title: Portable thermal lens spectrometer with focusing system.
abstract: A portable thermal lens spectrometer with a precise focusing system was developed. Astigmatism of the reflected excitation beam from the microchip was used for depth direction focusing. For width direction focusing, the scattering effect of the transmitted probe beam by a microchannel edge was used. The focusing system was evaluated with a 250 microm wide x 50 microm deep microchannel. Focusing resolutions for depth and width directions were 1 and 10 microm, respectively. The repeatability of the thermal lens signal (40 microM xylenecyanol solution) was proved to be approximately 1% coefficient of variance when using these focusing methods. The limit of detection for a xylenecyanol solution was 30 nM, and the absorbance was 4.7 x 10(-6) AU. The sensitivity was 20-100 times higher than that obtained by spectrophotometry. In consequence, a practical thermal lens spectrometer was realized.
authors.affiliation: Central Research Laboratory, Asahi Kasei Corporation, 2-1 Samejima, Fuji, Shizuoka 416-8501, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Mawatari
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Naganuma
authors.forename: Koji
authors.initials: K
authors.lastname: Shimoide