OC-4000 Optical Chopper Photon Technology International . . 8 H-V180 and black anodized. Frequency is displayed directly on the control unit digital display.
Speed is controlled either manually with a ten-turn dial or by an externally applied voltage.
A synchronous reference signal is provided that can be phase- shifted. Hz via a TTL signal. The unit also allows standard analog control. Hz Exposure time 750 sec. Photon Technology International.