CN100588934C - Core shift measuring method - Google Patents

Abstract

The invention provides the method for measuring amount of deviation core, comprising the following steps: getting the difference deltar of locus radius r<SUB>1</SUB> and r<SUB>2</SUB> which are formedon image surface from checking surface (10A) and installing surface (10B), multiplying thedeltar by K, which is ratio of distance in real space position and distance of imaging surface, and getting the amount of deviation core. Even if there is deviation, the invention can easily and accurately measure the amount of deviation core.

Description

Core shift measuring method

Technical field

The present invention relates to the core shift measuring method that a kind of core shift amount of the plane was seized to optical elements such as lens is measured.

Background technology

Big event as the evaluation or the inspection of lens has pair lens face to carry out the measurement of core shift amount.

The core shift amount of lens face is represented by the center of curvature of this lens face and the side-play amount of lens center axle.

As the measuring method of this type of core shift amount, known have a method that is called as autocollimation (auto collimation) method shown in following patent documentation 1 grade.For example, core shift measuring method shown in Figure 8 is to have used the method for the emission-type core shift measurement mechanism of autocollimation method by employing, and it comprises: pedestal 122, and it can be that the center is rotated with its central shaft that tested lens (spherical lens) 110 are arranged to; Light source 111; Identification plate (pinhole plate: pinhole board) 112, the light from light source 111 is passed through; Measure with optical system 131, along optical axis with rayed to tested lens 110; And image mechanism, be used to observe light from tested lens 110.

Described measurement possesses with optical system 131: beam splitter (beam splitter) 113, and will be 111 that penetrate, the light by identification plate 112 reflects with approximate right angle from light source; Collimator lens 114 will form parallel beam from the light of beam splitter 113; With object lens 115, make this parallel beam converge in the paraxial focus of tested lens 110.In addition, described image mechanism is made of CCD camera 121, and this CCD camera 121 possesses seeing through shooting face described beam splitter 113, that observe from the light of tested lens 110.

When utilizing described core shift measurement mechanism to carry out core shift measurement amount, will be mapped to tested lens 110 by the illumination from light source 111 of identification plate 112 with optical system 131 by measuring.

At this moment, the light by mobile object lens 115 converges position P, and it is consistent with the center of curvature of the plane was seized (top) of tested lens 110 to make light converge position P.So, can think to be equal to the light of the plane was seized that incides tested lens 110 with the light that sends from the center of curvature of this plane was seized, so, be reflected in mode from plane was seized against incident path.This reflected light sees through beam splitter 113 and incides CCD camera 121.After this, if in rotating basis 122, observation then ought exist under the situation of core shift from the reflection image of tested lens 110, and the track of the picture of pin hole can be described circle, can try to achieve the core shift amount of tested lens 110 by this radius of a circle is carried out instrumentation.

At this, tested lens 110, the face (installed surface) of itself and plane was seized opposition side is supported on the pedestal.Because this installed surface also is a sphere, so even tested lens 110 misplace on pedestal 122, the position of the installed surface center of curvature can not change basically yet.Therefore, in such core shift measurement mechanism, the core shift that records is measured value directly as the final core shift amount of plane was seized.

[patent documentation 1] spy opens the 2005-55202 communique

But,, in fact exist the error on the machining making the pedestal 122 that is provided with tested lens 110 or measuring with optical system 131 in the mechanism that optical axis direction moves.Therefore, between the optical axis of the turning axle of pedestal 122 and tested lens 110 or the turning axle of pedestal 122 and should measuring with between the optical axis of optical system 131 etc., the existence of this skew exists small skew, owing to will be difficult to improve the measuring accuracy of core shift amount.Particularly along with the high performance of optical device, the existence that hinders the described minor shifts of core shift measurement accuracy of measurement raising becomes a big problem.

Certainly, make the center of curvature of installed surface be positioned on the lens turning axle, measuring accuracy is improved, but such optics adjustment need spend bigger labour, make the people can't bear that it is loaded down with trivial details if carry out the optics adjustment.

