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US 9,851,385 B2Granted
Method and apparatus for determining the presence of an electrical charge on the surface of a lens mold
AssigneeNovartis AG
InventorRene Ochrombel
Life of this patent
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Abstract
A method for determining the presence of an electrical charge on a surface of an ophthalmic lens mold including the steps of exposing a sensor crystal of a sensor element to a surface of an ophthalmic lens mold on which an electrical charge generating an electrical field may be present, converting a light beam emitted from a laser light source into a linearly polarized measurement light beam by passing the light beam through the sensor element, processing the linearly polarized measurement light beam exiting the sensor element in a measurement unit, wherein the sensor crystal is selected from a non-centrosymmetrical crystallographic point group 43 m.
Claims20
A method for determining the presence of an electrical charge on a surface of an ophthalmic lens mold (1, 10), the method comprising the steps of
- exposing a sensor crystal (22) of a sensor element (2) to a surface of an ophthalmic lens mold (1) on which an electrical charge generating an electrical field may be present,
- converting a light beam (31) emitted from a laser light source (3) into a linearly polarized measurement light beam (34) by passing the light beam (31) through the sensor element (2),
- processing the linearly polarized measurement light beam (34) exiting the sensor element (2) in a measurement unit (4),
- wherein the step of converting the light beam (31) into a linearly polarized measurement light beam (34) by passing the light beam (31) through the sensor element (2) comprises:
- converting the light beam (31) emitted from the laser light source (3) into a linearly polarized light beam (32) having a first polarization direction by passing the light beam (31) through a linear polarizer (21),
- converting the linearly polarized light beam (32) exiting the linear polarizer (21) into an elliptically polarized light beam (33) by passing the linearly polarized light beam (32) through the sensor crystal (22), the sensor crystal being selected from a non-centrosymmetrical crystallographic point group 43 m,
- converting the elliptically polarized light beam (33) exiting the sensor crystal (22) into the linearly polarized measurement light beam (34) by passing the elliptically polarized light beam (33) through a quarter-wave polarizer (23), wherein the linearly polarized measurement light beam (34) has a second polarization direction forming a polarization angle (φ) with the first polarization direction of the linearly polarized light beam (32) exiting the linear polarizer (21) and entering the sensor crystal (22), the polarization angle (φ) of the linearly polarized measurement light beam (34) being representative of the presence of the electrical field generated by the electrical charge on the surface of the lens mold (1) which the sensor crystal (22) is exposed to, and
- wherein the step of processing the linearly polarized measurement light beam (34) in the measurement unit (4) comprises:
- rotating the second polarization direction of the linearly polarized measurement light beam (34) by passing the polarized measurement light beam through a Faraday rotator (41, 42) thereby forming a rotated linearly polarized measurement light beam (35, 36),
- converting the rotated linearly polarized measurement light beam (35, 36) into an analyzer light beam (37) by passing the rotated linearly polarized measurement light beam (35, 36) through an analyzer (43),
- converting the analyzer light beam (37) into an electrical detection signal (441) with the aid of a photodetector (44) and evaluating the electrical detection signal (441) generated by the photodetector (44) with the aid of an evaluator (45) thereby determining the presence of the electrical charge on the surface of the ophthalmic lens mold (1).
8 more elements
An apparatus for determining the presence of an electrical charge on a surface of an ophthalmic lens mold (1) comprising:
- a laser light source (3) for emitting a light beam (31) defining a beam path,
- a sensor element (2) comprising a sensor crystal (22) arranged in the beam path of the light beam (31), the sensor crystal (22) being exposable to a surface of an ophthalmic lens mold on which an electrical charge generating an electrical field (11) may be present, the sensor element (2) being configured for converting the light beam (31) emitted by the laser light source (3) into a linearly polarized measurement light beam (34) by having the light beam (31) emitted by the laser light source (3) pass through the sensor element (2),
- a measurement unit (4) for processing the linearly polarized measurement beam (34) exiting the sensor element (2),
- wherein the sensor element (2) comprises
- a linear polarizer (21) having a first polarization direction and being arranged in the beam path of the light beam (31), the linear polarizer (21) being configured for converting the light beam (31) emitted from the laser light source (3) into a linearly polarized light beam (32) having a first polarization direction,
- the sensor crystal (22) which is selected from the non-centrosymmetrical crystallographic point group 43m, the sensor crystal (22) being arranged in the beam path of the linearly polarized light beam (32) for converting the linearly polarized light beam (32) exiting the linear polarizer (21) into an elliptically polarized light beam (33), and
- a quarter-wave polarizer (23) being arranged in the beam path of the elliptically polarized light beam (33) exiting the sensor crystal (22), the quarter-wave polarizer (23) being configured for converting the elliptically polarized light beam (33) into the linearly polarized measurement light beam (34) having a second polarization direction forming a polarization angle (φ) with the first polarization direction of the linearly polarized light beam (32) exiting the linear polarizer (21) and entering the sensor crystal (22), the polarization angle (φ) of the linearly polarized measurement light beam (34) being representative of the presence of the electrical field generated by the electrical charge on the surface of the lens mold (1) which the sensor crystal (22) is exposable to,
- and wherein the measurement unit (4) comprises
- a Faraday rotator (41, 42) arranged in the beam path of the linearly polarized measurement light beam (34) and configured for rotating the second polarization direction of the linearly polarized measurement light beam (34) to form a rotated linearly polarized measurement light beam (35, 36)
- an analyzer (43) being arranged in the beam path of the rotated linearly polarized measurement light beam (35), the analyzer being configured for converting the rotated linearly polarized measurement light beam (35, 36) into an analyzer light beam (37),
- a photodetector (44) for converting the analyzer light beam (37) into an electrical detection signal (440, 441), and
- an evaluator (45) for evaluating the electrical detection signal (440, 441) generated by the photodetector (44) to determine the presence of the electrical charge on the surface of the ophthalmic lens mold (1).
9 more elements
Dependencies are inferred from the claim text.