EP3286547A1

EP3286547A1 - Method for calibrating a polarization axis measuring device and method for determining polarization axes of spectacle lenses for a polarization axis measuring device

Info

Publication number: EP3286547A1
Application number: EP16717615.5A
Authority: EP
Inventors: Stephan Trumm; Johann Auer; Werner Müller
Original assignee: Rodenstock GmbH
Current assignee: Rodenstock GmbH
Priority date: 2015-04-20
Filing date: 2016-04-15
Publication date: 2018-02-28
Also published as: JP2018519497A; DE102015106041A1; US20180052074A1; WO2016169862A1; US10161828B2; JP6681407B2; DE102015106041B4

Abstract

The invention relates to a method for calibrating a polarization axis measuring device (100), wherein both flat sides (26, 28) of a calibration element (10) in a polarization axis measuring device (100) are irradiated with polarized light, wherein the method involves aligning in each case at least one polarization direction of the light in a first and/or second rotational position with a principal axis (134) in a predefined angular relationship with respect to a polarization axis (40) of the calibration element (10). Determining the rotational position of an axis (30) of the calibration element (10) is carried out by determining an angle bisector between the first and second rotational positions of the polarization direction of the incident light. The method involves assigning a predefined angle value for the rotational position of the principal axis (134) of the polarization direction for which the latter is in the predefined angular relationship with respect to the axis (30) of the calibration element (10) inserted as intended. Furthermore, the invention relates to a method for determining polarization axes of spectacle lenses, to a calibration element (10), and to a polarization axis measuring device (100) comprising a calibration element (10).

Description

Description title

Method for calibrating a polarization axis measuring device and method for determining polarization axes of spectacle lenses for a polarization axis measuring device

State of the art

The invention relates to a method for calibrating a polarization axis measuring device, a method for determining polarization axes of spectacle lenses, a calibration element for a polarization axis measuring device and a

Polarization axes measuring device.

Polarization axis measuring devices are used in the field of spectacle optics in order to determine the orientation of the polarization plane in polarizing spectacle lenses and to check. Polarizing glasses can suppress unwanted, dazzling reflections, such as occur on water surfaces. To a lesser extent, this also applies to the light scattered in the atmosphere of the sun, so that these glasses to some extent contrast-enhancing effect. In the case of reflection on non-metallic surfaces, the proportion of light whose polarization direction is perpendicular to the plane of incidence is predominantly reflected at suitable angles. Accordingly, a spectacle lens should suppress horizontally polarized light. For measuring the polarization axis, ie orientation of the plane of polarization, of a polarizing spectacle lens is usually used a method that follows the relevant standard DIN EN ISO 8980-3: 2014-03. Such polarization axis measuring devices are usually calibrated with a calibration body of polarizing material with known polarization plane orientation. The preparation of such calibration is complicated and the calibration prone to systematic errors.

In this case, the polarization plane of the plane of polarization of linearly polarized transmitted light is designated as the polarization axis with the plane of a test object or of a polarizer. The polarization plane is defined as the plane which is perpendicular to the plane of oscillation of the electric field of the light wave. As the polarization direction, however, the oscillation direction of the electric field of the light wave is indicated. The plane of incidence is the plane which is spanned by the propagation direction of the incident light and the solder on the reflective surface. Thus, it also contains the propagation direction of the reflected light.

Disclosure of the invention

The object of the invention is to provide a method for calibrating a polarization axis measuring device with such a calibration element, which enables a precise and reproducible calibration.

Another object of the invention is to provide a method for determining polarization axes of spectacle lenses with such a polarization axis measuring device, which enables a reproducible determination of the polarization axes. Another object of the invention is to provide a calibration element for a polarization axis measuring device which is easy to manufacture and allows precise calibration of a polarization axis measuring device with such a method of calibrating a polarization axis measuring device.

Another object of the invention is to provide a polarization axis measuring device with such a calibration element which is easy to manufacture and allows precise calibration of the polarization axis measuring device.

The objects are achieved by the features of the independent claims. Favorable embodiments and advantages of the invention will become apparent from the further claims, the description and the drawings.

The invention relates, in one aspect, to a method for calibrating a polarization axis measuring device with a calibration element, comprising the steps of (i) inserting a calibration element into the polarization axis measuring device and irradiating a first flat side of the calibration element with polarized light, (ii) aligning at least one polarization direction of the light in one first rotational position with a major axis in a predetermined angular relationship to a polarization axis of the calibration element, (iii) placing the calibration element and irradiating its second flat side with polarized light, (iv) aligning the at least one polarization direction of the light in a second rotational position with the major axis in FIG the predetermined angular relationship to the polarization axis of the calibration element, (v) determining the rotational position of an axis of the calibration element by determining an angle bisector between the first and d the second rotational position of the polarization direction of the incident light and

(vi) assigning a predetermined angular value of the rotational position of the main axis of the polarization direction, in which this is in the predetermined angular relationship to the axis of the intended inserted calibration element.

In a first embodiment, a polarizer may be used in combination with a light source emitting unpolarized light. In an alternative embodiment, at least one light source emitting polarized light may instead be used.

The predetermined angular relationship may be a parallel or perpendicular orientation of the major axis to the polarization axis of the calibration element. In one embodiment of the method, the insertion of the Kalibnerelements in the polarization axis measuring device can be made directed with its first flat side to the polarizer, which is irradiated with unpolarized light and for aligning the polarization direction, aligning the polarizer in a first rotational position of the polarizer with a major axis in a predetermined angular relationship with respect to a polarization axis of the calibration element and / or alignment of a receptacle for the calibration element take place, wherein light is transmitted from the first flat side through the calibration element. The insertion of the calibration element can be directed with the second flat side to the polarizer, and for aligning the polarization direction, the alignment of the polarizer in a second rotational position of the polarizer with the major axis in the predetermined angular relationship to the polarization axis of the calibration and / or aligning the Recording for the calibration carried out, wherein light is transmitted from the second flat side through the calibration.

The determination of the rotational position of the axis of the calibration element can be effected by determining an angle bisector between the first and the second rotational position of the polarizer.

In one embodiment, the polarizer may be rotatable about an optical axis. Alternatively, a receptacle can be rotatably arranged about the optical axis, which accommodates the calibration element. Alternatively, both the polarizer and the receptacle may be rotatable about the optical axis. The main axis may advantageously be aligned in the predetermined angular relationship parallel or perpendicular to the polarization axis of Kalijnerelennents. However, in principle, another angular relationship is conceivable. In this case, the rotary position of the main axis of the polarizer is assigned a predetermined angle value at which it is in the predetermined angular relationship to the axis of the calibration element inserted as intended.

In this case, the predetermined angle value does not have to coincide with the angular relationship predetermined by the calibration. The given angular relationship refers to the calibration procedure during calibration. If there is an angular offset between the axis of the calibration element and the main axis of the polarizer, this angular offset can be taken into account as a fixed angular relationship in the calibration. Furthermore, the predetermined angle value may include an angular relationship during the adjustment during the measurement of the test object.

