Method for automated in-line determination of center thickness of an ophthalmic lens

Patent metadata

Field	Value
Publication number	US-10048164-B2
Application number	US-201314038071-A
Country	US
Kind code	B2
Filing date	Sep 26, 2013
Priority date	Sep 28, 2012
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A method for automated in-line determination of the center thickness of an ophthalmic lens including providing an inspection cuvette (2) having an optically transparent bottom (21) and a concave inner surface (210) and containing the lens immersed in a liquid, providing an interferometer having a light source and a focusing probe (30) focusing light coming from the light source to a set position (310) of the lens. Focusing probe (30) also directs light reflected at the boundary between the back surface of the lens and the liquid as well as light reflected at the boundary between the front surface of the lens and the liquid or at the boundary between the front surface of the lens and the concave inner surface (210) to a detector of the interferometer. The center thickness of the lens is determined using the light reflected at the respective boundary at the back surface and at the front surface of the lens.

First claim

The invention claimed is:

1. Method for an automated in-line determination of the center thickness ( 55 ) of an ophthalmic lens ( 5 ) in an automated manufacturing line for ophthalmic lenses, the method comprising the steps of:
providing an inspection cuvette ( 2 ) comprising an optically transparent bottom ( 21 ) having a concave inner surface ( 210 ) and containing the ophthalmic lens ( 5 ) immersed in a liquid, and positioning the inspection cuvette ( 2 ) at a first inspection location ( 800 ) of an inspection module ( 1 ) of the automated manufacturing line;
providing an interferometer ( 3 ) comprising a light source and a focusing probe ( 30 ), the focusing probe focusing light coming from the light source to a set position ( 310 ) of the ophthalmic lens at the center of the concave inner surface of the optically transparent bottom of the inspection cuvette, and the focusing probe ( 30 ) further directing light reflected at the boundary ( 510 ) between the back surface ( 51 ) of the ophthalmic lens and the liquid as well as light reflected at the boundary ( 500 ) between the front surface ( 50 ) of the ophthalmic lens and the liquid or light reflected at the boundary ( 502 ) between the front surface ( 50 ) of the ophthalmic lens ( 5 ) and the concave inner surface ( 210 ) of the optically transparent bottom ( 21 ) of the inspection cuvette ( 2 ) to a detector of the interferometer ( 3 );
determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ) from the signals generated at the detector by the light reflected at the respective boundary ( 510 ; 500 , 502 ) at the back surface ( 51 ) and at the front surface ( 50 ) of the ophthalmic lens ( 5 ), and

wherein the step of determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ) comprises
counting the number of signals generated by the light reflected at the respective boundary ( 510 ; 500 , 502 ), and
for a counted number of two signals, selecting the two signals for determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ),
for a counted number of three signals, ignoring the signal corresponding to the light reflected at the boundary ( 200 ) between the concave inner surface ( 210 ) of the optically transparent bottom ( 21 ) of the inspection cuvette ( 2 ) and the liquid, and selecting the remaining two signals for determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ).

2. The method according to claim 1 , further comprising the steps of
comparing the determined center thickness ( 55 ) of the ophthalmic lens ( 5 ) with a predetermined set value for the center thickness and
identifying the ophthalmic lens ( 5 ) as having an unacceptable center thickness if the determined center thickness ( 55 ) is outside a predetermined range of tolerance around the predetermined set value for the center thickness, or
identifying the ophthalmic lens ( 5 ) as having an acceptable center thickness if the determined center thickness ( 55 ) is within the predetermined range of tolerance around the predetermined set value for the center thickness, and
removing the ophthalmic lens ( 5 ) from the manufacturing line in case the ophthalmic lens has been identified as having an unacceptable center thickness ( 55 ), but further processing the ophthalmic lens ( 5 ) in the manufacturing line in case the ophthalmic lens ( 5 ) has been identified as having an acceptable center thickness ( 55 ).

