A chopper and method of making same, the chopper being fabricated by initially generating a photomask in conjunction with software. The software provides the lens design to be finally stamped onto the chopper element. A silicon wafer is then etched by reactive ion etching using the photomask to provide the pattern and resulting in a silicon wafer master of the chopper pattern with regions in the shape of lenslets to be formed of desired dimension. The chopper pattern on the silicon wafer is then replicated with a hard material which can be easily stripped from the silicon wafer without damaging either the wafer or the hard material, preferably deposited nickel. The separated nickel replication is then used in conjunction with a heavy press to stamp out sheets of an infrared transmissive flexible film, preferably polyethylene, with the lens pattern in the replication. The film with the lens pattern thereon is the chopper element. The system is designed to operate in the 8 to 13.5 micron range. While the software is designed for an individual lens, each lens is preferably in the shape of a hexagon with a plurality of such hexagons positioned on the film in a predetermined pattern, preferably that of an involute or spiral. The chopper is designed for rotation about its central axis.

Title
Infrared chopper using binary diffractive optics
Application Number
9/841772
Publication Number
20010038974
Application Date
April 24, 2001
Publication Date
November 8, 2001
Inventor
Michael C Bell
Garland
TX, US
Richard R Chang
McKinney
TX, US
S Charles Baber
Richardson
TX, US
Samuel R McKenney
Dallas
TX, US
Robert C Gibbons
Richardson
TX, US
Agent
Baker Botts
TX, US
Agent
Jerry W Mills Esq
TX, US
Assignee
Raytheon Company
IPC
G03C 05/00
B29D 11/00
G03F 07/26
G02B 26/08
G02B 05/18
G02B 03/00
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