The calibration consists in establishing a relationship between a defined position of the main axis of the polarizer and an axis of the recording with the aid of a caliber element. A polarizer with an undivided field of view can be used in which the polarization axis represents the main axis. It may alternatively be

Split-face polarizer, in which two areas with different polarization axes adjoin one another on the major axis. For example, light passing through the polarizer with split field of view has two polarization directions. Alternatively, instead of the polarizer with undivided field of view, a light source with polarized light can be used. Instead of the polarizer with split field of view, two light sources with polarized light can be used, whose polarization axes are symmetrical to the main axis.

In contrast to the prior art, in which usually a calibrated polarizer with known orientation of the polarization axis, instead of the specimen inserted into the device, the polarizer adjusted to maximum extinction of both fields, or in the simplified method to the minimum or maximum transmitted light intensity adjusted, and the orientation of the main axis of the polarizer achieved after this adjustment is assigned to the known position of the polarization axis of the calibration, need not be known in the inventive method, the exact position of the polarization axis of the calibration.

In the procedure according to the invention, rather, the absolute orientation of the polarization axis of the calibration body has no influence on the calibration result. This is achieved by measuring the calibration body twice with the as yet uncalibrated polarization axis measuring device, between the first and the second measurement about an axis lying in the plane of the polarizer (or the at least one light source with polarized light), the axis of the Calibration element to

Rotated 180 °, i. turned, so that once a first flat side to the polarizer shows and once a second flat side. As a result, a deviation of the position of the polarization axis of the calibration body from the axis of the calibration element results in the same measurements in both measurements to deviations in the respective measurement results, which cancel each other in the subsequent arithmetic averaging of the rotational position of the main axis of the polarizer.

The determination of the rotational positions can in each case be carried out several times and the respective measured values as averages of the

Single measurements can be taken to improve the statistical measurement uncertainty.

According to an advantageous embodiment, a split-face polarizer may be used which comprises at least a first region having a first polarization axis and a second region having a second polarization axis, wherein the first polarization axis and the second polarization axis have an equal angle of opposite magnitude to the major axis wherein the angle is preferably between 2 ° and 5 °, more preferably between 2.5 ° and 3.5 °, most preferably at 3 °. The decisive factor is less the exact amount of the angle than the fact that the amounts are the same. According to an advantageous embodiment, aligning the main axis of the polarizer (or the light sources with polarized light) by matching a transmitted through the first region of the polarizer with a first polarization axis light intensity and transmitted through the second region of the polarizer with a second polarization axis light intensity to the same Brightness, in particular to low brightness, done.

The case of minimal transmission is chosen to be advantageous, since the human eye has a logarithmic sensitivity and therefore small differences in the brightness of two dark fields can be more accurately perceived than differences in the brightness of two bright fields. An automatic measurement with an analysis unit, which measures the transmitted light intensity through the optional mirror or without the use of the optional mirror, can work with both minimum and maximum brightness.

According to an advantageous embodiment, a polarizer with undivided field of view may be used which comprises at least one region with a polarization axis, wherein the polarization axis forms the main axis. In this case, can be dispensed with a division of the polarizer. The advantage here is a simpler and cheaper version of the polarizer.

According to an advantageous embodiment, alignment of the main axis of the polarizer (or the at least one light source with polarized light) may be accomplished by minimizing or maximizing a light intensity transmitted through a region of the polarizer with a polarization axis. In this embodiment, the division of the polarizer is dispensed with. The advantage here is a simpler and cheaper version of the polarizer. Conveniently, the polarization axis of the polarizer coincides with its main axis.

For the measurement is adjusted to the minimum or maximum of the transmitted light intensity. In particular, for automated processes in which the transmitted light intensity for different angular positions can be detected by a sensor, such an embodiment is well suited.

Preferably, prior to carrying out the method according to the invention for calibrating the polarization axis measuring device, a precalibration in the form of an angular calibration of the rotatably arranged polarizer is carried out. In the pre-calibration, an arbitrarily chosen position / position of the polarizer (or the at least one light source with polarized light) is assigned an also arbitrarily chosen angle value. This is an indication of the angular position of the polarizer (or the at least one light source with polarized light) given, which can be used during the calibration process according to the invention for determining the polarization axes of the calibration.

According to an advantageous embodiment of the inventive method for calibrating a polarization axis measuring device, a value zero of a third rotational position of the main axis of the polarizer (or the at least one light source with polarized light) are assigned, in which this is in the predetermined angular relationship to the axis of the intended inserted calibration , Advantageously, this third position of the polarizer (or the at least one light source with polarized light) corresponds to an axis defined by markings on the receptacle of the polarization measuring device. Thus, a direct assignment of angular degrees is advantageously given as the angular distance of the polarization axis of the specimen to the axis defined by the markers of the recording, allowing an advantageous registration and evaluation of the measurement results of the determination of the polarization axes.

If the axis predetermined by the receptacle for the calibration element and the axis predetermined by the markings do not match the alignment of the test objects, the difference between these two axis positions can be taken into account when assigning the calibration value. Advantageously, the value zero here corresponds to the orientation of the main axis of the polarizer parallel or perpendicular to the axis predetermined by the marking of the support for the test specimens.

In a further aspect, the invention relates to a method for determining polarization axes of spectacle lenses. Eyeglass lenses may include tubular and form-edged lenses or lenses mounted in frames, spectacle lens pairs and spectacle lens blanks. The method includes calibrating a

Polarization axis measuring device according to the method described above.

Furthermore, the method comprises the oriented insertion of a spectacle lens into a receptacle of the polarization axis measuring device by aligning with a marking of the recording, aligning a main axis of a polarizer in a predetermined angular relationship to the polarization axis of the spectacle lens and thus subsequently determining the angular difference of the rotational position of the polarizer and the Marking the recording and, consequently, determining the polarization axis of the spectacle lens relative to an orientation of the spectacle lens. The method according to the invention for determining polarization axes of spectacle lenses can be used in the field of spectacle optics in order to determine and check the orientation of the polarization plane in polarizing spectacle lenses, in particular in quality assurance. With the method, a polarization axis of a spectacle lens can be reliably and reproducibly determined, since the polarization axis measuring device has previously been reliably and reproducibly calibrated by means of the Kalilbrierelements, the calibration is easy to manufacture. In this case, the precision of the measurement can be increased by repeatedly performing and thus improving the statistics accordingly. Also, if necessary, the quality of the calibration can be checked by re-measuring the calibration element and the

Polarization axis measuring device, if necessary, also be recalibrated.

For measuring mounted spectacle lenses, the markings for aligning the lenses may be a contact rail, to which the socket in which the glasses are mounted, can be applied and which may correspond to the frame horizontal.

Conveniently, the predetermined angular relationship may in particular comprise a parallel or vertical orientation of the main axis to the polarization axis of the spectacle lens.

