[23a-P01-1~4] 3.8 Optical measurement, instrumentation, and sensor

[23a-P01-2] Fast Auto-Balance Noise Cancellation beyond Sample Modulation based on Correlation of Optical Source Noise and Output Noise

〇Keisuke Seto¹, Takayoshi Kobayashi², Eiji Tokunaga¹ (1.Tokyo Univ. Sci., 2.Univ. Electro-Commun.)

Keywords:noise-cancellation, Imaging

Probe light source noise dominates signal-to-noise ratio (S/N) in pump/probe measurement such as the stimulated Raman microscopy and the photothermal microscopy. The noise on the probe signal is suppressed by taking the difference between the probe signal and the reference signal that replicates the noise. For maximum noise-canceling efficiency, the intensity balance of the probe and reference signals should be unity. There is the auto-balancing scheme where the signal gain balance is feedback-controlled based on the DC component in the difference of the probe and reference signals. However, the dynamic range, stability, and feedback control speed are limited by this conventional scheme. We develop and demonstrate an auto-balancing method based on the noise correlation between the difference and reference signals to enhance dynamic range, stability, and feedback control speed.