Laser assisted demolding of ophthalmic lenses

Details Laser assisted demolding of ophthalmic lenses Laser assisted demolding of ophthalmic lenses

1992-09-18

1994-03-15

Lowe, James

Plastic and nonmetallic article shaping or treating: processes

Optical article shaping or treating

Utilizing plasma, electric, electromagnetic, particulate, or...

264 23, B29D 1100

Patent

active

052943798

ABSTRACT:
An apparatus and method for removing a molded ophthalmic lens from between the mold portions in which it is produced. A source of intense electromagnetic radiation, preferably a carbon dioxide (CO.sub.2) laser of about 80 Watts at a wavelength of 10.6 .mu.m, is applied to at least one of the mold portions. The exposure of the mold portion to the laser is between one half and one second. Differential expansion of the heated mold polymer relative to the cooler polymer shifts one surface with respect to the other, and the shear force breaks the polymerized lens polymer mold adhesion and assists in the separation of mold portions. The greater the temperature gradient between the surfaces of the mold portions, the greater the shearing force and the easier the mold portions separate. The heated back mold portion is promptly removed so that very little energy is transferred to the polymer lens, avoiding the possibility of thermal decomposition of the lens.

REFERENCES:
patent: 3938775 (1976-02-01), Sarofeen
patent: 4382902 (1983-05-01), Feurer
patent: 4390482 (1983-06-01), Feurer
patent: 4568262 (1986-02-01), Feurer
patent: 4652721 (1987-03-01), Miller et al.
patent: 4728469 (1988-03-01), Danner et al.
patent: 5160749 (1992-11-01), Fogarty

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