CN204314054U - Wide-angle lens distortion testing device - Google Patents

Abstract

A kind of wide-angle lens distortion testing device, comprise target target plate, this target target plate is ring target; Ring target comprises inner circle and the cylindrical concentric with inner circle; The semidiameter of inner circle and cylindrical is determined by the CCD pixel dimension of the focal length of wide-angle lens, the focal length of parallel light tube, the object lens enlargement ratio of CCD micrometering system and CCD micrometering system; Transmission region is formed between ring target inner circle and cylindrical; Transmission region imaging on CCD accounts for 3 ~ 5 pixels at ring target radial direction; Inner circle imaging on CCD of ring target accounts for 30 ~ 50 pixels at radial direction.The utility model provides a kind of wide-angle lens distortion testing device improving testing efficiency and measuring accuracy.

Description

Wide-angle lens distortion testing device

Technical field

The utility model belongs to photoelectricity test field, relates to a kind of wide-angle lens distortion testing device.

Background technology

At present, the usual means of optical lens distortion test adopts parallel light tube, high precision turntable, CCD micrometering system composition; Thering is provided point target by installing star tester at the focal plane of parallel light tube, under different visual field, the barycenter of asterism being gathered to CCD and studies and judges, the line amount under the displacement platform of combined high precision or the given different visual field of laser interference length-measuring instrument; The angle value of different visual field is given by high precision turntable, obtains the focal length value under different visual field by precision angle method, obtains ideal focal distance, finally obtain the difference of the desirable image height in different visual field and actual image height, namely distort by the full filed minimum matching that distorts.

The method distorts in test process at wide-angle lens, the feature due to wide-angle lens self: visual field is large, central vision distortion is little, distortion change is more slow; Axle outer visual field distortion is large, distortion change is very fast, and axle outer visual field coma, astigmatism are comparatively serious, need to consider especially:

1) test distorted is by the angle under the different visual field of discrete acquisitions, line amount under corresponding angle; Distortion is obtained by discrete sampling, in Conventional distortion test process, is rule of thumb, at equal intervals choose for test interval, choosing of test point.Wide-angle lens visual field is comparatively large, and on axle, visual field distortion change is more slow, and axle outer visual field distortion localized variation is very fast.From sampling thheorem, change region faster for distortion, test interval is little, and test point wants many; For the region that distortion change is comparatively slow, suitably can increase test interval, reduce test point, especially change near comparatively slow regional center visual field for distortion, because the line amount of angular amount and correspondence is all less, therefore test error is comparatively large, reduces test point and can reduce due to the test error brought of sampling.Rational sampling plan is the key of wide-angle lens distortion test.

2) distortion is vertical axial aberration, and it only changes the image space on the resonable imagination face of extra-axial object point, make the shape of picture produce distortion, but can not change the image quality of optical system, therefore distortion can not cause the change of asterism energy distribution.It is to ask under different visual field asterism energy distribution center in the displacement of CCD target surface that traditional asterism barycenter is studied and judged, the line amount under the displacement platform of combined high precision or the given different visual field of laser interference length-measuring instrument; And coma, astigmatism iseikonia missionary society cause the change of asterism energy distribution, therefore in distortion test process, when studying and judging according to asterism barycenter, the impact of the aberration such as coma, astigmatism on distortion test should be considered.

Because wide-angle lens off-axis aberration is comparatively large, adopting asterism barycenter to study and judge is the center asking asterism energy distribution, the impact of other aberrations such as coma, astigmatism can be brought in distortion test.

Utility model content

In order to solve the above-mentioned technical matters existed in background technology, the utility model provides a kind of wide-angle lens distortion testing device improving testing efficiency and measuring accuracy.

Technical solution of the present utility model is: the utility model provides a kind of wide-angle lens distortion testing device, comprises target target plate, and its special character is: described target target plate is ring target.

Above-mentioned ring target comprises inner circle and the cylindrical concentric with inner circle; The semidiameter of described inner circle and cylindrical is determined by the CCD pixel dimension of the focal length of wide-angle lens, the focal length of parallel light tube, the object lens enlargement ratio of CCD micrometering system and CCD micrometering system; Transmission region is formed between described ring target inner circle and cylindrical; Described transmission region imaging on CCD accounts for 3 ~ 5 pixels at ring target radial direction; Inner circle imaging on CCD of described ring target accounts for 30 ~ 50 pixels at radial direction.

The determination mode of the semidiameter of above-mentioned inner circle and cylindrical is:

$\mathrm{\Δd}=\frac{(3~5)\×d_{\mathrm{CCD}}\×W\×f_{\mathrm{OP}}}{f_{\mathrm{TEST}}}$

Wherein:

F _tESTit is the focal length of wide-angle lens;

F _oPit is the focal length of parallel light tube;

W is the object lens enlargement ratio of CCD micrometering system;

D _cCDit is the CCD pixel dimension of CCD micrometering system;

Δ d is the cylindrical of ring target and the semidiameter of inner circle.

