DE102004030896A1 - Lens aligning device, has light source provided with reference to spindle axis and axially shiftable to socket, and light detector e.g. camera unit, provided with sensor e.g. CCD-chip, for detecting and evaluating luminance of beam - Google Patents

Abstract

The device has component spindles with axes. A centered socket is provided on a front side of the spindles for retaining a lens. A light source (4) is provided with reference to the spindle axes and axially shiftable to the socket for coaxially aligning a light beam (5) to the spindle. A light detector e.g. camera unit, is provided with a sensor e.g. CCD-chip, for detecting and evaluating luminance generated by the beam.

Description

The The invention relates to a device for aligning a optical axis of a lens with two spindle axes w having workpiece spindles, the at their front side in each case a centering bell for receiving having the lens, wherein one with respect to the spindle axis w axially to Centering arranged offset light source for a coaxial with the workpiece spindle be aligned, attachable by the between the centering Lens passing light beam and with respect to the centering bell opposite arranged first light detector for the light beam provided are.

It is already a lens edge grinding machine with a tool spindle and two coaxially arranged centering from the DE 198 25 922 C2 known. According to column 9, lines 22 ff, the use of a laser device and a laser detector is provided, by means of which it can be determined to which side the only inaccurately placed lens protrudes eccentrically. Through controlled rotation in the C-axis, the lower centering spindle is then adjusted so that the lens with its eccentric projection points towards the tool spindle. The tool spindle is then fitted with a grinding tool or a special alignment tool, which is removed from the tool magazine. By moving the grinding tool this is brought into contact with the lens and moved by slow movement of the carriage, the lens until its axis coincides with the geometric axis of rotation of Zent rierspindel. This match is registered by means of laser measurement and the process of centering is stopped by the CNC control.

In In this context, it is the general state of the art, under Using a focusing unit emitted by the laser To focus light beam before passing through the lens, order a correspondingly small light spot on the laser detector to create. The laser detector is designed as a simple PSD transducer, the determination of any light pixels from the set of all through allows the light beam illuminated pixels. An evaluation of the am respective pixel prevailing light intensity is not possible.

Of the Invention is based on the object, an alignment and to design and arrange a method for aligning lenses in such a way that ensures a fast and accurate alignment of the lens is.

Is solved the task according to the invention by that the light detector is designed as a camera unit, the one Sensor like a CCD chip for detection and evaluation of the through the Light beam generated light intensity has. This will achieved that on the light detector or on the camera sensor incident light beam can be evaluated according to its intensity. The light beam impinging on the sensor generates a light beam position P, which is a dependent on the scattering of the light beam and its deflection geometric Form has. The use of a camera unit or a CCD chip guaranteed the evaluation of this form or the underlying this form Light intensity at the respective pixels for determining the distance a between the thus formed light beam position P and the spindle axis w.

Advantageous It is also that the light source as a light deflection unit is formed, wherein a light source activating laser is provided, the radially offset with respect to the spindle axis w to the light source is arranged. By using the light deflection unit such. B. a prism is the use of the device for transparent Lenses (transmitted light lenses) on the one hand and opaque lenses (Auflichtlinsen) on the other hand possible. It refers to visible light, which is the generation a visible light beam position P guaranteed. Especially at the alignment of Auflichtlinsen is that of the light deflection unit or from the prism to the lens surface incident light beam reflects on the lens surface and in turn occurs through the light deflection unit or the prism through to on the Sensor of the camera unit. The for the generation of the light beam required laser is offset laterally in the radial direction arranged to and thus does not hinder this beam path.

A additional possibility is according to a further development, that the light source is arranged on a first X-Y adjustment stage is a stepless positioning in a right angle to the Spindle axis w arranged X-Y plane guaranteed. The use of the X-Y adjustment table leaves the calibration of the system, ie the orientation of the light beam, at right angles to the sensor surface and coaxial with the spindle axis w.