It is proposed according to a further aspect of the invention, a calibration, which is intended for insertion into a receptacle of a polarization axis measuring device, which is designed and determined for carrying out the method according to the invention. The calibration element comprises a transilluminable calibration of polarizing material, the calibration, with a first and an opposite second flat side, and a holder for grasping the calibration, which holder has at least one positioning for the intended reproducible arrangement in a receptacle.

In this case, the holder has a transmission range for irradiating the calibration body with light. The positioning device has at least two diametrically opposite positioning elements, wherein the holder with the calibration body can be inserted either with its first flat side or with its second flat side into the receptacle of the polarization axis measuring device. The holder for grasping the calibrating body and the calibrating body can form a component, wherein preferably the holder can form an edge region of the calibrating body.

In the simplest case, the calibration element according to the invention comprises a piece of polarizing material which can be transilluminated by a light source. The calibration element is provided with a positioning device which permits precise alignment of the calibration element in the polarization axis measuring device. For example, the calibration body is fitted in a socket which is provided with markings for correct installation, or the calibration body is provided directly with these markings. The advantage here is that an axis of the calibration, which axis lies in the plane of the calibration, is determined by the markers and a precise alignment of the mark to the polarization axis of the calibration is not necessary. Particularly advantageously, the calibration element is provided with a mechanical positioning device, which allows a correct and precise alignment of the calibration to the polarization axis measuring device, preferably prevents twisting of the calibration within its plane about its vertical axis perpendicular to the plane and in particular only a turn around the axis of the calibration 180 ° permits. The mechanical positioning device can take over the function of the markings. Advantageously, the positioning can be designed so that the intended use of the holder against rotation about an optical axis of the polarization axis measuring device in the recording can be arranged.

According to an advantageous embodiment, the positioning device may comprise at least one pin as a positioning, which projects beyond both the first flat side and on the second flat side. With one or more such pins, which may be designed as dowel pins, it is possible that the holder of the calibration with the calibration either with its first flat side or with its second flat side in the recording of

Polarization axis measuring device is used.

This positioning of the calibration in the polarization axis measuring device is very reliable and reproducible possible, so calibration inaccuracies in the measurement can be largely excluded.

According to an advantageous embodiment, the positioning device may have at least one opening as a positioning element. As an alternative to the embodiment with dowel pins in the holder of the calibration element, the dowel pins can also be provided in the receptacle of the polarization axis measuring device, and expediently openings are provided in the holder of the calibration element, in which the dowel pins are then inserted as intended, so that a positioning of the calibration element in the polarization axis measuring device It is very reliable and reproducible possible.

According to an advantageous embodiment, the positioning device can have at least one marking, such as a notch or a bar mark, as the positioning element. Such a marking can also be another efficient way of positioning the calibration element precisely and reproducibly in the polarization axis measuring device.

According to an advantageous embodiment, the positioning device may have at least one contact edge as a positioning element. In this case, preferably, the abutment edge forms part of the circumference of the holder, that is, for example, designed as a milled edge on the circumference of the holder. The abutment edge could also be mounted as a rail on the holder of the calibration. Such a system may be another efficient way of accurately and reproducibly positioning the calibration element in the polarization axis measuring device.

Alternative possibilities for reliable and reproducible positioning of the calibration element in the recording of the polarization axis measuring device, for example in combinations of the aforementioned positioning elements are conceivable. For example, the holder of the calibration element may alternatively have two dowel pins, or two openings. Preferably, the openings or dowel pins are configured such that a twisting or a twisted insertion of Kalib erelements is prevented by 180 ° about a vertical axis of the calibration. To achieve this, the openings or the dowel pins, for example, be configured differently sized. If identical openings or dowel pins are to be provided in each case, the holder preferably has further openings or dowel pins and / or markings which are arranged in such a manner that a clear insertion of the calibration element is made possible.

Furthermore, the holder may comprise combinations of different positioning elements. The corresponding counter-elements are respectively provided in the receptacle of the polarization axis measuring device.

According to an advantageous embodiment, the calibration body can have a transilluminable region with a polarization axis. The calibration element may conveniently comprise a calibration body of a polarizing material having a polarization axis. It is expedient if the calibration body is designed to be transilluminable at least in one area, so that the calibration element can be brought into a light beam of the polarization axis measuring device and the transmitted light intensity can be used for calibration.

According to a further aspect, the invention relates to a polarization axis measuring device having such a calibration element, wherein the polarization axis measuring device is designed and intended for carrying out the method according to the invention, and which comprises a light source with unpolarized light, a polarizer rotatable about an optical axis with a main axis, and a receptacle for a candidate. The rotatably arranged polarizer is also called Messpolarisator. In this case, the calibration element comprises a transilluminating calibration body made of polarizing material, and a holder for grasping the calibration body, wherein the holder has at least one positioning device for reproducible arrangement in the receptacle. The calibration element is selectively arranged with a first flat side or with a second flat side to the polarizer as a DUT in the recording can be arranged.

Alternatively, instead of the polarizer with unpolarized light, at least one light source with a main axis which emits polarized light can be used. Furthermore, as an alternative to the polarizer, the receptacle can also be arranged to be rotatable about the optical axis.

The polarization axis measuring device according to the invention is used to measure the exact position of the polarization axis of polarizing material, as used for example in glasses for polarizing sunglasses.

Advantageously, a mirror can also be provided for observing a light intensity transmitted by the light source parallel to the optical axis through the polarizer and the specimen, which allows an ergonomically favorable operation of the polarization axis measuring device, since the user does not have to bend over the device but rather from the front Mirror image of the test specimen in properly aligned mirror can consider.

The measuring principle is based on the fact that when passing linearly polarized light through polarizing media, the intensity of the transmitted light is sensitive to the angle between the polarization plane of the light and the polarization axis of the material. For this purpose, the light of an a priori non-polarized light source is polarized with a polarizer. Since the polarizer is expediently mounted on a precision rotary holder, the polarization direction can be specified. The thus polarized light passes through the specimen. This allows only the component corresponding to the position of its polarization axis to pass from the polarized light. If the polarization axes of both components are parallel to each other, the transmission is maximal (complete for ideal components), they are vertical, minimal (perfect components are completely extinguished for ideal components).

At the beginning of the measurement, the test specimen is brought into a defined position in which it remains fixed during the measurement. The specimen is preferably arranged so that it can not be moved only during the measurement, but after the measurement is easily removed from the receptacle. A simple edition in which the specimen is not rotated, but in principle could be rotated, is conceivable. The light source is then viewed through the specimen and the polarizer and the polarizer is aligned with a rotating mount so that as little light as possible passes through the combination of polarizer and specimen.

The polarization axis measuring device according to the invention enables autarkic calibration. This means that the polarization axis measuring device can be calibrated without the aid of pre-calibrated objects or devices. According to the invention, a polarizing calibration body, for example a polarizing film, is used whose polarization axis also does not have to be known a priori. On the calibration element an axis lying in the plane of the calibration element is distinguished, around which it can be turned. This award is visible from both flat pages, which can be arbitrarily set. The axis of the calibration element can be chosen arbitrarily and does not have to match either the polarization axis or a geometric axis of symmetry. For example, the axis may be given by the connection axis of two dowel pins. By turning the calibration element is also ensured that even systematic errors are compensated.

