Photothermal deflection spectroscopy is combined with a Sagnac interferometer to enhance the sensitivity of the absorption measurement by converting the photothermal beam deflection effect into the light intensity change by the interference effect. Because of stable light interference due to the common path, the signal intensity can be amplified without increasing the noise by extending the optical path length between a sample and a photodetector. The sensitivity is further improved by the use of focusing optics and double-pass geometry. This makes photothermal deflection spectroscopy applicable to any kind of material in the whole visible region with a xenon lamp for excitation and water or air as a deflection medium.
© 2012 Optical Society of America
Instrumentation, Measurement, and Metrology
Original Manuscript: April 23, 2012
Manuscript Accepted: April 23, 2012
Published: June 25, 2012
Naoyuki Shiokawa, Yuki Mizuno, Harumasa Tsuchiya, and Eiji Tokunaga, "Sagnac interferometer for photothermal deflection spectroscopy," Opt. Lett. 37, 2655-2657 (2012)