Further, it is advantageous that a second light detector is provided, which is arranged with respect to the light source gegenüberlie quietly to the first light detector. Since the first light detector with respect to the lens is arranged opposite to the light deflection unit, that is used for transmitted light lenses is, the second light detector is provided for aligning Auflichtlinsen. It detects the above-described, reflected by the lens light beam of a Auflichtlinse or an opaque lens.

Advantageous it is also that the first and / or the second light detector on a second X-Y adjustment stage is arranged, which provides a stepless positioning guaranteed in the X-Y plane. Thus, the calibration of the system, so the orientation of the respective detectors or sensors, relative to the generated light beam possible.

there It is advantageously provided that the angular position of the Light source and / or the light detector to the spindle axis w adjustable is. In addition to the lateral orientation in the X-Y plane is the Alignment in an X-Z or Y-Z plane also the calibration of the system with consideration to a possible Tilting the prism or the light source.

The The invention further relates to a method for alignment a resting on a centering lens through which a generated by a light source, coaxial or parallel to the spindle axis w aligned light beam sent from a detector and the Light beam position P is detected, the position of the lens after evaluating the position P of the light beam on the detector perpendicular to the spindle axis w in the direction of an x-axis movable Tool is automatically corrected. The above task is solved by the distance a of the light beam position P to the spindle axis w be calculated and the lens depending on the determined Light beam positions P is aligned to the tool so that the, the light beam position P founding Part of the lens or at least one point of intersection of the lens with the Light beam on a spindle axis w and a tool axis z connecting degrees, between the spindle axis w and the tool axis z is arranged. The intersection of the lens with the light beam is the point from which the light beam from the lens falls on the detector. This is arranged with tilted lens eccentric to the spindle axis w.

By the rotation of the lens about the spindle axis w is achieved the sensor of the camera unit different light beam positions P described by the rotation in conjunction with the Angle error α the Lens are arranged on a position circle. The different distances a of the light beam positions P to the spindle axis w can thus calculated and for the orientation of the lens favorable Displacement corrections and displacement routes are determined so that only one alignment process is necessary. When moving the lens on the centering bell is to be noted that a combined movement the lens is done. The lens translates when moving, moved at right angles to the spindle axis w and at the same time around the Center of the centering bell facing lens radius R2 pivoted.

From special meaning is for the present invention that for determining the distance a of Light beam positions P, the light intensity distribution on the as a CCD chip trained detector is detected and of the geometric shape the light beam positions P, which are divided by the light intensity distribution gives, a center point or a geometric center of gravity and its Distance a to the spindle axis w is calculated. The consideration the center or the geometric center of gravity of the thus formed Light beam position P gives very accurate the actual support conditions the lens or its angular error α against.

in the Connection with the construction and arrangement according to the invention it is advantageous that for the calculation of the center or the geometric center of gravity a perimeter of geometric Shape of the light beam positions P is determined. The consideration The circumference line serves to determine the center of gravity and also guides to a very accurate determination of the angular error α.

Advantageous it is further that between 1 and 50, in particular between 3 and 20 light beam positions P, P 'per Rotation of the lens can be determined. When selecting the to be determined Light beam positions P is the computation time required for the calculation on the one hand, and the number of available positions on the other weigh.

Besides that is It is advantageous that starting from the distance a at least one Light beam position P, an angular error α of the lens is calculated. The angle error α represents the authoritative, for the user most meaningful Size, so take this into consideration the given tolerances, such. B. the resolution of the sensor or any lens defects, determine the accuracy of the alignment or lens position or knows.

Further it is advantageous that in the calculation of the angular error α, the center thickness Md the lens, the two Krüm radius of movement R1, R2 of the lens, the refractive index of the lens surrounding the lens Medium and / or the distance of the lens to the detector considered becomes.

Finally, it is advantageous that an intensity threshold value for the individual pixel brightness values is defined for the evaluation of the light intensity distribution on the detector, and only those Pixels whose brightness value is above the intensity threshold, are used for the determination of the geometric shape of the light beam positions P. The consideration or the use of an intensity threshold also ensures a very precise evaluation of the given contact conditions of the lens. Due to the associated hiding very weakly illuminated sensor sections or pixels scattered light and the associated influences are not taken into account in the evaluation.