In order to achieve the most accurate calibration, it is expedient not only to adjust the disappearance of the contrast when the test piece with a known polarization axis rests, but with a rotary support of the rotatably arranged polarizer a "zero position" resulting from the averaging of several measurements This may cause inaccuracy in the measurement of the axis of the calibration body, for example due to inaccuracy in adjusting the pivot mount during the calibration process, which manifests itself as a systematic error in later measurements based on the calibration thus obtained reduce the statistical inaccuracy of a measurement to the measurement uncertainty of a measurement series.

Instead of a simple polarizer, as described in the corresponding standard DIN EN-ISO-8980-3: 2014-03 from 2014, a polarizer with a split field of view, namely two areas with differently oriented polarization axes can be used. This usually consists of two semicircular polarization elements. The boundary between the two fields of view is called the main axis. According to an advantageous embodiment, the polarizer may thus comprise at least a first region with a first polarization axis and a second region with a second polarization axis, the first polarization axis and the second polarization axis having a magnitude equal in magnitude to the major axis with opposite signs, the angle being preferred between 2 ° and 5 °, more preferably between 2.5 ° and 3.5 °, most preferably at 3 °. The decisive factor is less the exact amount of the angle than the fact that the amounts are the same.

As an alternative to the split-field polarizer with the two differently oriented polarization axes, it is also possible to use polarized light with two differently oriented polarization axes, for example two light sources emitting polarized light. In this case, the main axis represents the bisecting line between the two polarization axes.

Through the sample through the optional mirror, the light source can be viewed, with the light being polarized by the polarizer through the two regions of the split field polarizer. The observed brightness depends on the relative position of the main axis as the bisector between the two polarization axes of the polarizer to the polarization axis of the specimen. For the measurement is adjusted to the disappearance of the contrast between the two fields of view at maximum extinction. Since the brightness of the two visual fields at the border is immediately recognizable, a high accuracy and safety of the measurement can be achieved despite the manual procedure. After a corresponding calibration, the angle of the polarization axis of the test object can now be read directly on the digital display of a connected rotary encoder. According to an advantageous embodiment, the polarizer may alternatively comprise at least one region with a polarization axis. In this case, the polarization axis forms the main axis of the polarizer. In this embodiment, the division of the polarizer is dispensed with.

The advantage here is a simpler and cheaper version of the polarizer. In this case, the polarization axis of the polarizer is set as its main axis. For the measurement is adjusted to the minimum or maximum of the transmitted light intensity. For automated processes in which the transmitted light intensity for different angular positions can be detected with a sensor, such an embodiment is well suited.

The invention further relates to a computer program product for calibrating a polarization axis measuring device, comprising a computer-readable storage medium containing a program code which is designed to carry out the method according to the invention for calibrating a polarization axis measuring device when the program code is executed on a data processing device. The computer program product may be used, for example, in a computer coupled to the polarization axis measuring device.

The invention also relates to a computer program product for determining polarization axes of spectacle lenses, comprising a computer-readable storage medium containing a program code which is designed to carry out the method according to the invention for determining polarization axes of spectacle lenses when the program code is executed on a data processing device. The Connputerprogrannnnprodukt can be used for example in a computer which is coupled to a corresponding measuring device for determining polarization axes of spectacle lenses.

drawings

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

They show by way of example:

1 is a plan view of a calibration after a

Embodiment of the invention with two dowel pins as positioning elements;

Fig. 2 of the calibration of polarizable material of

Calibration element of Fig. 1;

Fig. 3 is a plan view of a calibration element after another

Embodiment of the invention with two openings as positioning elements;

Fig. 4 is a plan view of a calibration element after another

Embodiment of the invention with two abutment edges as positioning elements; Fig. 5 is a plan view of a Kalib erelement according to another embodiment of the invention with two markers as positioning elements; Fig. 6 is a schematic representation of a

Polarization axis measuring device according to a

Embodiment of the invention;

Fig. 7 is an isometric view of

Polarization axis measuring device of Fig. 6;

Fig. 8 is a plan view of a receptacle of a specimen of a

Polarization axis measuring device according to a

Embodiment of the invention;

9 is a plan view of a polarizer of a

Polarization axis measuring device according to a

Embodiment of the invention; 10 is a flowchart of a method for calibrating a

Polarization axis measuring device according to a

Embodiment of the invention; and

1 1 is a flowchart of a method for determining

Polarization axes of spectacle lenses according to an embodiment of the invention.

Embodiments of the invention In the figures, like or equivalent components are numbered with like reference numerals. The figures are merely examples and are not intended to be limiting.

1 shows a plan view of a calibration element 10 according to an embodiment of the invention with two dowel pins as positioning elements 22, 24. The calibration element 10 for insertion into a receptacle 108 of a polarization axis measuring device 100 (shown in FIG. 6) comprises a transilluminatable calibration element 12 made of polarizing material with a first and an opposite second flat side 26, 28, in particular a front side 26 and a rear side 28. Further, the calibration element 10 comprises a holder 14 for grasping the calibration body 12, which holder 14 is executed in Figure 1 in the form of a ring and at least one Positioning device 20 for intended reproducible arrangement in a receptacle 108 has. In the exemplary embodiment in FIG. 1, the positioning device 20 has dowel pins with different diameters as positioning elements 22, 24 which project beyond both the first flat side 26 and the second flat side 28, whereby the holder 14 is secured against rotation about an optical axis of a polarization axis measuring device Recording can be arranged. The holder 14 has a transmission area 16 for irradiating the calibration body 12 with light.

The positioning device 20 has at least two diametrically opposite positioning elements 22, 24, 32, 34, 42 (see FIGS. 1, 3, 4, 5). The holder 14 with the calibration body 12 can be inserted either with its first flat side 26 or with its second flat side 28 into the receptacle 108 of the polarization axis measuring device 100. The calibration body 12 has a transilluminable region 18 with a polarization axis 40. The two positioning elements 22, 24 are arranged on an axis 30 of the calibration body 12 (shown in FIG. 1), around which axis 30 of the calibration body 12 turned into the receptacle 108 of the polarization axis measuring device 100 can be used. The polarization axis 40 of the calibration body 12 is shown in FIGS. 1 to 5. The hatching of the calibration body 12 should specify its polarization direction.

In FIG. 2, the calibration body 12 is shown separated from polarizable material of the calibration element 10 of FIG. In the simplest case, the calibration body 12 can be formed from a polarizable film which can be glued onto a holder 14, for example, so as to maintain a fixed orientation on the calibration element 12. Alternatively, holder 14 and calibration body 12 form a component, preferably, the holder 14 can form an edge region of the calibration body 12.

