A method for assessing of blood flow in tissue, the method comprising: using a coherent laser light source (108, 202, 302, 501) to apply light to the tissue; using a multi-pixel image sensor (110, 204, 312, 313, 511) to capture optical information including at least a intensity of light transmitted through the tissue; and wherein the light is directed via an input optical fiber (304, 505, 712) positioned directly onto a first location of a patient's skin; wherein the multi-pixel image sensor (110, 204, 312, 313, 511) captures optical information at a second location of the patient's skin surface; wherein the multi-pixel image sensor (110, 204, 312, 313, 511) captures optical information including said intensity of light transmitted through the tissue at a depth of penetration of between 0.5cm and 5cm according to a distance between said first and said second location, wherein the light is scattered diffusively, at least in part, by the blood flow, and generates a spatial or time series of intensity measurements to provide spatial or time series data; using analyzer to analyze the optical information to determine blood flow in the tissue by calculating the spatial speckle contrast ratio (Ks) by dividing the standard deviation of the intensity of image pixels by the average of the intensity of image pixels, or by calculating temporal speckle contrast, K t, by dividing the temporal standard deviation of the time series data by the temporal average of the time series data, and calculating 1/K s 2 or 1/K t 2, wherein 1/K s 2 and 1/K t 2 are related to flow rate in a substantially linear fashion; and using a feedback device to provide a signal indicative of the blood flow determined by the analyzer. using a coherent laser light source (108, 202, 302, 501) to apply light to the tissue; using a multi-pixel image sensor (110, 204, 312, 313, 511) to capture optical information including at least a intensity of light transmitted through the tissue; and wherein the light is directed via an input optical fiber (304, 505, 712) positioned directly onto a first location of a patient's skin; wherein the multi-pixel image sensor (110, 204, 312, 313, 511) captures optical information at a second location of the patient's skin surface; wherein the multi-pixel image sensor (110, 204, 312, 313, 511) captures optical information including said intensity of light transmitted through the tissue at a depth of penetration of between 0.5cm and 5cm according to a distance between said first and said second location, wherein the light is scattered diffusively, at least in part, by the blood flow, and generates a spatial or time series of intensity measurements to provide spatial or time series data; using analyzer to analyze the optical information to determine blood flow in the tissue by calculating the spatial speckle contrast ratio (Ks) by dividing the standard deviation of the intensity of image pixels by the average of the intensity of image pixels, or by calculating temporal speckle contrast, K t, by dividing the temporal standard deviation of the time series data by the temporal average of the time series data, and calculating 1/K s 2 or 1/K t 2, wherein 1/K s 2 and 1/K t 2 are related to flow rate in a substantially linear fashion; and using a feedback device to provide a signal indicative of the blood flow determined by the analyzer.