CN101210804A - Measuring method of coaxiality between laser emission axis and mechanical reference plane based on corner prism - Google Patents

Abstract

A method for measuring the coaxiality between the laser emitting axis and the mechanical reference plane based on a corner prism. The invention relates to the field of measurement, which solves the problem that the angle between the laser emission axis and the mechanical reference plane needs to be strictly measured in an optical test system with small beam divergence angle and high pointing control precision, and there is no method to measure it at present. question. The steps are as follows: Firstly, the reflective surface of the high-precision flat mirror is bonded to the measured mechanical reference surface; secondly, the measurement is performed, and the emitted laser beam is focused through the telephoto collimator and irradiated on the 1:1 beam splitter of the telephoto collimator 50% of the beam is reflected on the CCD detector by the beam splitter, and the other 50% is transmitted to the corner prism; after that, the beam of the corner prism returns along the original optical path, and the beam is reflected by the high-precision flat mirror (2) and re-enters the telephoto collimator. The image is imaged on the CCD detector (4); finally, the direction angle deviation α and the pitch angle deviation β of the two light spots are obtained. The measurement precision of the invention is improved to more than 0.1μrad.

Description

Measuring method of coaxiality between laser emission axis and mechanical reference plane based on corner prism

technical field

The invention relates to the field of measurement, in particular to a method for measuring the coaxiality of a laser emission axis and a mechanical reference plane based on a corner prism.

Background technique

When installing the laser emission system on the mechanical support platform, it is required that the laser emission axis be precisely aligned with the normal line of the reference plane of the support platform, which requires high-precision coaxiality between the laser emission axis and the mechanical reference plane during the installation process. Measurement. At present, most optical systems do not have strict requirements on the angular difference between the optical axis and the mechanical axis, and do not need to accurately measure the difference between them. However, for an optical test system with a small beam divergence angle and high pointing control accuracy, the angle between the laser emission axis and the mechanical reference plane needs to be strictly measured, and there is currently no way to measure it.

Contents of the invention

In order to solve the problem that the angle between the laser emitting axis and the mechanical reference plane needs to be strictly measured in an optical test system with small beam divergence angle and high pointing control precision, and there is no way to measure it at present, the present invention proposes A method for measuring the coaxiality between a laser emitting axis and a mechanical reference plane based on a corner prism.

The steps of the present invention are as follows:

Step 1: Bond the reflective surface of the high-precision flat mirror 2 to the measured mechanical reference surface 6, so that the normal direction of the high-precision flat mirror 2 is parallel to the normal direction of the measured mechanical reference surface 6, and the high-precision flat mirror 2 blocks the laser emission system 7 light exit aperture, the working surface bonded to the measured mechanical reference surface 6 is coated with a semi-transparent and semi-reflective film with a reflectivity of 50%, and the opposite working surface is coated with an anti-reflection film;

Step 2: When measuring, the laser emission system 7 under test emits a laser beam, the laser beam is focused by the telephoto collimator 1, and after focusing, the measured laser beam is irradiated on the 1 between the light outlet and the focal point of the telephoto collimator 1 : 1 on the beam splitter 5, 50% of the light beam is reflected and focused on the CCD detector 4 by the beam splitter 5, and the other 50% of the light beam is incident on the angle prism 3 after being transmitted by the beam splitter 5;

Step 3: The corner prism 3 will make the incident beam of the measured laser beam return along the original optical path, and the reflected beam of the measured laser beam will be incident on the high-precision plane mirror 2 after passing through the telephoto collimator 1, and the reflected beam of the measured laser beam will After being reflected by the high-precision plane mirror 2, it re-enters the telephoto collimator 1, and the reflected beam of the high-precision plane mirror 2 is imaged on the CCD detector 4;

Step 4: When there is an angular deviation between the optical axis of the laser emitting system 7 and the normal line of the measured mechanical reference plane 6, the incident beam imaging spot A of the measured laser beam does not coincide with the reflected beam imaging spot B of the high-precision flat mirror 2; When the position deviation of the two light spots along the x-axis direction is Δx, and the position deviation along the y-axis direction is Δy, then the angle deviation α between the optical axis of the laser emitting system and the normal line of the mechanical reference plane along the direction of the azimuth axis, and the deviation of the pitch angle β They are:

α=Δx/F, β=Δy/F

Wherein F is the focal length of the telephoto collimator 1 .

The invention proposes a method for accurately measuring the coaxiality of a laser emitting axis and a mechanical reference plane, which is applied in a high-precision optical testing system. Based on the corner prism and spectroscopic system, the measurement accuracy is improved to above 0.1μrad. When the focal length of the telephoto collimator is 10m, the measurement position deviation is 1μm, and the measurement accuracy can reach 0.1μrad.

Description of drawings

Fig. 1 is a schematic diagram of the connection structure of the device of the present invention; Fig. 2 is an effect diagram of the incident beam imaging spot of the measured laser beam and the reflected beam imaging spot of the high-precision plane mirror 2.

