High-speed laser Doppler perfusion imaging using an integrating CMOS image sensor

This paper describes the design and the performance of a new high-speed laser Doppler imaging system for monitoring blood flow over an area of tissue. The new imager delivers high-resolution flow images (256 x 256 pixels) every 2 to 10 seconds, depending on the number of points in the acquired time-domain signal (32-512 points). This new imaging modality utilizes a digital integrating CMOS image sensor to detect Doppler signals in a plurality of points over the area illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurements, which results in high-quality flow images. We made a series of measurements in vitro to test the performance of the system in terms of bandwidth, SNR, etc. Subsequently we give some examples of flow-related images measured on human skin, thus demonstrating the performance of the imager in vivo. The perspectives for future implementations of the imager for clinical and physiological applications are discussed. (c) 2005 Optical Society of America.