Summary of the invention

The present invention uses for reference described example, its purpose is to provide a kind of core shift measuring method, even this core shift measuring method is between the optical axis of the turning axle of the pedestal that is provided with tested lens and tested lens or at the turning axle of this pedestal with measure with existing under the situation of skew between the optical axis of optical system etc., also can be simply and carry out the core shift measurement amount of tested lens face accurately.

In order to address the above problem, core shift measuring method involved in the present invention, be on the rotatable pedestal in center tested optical element to be set with the predetermined axis, and via the measurement optical system that comprises regulation shape sign, to the plane was seized of this tested optical element that is set up be shone from the light of light source, when will or seeing through light from the reflected light of this plane was seized and guiding on the imaging surface, making the tested optical element that is arranged on this pedestal is that the center is rotated with the turning axle of stipulating, the motion track of the picture of the described sign that forms through light maybe is somebody's turn to do in observation on this imaging surface by this reflected light, measure the core shift amount of described plane was seized, it is characterized in that:

With the face of described plane was seized opposition side as installed surface, described tested optical element is arranged on the described pedestal;

Described measurement relatively moved with the optical axis direction of optical system along this measurement with optical system and described plane was seized adjust, make from the reflected light of described plane was seized or through light imaging on described imaging surface, and, is that the center is rotated by making described pedestal rotation make described tested optical element with described turning axle, measures the radius r that maybe should be seen through light motion track of formed described sign picture on this imaging surface by this reflected light ₁

Described measurement relatively moved with the optical axis direction of optical system along this measurement with optical system and described installed surface adjust, make from the reflected light of described installed surface or through light imaging on described imaging surface, and, making the described tested optical element that is arranged on the described pedestal is that the center is rotated with described turning axle, measures the radius r that maybe should be seen through light motion track of formed described sign picture on this imaging surface by this reflected light ₂

Calculate measured described radius r ₁With described radius r ₂Difference Δ r, and this Δ r be multiply by the corresponding predetermined coefficients K of ratio that asks for the distance on the relative imaging surface of distance of locus of core shift amount with reality expectation, ask for the core shift amount of described plane was seized.

In addition, described radius r ₁Measurement and described radius r ₂Measuring sequence, either party can carry out in advance.

Core shift measuring method involved in the present invention is based on following idea, promptly by asking for by the radius r from reflected light toroidal track of formed sign picture (graduation picture) on imaging surface of plane was seized ₁, with by radius r from reflected light toroidal track of formed sign picture (graduation picture) on imaging surface of installed surface (back side) ₂Difference Δ r, and to this Δ r multiply by with the real space position in the relative imaging surface of distance on the corresponding predetermined coefficients of ratio of distance, can try to achieve the core shift amount of plane was seized accurately.

That is to say, according to core shift measuring method of the present invention, by not only considering the information relevant with the The curvature center of plane was seized, also the consideration information relevant with the The curvature center of installed surface is carried out computing, even on pedestal that is provided with tested lens etc., there is error on the machining etc., between the optical axis of the turning axle of pedestal and tested lens or at the turning axle of pedestal with should measure with existing under the situation of skew between the optical axis of optical system etc., also can be simply and the core shift that carry out plane was seized accurately measure.

Description of drawings

Fig. 1 is the summary pie graph that is used to implement the core shift measuring device of the related core shift measuring method of an embodiment of the present invention.

Fig. 2 is the approximate three-dimensional map of chuck (chuck) mechanism that is made of V-shaped groove piece and rotating circular disk of expression.

Fig. 3 is the figure that is used to illustrate the definition of core shift amount Ec.

Fig. 4 is the figure of the track of the graduation picture that formed on shooting face by the reflected light from plane was seized or installed surface of expression.