FIG. 3 further shows a plan view of a calibration element 10 according to another exemplary embodiment of the invention with two openings as positioning elements 42. A design with two openings in the holder 14 of the calibration element 10 is particularly advantageous if in the receptacle 108 of the polarization axis measuring device 100 correspondingly complementary alignment pins are provided. In this way, the calibration element 10 can be inserted into the receptacle 108 with a first flat side 26 or a second flat side 28.

FIG. 4 shows a plan view of a calibration element 10 according to a further exemplary embodiment of the invention with two abutment edges 32 as positioning device 20. The abutment edge 32 preferably forms part of the circumference of the holder 14. The abutment edge 32 can be formed, for example, as a milled edge of the holder 14. Even with the aid of such systems 32, the calibration element 10 can be used reproducibly with a first flat side 26 or a second flat side 28 in the receptacle 108. In Figure 5 is a plan view of a caliber erelement 10 is shown according to a further embodiment of the invention with two markings 34 as a positioning device 20. With the aid of such markings 34, the calibration element can be aligned with corresponding markings 132, which are mounted in the receptacle 108 (shown in FIG. 7), when inserted into the receptacle 108. In this way too, a reproducible arrangement in the receptacle 108 is possible in order to obtain reliable measured values.

FIG. 6 shows a schematic illustration of a polarization axis measuring device 100 according to an embodiment of the invention. The polarization axis measuring device 100 comprises a light source 102 with unpolarized light, a polarizer 106 rotatable about an optical axis 104 with a major axis 134 (shown in FIG. 9), a receptacle 108 for a specimen 110, and a mirror 1 12 for visual matching from the light source 102 parallel to the optical axis 104 through the polarizer 106 and the specimen 1 10 transmitted light intensity by adjusting the rotatably mounted in a rotary holder 138 polarizer 106. The receptacle 108 has counter elements 124, for example in the form of two openings 126, 128 (in FIG 7) for the insertion of the calibration element 10 in the receptacle 108 by means of the positioning device 20. The mounted mirror 1 12 is inclined toward the operator of the polarization axis measuring device 100, so that the operator sees a mirror image of the DUT 10. The mirror 1 12 enhances the ergonomics of the polarization axis measuring device 100. It allows the user to operate the device completely from the front, without having to bend over the device during the support of the specimen 110 or during the measuring process. Since the test specimen 1 10 rests itself fixed, already taken spectacle lenses can be measured. For this purpose, the device can be extended with a corresponding stop for the spectacle frame.

The polarizer 106 comprises a first region 1 14 having a first polarization axis 1 18 and a second region 1 16 having a second polarization axis 120 adjoining the main axis 134 (shown in FIG. 9). The first polarization axis 118 and the second polarization axis 120 in this case have a magnitude equal to the main axis 134 angle 122, preferably between 2 ° and 5 °, more preferably between 2.5 ° and 3.5 °, most preferably 3 °. Through the specimen 110, the light source 102 is viewed with the mirror 112, the light being polarized by the polarizer 106 through the two regions 14,14,116 (shown in FIG. 8) of the split face polarizer 106. The observed brightness depends on the relative position of the main axis 134 as the bisector between the two polarization axes 1 18, 120 of the polarizer 106 to the polarization axis of the test piece 1 10 from. For the measurement, the disappearance of the contrast between the two visual fields is preferably adjusted at maximum extinction. Since the brightness of the two visual fields at the border is immediately recognizable, a high accuracy and safety of the measurement can be achieved despite the manual procedure. After a corresponding calibration, the angle of the polarization axis of the DUT 1 10 can now be read directly on the digital display of a connected rotary encoder.

Alternatively, the polarizer 106 may also be formed with an undivided field of view and comprise only a region 14 with a polarization axis 1 18, the polarization axis 18 forming the main axis 134. In this embodiment, the division of the polarizer 106 is dispensed with. The advantage consists in a simpler and cheaper version of the polarizer 106. In this case, the Polarization axis 134 of the polarizer 106 set as the main axis. For the measurement is adjusted to the minimum or maximum of the transmitted light intensity. In particular, for automated processes in which the transmitted light intensity for different angular positions can be detected by a sensor, such an embodiment is well suited.

Alternatively, instead of a polarizer 106 with undivided field of view, a light source with polarized light can be used. Instead of the polarizer 106 with split field of view, two light sources with polarized light can be used whose polarization axes 1 18, 120 are symmetrical to the main axis 134.

The associated calibration element 10 (shown in FIG. 1) for calibrating the polarization axis measuring device 100 comprises the transilluminatable calibration element 12 made of polarizing material and the holder 14 for gripping the calibration element 12, which holder 14 has the positioning device 20 for reproducible arrangement in the receptacle 108. The calibration element 10 can optionally be arranged with the first flat side 26 or with the second flat side 28 directed toward the polarizer 106 as the test object 110 in the receptacle 108.

FIG. 7 shows an isometric view of the polarization axis measuring device 100, which is shown purely schematically in FIG. The various elements of the polarization axis measuring device 100 are arranged on a frame 148. The frame 148 is supported by a base plate 146 on which the light source 102 rests centrally. A mounting plate 144 carries the rotary holder 138 of the polarizer 106 with drive and angle encoder. Another mounting plate 142 carries the receptacle 108 for the DUT 1 10. On a further mounting plate 140 of the mirror 1 12 is arranged at an angle to the vertical, for example, 45 °. The Light rays from the light source 102 can thus be observed along the optical axis 104 through the polarizer 106, through the viewing region 130 of the receptacle 108 and the DUT 1 10 (not shown) on the receptacle above the tilted mirror 12. By means of the drive of the rotary holder 138, the polarizer 106 can be rotated about the optical axis 104 and thus be adjusted to equal brightness ranges of the polarizer 106.

FIG. 8 shows a plan view of the receptacle 108 of the test object 110 of a polarization axis measuring device 100 according to an exemplary embodiment of the invention. The receptacle 108 has an annular support with an opening 130 as the transmission area. Two counter elements 124 for the positioning elements 22, 24 of the calibration element 10 are arranged on the carrier in order to be able to reproducibly position the calibration element 10 with the help thereof. The counter-elements 124 are executed in the embodiment in Figure 8 as holes 126, 128 to accommodate the dowel pins 22, 24 of the calibration element 10 of Figure 1 can. The counter-elements 124 are arranged on an axis 136 of the receptacle 108. Next 108 markings 132 for the reproducible positioning of specimens 1 10 are mounted on the support of the recording.

FIG. 9 shows a top view of the polarizer 106 of the polarization axis measuring device 100 according to an embodiment of the invention. The polarizer 106 comprises a first region 1 14 having a first polarization axis 1 18 and a second region 1 16 having a second polarization axis 120 adjoining the main axis 134. In this case, the first polarization axis 118 and the second polarization axis 120 have an angle 122 to the main axis 134 between 2 ° and 5 °, preferably between 2.5 ° and 3.5 °, particularly preferably of 3 °. The drawn in Figure 9 angle 122 of the two Polarization axes 1 18, 120 to the main axis 134 is greatly exaggerated to illustrate the effect.

