High-bandwidth noise-reduced absorption-corrected autobalanced detection

Lemberger, Nick S.; Wallmeier, Kristin; Fallnich, Carsten

Abstract

A compact and easy-to-use high-bandwidth autobalanced detector for microscopy is presented, being able to remove up to 67 dB of correlated noise, thus, allowing for shot-noise limited image acquisition even in the presence of high laser excess noise. Detecting a 20 MHz modulation frequency at half the repetition rate of the driving pulsed laser, the autobalanced detector is able to exploit an extra +3 dB increase in signal-to-noise ratio due to the coherent addition of modulation sidebands in stimulated Raman scattering. Pixel-by-pixel noise canceling and correction of sample transmission losses are possible for pixel scan rates of more than 1.7 Mpx/s, enabling full autobalanced operation at imaging speeds of more than 6.5 frames per second for 512 x 512 px images. It is demonstrated that the autobalanced detector is able to separate an overlaying parasitic loss-induced image from a stimulated Raman scattering microscopy image, providing both the noise and transmission corrected stimulated Raman scattering image as well as an attenuation image simultaneously.