Wide-field Intensity Fluctuation Imaging

Abstract

The temporal intensity fluctuations contain important information about the light source and light-medium interaction and are typically characterized by the intensity autocorrelation function, g2({tau}). The measurement of g2({tau}) is a central topic in many optical sensing applications, ranging from stellar intensity interferometer in astrophysics, to fluorescence correlation spectroscopy in biomedical sciences and blood flow measurement with dynamic light scattering. Currently, g2({tau}) at a single point is readily accessible through high-frequency sampling of the intensity signal. However, two-dimensional widefield measurement of g2({tau}) is still limited by camera frame rates. We propose and demonstrate a 2-pulse within-exposure modulation approach to break through the camera frame rate limit and obtain the quasi g2({tau}) map in wide field with cameras of only ordinary frame rates. HighlightsO_LIThe quasi intensity autocorrelation function can be measured at almost arbitrary time lags C_LIO_LICameras of ordinary frame rates are sufficient for the measurement C_LIO_LIIllumination within the camera exposure is modulated by an acoustic optical modulator using two short pulses C_LI