Patent ID: 7230691

Claim:
A photometer, comprising: a wavelength-band-component extractor that extracts a component of a predetermined wavelength band from incident light; a brancher that branches the predetermined wavelength band component into a first direction and a second direction; an optical connector that comprises a first input terminal, a second input terminal, a first output terminal, and a second output terminal, said first input terminal being connected to one end of an device under test, and said second input terminal being connected to a side in the first direction of said brancher; an optical amplifier that receives light from said second output terminal, and outputs amplified light, which is obtained by amplifying the light, to an incident light receiving section of said wavelength-band-component extractor; and a photodetector that is connected to said first output terminal, and detects light, wherein: the other end of the device under test is connected to a side in the second direction of said brancher; and said optical connector (1) connects between said first input terminal and said first output terminal, and between said second input terminal and said second output terminal, or (2) connects between said first input terminal and said second output terminal, and between said second input terminal and said first output terminal.