively

And a second division plate

Thereby establishing a primary mirror reference optical axis.

Further, the spatial position of the target ball is recorded using a laser tracker.

Furthermore, software in the laser tracker is utilized to establish the outline of the primary mirror, and the position coordinates of the target ball are monitored in real time in the laser tracker software.

Further, the first reticle position was fine-tuned using a micrometer microscope.

Compared with the prior art, the invention has the advantages that:

the method for establishing the assembling and adjusting reference axis of the optical system such as the telescope can quickly and accurately establish the assembling and adjusting reference optical axis for the optical system, provide reliable and accurate assembling and adjusting reference for subsequent assembling and adjusting detection work, and ensure that the performance of the optical system meets the design requirement. The invention has strong adaptability, and can be applied to various optical systems: the optical system of various traditional telescopes, collimator tubes and annular primary mirrors. The optical-mechanical system established by the invention has the advantages of high assembly and adjustment reference axis precision, high digitization degree, high establishment speed of the reference, and simple and efficient overall scheme.

Drawings

FIG. 1 is a schematic diagram of primary mirror optical axis modeling;

FIG. 2 is a schematic view of a target ball positioning light path;

FIG. 3 is a schematic view of a reticle positioning optical path;

FIG. 4 is a schematic illustration of the main optical axis positioning;

FIG. 5 is a front view of a 2m ring primary mirror;

FIG. 6 is a cross-sectional view of a 2m ring primary mirror;

fig. 7 is a measurement flowchart.

The labels in the figure are: 1. a laser tracker; 2. a target ball; 3. a high-precision translation stage; 4. an interferometer; 5. a first reticle; 6. a second reticle; 7. a primary mirror; 8. a theodolite; 9. a micrometric microscope; 10. a central axis.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The method for establishing the reference optical axis of the large-aperture optical system in the embodiment uses alaser tracker 1, atarget ball 2, a three-dimensional high-precision translation 3, aninterferometer 4, afirst reticle 5, asecond reticle 6, aprimary mirror 7, atheodolite 8 and a micrometering microscope 9 to establish the reference optical axis. The embodiment can quickly establish the installation and adjustment reference optical axis of an optical system such as a telescope. The following embodiment exemplifies a 2m ring-shaped primary mirror.

Step 1 (shown in fig. 1): placing thetarget ball 2 at the edge of themain mirror 7, recording the spatial position of thetarget ball 2 by using thelaser tracker 1, moving thetarget ball 2 at the edge of themain mirror 7 to obtainn target ball 2 coordinates

。

Step 2: establishing an equation of the outer contour cylindrical surface or the middle hole cylindrical surface of theprimary mirror 7 in the software of thelaser tracker 1 according to the coordinates acquired in thestep 1

And calculating to obtain a space linear equation of the virtual central axis

。

Step 3 (shown in fig. 2): moving thetarget ball 2, and monitoring the position coordinates of thetarget ball 2 in real time in the software of thelaser tracker 1 until the coordinates of thetarget ball 2

Satisfy the space linear equation

Thetarget ball 2 center point is now on the central axis.

And 4, step 4: and aligning theinterferometer 4 to themeasurement target ball 2, and adjusting the position of theinterferometer 4 along the direction of the virtual central axis until theinterferometer 4 obtains interference fringes which are close to 0 fringe in a visual field, which indicates that the focal point of the lens of theinterferometer 4 is coincident with the center of thetarget ball 2.

Step 5 (shown in fig. 3): removing thetarget ball 2, finely adjusting the position of thefirst reticle 5 by using a micrometering microscope 9 until the convergent light spot of theinterferometer 4 coincides with the intersection point of the cross lines of thefirst reticle 5, namely, thefirst reticle 5 is adjusted in place, and fixing thefirst reticle 5 in space

。

Step 6: replacing the position of thetarget ball 2, repeating the steps 3-5, and determining the position of another point on the central shaft

And identified using thesecond reticle 6.

Step 7 (shown in fig. 4): thelaser tracker 1, thetarget ball 2 and theinterferometer 4 are removed and thefirst reticle 5 is aligned separately using thetheodolite 8

And asecond division plate 6

Thereby establishing a reference optical axis of theprimary mirror 7.

Fig. 5-6 are schematic structural views of the 2m ring-shapedprimary mirror 7. Fig. 7 is a measurement flowchart.

In summary, the method for establishing the reference optical axis of the large-aperture optical system comprises a laser tracker, a target ball, a three-dimensional high-precision translation stage, an interferometer, a primary mirror, a reticle, a micrometering microscope and a theodolite. The method mainly comprises the following steps: (1) the laser tracker scans the primary mirror to model and calculate the virtual central axis; (2) adjusting the position of the target ball to meet the virtual central axis space equation; (3) the interferometer marks the central position of the target ball; (4) adjusting the center of the reticle to coincide with the center of a converged light spot of the interferometer to complete the marking of a space point on the virtual central axis; (5) repeating the steps 2-4 to finish marking another space point on the virtual central axis; (6) the theodolite is aligned with the centers of the two reticles to determine a reference optical axis. The method can realize the quick and accurate establishment of the installation and adjustment reference optical axis of optical systems such as a telescope and the like in the installation and adjustment stage, and provides accurate and reliable installation and adjustment reference for the subsequent installation and adjustment process.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the present invention. Those skilled in the art will appreciate that the details of the invention not described in detail in the specification are within the skill of those skilled in the art. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (4)

1. A method for establishing a reference optical axis of a large-aperture optical system, comprising:

step 1: placing the target ball (2) at the edge of the main mirror (7), recording the spatial position of the target ball (2), moving the target ball (2) at the edge of the main mirror (7) to obtain n target ball (2) coordinates

；

Step 2: establishing the outer contour of the primary mirror (7) according to the coordinates obtained in the step (1)

And calculating to obtain a space linear equation of the virtual central axis

；

And step 3: moving the target ball (2), and monitoring the position coordinate of the target ball (2) in real time until the coordinate of the target ball (2)

Satisfy the space linear equation

The central point of the target ball (2) is positioned on the central shaft;

and 4, step 4: aligning the interferometer (4) to the measurement target ball (2), and adjusting the position of the interferometer (4) along the direction of the virtual central axis until the interferometer (4) obtains interference fringes which are close to 0 fringe in a view field, which indicates that the focus of the lens of the interferometer coincides with the center of the target ball (2);

and 5: removing the target ball (2), finely adjusting the position of the first reticle (5) until the intersection point of the convergent light spot of the interferometer (4) and the cross line of the first reticle (5) is superposed, namely the first reticle (5) is adjusted in place, and fixing the first reticle (5) in space

；

Step 6: changing the position of the target ball (2)Repeating the steps 3-5 to determine the position of another point on the central shaft

And is identified by a second reticle (6);

and 7: respectively aligning the first reticle (5) using a theodolite (8)

And a second reticle (6)

Thereby establishing a reference optical axis of the primary mirror (7).

2. The method for establishing the reference optical axis of the large-aperture optical system according to claim 1, wherein the spatial position of the target ball (2) is recorded by using a laser tracker (1).

3. The method for establishing the reference optical axis of the large-aperture optical system according to claim 2, characterized in that the outer contour of the main mirror (7) is established by software in the laser tracker (1), and the position coordinates of the target ball (2) are monitored in real time in the software of the laser tracker (1).

4. The method for establishing the reference optical axis of the large-caliber optical system according to claim 1, wherein the position of the first reticle (5) is finely adjusted by using a micrometer microscope (9).

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