An optical detection system includes a sample portion accommodating a sample, a wave source emitting waves to the sample portion, an optical portion provided on a path of an output wave output from the sample portion, and comprising a first spatial light modulator that modulates part of the output wave to a first wave and a second spatial light modulator that modulates part of the output wave to a second wave, a lens portion focusing the first wave and the second wave output from the optical portion, and a detection portion detecting a focused wave that is focused by the lens portion, in which the first spatial light modulator and the second spatial light modulator modulate the output wave such that the first wave and the second wave have destructive interference with respect to the sample under an already known condition.