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EP-4513160-B1 - TESTING DEVICE FOR AN OPTICAL TEST OBJECT AND METHOD FOR TESTING AN OPTICAL TEST OBJECT

EP4513160B1EP 4513160 B1EP4513160 B1EP 4513160B1EP-4513160-B1

Inventors

  • RUPRECHT, AIKO

Dates

Publication Date
20260513
Application Date
20240820

Claims (14)

  1. Testing device (100) for an optical test object (105), wherein the testing device (100) has the following features: - a beam source (145) for emitting a beam bundle (115) along an optical axis (117); - an optical element (125) formed in the optical axis (117) as a polarization-influencing or polarization-filtering optical element for imposing a specific polarization direction of the light of the beam bundle (115) and for filtering light reflected by the test object (105); - a rotation unit (135) designed to rotate the test object (105) lying in the optical axis (117) relative to the testing device, and/or individual assemblies thereof, about a beam axis and/or the optical axis (117); and - a detector unit (147) designed to determine, simultaneously, a polarization axis of the test object (105) and the decentration thereof from a rotation angle (140) and a light beam of the beam bundle (115) that is reflected by the test object (105).
  2. Testing device (100) for an optical test object (105), wherein the testing device (100) comprises the following features: - a beam source (145) for emitting a beam bundle (115) along an optical axis (117); - an optical element for collimating the emitted beam bundle; - an optical element formed as a polarization-influencing optical element for imposing a specific polarization direction of the light of the beam bundle (115); - an element for mounting the optical test object; - an optical element for recollimating the beam bundle focused by the test object; - an optical element formed as a polarization-filtering optical element for filtering light transmitted by the test object (105); - an optical element for refocusing the light transmitted by the test object onto a detection plane; - a rotation unit (135) designed to rotate the test object (105) lying in the optical axis (117) relative to the testing device, and/or individual assemblies thereof, about a beam axis and/or the optical axis (117); and - a detector unit (147) designed to determine, simultaneously, a polarization axis of the test object (105) and the decentration thereof from the rotation angle (140) and a light beam of the beam bundle (115) that is transmitted by the test object (105).
  3. Testing device (100) according to Claim 1 or 2, characterized in that the polarization-influencing elements in the beam path are mechanically and/or optically rotatable.
  4. Testing device (100) according to Claim 1 or 2, characterized in that the detector unit (147) is designed to determine the polarization axis of the test object (105) using a brightness, a brightness pattern and/or a light intensity pattern (210) of the reflected or transmitted light beam of the beam bundle (115).
  5. Testing device (100) according to any of the preceding claims, characterized in that the polarizer (125) is designed to impose a circular or linear polarization direction on the light, and wherein the detector unit (147) has an analyser designed to allow circularly or linearly polarized light to pass through.
  6. Testing device (100) according to Claim 5, characterized in that the polarizer (125) and the analyser are arranged with respect to one another in such a way that a predefined azimuthal angle is set between the polarization direction defined by the polarizer (125) and a polarization direction, defined by the analyser, of the light passing through the analyser.
  7. Testing device (100) according to any of the preceding claims, characterized in that the detector unit (147) is designed to ascertain a measure of a decentration from a detected circle of incidence (220) of a brightness variation.
  8. Testing device (100) according to any of the preceding claims, characterized in that the beam source (145) and a sensor (110) are installed in an autocollimator together with the polarizer (125) and/or an analyser in the optical axis (117) and wherein a beam splitter (120) is provided in order to couple light reflected by the test object (105) out of a beam path parallel to the light radiated in by the beam source (145).
  9. Method (500) for testing an optical test object (105), wherein the method (500) is carried out using a testing device (100) according to any of the preceding Claims 1 to 8 and has the following steps: - emitting (510) light of a beam bundle (115) from the beam source (145) onto the test object (105), wherein firstly a polarization is imposed on the beam bundle, and receiving light of the beam bundle (115) that is reflected by the test object (105) or transmitted by the test object in the detector unit (147); - rotating (520) the test object (105) relative to the testing device (100) and/or individual assemblies of the testing device; and - simultaneously determining (530) the polarization axis of the test object (105) and the decentration thereof from the light reflected or transmitted by the test object (105).
  10. Method (500) according to Claim 9, characterized in that the polarization-influencing elements are rotated relative to the testing device and in that , for each azimuthal angular position of the test object in the course of at least two revolutions, a first intensity signal and a second intensity signal deviating therefrom are detected.
  11. Method (500) according to Claim 10, characterized in that the first intensity signal and the second intensity signal are added in order to obtain a circle of incidence with an intensity variation within a tolerance range for the purpose of measuring the decentration.
  12. Control unit (150) configured to execute and/or control the steps (510, 520, 530) of the method (500) according to any of the preceding claims in corresponding units (155, 160, 170).
  13. Computer program comprising commands which, when executed by a computer, cause the computer to execute and/or control the steps (510, 520, 530) of the method (500) according to claim 9.
  14. Machine-readable storage medium on which the computer program according to Claim 13 is stored.

