Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 13: Poster Session I
HL 13.67: Poster
Monday, March 12, 2018, 17:30–19:30, Poster B
3D stabilization of an optical µ-absorption spectrometer — •Jurek Lange and Sangam Chatterjee — Institute of Experimental Physics I, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
Spectroscopy of microscopic or even nanoscopic particles requires extreme mechanical stability to enable significantly long exposure times; e.g., even small changes in the ambient temperature can result in sample drifts, which blur or even distort the measurements.
Here, we actively stabilize a home-built optical microscope equipped with a 3D nanopositioner to measure optical transmission in sample areas of less than 1 µ m2 (0.65 NA). A permanent feedback loop is implemented to rectify the thermal drift in the measuring algorithm. It is based on a live image analysis on multi-dimensional Fourier transform analysis and corrects both the focus and shifts with in the focal plane. The reliability of the approach is verified by stabilizing the optical system using a 1951 USAF target in for 35-hour measurement. The sample drift was reduced from 12 µ m to 0.4 µ m for while the ambient temperature randomly changed between 19 and 21 ∘C.