Advantageous it is also this, that for the evaluation of the light intensity distribution on the detector a comparison with an earlier, known light intensity distribution he follows. The different examples of possible light intensity distributions, in particular from very bad or off-center put on lenses, can are generated as an example, so for the evaluation of a recourse on this data for estimation the current conditions of support the lens possible is. If the comparison with an earlier, known light intensity distribution positive, So if an evaluable image of the light beam position P exists is, then the alignment process is initiated immediately. Should but no evaluation available Picture present, so in so far undefined reflection of the light beam on the inside of the spindle, the lens must be pre-set, as described below, be roughly aligned.

Ultimately It is advantageous that the tool moved up to the lens is moved and the lens by further feed v of the tool becomes, whereby the with it changing Light beam position P is determined in a frequency f. By the determination of each new light beam position with given Frequency can thus be the changing one Distance a and thus the changing Angle error α determined so that the move process after reaching a desired Minimum distance or after falling below an adjustable distance threshold ends. Should while of the shifting process, the distance will get bigger again because of the lens in an unwanted Direction is moved, the shift process also ends. The for the determination of the required frequency f is decisive depending on the sliding speed, so at very low displacement speeds a correspondingly lower frequency can be selected.

Advantageous it is also that the frequency f is between 1 and 50 Hz, in particular between 10 and 20 Hz. In addition, frequencies are less than 1 Hz, ie between 0.01 Hz and 0.9 Hz.

Further It is advantageous that the tool moved up to the lens and the lens is moved by further feed v of the tool, where the feed v is continuous or at intervals between 1 μm and 200 μm, in particular between 5 μm and 50 μm he follows. The above measurement frequency f would be at continuous displacement of the tool or continuous movement of the tool. When interval movements are used, ie gradual movements of the tool, the respective measurement of the new distance takes place after the respective shift interval, ie between the different shift movements. Here is a consideration of the changing Tool diameter not necessary.

Besides that is It is advantageous that the diameter change of the tool by Evaluation of the target-actual comparison of the diameter of the lens determined and as a correction value for the current tool diameter is taken into account. That's it necessary, the lenses to be processed before and after editing to measure, so the deviation between the desired Target value and the achieved actual value is detected. This deviation is therefore a measure of the removal or inaccuracy of the tool and can thus in future Measurements find influence. The tool can thus be positioned more precisely and the lens can be approached faster.

From special meaning is for the present invention that the feed rate of the Tool when approaching the lens between 10 mm / min and 200 mm / min, in particular between 30 mm / min and 60 mm / min and / or at Moving the lens between 0.1 mm / min and 100 mm / min, in particular between 0.5 mm / min and 10 mm / min. In a continuous Displacement of the tool, as already described above, is in dependence the desired Measuring frequency and depending of the to be covered Move the desired Feed rate to choose.

It is also advantageous that, during the rotation and before detecting the light beam positions P on the detector, the tool for aligning the lens is positioned at a distance rt to the spindle axis w, where rt is the radius r of the lens plus a tolerance value t and the tolerance value t depending on the tool diameter between 20 .mu.m and 1000 .mu.m, in particular between 50 .mu.m and 300 .mu.m. In this case, it is taken into account that a lens comes to rest very coarse off-center, so that a direct light spot position on the sensor is not initially generated due to considerable angular errors α and thus an evaluation is not possible. The passing through spindles light beam is inside the spindle through the Spindelinnensei te reflects and so far uncontrolled on the sensor. In this case, a coarse concentric alignment of the lens is possible up to an automatic alignment allowing angular error α. In this orientation, it is advantageous if the lens and the grinding wheel at the contact point have the same circumferential speed, ie, roll against each other, so that in addition to the contact forces of the lens on the centering no additional frictional forces act on the lens.

