Some Photographic Studies of the Light Output of an Intracavity-Modulated Gas Maser
L. E. Hargrove, J. S. Courtney-Pratt
Using a high-speed rotating mirror to sweep the image, we photographed the light output from a helium-neon gas maser with and without intracavity modulation at the locking frequency fo, which corresponds to the reciprocal of the round-trip travel time for light within the maser, and which also equals the cavity mode spacing. When the maser was locked, the photographic record showed regular pulses. The light level was 1,500 times the minimum required to record individual dots. When the maser was not locked, the photographs showed beats at harmonics of the mode spacing. The amplitudes of the beat frequencies varied most irregularly from moment to moment, sometimes changing noticeably in less than half a microsecond and radically in less than a millisecond. — We found no evidence of reciprocity failure for Eastman Kodak Type 1F emulsion to the accuracy of the energy measurements (i.e., to a factor of 2 up or down from the mean), for exposure times from 1 nanosec to 30 sec.