Stanford Research Systems SRS SR540

Low Jitter Optical Chopper The Stanford Research System SR540 Low jitter optical chopper handles all your optical chopping requirements - from simple measurements to dual-beam and intermodulation experiments. The SR540 has a 4-digit frequency display, front-panel frequency control, analog voltage frequency control and two reference outputs with selectable operating modes. Two anodized aluminum blades are provided: a 5/6 slot blade for frequencies up to 400 Hz, and a 25/30 slot blade for frequencies up to 3.7 kHz. Reference outputs are provided for frequencies corresponding to each row of slots, as well as the sum and difference frequencies. Single-Beam Experiment In this application, a single optical beam is chopped by the outer row of slots, and the reference output from the right BNC is used to lock the lock-in amplifier to the chop frequency. The inner row of slots could also be used, in which case the left BNC would be the reference output.