Fig. 3: OPTM imaging of microparticles in a scattering medium.
From: Ultrasensitive in vivo infrared spectroscopic imaging via oblique photothermal microscopy
10-µm PMMA beads was embedded in a scattering medium and imaged by OPTM. a DC images of PD1 and PD2. b phase gradient and absorption DC images. c Line plotted indicated by the white arrows in (b). d In-Phase (X) and quadrature (Y) images of each photodiode from the lock-in amplifier. e Scatter plotted in region of interest indicated by black arrow in (d). f Photothermal phase gradient (PTPG) and sum images. g Spectra at position indicated by the white arrow in (f). Scale bar 10 µm. Field of view 75\(\times 75\,\)µm2. Probe power on sample was 10 mW. IR power on sample was ~2 mW with repetition rate 390 kHz, pulse width 80 ns. The imaging speed was 2.5 frame per second with a pixel dwell time of 10 µs. Std standard deviation, SNR signal-to-noise ratio.
