반투과막의 두께가 얇아질수록 빛의 투과율이 높아지고, 두께가 두꺼워질수록 빛의 투과율이 낮아진다.
As the thickness of the semi-transmissive film becomes thinner, the transmittance of light becomes higher, and as the thickness thereof becomes thicker, the transmittance of light becomes lower.