High Speed Measurement in Spectral Drill using Q-plate and Camera

We have proposed a method to scan resonance modes in a Fabry-Pérot cavity applying a geometric phase shifter, named as spectral drill. When the geometric phase shifter consists of two quarter wave plates and a half wave plate sandwiched by them is put into a cavity, the resonance modes can be scanned by the rotation of the half wave plate. Since a mechanical rotation stage has been used for scanning the cavity in our prior works, the scanning rate was limited by the rotational speed of the stage. In this work, by replacing the half wave plate to a q-plate with removing the mechanical stage and by taking transmission images by a camera, we succeeded in 720 times faster acquisition of the transmission spectrum of the spectral drill.