3. The method according to claim 1 , further comprising the steps of:
providing a plurality of inspection cuvettes ( 2 ), each inspection cuvette ( 2 ) comprising an optically transparent bottom ( 21 ) having a concave inner surface ( 210 ) and containing an ophthalmic lens ( 5 ) immersed in a liquid, and positioning the plurality of inspection cuvettes ( 2 ) at the first inspection location ( 800 ) of the inspection module ( 1 );
providing a plurality of focusing probes ( 30 ) corresponding to the plurality of inspection cuvettes ( 2 ), each of the focusing probes ( 30 ) focusing light to a set position ( 310 ) of the ophthalmic lens ( 5 ) at the center of the concave inner surface of the optically transparent bottom of a corresponding inspection cuvette ( 2 ), and each of the focusing probes ( 30 ) directing light reflected at the respective boundary ( 510 ; 500 , 502 ) at the back surface ( 51 ) and at the front surface ( 50 ) of the respective ophthalmic lens ( 5 ) to the detector of the interferometer ( 3 ); and
determining the center thickness ( 55 ) of each ophthalmic lens ( 5 ).

4. The method according to claim 3 , wherein focusing light to the set position ( 310 ) of the ophthalmic lens ( 5 ) is performed sequentially for the plurality of inspection cuvettes ( 2 ) by directing light from the light source of the interferometer ( 3 ) via a first focusing probe ( 30 ) of the plurality of focusing probes to the set position ( 310 ) of the ophthalmic lens ( 5 ) contained in a first inspection cuvette ( 2 ) of the plurality of inspection cuvettes, subsequently directing light from the light source of the interferometer via a second focusing probe ( 30 ) to the set position of the ophthalmic lens ( 5 ) contained in a second inspection cuvette ( 2 ) of the plurality of inspection cuvettes, and so on, until light from the light source of the interferometer ( 1 ) is directed via a last focusing probe ( 30 ) of the plurality of focusing probes to the set position ( 310 ) of the ophthalmic lens ( 5 ) contained in a last inspection cuvette ( 2 ) of the plurality of inspection cuvettes.

5. The method according to claim 4 , wherein sequentially focusing light to a set position ( 310 ) of the ophthalmic lens ( 5 ) for the plurality of inspection cuvettes ( 2 ) comprises
providing a plurality of deflectors ( 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) corresponding to the plurality of focusing probes ( 30 ), the individual deflectors of the plurality of deflectors ( 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) each being capable of being switched between an active state, in which the respective deflector ( 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) directs light coming from the light source of the interferometer to the corresponding focusing probe ( 30 ) and in which the respective deflector ( 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) directs light reflected at the respective boundary ( 510 , 500 , 502 ) to the detector of the interferometer ( 3 ), and a passive state, in which the respective deflector allows the light coming from the light source to pass to the next deflector which is in the active state and which is arranged in an optical path of the light, and
sequentially switching a first deflector ( 41 1 ) of the plurality of deflectors ( 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) from the active state to the passive state after determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ) contained in the first inspection cuvette ( 2 ), switching a second deflector ( 41 2 ) of the plurality of deflectors ( 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) from the active state to the passive state after determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ) contained in the second inspection cuvette ( 2 ), and so on, until switching a second last deflector ( 41 n-1 ) of the plurality of deflectors 41 1 , 41 2 , 41 3 , . . . , 41 n-1 , 41 n ) from the active state to the passive state after determining the center thickness ( 55 ) of the ophthalmic lens ( 5 ) contained in the second last inspection cuvette ( 2 ), and then determining the center thickness ( 55 ) of the ophthalmic lens contained in the last inspection cuvette ( 2 ) with the last deflector ( 41 n ) being in the active state.

6. The method a

Assignees

• Novartis Ag

Inventors

• Biel Roger
• Schwab Matthias

Classifications

• G01B11/0675

  using interferometry · CPC title

• B29D11/00259

  Plants for the production of contact lenses · CPC title

• B29D11/0098

  Inspecting lenses · CPC title

• Y10T29/54

  Miscellaneous apparatus · CPC title

• G01M11/0271 Primary

  by using interferometric methods · CPC title