- Later developers of the photoelastic modulator include J . C Kemp, S . N Jasperson and S . E Schnatterly.
- The basic design of a photoelastic modulator consists of a piezoelectric transducer and a half wave resonant bar; the bar being a transparent material ( now most commonly fused silica ).
- If the signal is either slowly varying or otherwise constant ( essentially a DC signal ), then acousto-optical modulator, photoelastic modulator at a large enough frequency so that 1 / " f " noise drops off significantly, and the lock-in amplifier is referenced to the operating frequency of the modulator.