Fig. 5 is by each mode corresponding with the relation of each between centers, when present embodiment is verified, the simulation drawing represented intuitively of the state of each mode (between measuring and measure between the turning axle of the shifting axle of usefulness optical system Z-direction and lens, do not have the situation of skew) just with the turning axle of the optical axis of optical system and lens.

Fig. 6 is by each mode corresponding with the relation of each between centers, when present embodiment is verified, and the simulation drawing that the state of each mode is represented intuitively (between the turning axle of measuring with the optical axis of optical system and lens, having situation about being offset).

Fig. 7 is by each mode corresponding with the relation of each between centers, when present embodiment is verified, the simulation drawing that the state of each mode is represented intuitively (between the turning axle of measuring with the shifting axle of optical system Z-direction and lens, producing the situation of inclination).

Fig. 8 is the summary pie graph of the existing core shift measuring device of expression.

Among the figure: 1-core shift measuring device, 10, the tested lens of 110-, 10A-plane was seized, 10B-installed surface, 11,111-light source, 12-graticule (reticule board), 13,113-beam splitter (beam splitter), 14, the 114-collimator lens, 15,115-object lens, 21,121-CCD camera, 22-lens mounting parts, the tested lens rotary drive mechanism of 23-, 24-Z axle transfer table, the 25-fixed station, 31,131-measures and to use optical system, 32-resolves operational part, 51-V shape geosynclinal block, the 52-rotating circular disk, 112-identification plate (pinhole plate), 122-pedestal.

Embodiment

Below, with reference to accompanying drawing, embodiment involved in the present invention is at length described.

At first, based on Fig. 1, the summary of the reflection-type core shift measuring device that is used to implement the related core shift measuring method of an embodiment of the present invention constituted describe.

This core shift measuring device 1 is the device that the core shift amount of plane was seized (top) 10A of tested lens 10 is measured, and has: with the light source 11 of rayed plane was seized 10A and installed surface (following) 10B; The graticule (reticule board) 12 that light beam from light source is passed through; Measure with optical system 31.This measurement possesses with optical system 31: make the beam splitter 13 that the light from graticule 12 reflects with approximate right angle, the light that makes incident form the collimator lens 14 of parallel beam and make parallel beam converge at the object lens 15 of assigned position (light convergent point) P.

And, this core shift measuring device 1 has CCD camera 21, this CCD camera 21 is launched into the reflected light from plane was seized 10A and installed surface 10B via object lens 15, collimator lens 14 and beam splitter 13 incidents, and the graduation of graticule 12 is looked like to make a video recording.

And this core shift measuring device 1 has: lens mounting parts 22, the tested lens 10 of its mounting; Tested lens rotary drive mechanism 23, it makes these lens mounting parts 22 is that the center is rotated with the turning axle of regulation; Z axle transfer table 24, it remains one with described measurement with optical system 31 and described CCD camera 21, and, the two is moved along the direction of this measurement with the optical axis Z of optical system 31; With fixed station 25, it established tested lens rotary drive mechanism 23 and Z axle transfer table in 24 years and is fixed as one.

In addition, be provided with and resolve operational part 32, its to CCD camera 21 obtained as information resolve, computing.

At this, described lens mounting parts 22 also can utilize end face edge portion above it, the mounting parts of the drum that tested lens 10 are supported, if utilize chuck (chuck) mechanism as shown in Figure 2, that constitute by V-shaped groove piece 51 and rotating circular disk 52, tested lens 10 are clamped in its side, and, make tested lens 10 rotations by this rotating circular disk 52 of rotation driving, then can carry out the location of tested lens 10 with high precision.

In addition, by under the situation of the tested lens 10 of any means mounting, all preferably carry out the position adjustment in the turning axle W of tested lens 10 mode consistent with the optical axis z of tested lens 10.

And cross shape is adopted in the division line of preferred described graticule 12 (reticule), but also can adopt circular pin hole etc.In addition, preferably the equipping position of this graticule 12 is consistent with the focal position of the light source side of collimator lens 14.