The utility model has the advantage of:

1) according to the design theory distortion curve of wide-angle lens, the unequal interval sampling plan of distortion test is given.Improve efficiency and the degree of confidence of test.

2) according to the configuration of tested wide-angle lens and testing apparatus, annular target plate needed for careful design test, this ring target inner circle is light tight, decrease other aberrations such as coma, astigmatism to the impact of annular penetrating region, by the cylindrical of careful design ring target and the semidiameter of inner circle, alternative edge detection algorithm, ellipse fitting, calculate the center of its fitted ellipse, realizes the location to inner circle.By the line amount under the displacement platform of the displacement combined high precision of the centre of form of ring target inner circle under different visual field or the given different visual field of laser interference length-measuring instrument.The use of ring target decreases the impact of other aberrations such as coma, astigmatism on distortion test, improves measuring accuracy.

Accompanying drawing explanation

Fig. 1 is the structural representation of the target target plate that the utility model adopts.

Embodiment

See Fig. 1, the utility model provides a kind of wide-angle lens distortion testing device, comprises target target plate, and this target target plate is ring target.

Ring target comprises inner circle and the cylindrical concentric with inner circle; The semidiameter of inner circle and cylindrical is determined by the CCD pixel dimension of the focal length of wide-angle lens, the focal length of parallel light tube, the object lens enlargement ratio of CCD micrometering system and CCD micrometering system; Transmission region is formed between ring target inner circle and cylindrical; Transmission region imaging on CCD accounts for 3 ~ 5 pixels at ring target radial direction; Inner circle imaging on CCD of ring target accounts for 30 ~ 50 pixels at radial direction.

The determination mode of the semidiameter of inner circle and cylindrical is:

$\mathrm{\Δd}=\frac{(3~5)\×d_{\mathrm{CCD}}\×W\×f_{\mathrm{OP}}}{f_{\mathrm{TEST}}}$

Wherein:

F _tESTit is the focal length of wide-angle lens;

F _oPit is the focal length of parallel light tube;

W is the object lens enlargement ratio of CCD micrometering system;

D _cCDit is the CCD pixel dimension of CCD micrometering system;

Δ d is the cylindrical of ring target and the semidiameter of inner circle.

Meanwhile, the sampling defining method based on the wide-angle lens distortion test of wide-angle lens distortion testing device as mentioned above comprises the following steps:

1) the design theory distortion curve of wide-angle lens is obtained;

2) to step 1) the design theory distortion curve of wide-angle lens that obtains gets first order derivative, obtains the design theory photogrammetric distortion component curve of wide-angle lens;

3) sectional straight line fitting is carried out to the design theory photogrammetric distortion component curve of wide-angle lens, segmentation is carried out to the distortion test sampling of the design theory photogrammetric distortion component curve of wide-angle lens;

4) second order difference is got to the design theory distortion curve of every section of wide-angle lens, obtain the design theory distortion second order difference curve of the wide-angle lens in segmentation;

5) fitting of a polynomial is carried out to the design theory distortion second order difference curve of the wide-angle lens in segmentation, determine its intersegmental minimum sampling number by the progression of fitting of a polynomial.

6) judge that present sample is counted and whether be greater than step 5) in minimum sampling number; If so, by the result of fitting of a polynomial, least square fitting is carried out to oversampled points, to the result after least square fitting, by point larger for its residual error, as test gross error point, rejected; If not, then according to step 5) in minimum sampling number sample.

Claims (2)

1. a wide-angle lens distortion testing device, comprises target target plate, it is characterized in that: described target target plate is ring target;

Described ring target comprises inner circle and the cylindrical concentric with inner circle; The semidiameter of described inner circle and cylindrical is determined by the CCD pixel dimension of the focal length of wide-angle lens, the focal length of parallel light tube, the object lens enlargement ratio of CCD micrometering system and CCD micrometering system; Transmission region is formed between described ring target inner circle and cylindrical; Described transmission region imaging on CCD accounts for 3 ~ 5 pixels at ring target radial direction; Inner circle imaging on CCD of described ring target accounts for 30 ~ 50 pixels at radial direction.

2. wide-angle lens distortion testing device according to claim 1, is characterized in that: the determination mode of the semidiameter of described inner circle and cylindrical is:

Wherein:

F _tESTit is the focal length of wide-angle lens;

F _oPit is the focal length of parallel light tube;

W is the object lens enlargement ratio of CCD micrometering system;

D _cCDit is the CCD pixel dimension of CCD micrometering system;

Δ d is the cylindrical of ring target and the semidiameter of inner circle.