In the last two decades we have studied and developed two types of laser speckle flowgraphy (LSFG) systems to visualize blood flow distribution in skin tissue, human retina, etc.. The system based on analyses of the laser scattering phenomena consists of a diode laser, illuminating and imaging optical systems, an image sensor, a frame capture board, and a personal computer. By evaluating the time variation of the image speckles at each pixel point in the image sensor, and displaying the results in a two-dimensional (2D) color coded map, the blood flow distribution in the target tissue appears on the personal computer monitor. Currently LSFG systems are divided into two types. One type uses a charge coupled device (CCD) camera and is capable of visualizing the fast blood flow change with a rate of 30 maps/s and useful for ophthalmologic research. The other one consists of a line sensor and a stepping motor which is suitable for measuring the blood flow in a wide area of skin tissue. Various types of LSFG instruments used in clinical studies are demonstrated.
© 2007 Chinese Optics LettersPDF Article