Description

The approach presented here provides a test fixture for an optical test specimen and a method for testing an optical test specimen according to the main claims. Some lenses have polarization-influencing properties because they either generate their refractive power through this property (liquid crystal lenses) or are coated accordingly (polarizing layers, lambda/4 layers, etc.). When installing such lenses, both their centering and the alignment of the polarization axis are important. Often, however, several steps are required to measure both the centering and the alignment of the polarization axis. This multi-step process necessitates additional effort in the design of the test fixture, as it requires separate measurements of centering and polarization axis alignment. Furthermore, such a test fixture requires more installation space. This would necessitate sequential measurements of centering and polarization using two different measuring heads. Consequently, the measurement technology requires considerable installation space, and the two separate measurements result in long measurement times. US2014/233038A1 and DE102014205406A1 reveal test devices for an optical test specimen. Against this background, the object of the present invention is to provide an improved testing device for an optical test object and an improved method for testing an optical test object. This problem is solved by the subject matter of the main claims. The approach presented here creates a test device for an optical test specimen to determine the decentering and polarization properties of the test specimen, wherein the test device has the following features: a beam source for emitting a beam of rays along an optical axis; an optical element designed as a filter element in the optical axis for imprinting or filtering a specific polarization direction of the light of the beam or of light reflected or transmitted by the test object; a rotation unit designed to rotate the test specimen, which is located at least near the optical axis, by an angle of rotation relative to a measuring system and/or the test unit; a detector unit designed to capture the light reflected or transmitted by the test specimen and to produce at least an approximately sharp image of the light source or reticle; and an evaluation unit which is designed to determine both a characteristic value for the centering from the measured impact circle and a polarization axis of the test object from the rotation angle and the associated variation of the signal brightness of the light beam of the beam reflected by or transmitted through the test object. Furthermore, the approach presented here creates a test device for an optical test object, the test device comprising the following features: a beam source for emitting a beam of rays along an optical axis; an optical element for collimating the emitted beam of rays; an optical element designed to influence polarization, for imprinting a specific polarization direction on the light of the beam; an element for holding the optical test specimen; an optical element for recollimating the beam of light focused by the test object; an optical element designed as a polarization filter for filtering light transmitted by the test object; an optical element for refocusing the light transmitted by the test object onto a detection plane; a rotation unit designed to rotate the test specimen lying in the optical axis relative to the test fixture and/or individual assemblies thereof, about a beam axis and/or the optical axis; and a detector unit designed to simultaneously determine a polarization axis of the test object and its decentering from the rotation angle and a light beam of the beam transmitted by the test object. A beam source can be, for example, a light source or lamp that emits corresponding light rays as beams along the optical axis. Alternatively, it can also be an illuminated reticle. A filter element can be, for example, an optical element that filters an incident light source. Light is imprinted with a corresponding polarization direction. A rotation unit can be, for example, a mechanical unit that rotates the test specimen relative to the measuring device. This can be achieved either by actively rotating the test specimen itself while the filter element is stationary, or by rotating the measuring device while the test specimen is stationary. For example, the rotation unit can be designed to rotate the measuring device or the test specimen by a specific angle of rotation, such as around the optical axis or an axis of the beam, using an electric drive. A detection unit can be, for example, an optical sensor or a projection surface onto which light reflected from or transmitted through the test specimen is projected and subsequently evaluated by a corresponding evaluation unit with regard to the position of the test specimen's polarization axis. The approach presented here is based on the understanding that the position of t