LINEAR VARIABLE LIGHT ATTENUATOR

• US 3,746,429 A
• Filed: 08/05/1971
• Issued: 07/17/1973
• Est. Priority Date: 08/05/1971
• Status: Expired due to Term

• Current Assignee: Abraham Spindel, James F. Maas
• Original Assignee: Abraham Spindel, James F. Maas
• Inventors: Spindel, Abraham, Maas, James F.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Evans, F. L.
• Application Number:
  US05/169,202
• Time in Patent Office: 712 Days
• Field of Search: 350/266 356/235 250/233
• US Class Current: 359/888
• CPC Class Codes: G01J 1/24 using electric radiation detectors
• CPC Class Codes: G02B 5/205 Neutral density filters

Abstract

A compact variable light beam attenuator adapted for use in laser system. A pair of optical wedges having flat, parallel surfaces are movably mounted in a light beam path. The wedges are movable with respect to each other along a line having a component normal to the light beam path. The optical density of one wedge increases and that of the other wedge decreases in a given direction along the line of movement. The sum of the optical densities of the areas of the wedges in the light beam path is the effective density of the attenuator.

Claims

1. A variable attenuator for a laser light beam comprising, in combination:

a. first and second optical wedges each having a pair of plane parallel surfaces and each comprised of an optically flat transparent plate with one surface coated with a layer of evaporated metal, the density of the layer varying as a function of the distance from one end of the plate, the rate of increase of the function representing the optical density of the first wedge, being equal to the rate of decrease of the function representing the optical density of the second wedge;

b. mechanical means for holding the wedges in spaced relationship to each other and for moving the wedges simultaneously in opposite directions along a direction having a component in a plane normal to the laser light beam; and

, c. means defining a light beam path through the wedges, the parallel surfaces of the first wedge being inclined at a small angle of the order of one degree to the parallel surfaces of the second wedge to divert from the light beam path unwanted multiple reflections of the light beam occuring in the space between the wedges, whereby coherent laser light may be continuously attenuated with the sum of the functions representing the optical densities being constant over the cross section of the light beam path through the wedges for all working positions of the wedges with respect to each other.