CN203011354U - Vernier slit type photoelectric autocollimator - Google Patents

Abstract

The utility model provides a vernier slit type photoelectric autocollimator with high precision and good reliability. The vernier slit photoelectric autocollimator includes a monochromatic light source (1), a multi-slit (2), a beam splitter (3), a collimating objective lens (4), and a rotatable plane arranged sequentially on the main optical path. The reflector (5) and the linear CCD (6) arranged on the optical path of the beam splitter, the multi-slit (2) is conjugated to the linear CCD (6); the multi-slit (2) consists of multiple parallel single Composed of slits, the slit width and spacing of each parallel single slit are equal; the linear array CCD is used as the main scale, and the image of the multi-slit (2) is used as the vernier scale, and the vernier scale and the main scale meet the principle of vernier subdivision. The utility model can be widely used in high-precision small-angle precision testing, high-precision measurement of dynamic and static small-angle errors of reflectors, angle calibration of angular displacement sensors, small-angle measurement of optical plane cold-worked parts, and the like.

Description

Vernier slit photoelectric auto-collimator

Technical field

The utility model relates to a kind of high precision angular displacement detecting device, is specifically related to a kind of vernier slit photoelectric auto-collimator.

Background technology

In the precision measurement field of measuring techniques, the fields of measurement such as the flatness that is widely used in small angle measurement, high precision Angle Calibration, guide rail of photoelectric auto-collimator, the flatness of precision surface plate, revolving table position uncertainty are the routine measurement instruments of department's indispensabilities such as machine-building, shipbuilding, Aero-Space, metrology and measurement, scientific research.Particularly aspect accurate, ultraprecise location, irreplaceable effect is arranged more.It both can be used for separately engineering survey, also can be used as aiming and measurement component in the optical metrological instruments such as transit, angular instrument, optical comparator.

Because photoelectric auto-collimator essence is high-precision digital picture micrometric displacement detection system, changes slit type and become the key element that improves its precision.At present, in photoelectric auto-collimator, slit type used mainly contains: crosshair, circular hole, M shape/V-arrangement/N shape graduation, single slit, grating etc.Crosshair, circular hole etc. directly coordinate with planar array detector completes two-dimensional measurement, is subject to the principle of work of face battle array device self, and its measuring speed and precision all can be restricted.M shape/V-arrangement/N shape graticule mainly is combined with single linear CCD and is realized two-dimentional outer corner measurement, slit and line array CCD installation accuracy is had relatively high expectations, and then affect measurement range and measuring accuracy.If adopt single slit, when single slit was as image, image-element was only seamed wide, is unfavorable for improving precision.The appearance of optical grating photoelectric self-collimator is a kind of new exploration, and the type autocollimator obtains the angular displacement information of level crossing by the displacement of the Moire fringe of a pair of optical grating pair generation.Moire fringe displacement information not only with optical grating pair between the pitch difference of single grid line relevant, also with optical grating pair between angle relevant, cause such autocollimator higher to the installation of grating, the complicacy of Moire fringe itself in addition, to accurately locate it, higher to the later image processing requirements, Surveying Actual Precision and reliability also are restricted (if the error that exists explorer response or grating to portray, impact will be even more serious).

The utility model content

The deficiency that exists for overcoming aforementioned background art, the utility model provide that a kind of precision is high, the vernier slit photoelectric auto-collimator of good reliability.

Technical solution of the present utility model is:

Vernier slit photoelectric auto-collimator, the line array CCD (6) that is included in the monochromatic source (1) that sets gradually on main optical path, many slits (2), spectroscope (3), collimator objective (4), rotating plane mirror (5) and arranges on the spectroscope light splitting optical path, many slits (2) and line array CCD (6) conjugation, the light that light source (1) sends images in line array CCD (6) and locates by many slits (2), is reflected back the spectroscope light splitting at plane mirror (5) after the spectroscope transmission; Its special character is:

Described many slits (2) are comprised of a plurality of parallel single slits, and parallel single slit seam is wide all equates with kerf spacing for each; As main scale, the picture of many slits (2) is as vernier scale with line array CCD, and vernier scale and main scale satisfy the vernier Principle of sub-division.

Like this, when plane mirror (5) rotates a low-angle, many slits (can be referred to as " vernier slit ") image has the certain displacement amount at line array CCD, obtain inferior pixel displacement information after vernier segmentation by cursor principle, ccd output signal is through the A/D conversion, by the mathematics transformational relation, positional information is converted to angular metric, thereby accurately angles of display changes.

Based on above-mentioned basic technical scheme, the utility model has also carried out following optimization to be limited and improves:

The width of above-mentioned single slit is more than or equal to the line array CCD original image elemental size of 3 times.