Further It is advantageous that a device as described in the introduction is used.

Further Advantages and details of the invention are in the claims and explained in the description and shown in the figures. It shows:

1 a perspective view of the alignment device with spindles, lens and centering in section,

2 a top view of the detector with different light beam positions P, P ',

3 a lens in section with two radii R1, R2 and the optical axis.

The device for aligning a lens 1 is aligned coaxially with a spindle axis w. The core of the device is a first tool spindle 2.1 and a second tool spindle 2.2 , which are drivable by means not shown drive elements, wherein at least the upper spindle 2.1 is moved coaxially. At the respective end faces of the two spindles 2.1 . 2.2 each is a centering bell 3.1 . 3.2 provided for receiving the lens 1 serve. The respective centering bell 3.1 . 3.2 In this case has an annular end face, which can be applied against the lens surface or placed on the lens surface and aligned at right angles to the spindle axis w. Upwards to the first tool spindle 2.1 is a coaxial with the spindle axis w arranged, designed as a prism light source 4 arranged, which has a side to the prism 4 arranged laser 7 is exposed to light. The generated light beam 5 is thereby starting from the prism 4 coaxially deflected to the spindle axis w.

The two workpiece spindles 2.1 . 2.2 as well as the two centering bells 3.1 . 3.2 have a concentric recess or bore through which one of the prism 4 outgoing light beam 5 can pass through or go through. This passes through the light beam 5 between the two centering bells 3.1 . 3.2 recorded lens 1 ,

Below the tool spindles 2.1 . 2.2 is a first camera unit 6.1 arranged, which has a first sensor 6.3 for detecting the lens 1 deflected light beam 5 serves.

The Lens 1 is tilted with an angle error α within the two centering arranged so that between its optical axis 1.1 and the spindle axis w is the angle α.

Opposite to the first camera unit 6.1 is a second camera unit 6.2 arranged in alignment with opaque lenses 1 or Auflichtlinsen for detecting the also rejected light beam 5 serves. The light beam 5 steps out of the prism 4 out, is reflected on the lens surface and meets after re-passage through the prism 4 on a second sensor 6.4 the second camera unit 6.2 on.

Both the first camera unit 6.1 as well as the second camera unit 6.2 as well as the prism 4 are each on an XY adjustment table 8.1 to 8.3 arranged. The XY adjustment table is translationally adjustable in the direction of an X axis and in the direction of a Y axis. Next to them are the two camera units 6.1 . 6.2 as well as the prism 4 via a tilting device, not shown 10.1 . 10.3 adjustable in its angular position to the spindle axis w.

In addition, the camera units 6.1 . 6.2 as well as the prism 4 with a height adjustment 11.1 - 11.3 fitted.

Laterally offset to the lens 1 is a not further illustrated, designed as a grinding wheel tool 9 provided, which is driven translationally movable in the direction of the X-axis and in the direction of the Z-axis.

The in 2 illustrated sensor 6.3 or its sensor surface has approximately 10 ⁶ pixels, not shown, for detecting the incident on him light intensity. On a sensor surface 6.5 By way of example, a plurality of light beam positions P, P 'generated by the deflected light beam are shown as they result by rotation of the lens 1 offset in time. The respective light beam position P, P 'in this case has an approximately circular geometric shape whose center of gravity is determined after evaluation of the light intensity distribution. The various light beam positions P, P 'are located on an approximately circular path which is positioned concentrically or eccentrically to the spindle axis w.

By evaluating the distance a between the light beam position P, P 'and the spindle axis w of this deflection underlying angle error α, ie the tilt of the lens 1 within half of her intake.

