beam splitter

Abstract

The optical detection element of the beam splitter of the present invention has a first optical detection region, a second optical detection region, and a third optical detection region. The beam splitter directs light of a first wavelength range into the first optical detection region, directs light of a second wavelength range (longer than the first wavelength range) into the second optical detection region, and directs light of a third wavelength range (longer than the second wavelength range) into the third optical detection region. The silicon nitride film coverage in the third optical detection region is greater than the silicon nitride film coverage in the first optical detection region. The silicon nitride film coverage in the second optical detection region is greater than or equal to the silicon nitride film coverage in the first optical detection region, and less than or equal to the silicon nitride film coverage in the third optical detection region.