This is an EG&G 6 GHz optical comb generator. Optical comb generators are used to test and calibrate streak camera systems. They are small, portable light sources that produce a series of temporally short, uniformly spaced, optical pulses. Signal output is via a fiber-optical connector. Signal is transported from comb generator to streak camera via a multimode graded-index optical fiber. Comb generators perform two important functions for streak camera users. First, comb generators are used as a precision time-mark generator for calibrating streak camera sweep rates. Accuracy is achieved by averaging many streak camera images of comb generator signals. Timebase calibrations with portable comb generators are easily done in both the calibration laboratory and in situ. Second, comb signals are applied to a streak camera just before and at shot time to verify that the streak camera sweep unit is functioning properly. A comb signal applied at shot time does not have the statistical quality of the multiple recordings used to calibrate a streak camera time base. However, it does allow the user to verify that the correct sweep card is installed and that it is functioning within about 1.5% of its expected speed. It should be noted that the series of optical pulses produced by this instrument is not continuous, but rather consists of gated bursts on the order of 1 µs in duration. Gating can either be accomplished internally, or via an external gate input. Output power may be varied from the front panel.