In the 3 illustrated lens 1 has two different radii of curvature R1, R2, the centers of which through the optical axis 1.1 are connected. Due to the angular error α of the lens 1 on the centering bell shown only sketched 3.2 closes this with the spindle axis w the angle error α. The light beam 5 coincides with coaxial with the spindle axis w and offset to the optical axis 1.1 on the lens 1 up, gets broken and runs through the lens 1 to the bottom, where it is offset to the optical axis 1.1 and offset to the spindle axis w exits and is broken again. After passing through the spindle 2.2 he meets on the sensor 6.5 or the CCD pickup. The resulting distance a is evaluated as described above and the angle error α determined.

After aligning the lens 1 that is, the displacement of the lens 1 in the direction of the x-axis is the optical axis 1.1 Preferably aligned coaxially with the spindle axis w and thus the lens 1 centered. The subsequent editing of the side edge of the lens 1 ensures a later defined alignment of the optical axis 1.1 the lens 1 ,

1

lens

1.1

optical axis

2.1

Workpiece spindle

2.2

Workpiece spindle

3.1

centering

3.2

centering

4

Light source prism

5

beam of light

6.1

first Light detector, camera unit

6.2

second Light detector, camera unit

6.3

first sensor

6.4

second sensor

6.5

sensor surface

7

laser

8.1

first X-Y positioning table

8.2

second X-Y positioning table

8.3

third X-Y positioning table

9

Tool

10.1

Verkippvorrichtung

10.3

Verkippvorrichtung

11.1

height adjustment

11.2

height adjustment

11.3

height adjustment

a

distance

α

angular error

Md

center thickness

P

Light beam position

P '

Light beam position

R1

radius of curvature

R2

radius of curvature

w

spindle axis

x

axis

y

axis

z

axis

f

frequency

v

feed

rt

distance

r

radius

t

tolerance

Claims (21)