And, with optical system 31 and described CCD camera 21, can use the autocollimator device to constitute one as described measurement.

At this, utilize Fig. 3 that the definition of core shift amount Ec is described.

That is to say, if the two sides of tested lens 10 (plane was seized 10A, installed surface 10B) is all sphere, the then center of curvature C of plane was seized 10A ₁Be positioned on the optical axis of plane was seized 10A the center of curvature C of installed surface 10B ₂Be positioned on the optical axis of installed surface 10B.Link 2 center of curvature C ₁, C ₂Straight line be the optical axis z of tested lens 10, if the turning axle W of tested lens 10 is consistent with the optical axis of installed surface 10B, then under the situation that the optical axis of the optical axis z of these tested lens 10 and installed surface 10B intersects at a certain angle, will be from the center of curvature C of plane was seized 10A ₁Length of perpendicular to the optical axis of installed surface 10B is defined as core shift amount Ec.Under the inconsistent situation of optical axis of the turning axle W of tested lens 10 and installed surface 10B, will be from the center of curvature C of plane was seized 10A ₁Extremely the length of perpendicular of the turning axle W of tested lens 10 is made as core shift amount Ec.

Below, the core shift measuring method that the present embodiment of having utilized described core shift measuring device 1 is related to describes.

(1) at first, the tested lens 10 of mounting make its installed surface 10B be arranged on reliably on the lens mounting parts 22;

(2) then, will be from the tested lens 10 of the rayed of light source 11;

(3) then, drive Z axle transfer table 24 and also adjust, make that the entrained graduation of reflected light from the plane was seized 10A of tested lens 10 looks like to image on the shooting face of CCD camera 21.Finishing under the adjusted state center of curvature C of plane was seized 10A ₁P is consistent with described assigned position (light convergent point).

(4) then, rotation drives tested lens rotary drive mechanism 23, makes tested lens 10 rotations, thereby, by on shooting face, depict circular track from the catoptrical graduation picture of plane was seized 10A.

(5) by resolving 32 couples of radius of a circle r that on this shooting face, described of operational part ₁Resolve, with its core shift amount information as plane was seized 10A.

(6) then, drive Z axle transfer table 24 once more and adjust, make that the entrained graduation of reflected light from the installed surface 10B of tested lens 10 looks like to image on the shooting face of CCD camera 21.Finishing under the adjusted state center of curvature C of installed surface 10B ₂P is consistent with described assigned position (light convergent point).

(7) then, rotation drives tested lens rotary drive mechanism 23, makes tested lens 10 rotations, thereby, by on shooting face, depict circular track from the catoptrical graduation picture of installed surface 10B.

(8) by resolving 32 couples of radius of a circle r that on this shooting face, described of operational part ₂Resolve, with its core shift amount information as installed surface 10B.

(9) then, in resolving operational part 32, calculate described radius r ₁With described radius r ₂Poor, try to achieve Δ r.

(10) by in resolving operational part 32, carrying out Δ r be multiply by the computing of predetermined coefficients K, try to achieve core shift amount Ec.

As described above like that, the core shift measuring method that present embodiment is related is by asking for the radius r of the toroidal track of formed each reflection image from plane was seized 10A and installed surface 10B on the shooting face ₁And radius r ₂Difference Δ r, and multiply by the corresponding predetermined coefficients K of ratio that asks for the distance on the relative imaging surface of distance of locus of core shift amount with reality expectation to this Δ r, can be in the hope of the correct core shift amount of plane was seized 10A.

Here, the afore mentioned rules COEFFICIENT K is represented with for example following formula (1).

[several 1]

$K=\frac{f_{\mathrm{head}}}{2f_{\mathrm{ACM}}}---\left(1\right)$

At this, f _HeadBe center of curvature C from object lens 15 to plane was seized 10A ₁Distance; f _ACMIt is distance from the shooting face of collimator lens 14 to CCD cameras 21.

