Figure 3: The experimental set-up of the stimulated Raman projection microscopic and tomographic imaging.
From: Volumetric chemical imaging by stimulated Raman projection microscopy and tomography
A tunable pulsed laser provides two synchronized femtosecond pulse trains as pump and Stokes beams. The Stokes beam is modulated by an AOM. The pump beam is first delayed by a translational stage, and is then spatially and temporally combined with the Stokes beam by a DM. The collinearly overlapped beams are sent to a pair of axicons for generating ring-shaped beams. By adjusting the beam size, the ring-shaped beams are first directed to a 2D galvo system for laser scanning, and then guided to an objective for Bessel beams generation. After the sample, the transmitted Bessel beams are collected by a condenser, and then directed to the PD. A pair of shortpass filters are fixed in front of PD to remove the Stokes beam composition. The photocurrent generated in the PD is amplified by a lab-built resonant amplifier, and then sent to a lock-in amplifier for signal extraction. A, axicon; AOM, acousto-optic modulator; DM, dichroic mirror; HWP, half wave-plate; L, lens; M, mirror; PBS, polarizing beam splitter; PD, photodiode.