Device for aligning an optical axis ( 1.1 ) of a lens ( 1 ) with two spindle spindles w having workpiece spindles ( 2.1 . 2.2 ), which at their front side in each case a centering bell ( 3.1 . 3.2 ) for receiving the lens ( 1 ), one for Zentrierglocke ( 3.1 . 3.2 ) offset in the axial direction of the spindle axis w light source ( 4 ) for a coaxial with the workpiece spindle ( 2.1 . 2.2 ), by which between the centering bells ( 3.1 . 3.2 ) attachable lens ( 1 ) passing light beam ( 5 ) and one in the direction of the light beam ( 5 ) after the centering bell ( 3.1 . 3.2 ) arranged first light detector ( 6.1 ) for the light beam ( 5 ) are provided, characterized in that the light detector as a camera unit ( 6.1 ) is formed, which has a sensor surface ( 6.5 ), such as a CCD chip for the detection and evaluation of the light beam ( 5 ) has generated light intensity. Device according to claim 1, characterized in that the light source ( 4 ) is designed as a light deflection unit, wherein the light source ( 4 ) activating laser ( 7 ) is provided, which is offset in the radial direction to the spindle axis w to the light source ( 4 ) is arranged. Apparatus according to claim 1 or 2, characterized in that the light source ( 4 ) on a first XY adjustment table ( 8.1 ) is arranged, which is infinitely positionable in a direction perpendicular to the spindle axis w extending XY plane. Device according to one of the preceding claims, characterized in that a second light detector ( 6.2 ) provided with respect to the light source ( 4 ) opposite to the first light detector ( 6.1 ) is arranged. Device according to one of the preceding claims, characterized in that the first and / or the second light detector ( 6.1 . 6.2 ) on a second XY adjustment table ( 8.2 ) is arranged, which is infinitely positionable in a direction perpendicular to the spindle axis w extending XY plane. Device according to one of the preceding claims, characterized in that the Win between the light source ( 4 ) and / or the light detector ( 6.1 . 6.2 ) and the spindle axis w via a tilting device ( 10.1 . 10.3 ) is adjustable. Method for aligning one on a centering bell ( 3.1 ) resting lens ( 1 ) with the following process steps: a) through the lens ( 1 ) one of a light source ( 4 ) generated light beam ( 5 ), b) the centering bell ( 3.1 ) with the lens ( 1 ) about a spindle axis w of the centering bell ( 3.1 ) and thereby at least one of a plurality of light beam positions P on a detector ( 6.1 c) the distance a of the light beam position P to the spindle axis w is calculated, d) the lens ( 1 ) is dependent on the determined light beam positions P and / or in dependence of the decency a so the tool ( 9 ) aligned so that at least one intersection of the lens ( 1 ) with the light beam ( 5 ) is arranged on a spindle connecting the spindle axis w and a tool axis z, e) the position of the lens ( 1 ) on the centering bell ( 3.1 ) is dependent on the light beam position P on the detector ( 6.1 ) by a movable in the radial direction to the spindle axis w tool ( 9 ) automatically corrected. Method according to claim 8, characterized in that that a) for determining the distance a of the light beam positions P is the light intensity distribution on the as a CCD chip trained detector is detected, b) from the geometric Shape of the light beam positions P, which results from the light intensity distribution, a center or a geometric center of gravity and its distance a is calculated to the spindle axis w. Method according to claim 8, characterized in that that for calculating the center point or the geometric center of gravity a circumferential line of the geometric shape of the light beam positions P is determined. Method according to one of claims 7 to 9, characterized that between 3 and 500, in particular between 10 and 50 light beam positions P, P 'per revolution the lens can be determined. Method according to one of claims 7 to 10, characterized in that starting from the distance a at least one light beam position P is an angular error α of the lens ( 1 ) is calculated. A method according to claim 11, characterized in that in the calculation of the angular error α, the center thickness Md of the lens ( 1 ), the two radii of curvature R1, R2 of the lens ( 1 ), the refractive index of the lens ( 1 ), which is the lens ( 1 ) surrounding medium and / or the distance of the lens to the detector is taken into account. Method according to one of claims 7 to 12, characterized in that a) for evaluating the light intensity distribution on the detector ( 6.1 ) an intensity threshold value for the individual pixel brightness values is defined, b) only those pixels whose brightness value is above the intensity threshold value are used for determining the geometric shape of the light beam positions P. Method according to one of claims 7 to 13, characterized in that for the evaluation of the light intensity distribution on the detector ( 6.1 ) a comparison with an earlier, known light intensity distribution takes place. Method according to one of claims 7 to 14, characterized in that the tool ( 9 ) to the lens ( 1 ) and the lens ( 1 ) by further feed v of the tool ( 9 ) is shifted, whereby the changing light beam position P is determined in a frequency f. Method according to claim 15, characterized in that that the frequency f is between 1 and 50 Hz, in particular between 10 and 20 Hz. Method according to one of claims 7 to 16, characterized in that the tool ( 9 ) to the lens ( 1 ) and the lens ( 1 ) by further feed v of the tool ( 9 ), wherein the feed v, which takes place continuously or at intervals between 1 .mu.m and 200 .mu.m, in particular between 5 .mu.m and 50 .mu.m. Method according to one of claims 7 to 17, characterized in that the change in diameter of the tool ( 9 ) by evaluating the target-actual comparison of the diameter of the lens ( 1 ) and taken into account as a correction value for the current tool diameter. Method according to one of claims 7 to 18, characterized in that the feed rate of the tool ( 9 ) when approaching the lens ( 1 ) between 10 mm / min and 100 mm / min, in particular between 30 mm / min and 60 mm / min and / or when moving the lens ( 1 ) between 0.1 mm / min and 100 mm / min, in particular between 0.5 mm / min and 10 mm / min. Method according to one of claims 7 to 19, characterized in that during the rotation and before detecting the light beam positions P on the detector ( 6.1 ) the tool ( 9 ) for aligning the lens ( 1 ) with distance rt to the spindle axis (w) is positioned, where rt is equal to the radius r of the lens plus a tolerance value t and the tolerance value t depending on the tool diameter between 20 .mu.m and 1000 .mu.m, in particular between 50 .mu.m and 300 .mu.m. Method according to one of claims 7 to 20, characterized a device according to one of claims 1 to 6 is used.