In addition, with the COEFFICIENT K of above-mentioned formula (1) expression, be that device is the coefficient under the reflection-type situation shown in Figure 1, the COEFFICIENT K under the infiltration type device situation is represented by following formula (2).

[several 2]

$K=\frac{f_{\mathrm{head}}}{f_{\mathrm{ACm}}}---\left(2\right)$

Then, Fig. 4 (A) is illustrated is to form circular situation by the track from the graduation picture of reflected light on shooting face of described plane was seized 10A or installed surface 10B.At this moment division line has utilized circular pin hole shape.That is, with pixel count the pixel network (pixel mesh) at the shooting face being gone up the radius of circle that the center line of formed ring belt as track forms calculates.In addition, shown in Fig. 4 (B),, try to achieve described radius of a circle, resolution characteristic is improved if pass through the track at weighting (weighted) center of each graduation picture.

Below, utilize Fig. 5～7, by each mode corresponding, verify present embodiment with the relation of each between centers.

In addition, in each figure of Fig. 5～7, the left side is the simulation drawing of each position relation of expression on the real space, and the right is to be illustrated under the situation of the position relation that the simulation drawing on the left side shows the motion track of the graduation picture on the shooting face.

" 1 " between the turning axle of the optical axis of measuring usefulness optical system 31 and lens 10 and between the turning axle of the shifting axle of the Z-direction of measurement usefulness optical system 31 and lens 10, do not produce the situation (Fig. 5 (A)～(D)) of skew

<a>

Fig. 5 (A) is that the optical axis optical axis of installed surface (below be called) of expression installed surface 10B is consistent with the lens turning axle, and does not produce the figure of the state of core shift, and core shift amount Ec at this moment is 0.

<b>

Fig. 5 (B) is that the optical axis of expression installed surface is consistent with the lens turning axle, and produces the figure of the state of core shift, and the core shift amount Ec of this moment is d ₁, pass through Kr ₁Try to achieve.

<c>

Fig. 5 (C) is that the optical axis and the lens turning axle of expression installed surface staggers in parallel to each other, and does not produce the figure of the state of core shift, and the core shift amount Ec of this moment is 0.

<d>

Fig. 5 (D) is that the optical axis and the lens turning axle of expression installed surface staggers in parallel to each other, and produces the figure of the state of core shift, and the core shift amount Ec of this moment is d ₁-d ₂, by K (r ₁-r ₂) try to achieve.

《2》

Between the turning axle of the optical axis of measuring usefulness optical system 31 and lens 10, produce the situation (Fig. 6 (A)～(D)) of skew.

<a>

Fig. 6 (A) is that the optical axis of expression installed surface is consistent with the lens turning axle, and does not produce the figure of the state of core shift, and the core shift amount Ec of this moment is 0.

<b>

Fig. 6 (B) is that the optical axis of expression installed surface is consistent with the lens turning axle, and produces the figure of the state of core shift, and the core shift amount Ec of this moment is d ₁, pass through Kr ₁Try to achieve.

<c>

Fig. 6 (C) is that the optical axis and the lens turning axle of expression installed surface staggers in parallel to each other, and does not produce the figure of the state of core shift, and the core shift amount Ec of this moment is 0.

<d>

Fig. 6 (D) is that the optical axis and the lens turning axle of expression installed surface staggers in parallel to each other, and produces the figure of the state of core shift, and the core shift amount Ec of this moment is d ₁-d ₂, by K (r ₁-r ₂) try to achieve.

" 3 " between the turning axle of the shifting axle of measuring the Z-direction of using optical system 31 and lens 10, produce the situation (Fig. 7 (A)～(D)) of inclination.

In addition, in Fig. 7 (A)～(D), C ₁, C ₂And e _Z, represent the center of curvature of the plane was seized 10A on the real space, the center of curvature and the skew between the turning axle of the shifting axle of measuring the Z-direction of using optical system 31 and lens 10 of installed surface 10B respectively.On the other hand, C ' ₁, C ' ₂And e ' _Z, expression on the shooting face and C ₁, C ₂And e _ZCorresponding position.

