METHOD OF PRODUCING AN OPTICAL ELEMENT

• US 20160040313A1
• Filed: 08/04/2015
• Published: 02/11/2016
• Est. Priority Date: 08/05/2014
• Status: Active Grant

• Current Assignee: Seek Thermal, Inc.
• Original Assignee: Seek Thermal, Inc.
• Inventors: Dayton, Scott, Parrish, William J., Finegold, Joseph G.
• Granted Patent: US 10,437,024 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B22D 17/2245 having walls provided with means for marking or patterning
• CPC Class Codes: B22D 17/2263 having tubular die cavities
• CPC Class Codes: B22D 21/007 with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
• CPC Class Codes: B22D 21/027 Casting heavy metals with low melting point, i.e. less than 1000 degrees C, e.g. Zn 419 degrees C, Pb 327 degrees C, Sn 232 degrees C
• CPC Class Codes: B23D 79/005 for thermal deburring B23D79/025 takes precedence
• CPC Class Codes: C25D 13/14 Tubes; Rings; Hollow bodies
• CPC Class Codes: C25D 7/04 Tubes; Rings; Hollow bodies
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 2005/065 by shielding
• CPC Class Codes: G01J 5/0215 Compact construction
• CPC Class Codes: G01J 5/046 Materials; Selection of thermal materials
• CPC Class Codes: G01J 5/0881 Compact construction
• CPC Class Codes: G02B 13/008 designed for infrared light
• CPC Class Codes: G02B 13/14 for use with infrared or ultraviolet radiation G02B13/008, G02B13/16 take precedence
• CPC Class Codes: G02B 7/02 for lenses supports for magnifying lenses G02B25/002

Abstract

A process for producing an optical element, which may be suitable for use in an infrared camera with sharp surface features and low emissivity surfaces, including the steps of casting the element in the desired shape in a zinc alloy, deburring the zinc alloy element with a thermal deburring operation, and coating the deburred zinc alloy element with an electrocoating operation.

Claims

1. A process for producing an optical element, the process comprising:

casting zinc alloy using a casting mold, the casting mold comprising a void in a targeted shape of the optical element, the targeted shape including one or more features in an interior portion of the optical element, wherein a total height, length, and width of the optical element are each less than or equal to about 10 mm;

deburring the cast zinc alloy element with a thermal deburring operation, the thermal deburring operation performed at a charging pressure between about 30 psi and about 120 psi, the thermal deburring operation configured to preserve physical features of the one or more features in the interior portion of the optical element; and

coating the deburred zinc alloy element with an electrocoating operation configured to apply a coating having a thickness between about 10 μ

m and about 25 μ

m,

wherein the interior portion of the optical element has a reflectivity that is less than or equal to about 5% for long-wavelength infrared light.

2. The process of claim 1 further comprising cleaning steps between the casting, deburring, or electrocoating operations.

3. The process of claim 1, wherein the deburring operation is performed at a charging pressure of about 90 psi in a methane-oxygen atmosphere with a methane to oxygen ratio of about 16 to 1.

4. The process of claim 1, wherein the electrocoating operation comprises applying a coating having a thickness between about 20 μ

m and about 25 μ

m.

5. The process of claim 1, wherein the electrocoat is substantially white.

6. The process of claim 1, wherein the electrocoat thickness is about 20 microns.

7. The process of claim 1, wherein the optical element is a lens mount for an infrared camera core.

8. The process of claim 7, wherein the lens mount is less than or equal to about 10 mm long and less than or equal to about 7 mm wide.

9. The process of claim 1, wherein the zinc alloy is Zamak3.

10. A process for producing an optical element, the process comprising:

forming the optical element in a targeted shape in a metal alloy, the targeted shape including an interior portion that includes one or more physical features;

deburring the metal alloy with a thermal deburring operation, the deburring operation configured to roughen a surface of the interior portion of the optical element;

coating the deburred metal alloy element with an electrocoating operation configured to apply a coating with a thickness that is less than or equal to about 25 μ

m, such that a combination of the deburring and coating steps result in the optical element having a reflectivity that is less than or equal to about 10%; and

mounting a lens to the optical element such that the lens is configured to direct light through the interior portion of the optical element.

11. The process of claim 10 further comprising mounting the optical element to a printed circuit board having an infrared sensor coupled thereto.

12. The process of claim 10, wherein thermal deburring is performed at a charging pressure between about 70 psi and about 100 psi.

13. The process of claim 12, wherein the electrocoating operation comprises coating the optical element with a material having reflectivity less than or equal to about 5% at wavelengths between about 7.5 μ

m and about 13 μ

m.

14. The process of claim 13, wherein the material has a reflectivity of less than about 2%.

15. The process of claim 10, wherein the targeted shape comprises a plurality of light baffle elements in the interior portion of the optical element.

16. The process of claim 10, wherein the metal alloy is a zinc alloy.

17. The process of claim 10, wherein the optical element is formed by casting.

18. The process of claim 10, wherein the formed optical element weighs less than about 3 grams.

19. An optical element made by a process comprising:

casting the optical element in the desired shape in a zinc alloy;

deburring the zinc alloy element with a thermal deburring operation; and

coating the deburred zinc alloy element with an electrocoating operation,

wherein the optical element has a reflectivity of less than about 5% in the wavelength region comprising long-wavelength infrared light.

20. The optical element of claim 19, further comprising a lens coupled to the optical element, wherein the optical element defines a plurality of light baffle elements.