CN103630090B - High resolution double shaft autocollimator system - Google Patents

Abstract

The invention relates to the technical field of geometric measurement and testing, and specifically discloses a high-resolution dual-axis autocollimator. In this system, the reflector reflects the horizontal light from the rear group of the objective lens and enters the beam splitting prism B and the beam splitting prism A, and a horizontal collimation reticle, a horizontal condenser and a horizontal LED light source are arranged on the vertical light path of the beam splitting prism A. On the horizontal light path reflected by the beam-splitting prism A, there is a microscopic objective lens B and a vertically installed second line array CCD; Array CCD, and vertical collimation reticles, vertical condenser mirrors and vertical LED light sources are installed in sequence on the reflected light path on the vertical and horizontal plane of beam splitter C. The system adopts the front group of the objective lens and the rear group of the objective lens to reduce the length of the collimated optical path, so that the length of the collimated optical path is smaller than the focal length of the objective lens; at the same time, the reflector of the folded optical path is used, so that the length of the optical system does not increase, only the width is increased.

Description

High-resolution dual-axis autocollimator system

technical field

The invention belongs to the technical field of geometric quantity measurement and testing, and in particular relates to a high-resolution dual-axis autocollimator.

Background technique

Autocollimator is the most widely used small-angle measuring instrument, which is used to measure the small angular displacement of the mirror. Optical autocollimators have been used for angle measurement since the mid-1930s, and by the late 1940s, instruments with an accuracy of 1 second were officially adopted. After replacing the naked eye with photoelectric technology, its accuracy has been greatly improved. In the 1960s, American, British and German manufacturers had produced a variety of photoelectric commercial autocollimators. In the following decades, the collimator has developed rapidly. Autocollimator has gone through three stages of development: visual type, photoelectric zero type and digital display type.

The appearance of the digital display autocollimator has made a qualitative leap in the performance of the autocollimator. The digital display has improved the accuracy of the instrument from 1″ to 0.1″, and the minimum display value has increased from 0.1″ to 0.01″ . The digital display autocollimator has high accuracy, is easy to use, simple to operate, and can realize automatic measurement. According to the classification of photoelectric conversion elements, typical digital display autocollimators include vibrator type, PSD type, and CCD type.

Improving resolution and display stability (reducing the amount of word jumps) is the development direction of general-purpose digital display autocollimators.

High resolution is the guarantee and premise of high accuracy, and high stability (small skip characters) is the guarantee and premise of high resolution. The amount of jumping characters is the characteristic and difficulty of the static digital display autocollimator. Dynamic measurement has only one numerical output for each sampling, which cannot reflect the jump of the displayed value. The difficulty lies in the dynamic response speed and dynamic accuracy. However, the general instrument needs to read the stable reading value of each position. If the jump is too large, it can only be estimated. , which affects the accuracy of the indication and also affects the resolution. Therefore, a lot of research work has been done to improve the resolution and stability of photoelectric autocollimators at home and abroad. The improvement of resolution is mainly through increasing the focal length of the autocollimator objective lens and increasing the subdivision number of image sub-pixel processing. Currently The most accurate digital display autocollimator is Germany The company's HR-type autocollimator, which uses CCD as the photoelectric conversion element, the focal length of the objective lens is 1100mm, the minimum display value is 0.001", the resolution is 0.005", and the indication error is ±0.01" in the range of 10" and ±0.01" in the range of 40". The range is ±0.02", and it is ±0.03" in the full range of 300"×300". There is no equivalent product in China.

However, increasing the focal length of the autocollimator objective lens will cause the volume, length and weight of the instrument to increase. However, increasing the number of sub-pixel processing subdivisions will aggravate the jumping of the indication value, decrease the stability, and reduce the subdivision reliability. Although the minimum display value of the German HR autocollimator can reach 0.001", the resolution in its technical documents is 0.005. ", according to the resolution formula:

$\mathrm{<span\; class="notranslate">\; d\&delta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; dt</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; N</span>}}$

In the formula, dδ is the angular resolution, the unit is arc second, dt is the distance between adjacent pixels in the CCD measurement direction, the unit is mm, ρ is the conversion constant from radian to angle, take 206265, f' is the focal length of the objective lens, the unit is mm, N is the subdivision number of CCD software. For example, a CCD with adjacent pixel spacing dt=0.007mm is selected as the photoelectric sensor, and the focal length of the objective lens is f′=1100mm. To achieve 0.001" resolution, the number of subdivisions needs to reach 657 subdivisions. Its reliability is difficult to guarantee, so Although HR can display up to 0.001", the resolution in its technical documents is 0.005", and the corresponding subdivision number is 131.4.

Contents of the invention

The object of the present invention is to provide a high-resolution dual-axis autocollimator system, which can achieve a resolution of 0.001" when the focal length is 1000mm and the number of subdivisions does not exceed 100.

