title: Gap thickness retrieval on air etalon by using a focused incoherent white-light beam.
abstract: In a transmittance spectrum of air etalon composed of ITO-coated glass plates, stronger spectral modulation is observed by using a focused white-light incident beam compared with that by using a conventionally collimated beam. The light source is a single commercial light-emitting diode. An angular integrated multiple-beam Fabry-Perot model is proposed that is well fitted to the measured transmittance spectra. The gap thickness of the air etalon is sensitively retrieved and mapped at a lateral surface resolution of about 1 mm, and the unparallelness of the etalon angled as low as several microradians is thereafter estimated.
authors.affiliation: Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Gao
authors.forename: Haihui
authors.initials: H
authors.lastname: Pu
authors.forename: Hongyue
authors.initials: H
authors.lastname: Gao
authors.forename: Dejin
authors.initials: D
authors.lastname: Yin
authors.forename: Jianhua
authors.initials: J
authors.lastname: Liu