Method and apparatus for controlling the reciprocating translation of an interferometer reflector or other body
AssigneeOn-Line Technologies, Inc.
InventorsRobert M. Carangelo, Paul C. Jette
Life of this patent
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Abstract
The method and apparatus effect reversal of a body moving at constant velocity, such as an interferometer reflector, by applying a retrograde electromagnetic force that varies in direct proportion to the distance the body has travelled past the point at which turn around is commenced. Circuitry employed is switched between proportional and integral control configurations, the latter permitting sine-wave oscillation to occur in a servo control loop during reversal.
Claims7
In a method for controlling the reciprocating translation of a body along a travel path having opposite ends, the steps comprising:
- applying a first electromagnetic force of such magnitude as is necessary to effect movement of said body along said travel path, at constant velocity, between points adjacent to, and short of, said opposite ends of said travel path;
- and
- applying a second electromagnetic force for a period of time commencing when said body reaches each of said points, said second force consisting of a static holding component and a retrograde component, said holding component having a magnitude that would be just sufficient to maintain said body at said point if said body were static, and said retrograde component being so directed as to effect reversal of said body and having a magnitude that varies in direct proportion to the distance said body lies beyond said point, said magnitude of said retrograde component increasing constantly from substantially zero at the beginning of said period to attain a maximum value when said body is at the adjacent end of said travel path, and then decreasing constantly to substantially zero at the end of said period of time.
Apparatus for controlling the reciprocating translation of a body, comprising;
- means for applying a first electromagnetic force having a magnitude that can be varied as necessary for moving a body at constant velocity in first and second opposite directions along a travel path, and for applying, at a certain point along said travel path in each of said directions, a second force to effect reversal of the direction of movement of the body, said second force consisting of a static holding component and a retrograde component, said holding component having a magnitude that would be just sufficient to maintain said body at said point if said body were static, and said retrograde component increasing constantly from substantially zero to a maximum value, and thereafter decreasing constantly to substantially zero;
- and
- electronic control means for controlling said means for applying to alternatively apply, at said certain point, either said first or second force.
In an interferometer, the combination comprising:
- (a) a reflective element;
- (b) a body supporting said reflective element for reciprocating translation along a substantially rectilinear travel path;
- (c) drive means for driving said body along said travel path;
- and
- (d) apparatus for controlling the translation of said body, said apparatus comprising:
- means for applying a first electromagnetic force having a magnitude that can be varied as necessary for moving a body at constant velocity in first and second opposite directions along a travel path, and for applying, at a certain point along said travel path in each of said directions, a second electromagnetic force to effect reversal of the direction of movement of the body, said second force consisting of a static holding component and a retrograde component, said holding component having a magnitude that would be just sufficient to maintain said body at said point if said body were static, and said retrograde component increasing constantly from substantially zero to a maximum value, and thereafter decreasing constantly to substantially zero;
- and
- electronic control means for controlling said means for applying to alternatively apply, at said certain point, either said first or second force.
Dependencies are inferred from the claim text.