FIG. 10 shows a flow chart of the method for calibrating the polarization axis measuring device 100 according to an exemplary embodiment of the invention. The calibration of the polarization axis measuring device 100 takes place with the aid of the calibration element 10.

The method comprises in step S1 10 the insertion of the calibration element 10 into the polarization axis measuring device 100 with the first flat side 26 directed to the polarizer 106. Then, in step S120, the polarizer 106 is aligned in a first rotational position with a major axis 134 in a predetermined angular relationship, preferably parallel or perpendicular to a polarization axis 40 of the calibration element 10, with light being transmitted from the first flat side 26 through the calibration element 10. Next, in step S130, the calibration element 10 with the second flat side 28 facing the polarizer 106 is inserted into the receptacle 108, before in step S140 the polarizer 106 is in a second rotational position with the major axis 134 in a predetermined angular relationship, preferably parallel or perpendicular is aligned with the polarization axis 40 of the calibration element 10, wherein light is transmitted from the second flat side 28 through the calibration element 10. Thereafter, in step S150, the rotational position of the axis 30 of the calibration element 10 is determined by determining the bisector, which is done by arithmetic averaging the first and second rotational positions of the polarizer 106. In step S160, the rotary position of the main axis 134 of the polarizer 106 is assigned a predetermined angle value in which it is in the predetermined angular relationship to the axis 30 of the calibration element 10 inserted as intended. The Reference numerals refer to the elements in Figures 1 to 9.

The alignment of the main axis 134 of the polarizer 106 in steps S120 and S140 thereby takes place by matching the light intensity transmitted through the first region 1 14 of the polarizer 106 with the first polarization axis 1 18 and through the second region 16 of the polarizer 106 with the second Polarization axis 120 transmitted light intensity to the same brightness. Alternatively, it is also conceivable to carry out the alignment of the main axis 134 of the polarizer 106 by minimizing or maximizing a light intensity transmitted through a single region 1 14 of the polarizer 106 with the polarization axis 1 18.

Preferably, before carrying out the method according to the invention for calibrating the polarization axis measuring device 100, a precalibration in the form of an angular calibration of the rotatably arranged polarizer 106 is carried out. During the pre-calibration, an arbitrarily selected position / position of the polarizer 106 is assigned an arbitrarily selected angle value as well. In this way, an indication is given during the rotation of the rotary holder 138 of the polarizer 136, for example in angular degrees, which can subsequently be used to determine the polarization axis 40 of the calibration element 10.

According to an advantageous embodiment of the method according to the invention for calibrating a polarization axis measuring device 100, a value zero can be assigned to a third rotational position of the main axis 134 of the polarizer 106 in which it is in the predetermined angular relationship to the axis 30 of the calibration element 10 inserted as intended. Advantageously, this third position of the polarizer 106 corresponds to one defined by marks 132 on the receptacle 108 of the polarization axis measuring device 100 Axis. This is expediently a direct assignment of angular degrees as a relative angular distance of the polarization axis of the specimen 1 10 given to the defined by the markings 132 of the receptacle 108 axis, which allows an advantageous registration and evaluation of the measurement results of the determination of the polarization axes.

If the axis 30 predetermined by the receptacle 108 for the calibration element 10 and the axis 136 predetermined by markings 132 do not coincide with each other for aligning the test objects 110, the difference between these two axis positions can be taken into account when assigning the calibration value. Advantageously, the value zero here corresponds to the orientation of the main axis 134 of the polarizer 106 parallel or perpendicular to the axis 136 predetermined by the marking 132 of the receptacle 108 for the test objects 1 10.

Carrying out a calibration of the

Polarization axis measuring device 100 is made so that the calibration element 10 is placed on the receptacle 108 such that the surface designated as the front surface (e.g., first flat side 26) faces upward. The mechanical fit between the holder 14 of the calibration element 10 and the Prüflingsaufnahme 108 a precise alignment on the markings 132 of the receptacle 108 is ensured. Now the position of the polarization axis 40 is to be measured.

If necessary, the measurement can be performed several times (n times, at least twice). Each time the position of the polarization axis 40 is read on the angle display and noted with the sign ψνον ΐ, or (pvor 2, ■■■ / (pvor n. It is advantageous to reissue the calibration element 10 every time in order to even out any measurement uncertainty that results from placing the calibration element 10 on.

The position of the polarization axis 40 in the relative coordinate system of the polarization axis measurement device 100 then results as an average value

and the measurement uncertainty too

The value for the correction factor t should be selected according to the desired confidence level and the exact number of individual measurements.

The calibration element 10 is subsequently turned around the fixed axis, so that the area designated as the rear surface (eg second flat side 28) points upwards. As in the last step, the position of the polarization axis 40 is to be measured repeatedly and the mean value φ, back and the measurement uncertainty Umck to be determined. The position of the geometric axis of the calibration element 10 in the coordinate system of the display of the polarization axis measuring device 100 is calculated as the mean of the positions of the polarization axes:

1

Ψθ = 2 ^X (<ΡνοΓ + <testcfc)

According to the Gaussian error propagation, this results in the calibration uncertainty

ucalib-

Furthermore, one obtains the position of the polarization axis of the calibration element 10 with respect to the geometric axis of the calibration element 10:

_ 1

ß-back TT X (^ back ^ before) ^

If necessary, the values should be rounded to the nearest hundredth of a degree and the signs should be taken into account.

The subsequent adjustment of the angle indication of the polarizer 106 can be carried out as follows, according to a preferred embodiment. First, the turntable of the polarizer 106 will approach the neutral position. For this purpose, the swivel mount is rotated until the value φ _{0 appears with the} correct sign in the display. Once the value is approximately reached, the exact value is set, for example with a fine drive. Now the display is set to zero. The accuracy of Calibration is then Umess = u _ca iib + Uanz imit u _ann = 0.01 ° as the accuracy of the display in an exemplary embodiment, which also limits how exactly the rotation mount can be set to the "true" value is finished.

To check the calibration, the calibration element can be remeasured.

Advantageously, a quick check of the polarization axis measuring device 100 with the calibration element 10 can be carried out in order to ensure the proper functioning of the polarization axis measuring device 100. For rapid inspection, the calibration element 10 is placed on the receptacle 108 such that the surface designated as the front surface (e.g., first flat side 26) faces upward. The mechanical fit between the holder 14 of the calibration element 10 and the Prüflingsaufnahme 108 a precise alignment on the markings 132 of the receptacle 108 is ensured. Now the position of the polarization axis 40 can be measured.

For example, the rapid test is considered passed if the measured value does not deviate from the value specified for the calibration element 10 by more than 0.5 degrees. If the deviation is greater, the measurement can be repeated. If the now measured value deviates from the specified value by no more than 0.5 degrees, the test is also passed. If this is not the case, carry out a second repetition. If this also turns out to be negative (deviation above 0.5 degrees), a detailed check must be carried out.

