Optical detecting system and method thereof

The invention discloses an optical detecting system and a method thereof. Raised flaws on a tested object of a solar cell are detected by shadow, the gray scale value of the tested object is measured by irradiating the tested objected with slant light; a shadow region is distinguished by comparing gray scale value variation of the tested object; the gray scale variation rate of the shadow region gray scale value and the tested object gray scale value is calculated to capture corresponding height value from the self-prestored corresponding relationship of the gray scale variation rate; the corresponding relationship is correspondence of the gray scale variation rate and the height value; and finally, when the captured height value exceeds a preset threshold, the position of the shadow region, which corresponds to the tested object, is the raised flaw. Thus, the invention can quickly compare and judge the raised flow without precise height calculation and conforms to rapid test requirements of a production line