High speed “realtime” multi-lambda PS and FT interferometry

Vibration, turbulence and thermal drift are critical in interferometry, especially when testing or fine adjusting high NA microscope objectives. We present an optimized multi-core software that does pretty fast Fourier Transform (FTI) as also Phase Shifting (PSI) interferometry with up to 25 frames/s in FTI and 14 4-bucket frames/s in PSI mode at 512x512 pixels (26 frames/s at 390x390 pixels) on an Intel i7 4-core computer while SIMULTANEOUSLY calculating and “live” displaying raw phase, modulation, unwrapped phase, Zernike fit and coefficients, artificial interferograms, PSF etc. Even higher speeds are achievable if some of the output is disabled, but for PSI actually the camera speed (currently 65Hz, optionally 135Hz @ >1 Mpixels with a double data rate GigE camera) limits the number of N-bucket frames/s. The light source can be switched to 8 different wavelengths from frame to frame, allowing “realtime” testing and adjustment of lateral and longitudinal color errors. We present a working setup with a Michelson interferometer and explain some details of the multithread structure to transfer buffers from the grabber thread to the freely selectable number of calculator threads.