In order to perform a precise check, the measurements are to be made from a front surface and from a back surface of the calibration element 10 as described in the method according to the invention. The individual measurements should be performed several times (at least three times) to reduce the inaccuracy of the test measurements. The instrument is considered to be properly calibrated if the amounts of the values of φ _ν0Γ and ck correspond within the predetermined uncertainty of measurement and the required accuracy.

FIG. 11 shows a flow diagram of a method for determining polarization axes of spectacle lenses according to an exemplary embodiment of the invention. Eyeglass lenses may include tubular and form-edged lenses or lenses mounted in frames, spectacle lens pairs and spectacle lens blanks. In the case of ready-mounted spectacle lenses, the polarization measuring device 100 preferably has a contact rail (not shown) to which the frame horizontal or the upper edge of the mount can be applied such that a respective glass can be arranged above the viewing area 130 of the polarization measuring device 100. The support rail assumes the function of the markers 132, which can be dispensed with in this case.

The method includes, in step S210, calibrating a polarization axis measurement device 100 using the method described above. In step 220, a spectacle lens is then inserted oriented in the receptacle 108 of the polarization axis measuring device 100 by being aligned with a marking 132 of the receptacle 108. In step S230, the polarization axis of the spectacle lens is determined by aligning a main axis 134 of a polarizer 10 in a predetermined angular relationship, preferably parallel or perpendicular to the polarization axis of the spectacle lens. Subsequently, in step S240, an angular difference of the rotational position of the polarizer 106 and the mark 132 of the receptacle 108 is determined. From this angular difference can be concluded that the polarization axis of the spectacle lens relative to an orientation of the spectacle lens. This is the determination of the polarization axis of the inserted spectacle lens completed and can be transmitted to the spectacle frame, for example, via the aforementioned contact rail.

The polarization axis measuring device 100 may be coupled to a data processing device (not shown) which

Program code adapted to execute the method of calibrating the polarization axis measuring device 100 when the program code is executed on the data processing device. Likewise, the data processing device may include program code, which is adapted to the method for

Bestirnnung of polarization axes of spectacle lenses run, the Progrannncode is performed on the data processing device.

Claims

claims

1 . Method for calibrating a polarization axis measuring device (100) comprising the following steps:

(i) inserting a calibration element (10) into the polarization axis measuring device (100) and irradiating a first flat side (26) of the calibration element (10) with polarized light,

(ii) aligning at least one polarization direction of the light in a first rotational position with a major axis (134) in a predetermined angular relationship to a polarization axis (40) of the calibration element (10),

(iii) inserting the calibration element (10) and irradiating its second flat side (28) with polarized light,

(iv) aligning the at least one polarization direction of the light in a second rotational position with the major axis (134) in the predetermined angular relationship with the polarization axis (40) of the calibration element (10),

(v) determining the rotational position of an axis (30) of the calibration element (10) by determining an angle bisector between the first and second rotational positions of the polarization direction of the incident light and

(vi) assigning a predetermined angle value of the rotational position of the main axis (134) of the polarization direction, in which this is in the predetermined angular relationship to the axis (30) of the calibration element (10) inserted as intended.

The method of claim 1, wherein the predetermined angular relationship is a parallel or perpendicular orientation of the major axis (134) to the polarization axis (40) of the calibration element (10).

The method of claim 1 or 2, wherein the insertion of the calibration element (10) in the polarization axis measuring device (100) directed with its first flat side (26) to a polarizer (106) which is irradiated with unpolarized light and wherein for aligning the polarization direction of aligning the polarizer (106) in a first rotational position with a main axis (134) in a predetermined angular relationship with the polarization axis (40) of the calibration element (10) and / or aligning a receptacle (26) 109) for the calibration element (10),

wherein the insertion of the calibration element (10) with its second flat side (28) directed to the polarizer (106) and wherein for aligning the polarization direction of the light incident on the second flat side (28) aligning the polarizer (106) in a second rotational Position with the main axis (134) in the predetermined angular relationship with the polarization axis (40) of the calibration element (10) and / or the alignment of the receptacle (109) for the calibration element (10), and wherein determining the rotational position of the axis ( 30) of the calibration element (10) by determining an angle bisector between the first and the second rotational position of the polarizer (106) and assigning a predetermined angular value of the rotational position of the main axis (134) of the polarizer (106) takes place, in which this the predetermined angular relationship to the axis (30) of the intended purpose inserted calibration element (10).

Method according to one of claims 1 to 3, wherein a split-face polarizer (106) is used, the at least a first region (1 14) having a first polarization axis (1 18) and a second region (1 16) having a second polarization axis (120) adjoining one another on the main axis (134), and wherein the first polarization axis (1 18) and the second polarization axis (120) have, with respect to the main axis (134), an equal angle (122) of opposite sign in terms of magnitude Angle preferably between 2 ° and 5 °, more preferably between 2.5 ° and 3.5 °, most preferably at 3 °.

The method of claim 4, wherein aligning the major axis (134) of the polarizer (106) by matching a light intensity transmitted through the first region (1 14) of the polarizer (106) to a first polarization axis (1 18) and through the second region (1 16) of the polarizer (106) with a second polarization axis (120) transmitted light intensity to the same brightness, in particular to low brightness occurs.

Method according to one of claims 1 to 3, wherein an undivided field of view polarizer (106) is used which comprises at least one region (1 14) with a polarization axis (1 18), the polarization axis (1 18) representing the major axis (134) forms.

The method of claim 6, wherein aligning the major axis (134) of the polarizer (106) is accomplished by minimizing or maximizing a light intensity transmitted through a region (1 14) of the polarizer (106) having a polarization axis (1 18).

Method according to one of the preceding claims, wherein a value zero of a third rotational position of the main axis (134) of the polarizer (106) is assigned, in which this is in the predetermined angular relationship to the axis (30) of the intended inserted calibration element (10).

Method according to claim 1 or 2, wherein the calibration element (10) is irradiated with light of at least one light source emitting polarized light,

wherein alignment of the light source in a first rotational position with a major axis (134) in a predetermined angular relationship with the polarization axis (40) of the calibration element (10) for aligning the polarization direction of the light incident on the first flat side (26),

and wherein for aligning the polarization direction of the light incident on the second flat side (28) the alignment of the light source in a second rotational position with the main axis (134) takes place in the predetermined angular relationship with the polarization axis (40) of the calibration element (10),

and wherein the determining of the rotational position of the axis (30) of the calibration element (10) is effected by determining an angle bisector between the first and the second rotational position of the light source and assigning a predetermined angular value of the rotational position of the main axis (134) of the light source (106 ) takes place, in which this is in the predetermined angular relationship to the axis (30) of the intended purpose inserted calibration element (10).

10. The method of claim 9, wherein light of two, polarized light emitting light sources is passed to the calibration element (10), with a first polarization axis (1 18) and with a second polarization axis (120), which are arranged symmetrically to the main axis (134) , and wherein the first polarization axis (1 18) and the second polarization axis (120) have an opposite angle with respect to the main axis (134), the angle preferably being between 2 ° and 5 °, particularly preferably between 2 , 5 ° and 3.5 °, most preferably at 3 °.

