Coated optics to improve durability

• US 6,872,479 B2
• Filed: 11/18/2003
• Issued: 03/29/2005
• Est. Priority Date: 04/11/2003
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Then, Paul M., Maier, Robert L., Sparrow, Robert W.
• Primary Examiner(s): STEIN, STEPHEN J
• Application Number:
  US10/718,356
• Publication Number:
  US 20040202225A1
• Time in Patent Office: 497 Days
• Field of Search: 428/220, 428/332, 428/336, 428/688, 428/689, 428/696, 428/699, 428/700, 428/704
• US Class Current: 428/696
• CPC Class Codes: G02B 1/02 made of crystals, e.g. rock-salt, semi-conductors G02B1/08 takes precedence
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: H01S 3/034 Optical devices within, or forming part of, the tube, e.g. windows, mirrors reflectors having variable properties or positions for initial adjustment of the resonator H01S3/086
• CPC Class Codes: H01S 3/0346 Protection of windows or mirrors against deleterious effects cooling arrangements H01S3/0401
• CPC Class Codes: H01S 3/225 comprising an excimer or exciplex
• CPC Class Codes: H01S 3/2251 ArF, i.e. argon fluoride is comprised for lasing around 193 nm
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

The invention is directed to a coated metal fluoride crystals that are resistant to laser-induced damage by a below 250 nm UV laser beam; methods of making such coated crystals, and the use of such coated crystals. The method includes the steps of providing an uncoated metal fluoride crystal of general formula MF₂, where M is beryllium, magnesium, calcium, strontium and barium, and mixtures thereof, and coating the uncoated metal fluoride crystal with a coating of a selected material to thereby form a coated metal material resistant to laser induced damage. Preferred coating materials include MgF₂, MgF₂ doped fused silica and fluorine doped fused silica.

Claims

1. A coated optical material suitable for use as an optical path material in lasers operating below 250 nm comprising:

a shaped optical monocrystal having an entry face and an exit face for laser radiation entering and exiting said crystal, and

a coating on at least the exit face of said monocrystal, said coating selected from the group consisting of MgF₂ doped fused silica and fluorine doped fused silica;

wherein when the coating is MgF₂ doped fused silica and the MgF₂ content of said MgF₂ doped fused silica is in the range of 0.2% to 4% by weight; and

wherein when the coating is fluorine doped fused silica and the fluorine content of said fluorine doped fused silica is in the range of 0.2 to 4% by weight.

2. The coated optical material according to claim 1, wherein said monocrystal is of formula MF₂, wherein M is a metal selected from the group consisting of beryllium, magnesium, calcium, strontium and barium, and mixtures thereof, and F is fluorine.

3. The coated optical material according to claim 1, wherein the thickness of the coating is in the range of 20 to 300 nm.

4. The coated optical material 1 according to claim 1, wherein the thickness of the coating is in the range of 20 to 150 nm.

5. The coated optical material 1 according to claim 1, wherein the thickness of the coating is in the range of 20 to 100 nm.

6. The coated optical material according to claim 1, wherein the monocrystal is CaF2 and the coating is MgF₂ doped fused silica.

7. The coated optical material according to claim 1, wherein the monocrystal is CaF2 and the coating is fluorine doped fused silica.

8. A coated optical material suitable for use as an optical path material in lasers operating below 200 nm comprising:

a shaped optical monocrystal having an entry face and an exit face for laser radiation entering and exiting said crystal, and

a coating on at least the exit face of said monocrystal, said coating selected from the group consisting of MgF₂ doped fused silica where the MgF₂ content of said MgF₂ doped fused silica is in the range of 0.2 to 4% by weight and fluorine doped fused silica wherein the fluorine content of said fluorine doped fused silica is in the range 0.2 to 4% by weight.

9. The coated optical material according to claim 8, wherein said monocrystal is of formula MF₂, wherein M is a metal selected from the group consisting of beryllium, magnesium, calcium, strontium and barium, and mixtures thereof, and F is fluorine.

10. The coated optical material according to claim 8, wherein the thickness of the coating is in the range of 20 to 300 nm.

11. The coated optical material according to claim 8, wherein the thickness of the coating is in the range of 20 to 150 nm.

12. The coated optical material I according to claim 8, wherein the thickness of the coating is in the range of 20 to 100 nm.

13. The coated optical material according to claim 8 wherein the monococrystal is CaF₂ and the coating is MgF₂ doped fused silica.

14. The coated optical material according to claim 8 wherein the monococrystal is CaF₂ and the coating is fluorine doped fused silica.