Patent ID: 8767196

Claim:
A method for measuring propagation loss in a plane light guide plate applicable to a photocatalytic reactor, the photocatalytic reactor having an input light generator, an optical coupler, a plane light guide plate, an optical reflection device and an optical measurement device, the method comprising steps of: making an input light generated by the input light generator pass through the optical coupler, the optical reflection device individually, or pass through the optical coupler first and then the optical reflection device, and finally propagate toward the optical measurement device in order to obtain at least one optical parameter according to the optical coupler, the optical reflection device or combination thereof; and making the input light pass through the optical coupler and then the plane light guide plate, and further pass through the plane light guide plate from one side thereof toward the optical reflection device in order to reflect the input light to the optical measurement device, so as to obtain a propagation loss of the plane light guide plate according to the at least one optical parameter; wherein the optical reflection device is a cyclic metal ring, the cyclic metal ring includes a cyclic metal reflection surface such that the input light is substantially reflected from the cyclic metal reflection surface to the optical measurement device.