<a>

Fig. 7 (A) is that the optical axis of expression installed surface is consistent with the lens turning axle, and does not produce the figure of the state of core shift, and the core shift amount Ec of this moment is 0.

<b>

Fig. 7 (B) is that the optical axis of expression installed surface is consistent with the lens turning axle, and produces the figure of the state of core shift, and the core shift amount Ec of this moment is d ₁, pass through Kr ₁Try to achieve.

<c>

Fig. 7 (C) is that the optical axis and the lens turning axle of expression installed surface staggers in parallel to each other, and does not produce the figure of the state of core shift, and the core shift amount Ec of this moment is 0.

<d>

Fig. 7 (D) is that the optical axis and the lens turning axle of expression installed surface staggers in parallel to each other, and produces the figure of the state of core shift, and the core shift amount Ec of this moment is d ₁-d ₂, by K (r ₁-r ₂) try to achieve.

As above, also can know from the checking result who has used Fig. 5～7 and to know, according to present embodiment, even, also can try to achieve core shift amount Ec well producing skew between the turning axle of measuring with the optical axis of optical system 31 and lens 10, measuring between the turning axle with the shifting axle of the Z-direction of optical system 31 and lens 10 and produce inclination.

In addition, as core shift measuring method of the present invention, be not to be defined in described embodiment, also can implement the change of other variety of ways.

For example, also plane was seized can be set at tested lens below, under this situation, will be set at installed surface above the tested lens.

And rise, in the above description, as the device that present embodiment is utilized, main light reflex type device is illustrated, but also can use the device of light transmission type to replace.

And, in said embodiment, adopted by measurement is moved with optical system, make the center of curvature C of light convergent point P and plane was seized or installed surface ₁, C ₂Consistent mode still, also can adopt tested lens are moved, and makes the center of curvature C of plane was seized or installed surface ₁, C ₂With the consistent mode of light convergent point P.

In addition, as the determining method of COEFFICIENT K, can utilize the various determining methods except that above-mentioned.

Claims (1)

1, a kind of core shift measuring method, at the axle with regulation is on the rotatable pedestal in center tested optical element to be set, and via the measurement optical system of the sign that comprises the regulation shape, to the plane was seized of this tested optical element that is set up be shone from the light of light source, when will or seeing through light from the reflected light of this plane was seized and guiding on the imaging surface, making the tested optical element that is arranged on this pedestal is that the center is rotated with the turning axle of stipulating, the motion track of the picture of the described sign that forms through light maybe is somebody's turn to do in observation on this imaging surface by this reflected light, measure the core shift amount of described plane was seized

In described core shift measuring method,

With the face of described plane was seized opposition side as installed surface, described tested optical element is arranged on the described pedestal;

Described measurement relatively moved with the optical axis direction of optical system along this measurement with optical system and described plane was seized adjust, make from the reflected light of described plane was seized or through light imaging on described imaging surface, and, is that the center is rotated by making described pedestal rotation make described tested optical element with described turning axle, measures the radius r that maybe should be seen through light motion track of the picture of formed described sign on this imaging surface by this reflected light ₁

Described measurement relatively moved with the optical axis direction of optical system along this measurement with optical system and described installed surface adjust, make from the reflected light of described installed surface or through light imaging on described imaging surface, and, making the described tested optical element that is arranged on the described pedestal is that the center is rotated with described turning axle, measures the radius r that maybe should be seen through light motion track of the picture of formed described sign on this imaging surface by this reflected light ₂

Calculate measured described radius r ₁With described radius r ₂Difference Δ r, and this Δ r be multiply by the corresponding predetermined coefficients K of ratio that asks for the distance on the relative imaging surface of distance of locus of core shift amount with reality expectation, ask for the core shift amount of described plane was seized.

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