The technical scheme of the present invention is as follows: a high-resolution dual-axis autocollimator system, the system includes an instrument housing and an objective lens group sleeve fixed on the instrument housing, wherein the objective lens group sleeve is arranged in front of and behind the objective lens in sequence. It consists of a horizontal LED light source, a vertical LED light source, a horizontal collimation reticle, a vertical collimation reticle, beam splitting prism A, beam splitting prism B, beam splitting prism C and reflectors, among which , the mirror reflects the horizontal light passing through the rear group of the objective lens to form a vertical light, which is injected into two sequentially arranged beam-splitting prisms B and beam-splitting prism A. Scribing board, horizontal condenser and horizontal LED light source, microscopic objective lens B and vertically installed second linear array CCD are installed in sequence on the horizontal light path reflected by dichroic prism A; dichroic prism C is sequentially installed on the horizontal light path reflected by dichroic prism B , a microscope objective lens A and a horizontally installed first line array CCD, and a vertical collimation reticle, a vertical condenser lens and a vertical LED light source are sequentially installed on the reflected light path on the vertical horizontal plane of the dichroic prism C.

The reflective mirror is composed of several reflective mirrors, which can fold and reflect the horizontal light passing through the rear group of the objective lens several times to form vertical light.

The horizontal collimation reticle or the vertical collimation reticle is installed on the focal planes of the front group of the objective lens and the rear group of the objective lens.

The aperture of the objective lens group sleeve is D=50mm, and the focal length f'=1000mm.

The optical magnification of the microscope objective lens A or the microscope objective lens B is K=7.5.

The remarkable effect of the present invention is: a kind of high-resolution dual-axis autocollimator system described in the present invention adopts the objective lens front group and the objective lens rear group, reduces the length of the collimating optical path, makes the length of the collimating optical path smaller than the focal length of the objective lens; At the same time, the reflector with folded optical path is used, so that the length and dimension of the optical system do not increase, but only the width; Character size <0.002", the indication error within the measurement range of ±10" does not exceed ±0.01", and within the range of ±40", the error does not exceed ±0.02".

Description of drawings

Fig. 1 is a kind of high-resolution biaxial autocollimator system optical path schematic diagram shown in the present invention;

Fig. 2 is A-A direction view;

In the figure: 1. Front group of objective lens; 2. Sleeve of objective lens group; 3. First linear array CCD; 4. Rear group of objective lens; 5. Second linear array CCD; 6. Microscopic objective A; 7. Microscopic objective B ;8. Horizontal LED light source; 9. Horizontal condenser; 10. Horizontal collimation reticle; 11. Splitter prism A; 12. Splitter prism B; 13. Reflector; 14. Instrument shell; 15. Workpiece reflector; 1. Splitter prism C; 17. Vertical collimation reticle; 18. Vertical condenser; 19. Vertical LED light source.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figures 1 and 2, a high-resolution dual-axis autocollimator system includes an objective lens group sleeve 2 and an instrument housing 14, and the objective lens group sleeve 2 is fixed on the instrument housing 14, wherein the objective lens group sleeve Cylinder 2 is composed of objective lens front group 1 and objective lens rear group 4 placed in sequence, and the objective lens group sleeve 2 has a clear diameter D=50mm, a focal length f′=1000mm, and a relative aperture D/f′=1/20; the instrument shell 14 is equipped with horizontal LED light source 8, vertical LED light source 19, horizontal collimation reticle 10, vertical collimation reticle 17, beam splitting prism A11, beam splitting prism B12, beam splitting prism C16 and reflector 13, wherein, reflector 13 is composed of several reflective mirrors, which can fold and reflect the horizontal light passing through the rear group 4 of the objective lens several times to form a vertical light, which is injected into two sequentially arranged beam-splitting prisms B12 and A11, and passes through the beam-splitting prism A11 A horizontal collimation reticle 10, a horizontal condenser lens 9 and a horizontal LED light source 8 are successively installed on the vertical light path, wherein the horizontal collimation reticle 10 is located on the focal plane of the front group 1 of the objective lens and the rear group 4 of the objective lens; The horizontal light path reflected by A11 is successively equipped with microscopic objective lens B7 and the second line array CCD5 of vertical installation; A linear array CCD3, and a vertical collimation reticle 17, a vertical condenser lens 18, and a vertical LED light source 19 are sequentially installed on the reflected light path of the vertical horizontal plane of the dichroic prism C16, wherein the vertical collimation reticle 17 is located in the front group 1 of the objective lens with the focal plane of the objective rear group 4.