1 1. The method of claim 10, wherein aligning the main axis (134) of the light sources by equalizing the light intensity with the first polarization axis (1 18) and the light intensity with the second polarization axis (120) to the same brightness, in particular to low brightness.

12. The method of claim 9, wherein a single polarized light source used with a polarization axis (1 18), wherein the polarization axis (1 18) forms the main axis (134).

13. The method of claim 12, wherein aligning the main axis (134) of the light source by minimizing or maximizing a light intensity with the polarization axis (1 18) takes place.

14. The method according to any one of the preceding claims, wherein as calibration element (10) an element is used with a transilluminating calibration body (12) made of polarizing material, which is transilluminated by the incident light, which comprises a holder (14) for grasping the calibration body (12). comprising, which holder (14) at least one positioning device (20) for reproducible arrangement in a receptacle (108) for a DUT (1 10), wherein the holder (14) has a transmission area (16) for irradiating the calibration body (12) Light, and wherein the positioning device (20) has at least two diametrically opposite positioning elements (22, 24, 32, 34, 42), and wherein the calibration element (10) optionally with a first flat side (26) or with a second flat side ( 28) of its calibration body (12) to the polarizer (106) directed as a test piece (1 10) in the receptacle (108) of the polarization axis measuring device (1 00) is used.

15. The method according to any one of the preceding claims, wherein a value zero of a third rotational position of the main axis (134) of the at least one light source is assigned, in which this is in the predetermined angular relationship to the axis (30) of the intended inserted calibration element (10).

16. A method for determining polarization axes of spectacle lenses, comprising the steps

(i) calibrating a polarization axis measuring device (100) with a method according to one of the preceding claims,

(ii) oriented insertion of a spectacle lens into a receptacle (108) of the polarization axis measuring device (100) by aligning with a marking (132) of the receptacle (108),

(iii) determining the polarization axis of the spectacle lens by aligning a major axis (134) of a polarizer (106) in a predetermined angular relationship with the polarization axis of the spectacle lens and

(iv) determining the angular difference of the rotational position of the polarizer (106) and the mark (132) of the receptacle (108) and determining therefrom the polarization axis of the spectacle lens relative to an orientation of the spectacle lens.

The method of claim 16, wherein the predetermined angular relationship is a parallel or perpendicular orientation of the major axis (134) to the polarization axis (40) of the spectacle lens.

A callous blade (10) adapted for insertion into a receptacle (108) of a polarization axis measuring device (100) adapted to perform a method according to any one of the preceding claims

a radiotranslucent calibration body (12) made of polarizing material having a first and an opposite second flat side (26, 28),

a holder (14) for grasping the calibration body (12), which holder (14) has at least one positioning device (20) for the intended reproducible arrangement in a receptacle (108),

wherein the holder (14) has a transmission region (16) for irradiating the calibration body (12) with light, and wherein the positioning device (20) has at least two diametrically opposite positioning elements (22, 24, 32, 34, 42), wherein the Holder (14) with the calibration body (12) optionally with its first flat side (26) or with its second flat side (28) in the receptacle (108) of the polarization axis measuring device (100) can be inserted.

19. Calibration element according to claim 18, wherein the holder (14) for holding the calibration body (12) and the calibration body (12) form a component, wherein preferably the holder (14) forms an edge region of the calibration body (12).

20. Calibration element according to claim 18 or 19, wherein the positioning device (20) is designed such that the holder (14) can be arranged against rotation about an optical axis (104) of the polarization axis measuring device (100) in the receptacle (108).

21. A caliper blade according to any one of claims 18 to 20, wherein the positioning means (20) comprises at least one pin as a positioning element (22, 24) which projects beyond both the first flat side (26) and the second flat side (28).

22. Calibration element according to one of claims 18 to 21, wherein the positioning device (20) as a positioning element (42) at least one opening and / or a marking and / or a contact edge (32), wherein preferably the abutment edge (32) forms part of Scope of the holder (14) forms.

23. Calibration element according to one of claims 18 to 22, wherein the calibration body (12) has a transilluminable region (18) with a polarization axis (40).

24. polarization axis measuring device (100) with a calibration element

(10) according to any one of claims 18 to 23, which is intended for carrying out a method according to any one of claims 1 to 15, comprising

(i) a receptacle (108) for a test object (110),

(11) a light source (102) with unpolarized light and a polarizer (106) with a major axis (134), or

(iii) at least one polarized light source having a

Main axis (134),

wherein the calibration element (10) comprises a transilluminable calibration body

(12) comprising polarizing material, and a holder (14) for holding the calibration body (12), which holder (14) has at least one positioning device (20) for reproducible arrangement in the receptacle (108),

wherein the calibration element (10) selectively with a first flat side (26) or with a second flat side (28) to the polarizer (106) directed as a specimen (1 10) in the receptacle (108) can be arranged.

25. A polarization axis measuring apparatus according to claim 24, wherein said polarizer (106) is rotatably disposed about an optical axis (104).

26. A polarization axis measuring device according to claim 24 or 25, wherein the receptacle (108) is arranged rotatably about an optical axis (104).

27. polarization axis measuring device according to any one of claims 24 to 26, wherein the polarizer (106) has a split field of view with at least a first region (1 14) having a first polarization axis (1 18) and a second region (1 16) with a second polarization axis ( 120) adjoining one another on the main axis (134), and wherein the first polarization axis (1 18) and the second polarization axis (120) have an opposite angle (122) of opposite magnitude to the major axis (134) preferably between 2 ° and 5 °, more preferably between 2.5 ° and 3.5 °, most preferably at 3 °.

28. A polarization axis measuring device according to any one of claims 24 to 26, wherein the polarizer (106) comprises an undivided field of view with a region (1 14) having a polarization axis (1 18), wherein the polarization axis (1 18) forms the major axis (134).

29. polarization axis measuring device according to any one of claims 24 to 26, wherein the light source comprises at least a first polarization axis (1 18) and a second polarization axis (120) which are arranged symmetrically to the main axis (134), and wherein the first polarization axis (1 18) and the second polarization axis (120) against the major axis (134) having an equal angle (122) of opposite sign in magnitude, the angle preferably between 2 ° and 5 °, more preferably between 2.5 ° and 3.5 °, completely particularly preferably at 3 °.

30. A polarization axis measuring device according to claim 27, wherein a single polarized light source used with a polarization axis (1 18), wherein the polarization axis (1 18), the main axis (134).

31. A computer program product for calibrating a polarization axis measuring apparatus (100) comprising a computer readable storage medium including program code adapted to perform a method according to any one of claims 1 to 15 when the program code is executed on a data processing device.

32. Computer program product for determining polarization axes of spectacle lenses, comprising a computer-readable storage medium containing a program code, which is adapted to carry out a method according to claim 16 or 17, when the program code is executed on a data processing device.