Method for producing an ophthalmic lens comprising a step of laser marking in order to produce permanent etchings on one surface of said ophthalmic lens

1. A process for manufacturing an ophthalmic lens ( 10 ) made from at least one material, said process comprising:

a step of determining an operating point of a laser-marking machine configured to produce permanent engravings, having geometric characteristics (Di), upon a surface of said ophthalmic lens;

a laser-marking step ( 300 ) that produces said permanent engravings ( 24 ) on said surface ( 12 ) of said ophthalmic lens ( 10 ), said permanent engravings ( 24 ) comprising at least first deformations on said surface ( 12 ) of said ophthalmic lens ( 10 ), said first deformations shaped as craters including at least a recess formed in said surface of said ophthalmic lens and a rim surmounting said recess on said surface of said ophthalmic lens, a diameter and a depth of said recess defining said geometric characteristics of said engravings; and

subsequent to said laser-marking step ( 300 ), a predetermined step ( 400 , 500 ), including at least one of a coloring step and a varnishing step, applied to said surface ( 12 ) of said ophthalmic lens ( 10 ) and to the engravings ( 24 ) on said surface of said ophthalmic lens, said at least one predetermined step ( 400 , 500 ) being carried out during a treatment time and at a temperature which is close to stress relaxation threshold values of said at least one material of said ophthalmic lens such as to apply severe thermal stresses to said surface ( 12 ) and to the engravings ( 24 ) on said surface of said ophthalmic lens ( 12 ), said severe thermal stresses applied to said engravings by said predetermined step characterized at least by said treatment time and said temperature, and generating second deformations on said recesses and on said rims thereby generating post-marking stresses to said first deformations,

wherein said step of determining said operating point of the laser-marking machine includes the following steps:

determining ( 304 ) a value (C PM ) representative of the post-marking stresses in at least one treatment zone ( 25 ) of said surface of said ophthalmic lens in which said permanent engravings ( 24 ) are produced, from i) said severe thermal stresses to be applied to said engravings ( 24 ) on said surface ( 12 ) of said ophthalmic lens during the predetermined step ( 400 , 500 ), and from ii) data relating to said material from which said ophthalmic lens ( 10 ) is formed; and

deducing said operating point (P F ) i) from said value (C PM ) representative of said post-marking stresses in said at least one treatment zone ( 25 ) and ii) from said geometric characteristics (Di) of said permanent engravings ( 24 ).

2. The process as claimed in claim 1 , wherein said step of determining said operating point further comprises the following steps:

deducing ( 305 ) a post-marking stress level (A-G) from said value (C PM ) representative of said post-marking stresses (C PM ) and said geometric characteristics (Di) of said engravings ( 24 ), said post-marking stress level (A-G) providing a difficulty level (A-G); and

selecting ( 308 ) said operating point (P F ) based on said difficulty level (A-G), of geometric characteristics (x, y, z) of said surface ( 12 ) of said ophthalmic lens ( 10 ) to be marked and based on parameters specific to said laser-marking machine ( 1 ).

3. The process as claimed in claim 2 , wherein said post-marking stress level (A-G) is chosen from a plurality of post-marking stress levels (A-G) predetermined as a function of predetermined ranges of said geometric characteristics of said permanent engravings and predetermined ranges of values (C PM ) representative of said post-marking stresses.

4. The process as claimed in claim 3 , wherein said step of determining the value (C PM ) representative of post-marking stresses (C PM ) in said at least one treatment zone ( 25 ) includes a step of processing characteristics (T° i , Tp i ) of said severe thermal stresses while taking into account individual characteristics specific to each said predetermined step subsequent to said step ( 300 ) of laser marking the surface ( 12 ), all of said individual characteristics being taken into account.

5. The process as claimed in claim 2 , wherein said step of determining the value (C PM ) representative of post-marking stresses (C PM ) in said at least one treatment zone ( 25 ) includes a step of processing characteristics (T° i , Tp i ) of said severe thermal stresses while taking into account individual characteristics specific to each said predetermined step ( 400 , 500 ) subsequent to said step ( 300 ) of laser marking the surface ( 12 ), all of said individual characteristics being taken into account.

6. The process as claimed in claim 1 , wherein said step of determining the value (C PM ) representative of said post-marking stresses (C PM ) in said at least one treatment zone ( 25 ) includes a step of processing characteristics (T° i , Tp i ) of said severe thermal stresses while taking into account individual characteristics specific to each said predetermined step ( 400 , 500 ) subsequent to said step ( 300 ) of laser marking the surface ( 12 ), all of said individual characteristics being taken into account.

7. The process as claimed in claim 1 , further comprising:

a step ( 600 ) of checking a conformity, in terms of visibility, of the engravings ( 24 ) produced in said laser-marking step ( 300 ), after said ophthalmic lens ( 10 ) has undergone said at least one predetermined step ( 400 , 500 ) subsequent to said laser-marking step.

8. The process as claimed in claim 1 , wherein said determined operating point (P F ) includes at least one of a value representative of a final diameter (D F ) of said engravings ( 24 ) and a value representative of a final depth (Pr F ) of said permanent engravings ( 24 ).

9. The process as claimed in claim 1 , wherein said permanent engravings ( 24 ) each have a substantially circular shape.

10. The process as claimed in claim 1 , wherein said at least one treatment zone ( 25 ) of the surface ( 12 ) is located in a substantially annular zone around one of said engraving permanent engravings ( 24 ).

11. The process as claimed in claim 1 ,

wherein said at least one predetermined step subsequent to said laser-marking step ( 300 ) is a step ( 400 ) of coloring said ophthalmic lens ( 10 ), and

wherein the engravings produced in said laser-marking step ( 300 ) remain visible after said at least one predetermined step ( 400 , 500 ) applies the severe thermal stresses to the engravings ( 24 ).

12. The process as claimed in claim 1 ,

wherein said predetermined step subsequent to said laser-marking step ( 300 ) is a step ( 400 ) of varnishing said ophthalmic lens ( 10 ), and

wherein the engravings produced in said laser-marking step ( 300 ) remain visible after said at least one predetermined step ( 400 , 500 ) applies the severe thermal stresses to the permanent engravings ( 24 ).

13. A computer program including instructions configured to implement each of the steps of the process as claimed in claim 1 , when said computer program is run by a computer.

14. A command/control unit including system elements ( 3 , 4 , 5 ) configured to run a computer program in order to implement each of the steps of the process as claimed in claim 1 .

15. A laser-marking machine configured to produce permanent engravings ( 24 ) on a surface ( 12 ) of an ophthalmic lens ( 10 ) and including a command/control unit ( 2 ) as claimed in claim 14 .

16. The machine as claimed in claim 15 , wherein the laser-marking machine ( 1 ) employs a CO 2 laser configured to emit light radiation of wavelength comprised between about 8 μm and about 20 μm.

17. A client-server communication interface including devices ( 9 a , 9 b ) configured to transfer the operating point (P F ) of a laser-marking machine, said operating point being determined by a computer program that implements each of the steps of the process according to claim 1 , when said computer program is run in a command/control unit ( 2 ).