A kind of high-resolution dual-axis autocollimator system of the present invention, the specific working process is: this system is placed before workpiece reflective mirror 15, and objective lens group sleeve 2 is aimed at workpiece reflective mirror 15, when measuring At the horizontal angle, the vertical LED light source 19 is energized (at this time, the horizontal LED light source 8 is powered off), and after passing through the vertical condenser 18, the vertical collimation reticle 17 of the bright line structure in the dark field is illuminated, and the vertical collimation reticle 17 The vertical bright line light in the middle is reflected by dichroic prism C16, reflected by dichroic prism B12 and reflected by mirror 13, and then passes through objective lens rear group 4 and objective lens front group 1 to form parallel light and irradiates workpiece reflector 15, and is returned by workpiece reflector 15 After the light passes through the front group 1 of the objective lens and the rear group 4 of the objective lens, after being reflected by the mirror 13 and the dichroic prism B12, it passes through the dichroic prism C16, and after being amplified by the microscopic objective lens A6, it is converted from the horizontally installed first linear array CCD3 to Electric signal; when measuring the vertical angle, the horizontal LED light source 8 is energized (the vertical LED light source 19 is powered off), and after passing through the horizontal condenser 9, the horizontal collimation reticle 10 of the bright line structure in the dark field is illuminated, and the horizontal collimation The horizontal bright line in the middle of the straight reticle 10 passes through the dichroic prism A11 and the dichroic prism B12 in sequence, and after being reflected by the mirror 13, enters the rear group 4 of the objective lens and the front group 1 of the objective lens to form parallel light and irradiates the workpiece mirror 15. The light returned by the workpiece mirror 15 passes through the front group 1 of the objective lens and the rear group 4 of the objective lens, passes through the mirror 13, passes through the dichroic prism B12, and is reflected by the dichroic prism A11. The installed second linear array CCD5 is transformed into an electrical signal; although three beam-splitting prisms A11, B12 and C16 are installed in the system, after each power-on, the effective light path only passes through two beam-splitting prisms. Therefore, The loss rate of light energy will not be lower than 75%. Through the front group 1 of the objective lens and the rear group 4 of the objective lens, the horizontal collimation reticle 10 or the vertical collimation reticle 17 images are formed, and the width, length and displacement of the reticle images are all adjusted by the microscopic objective lens B7 or the microscopic objective lens A6. After being enlarged by K times, it is converted into an electrical signal by the CCD. Due to the amplification of the displacement, the sensitivity is increased by K times, the number of CCD software subdivisions required to achieve the same resolution is reduced by K times, and the measurement error caused by the CCD division error is reduced by K times. After adding optical magnification, the resolution formula is:

$\mathrm{<span\; class="notranslate">\; d\&delta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; dt</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; K</span>}}$

In the formula, dδ is the angular resolution, the unit is arc second, dt is the line value of a single pixel of CCD, the unit is mm, ρ is 206265, f' is the focal length of the objective lens, the unit is mm, N is the software subdivision number of CCD , K is the optical magnification of the microscope objective. Choose a CCD with a pixel dt=0.007mm as the photoelectric conversion element, the optical magnification of the microscope objective lens K=7.5, and the focal length of the objective lens f′=1000mm, then the resolution of 0.001" can be achieved when the software subdivision number N=96.

Claims (2)

1. a high-resolution dual-axis autocollimator system is characterized in that: the system comprises an instrument housing (14) and an objective lens group sleeve (2) fixed on the instrument housing (14), wherein the objective lens group sleeve The cylinder (2) is composed of the front group of objective lens (1) and the rear group of objective lens (4) which are arranged in sequence. The horizontal LED light source (8), the vertical LED light source (19), the horizontal collimator and the Reticle (10), vertical collimation reticle (17), beam splitting prism A (11), beam splitting prism B (12), beam splitting prism C (16) and mirror (13), wherein, mirror (13) Reflect the horizontal rays passing through the objective lens rear group (4) to form vertical rays, which are injected into two sequentially arranged beam-splitting prisms B (12) and beam-splitting prism A (11), and the vertical rays of beam-splitting prism A (11) A horizontal collimation reticle (10), a horizontal condenser lens (9) and a horizontal LED light source (8) are sequentially arranged on the path, and a microscope objective lens B (7) is sequentially installed on the horizontal light path reflected by the dichroic prism A (11) and the second linear array CCD (5) installed vertically; the horizontal light path reflected by the dichroic prism B (12) is successively installed with the first linear array CCD of the dichroic prism C (16), the microscope objective lens A (6) and the horizontal installation (3), and vertical collimating reticle (17), vertical condenser mirror (18) and vertical LED light source (19) are installed successively on the reflected light path of dichroic prism C (16) vertical horizontal plane; Described reflector (13) is made up of several reflective mirrors, can form vertical light after the horizontal light of group (4) through the objective lens rear group (4) is folded and reflected several times; Described objective lens group sleeve (2) aperture D=50mm, The focal length f'=1000mm; the optical magnification K of the described microscopic objective lens A (6) or microscopic objective lens B (7)=7.5. 2. A kind of high-resolution dual-axis autocollimator system according to claim 1, characterized in that: said horizontal collimation reticle (10) or vertical collimation reticle (17) is installed on The focal plane of the objective front group (1) and the objective rear group (4).