Claims
- 1. A method of forming an etching of predetermined configuration on a target surface with a laser beam directed through an opening of an aperture, said opening being of predetermined outline, said aperture being positioned between a source of said laser beam and said target surface such that said laser beam is directed to impinge upon said target surface to form said etching, and wherein a portion of said laser beam passing immediately adjacent the perimeter of said opening experiences a diffractive effect which causes an initial formation of a plurality of diffractive grooves having alternating peaks and troughs about the perimeter of said etching on said target surface, the method comprising:
- during formation of said etching, changing the positional relationship between said laser beam and said target surface in a first direction substantially transverse to said alternating peaks and troughs, said change in positional relationship being such as to satisfy the condition:
- A.sub.target .gtoreq.D
- wherein A.sub.target is the range over which said diffraction pattern is shifted, and D is the distance between the first peak, and the first trough on the groove pattern produced by a single pulse,
- whereby said formation of diffractive grooves is minimized.
- 2. The method of claim 1 wherein a focusing lens is placed between said aperture and said target surface and wherethrough said laser beam is directed.
- 3. The method of claim 1 wherein said aperture is moved relative to said target substrate in a predetermined motion at a predetermined velocity.
- 4. The method of claim 3 wherein said predetermined motion is an oscillating motion through a distance from 1 to 250 .mu.m.
- 5. The method of claim 3 wherein said predetermined motion is an off-axis rotational motion.
- 6. The method of claim 1 wherein said aperture is circular.
- 7. The method of claim 1 wherein said beam is pulsed.
- 8. The method of claim 1 wherein said beam is scanned.
- 9. The method of claim 1 wherein said beam remains stationary relative to said aperture.
- 10. The method of claim 1 wherein said target substrate is a cornea.
- 11. The method of claim 1 wherein said target substrate is a contact lens.
Parent Case Info
This is a divisional of application Ser. No. 08/075,704 filed on Jun. 11, 1993 abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0 346 116 |
Dec 1989 |
EPX |
60-166188 |
Aug 1985 |
JPX |
9101514 |
Feb 1991 |
WOX |
9108723 |
Jun 1991 |
WOX |
Non-Patent Literature Citations (1)
Entry |
Patent Abstracts of Japan, vol. 10, No. 2 (M-444) (2059) 8 Jan. 1986. |
Divisions (1)
|
Number |
Date |
Country |
Parent |
75704 |
Jun 1993 |
|