Device for acquiring functional image of tissue and method for generating same

A device for acquiring a functional image of tissue, the device comprising:

• a light source configured to emit coherent light to the tissue targeted to be scanned;
• an image acquisition unit configured to acquire an image having a speckle pattern formed as light emitted from the light source is scattered in the tissue, wherein a plurality of images different in exposure time from each other are acquired;
• an image processing unit configured to generate the functional image of the tissue based on the plurality of images acquired by the image acquisition unit;
• and
• a control unit configured to adjust the quantity of light emitted to the tissue and control operations of the image acquisition unit so that the plurality of images different in exposure time from each other can have brightness values within a common range,
• wherein the control unit measures variation in the brightness value of the image according to variation in the quantity of the light for each exposure time, and sets an appropriate light quantity value corresponding to each exposure time so that the plurality of images different in exposure time from each other can have the brightness values within the common range.