Optical coating with selectable transmittance characteristics and method of making the same

• US 4,006,378 A
• Filed: 10/01/1975
• Issued: 02/01/1977
• Est. Priority Date: 10/01/1975
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Silverstein, Seth D., Prener, Jerome S.
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US05/618,671
• Time in Patent Office: 489 Days
• Field of Search: 313/112, 313/221, 350/1, 350/311, 252/300
• US Class Current: 313/112
• CPC Class Codes: C03C 17/23 Oxides C03C17/02 takes precedence
• CPC Class Codes: C03C 2217/216 ZnO
• CPC Class Codes: C03C 2218/112 by spraying
• CPC Class Codes: H01J 61/40 by light filters; by coloured coatings in or on the envelope

Abstract

A layer of zinc oxide disposed on the surface of a substrate in thicknesses of between 500 and 10,000 Angstroms is characterized by a sharp absorption edge to substantially absorb selected wavelengths of radiation incident thereon while transmitting other selected wavelengths. The wavelength of the absorption edge is selectable as a function of temperature. A method of depositing the zinc oxide layer is also described.

Claims

1. In combination with a high intensity lamp including a source of radiant energy sealed within the lamp envelope and wherein said radiant energy is characterized by visible and ultraviolet radiation, the improvement comprising:

a layer of zinc oxide disposed on at least a selected portion of the inner surface of said lamp envelope, said layer having a thickness of between 500 and 10,000 Angstroms and the operating temperature of said layer being selected to cause said layer to exhibit a sharp absorption edge at a selected wavelength, whereby selected wavelengths of said ultraviolet radiation are absorbed while selected wavelengths of said visible radiation are transmitted.

2. The combination of claim 1 wherein said absorption edge is selectable over a range of wavelengths between approximately 400 and 465 nanometers that varies as the temperature of said layer varies between approximately 200 and 500°

C.

3. The combination of claim 1 wherein the thickness of said layer is between 1000 and 1500 Angstroms.

4. The combination of claim 1 wherein said lamp is a mercury arc lamp and the thickness of said layer is approximately 1350 Angstroms, the thickness at which said layer exhibits a maximum transmission characteristic.

5. The combination of claim 4 wherein the temperature of said zinc oxide layer is approximately 300°

C.

6. An optical system comprising:

a source of radiant energy including visible and ultraviolet radiation;

a substantially transmissive member interposed in the path of said radiant energy; and

a layer of zinc oxide disposed on a selected surface of said member, said layer of zinc oxide having a thickness the operating temperature of said layer being selected to cause said layer to exhibit a sharp absorption edge at a selected wavelength.

7. The optical system of claim 6 wherein said source is a vacuum-arc discharge lamp.

8. The optical system of claim 7 wherein said member is the envelope containing said lamp and said zinc oxide is disposed on the inner surface of said envelope.

9. The optical system of claim 8 wherein said zinc oxide layer has a thickness of between 1000 and 1500 Angstroms.

10. The optical system of claim 9 wherein the heat generated by said lamp maintains the temperature of said zinc oxide layer between 200°

C and 400°

C.