2002/08/15 by Dieter Braun, Albert Libchaber · 1 voice · 1 citation
Biochemistry, Genetics and Molecular Biology · Engineering · Physics and Astronomy · #Advanced Fluorescence Microscopy Techniques #Force Microscopy Techniques and Applications #Integrated Circuits and Semiconductor Failure Analysis
paper · doi:10.1364/ol.27.001418
openalex publication_date 2002/08/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/26
We implement a simple computer-based photon-counting lock-in that combines the signal-to-noise benefits of photon counting with lock-in detection. We experimentally specify the flatness and the noise characteristics of a flexible software implementation. The noise of amplitude and phase of the small signal is at the limit of photonic shot noise; from 1000 counted photons we reach an amplitude resolution of 4.5% and a phase resolution of 13 degrees . The photon-counting lock-in reduces illumination noise, detector dark count noise, and can suppress background. In particular, phase detection is useful to image the delay characteristics in microscopic systems by use of fluorescent probes that are designed to report membrane potential, temperature, or concentration in a chemical reaction.