Autocollimator

Abstract

Abstract AN IMPROVED AUTOCOLLIMATOR EMPLOYS A PAIR OF MODULATED LIGHT SOURCES AND A PAIR OF PLANE REFLECTING SURFACES TO DIRECT THE LIGHT OUT THROUGH AN OBJECTIVE LENS. BETWEEN THE REFLECTING SURFACES IS A WINDOW OR SLIT, AND BEHIND THE SLIT A LIGHT SENSOR. THE PURPOSE OF THE AUTOCOLLIMATOR IS TO DIRECT LIGHT ONTO AN EXTERNAL REFLECTOR AND MEASURE SENSITIVELY THE DIRECTION OF THE RELECTION. THE REFLECTED LIGHT REENTERS THE OBJECTIVE AND FORMS AN IMAGE WHICH MAY FALL CENTERED ON THE SLIT OR MAY FALL DISPLACED WITH RESPECT TO THE SLIT. THE DISPLACEMENT OF THE IMAGE IS A MEASURE OF THE ANGULAR DEVIATION OF THE RETURNING LIGHT BEAM AND IS DISPLAYED ON A ZERO-CENTER INDICATOR CONTROLLED BY THE LIGHT SENSOR THROUGH PHASE-SENSITIVE CIRCUITRY. THE DISPLACEMENT MAY BE MEASURED MORE ACCURATELY BY MEANS OF AN OPTICAL WEDGE, MOVABLE IN TRANSLATION BY A CALIBRATED MECHANISM. THE REFLECTOR AND LIGHT-SOURCE ASSEMBLY IS MOUNTED SLIGHTLY OFF-AXIS AND THE BEAM IS BENT TOWARD THE SLIT BY THE WEDGE. THUS, SMALL ANGULAR DISPLACEMENTS OF THE RETURNING BEAM ARE MEASURED BY SETTING THE POSITION OF THE OPTICAL WEDGE TO RE-ZERO THE INDICATOR READING.

Inventors

• 👤 Lawrence Zielke
• 👤 William H Thurston

Bibliographic Details