Animations & Visuals

RFJAS Animation: High-Precision Optical Alignment

This animation illustrates the working principle of the Radio Frequency Jitter Alignment Sensing (RFJAS) scheme. The primary component of this setup is an electro-optic beam deflector, which scatters a laser's carrier beam into higher-order Hermite-Gauss modes.

The animation demonstrates how this technique is used for high-precision optical alignment. The setup includes a laser source, a beam deflector, an optical cavity, and a demodulation photodiode.

Beam Spot Motion (BSM) on Quadrant Photodetectors (QPDs)

This animation shows an example of the spurious alignment signal appearing from the combination of mode mismatch and BSM. On the left is the phase difference between a mismatched and a mode-matched beam, displaced from the QPD center (color indicates the phase difference). On the right, the corresponding spurious alignment signal is plotted: the difference between QPD's left and right side RF demodulated outputs, with the spot position offset range given in units of the beam radius at the QPD. The RF demodulated output is normalized by the total DC power on the QPD. Click here to view the animation in a new tab.