High speed perfusion imaging based on laser speckle fluctuations

In this chapter an introduction will be given to the research areas of high-speed laser Doppler perfusion imaging and laser speckle contrast techniques. Furthermore, the aim of the performed research will be introduced, and finally an overview of the topics in this thesis will be given. 1.1 General Introduction Noninvasive imaging of blood flow in tissue is of major importance for certain applications in dermatology [1], neurology [2], surgery [3] and wound care [4]. Over recent decades, several techniques have been developed for imaging tissue perfusion. Most of these techniques exploit the random interference pattern generated from diffusely backscattered light from the skin, generally known as speckle pattern. The most well-known technique using this speckle pattern is laser Doppler perfusion imaging (LDPI) [5, 6]. In LDPI the skin is illuminated with coherent laser light. A fraction of the laser light interacts with moving red blood cells and obtains a Doppler shift. A mixture of Doppler shifted and unshifted light interferes on a detector, resulting in a speckle pattern which changes over time. This leads to the generation of a photocurrent that fluctuates in time. The moments of the power spectrum S(ω) of this photoelectric current are given by : Mi ∝ ∞ ∫