Detailed ways

Specific embodiment one: This embodiment is described in conjunction with Fig. 1, and the steps of this embodiment are as follows:

Step 1: Bond the reflective surface of the high-precision flat mirror 2 to the measured mechanical reference surface 6, so that the normal direction of the high-precision flat mirror 2 is parallel to the normal direction of the measured mechanical reference surface 6, and the high-precision flat mirror 2 blocks the laser emission system 7 light exit aperture, the working surface bonded to the measured mechanical reference surface 6 is coated with a semi-transparent and semi-reflective film with a reflectivity of 50%, and the opposite working surface is coated with an anti-reflection film;

Step 2: When measuring, the laser emission system 7 under test emits a laser beam, the laser beam is focused by the telephoto collimator 1, and after focusing, the measured laser beam is irradiated on the 1 between the light outlet and the focal point of the telephoto collimator 1 : 1 on the beam splitter 5, 50% of the light beam is reflected and focused on the CCD detector 4 by the beam splitter 5, and the other 50% of the light beam is incident on the angle prism 3 after being transmitted by the beam splitter 5;

Step 3: The corner prism 3 will make the incident beam of the measured laser beam return along the original optical path, and the reflected beam of the measured laser beam will be incident on the high-precision plane mirror 2 after passing through the telephoto collimator 1, and the reflected beam of the measured laser beam will After being reflected by the high-precision plane mirror 2, it re-enters the telephoto collimator 1, and the reflected beam of the high-precision plane mirror 2 is imaged on the CCD detector 4;

Step 4: When there is an angular deviation between the optical axis of the laser emitting system 7 and the normal line of the measured mechanical reference plane 6, the incident beam imaging spot A of the measured laser beam does not coincide with the reflected beam imaging spot B of the high-precision flat mirror 2; When the position deviation of the two light spots along the x-axis direction is Δx, and the position deviation along the y-axis direction is Δy, then the angle deviation α between the optical axis of the laser emitting system and the normal line of the mechanical reference plane along the direction of the azimuth axis, and the deviation of the pitch angle β They are:

α=Δx/F, β=Δy/F

Wherein F is the focal length of the telephoto collimator 1 .

Embodiment 2: This embodiment differs from Embodiment 1 in that the telephoto collimator 1 has a focal length of 12 m and an aperture of 400 mm. Other components and steps are the same as those in Embodiment 1.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that the high-precision plane mirror 2 is a plane mirror with a diameter of φ300, and the surface accuracy (RMS) is 1/70λ. Other components and steps are the same as those in Embodiment 1.

Embodiment 4: The difference between this embodiment and Embodiment 1 is that the CCD detector 4 adopts an area-array CCD camera with a pixel number of 795 (H)×596 (V). Other components and steps are the same as those in Embodiment 1. MTV-1801 produced by Mintong Company was selected.

Claims (4)

1. based on the Laser emission axle and the mechanical reference surface method for measuring coaxiality of angle prism, it is characterized in that its step is as follows:

Step 1: the reflecting surface of high precision plane mirror (2) is adhered on the tested mechanical reference surface (6), make high precision plane mirror (2) normal direction parallel with tested mechanical reference surface (6) normal direction, high precision plane mirror (2) blocks laser transmitting system (7) bright dipping aperture, it is adhered to workplace on the tested mechanical reference surface (6), and to be coated with reflectivity be 50% semi-transparent semi-reflecting film, opposite workplace plating anti-reflection film;

Step 2: when measuring, measured laser emission coefficient (7) is sent laser beam, laser beam focuses on through long burnt parallel light tube (1), focus on back measured laser light beam irradiates on 1: 1 optical splitter (5) between long burnt parallel light tube (1) light-emitting window and the focus, 50% light beam through optical splitter (5) reflect focalization in ccd detector (4), 50% light beam incident angle prism (3) after optical splitter (5) transmission in addition;

Step 3: angle prism (3) will make the incident beam of measured laser light beam return along original optical path, the folded light beam of measured laser light beam incides on the high precision plane mirror (2) behind long burnt parallel light tube (1), the folded light beam of measured laser light beam long burnt parallel light tube (1) of incident again after high precision plane mirror (2) reflection, the folded light beam of high precision plane mirror (2) images on the ccd detector (4);

Step 4: when laser transmitting system (7) optical axis and tested mechanical reference surface (6) when there is angular deviation in normal, the incident beam imaging luminous point A of measured laser light beam does not overlap with the folded light beam imaging luminous point B of high precision plane mirror (2); When two luminous points are Δ x along x direction of principal axis position deviation amount, when y direction of principal axis position deviation amount was Δ y, then laser transmitting system (7) optical axis and mechanical reference surface normal were respectively along azimuth axis orientation angle deviation α, luffing angle deviation β:

α＝Δx/F，β＝Δy/F

Wherein F is the focal length of long burnt parallel light tube (1).

2. Laser emission axle and mechanical reference surface method for measuring coaxiality based on angle prism according to claim 1 is characterized in that the focal length of long burnt parallel light tube (1) is 12m, and bore is 400mm.

3. Laser emission axle and mechanical reference surface method for measuring coaxiality based on angle prism according to claim 1 is characterized in that high precision plane mirror (2) is the level crossing of φ 300 for bore, and surface precision (RMS) is 1/70 λ.

4. Laser emission axle and mechanical reference surface method for measuring coaxiality based on angle prism according to claim 1 is characterized in that ccd detector (4) adopts several 795 (H) * 596 (V) the planar array type ccd video cameras of pixel.

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