If each parallel single slit seam is wide and kerf spacing is d, the slit number is N, and line array CCD pixel dimension and pixel spacing are P _d, the ccd signal of output has been carried out M times of hardware segmentation, vernier scale and main scale satisfy following mathematical relation:

$(2N-1)\×d=[k\×(2N-1)-1]\×\frac{P_d}{M},$ Wherein, N=1,2,3, M=1,2,3, K=1,2,3 ...

The value of above-mentioned each parameter is preferably 2≤N≤50; 2≤k≤100; 1≤M≤20.

Above-mentioned light source specifically can adopt LED light source, LASER Light Source etc.

Want to obtain higher measuring accuracy, the focal length of collimator objective (4) can be longer, and the pixel number of line array CCD can be less, adopts corresponding vernier narrow slit structure can obtain higher precision.

The utlity model has following advantage:

The ingenious vernier Principle of sub-division of having used of the utility model, this collimator can be realized high-acruracy survey in the situation that to debug requirement lower, reliability is high.The utility model can allow suitably to regulate the defocusing amount between line array CCD photosurface and best image planes.

The utility model can be widely used in the high-precision small-angle accuracy test, the high-acruracy survey of the verticality/flatness of small angle measurement, high precision table top or the workpiece of catoptron sound attitude small angle error high-acruracy survey, angular displacement sensor Angle Calibration, optical flat cold working part etc.

Description of drawings

Fig. 1 is principle schematic of the present utility model.

Fig. 2 is the mathematical relation schematic diagram between line array CCD of the utility model and vernier slit; Wherein, the whole pixel position of 7-, 8-line array CCD, the position of 9-segmentation pixel, 10-vernier slit;

Vernier slit location shown in Fig. 2 a is 0 pixel,

Vernier slit location shown in Fig. 2 b is

Pixel,

Vernier slit location shown in Fig. 2 c is 28 pixels,

Vernier slit location shown in Fig. 2 d is

Pixel.

Embodiment

As shown in Figure 1, include LED light source assembly (1), vernier slit (2), spectroscope (3), collimator objective (4), plane mirror (5), line array CCD (6).Vernier slit (2) and line array CCD (6) are positioned on the focal plane of collimator objective (4) or near it.The bright vernier slit of the illumination that LED light source assembly (1) sends (2), light collimate and image in line array CCD (6) after level crossing (5) reflections through collimator objective (4) and locate.When control plane catoptron (5) rotates a low-angle, the vernier slit image has the certain displacement amount at line array CCD, obtain inferior pixel displacement information after vernier segmentation by cursor principle, by the mathematics transformational relation, positional information is converted to angular metric, and angles of display changes in real time.

In Fig. 1, the LED light source assembly adopts the red-light LED light source.Line array CCD adopts single linear CCD, and single pixel dimension and pixel spacing are 7 μ m, and single pixel dimension and pixel spacing also can be less; Equate to be all d with kerf spacing when the seam of vernier slit (2) is wide, when vernier slit number is N, and single linear CCD pixel dimension and pixel spacing are P _d, as main scale, the picture of vernier slit (2) is as vernier scale with line array CCD, when satisfying the vernier Principle of sub-division between the picture of vernier slit (2) and line array CCD (6), and when namely satisfying following mathematical relation,

(2N-1) * d=[k * (2N-1)-1] * P _d, N=1 wherein, 2,3, K=1,2,3 ... (A)

The picture of vernier slit (2) is to line array CCD (6) the pixel P of unit _dRealized satisfying the error free segmentation of cursor principle, the segmentation multiple is:

$f=\frac{1}{2N-1}---\left(B\right)$

Namely working as the vernier slit moves $\frac{l}{2N-1}{P}_d(l=\mathrm{1,2},\·\·\·,2N-1)$ The time, on the vernier slit, the justified margin of the slit edge of correspondence position and line array CCD pixel, realized sub-pixel subdivision, the whole pixel of the CCD that on vernier scale, the edge of first slit is corresponding, the error free inferior pixel displacement of both sum reaction vernier slit chis.

Ccd output signal through A/D conversion, is digital signal by analog-signal transitions, when the A/D change over clock signal that adopts be CCD integral time M doubly, namely M times of hardware segmentation carried out in the ccd signal of output; Suppose that the original pixel number of CCD is N _c, the pixel number of output becomes MN _c, when adopting this divided method, the width of single slit is more preferably greater than 3 times of original Pixel sizes.In this case, when satisfying the vernier Principle of sub-division between the picture of vernier slit (2) and line array CCD (6), when namely satisfying following mathematical relation,

$(2N-1)\×d=[k\×(2N-1)-1]\×\frac{P_d}{M},$ Wherein, N=1,2,3, M=1,2,3, K=1,2,3 ... (C)

Unit pixel after the picture of vernier slit (2) segments line array CCD (6)

Realized satisfying the error free segmentation of cursor principle, the segmentation multiple is:

$f=\frac{1}{2N-1}---\left(D\right)$

Namely working as the vernier slit moves $\frac{l}{2N-1}\frac{P_d}{M}(l=\mathrm{1,2},\·\·\·,2N-1)$ The time, the justified margin of the slit edge of correspondence position and the line array CCD pixel after segmentation on the vernier slit, realized sub-pixel subdivision, the whole pixel of the CCD after the segmentation that on vernier scale, the edge of first slit is corresponding, the error free inferior pixel displacement of both sum reaction vernier slit chis.

If the focal length of collimator objective (4) is f, the distance that moves when many slit images is S, when tested level crossing (5) rotates θ, according to the autocollimation principle, has: S=ftan2 θ.If select the focal distance f=300mm of collimator objective (4), the single pixel dimension of line array CCD is 7 μ m, and the effective resolution of single pixel is: $\mathrm{\θ}=\frac{1}{2}\arctan \left(\frac{S}{f}\right)=\frac{1}{2}\arctan \left(\frac{7}{300\×1000}\right)\≈{2.4}^{\′\′}.$ Actual measuring accuracy is often lower than 2.4 ", satisfy four narrow slit structures (getting N=4) of above-mentioned condition (A) by employing, when getting k=5, namely single slit of vernier slit and kerf spacing are

Can realize line array CCD

Individual Image segmentation precision, the subdivision accuracy that can reach this moment is:

Doubly segment if Output Signal of Linear CCD's is carried out M=4, the effective resolution of the single pixel after segmentation is: $\mathrm{\θ}=\frac{1}{2}\arctan \left(\frac{S}{f}\right)=\frac{1}{2}\arctan \left(\frac{7}{300\×1000\×4}\right)\≈{0.6}^{\′\′},$ Four narrow slit structures (getting N=4) are when getting k=20, and namely single slit of vernier slit and kerf spacing are

Can realize the line array CCD after segmentation

Individual Image segmentation precision, the subdivision accuracy that can reach this moment is:

Mathematical relation schematic diagram between line array CCD and vernier slit as shown in Figure 2.

Want to obtain higher measuring accuracy, the focal length of collimator objective (4) can be longer, and the pixel number of line array CCD can be less, adopts corresponding vernier narrow slit structure can obtain higher precision.

The utility model can be widely used in the high-precision small-angle accuracy test, the high-acruracy survey of the verticality/flatness of small angle measurement, high precision table top or the workpiece of catoptron sound attitude small angle error high-acruracy survey, angular displacement sensor Angle Calibration, optical flat cold working part etc.

Claims (5)

1. vernier slit photoelectric auto-collimator, the line array CCD (6) that is included in the monochromatic source (1) that sets gradually on main optical path, many slits (2), spectroscope (3), collimator objective (4), rotating plane mirror (5) and arranges on the spectroscope light splitting optical path, many slits (2) and line array CCD (6) conjugation, the light that light source (1) sends images in line array CCD (6) and locates by many slits (2), is reflected back the spectroscope light splitting at plane mirror (5) after the spectroscope transmission; It is characterized in that:

Described many slits (2) are comprised of a plurality of parallel single slits, and parallel single slit seam is wide all equates with kerf spacing for each; As main scale, the picture of many slits (2) is as vernier scale with line array CCD, and vernier scale and main scale satisfy the vernier Principle of sub-division.

2. vernier slit photoelectric auto-collimator according to claim 1 is characterized in that: the width of described single slit is more than or equal to the line array CCD original image elemental size of 3 times.

3. vernier slit photoelectric auto-collimator according to claim 1 is characterized in that: establish each parallel single slit seam is wide and be d with kerf spacing, the slit number is N, and line array CCD pixel dimension and pixel spacing are P _d, the ccd signal of output has been carried out M times of hardware segmentation, vernier scale and main scale satisfy following mathematical relation:

$(2N-1)\×d=[k\×(2N-1)-1]\×\frac{P_d}{M},$ Wherein, N=1,2,3, M=1,2,3, K=1,2,3 ...

4. vernier slit photoelectric auto-collimator according to claim 3, it is characterized in that: the value of each parameter is 2≤N≤50; 2≤k≤100; 1≤M≤20.

5. vernier slit photoelectric auto-collimator according to claim 4, it is characterized in that: described light source is LED light source or LASER Light Source.

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