An overview of the latest advancements in Hyperspectral Coherent Raman Imaging

Within the CRIMSON project, Institut Fresnel CNRS has demonstrated hyperspectral coherent Raman imaging using temporally shaped probe pulses. The developed scheme uses impulsive excitation and time-domain detection using shaped probe pulses. The researchers have shown that probing the vibrational transient refractive index with two probe pulses separated by half the vibration period acts as a notch filter and makes the vibration line disappear from the molecular vibration spectrum. Using a fast acousto-optic programmable dispersive filter, the researchers could demonstrate hyperspectral imaging in the low frequency range (<200cm-1) with a pixel dwell time as low as 25µs.
Figure: a) carbamazepine dihydrate transmission image, (b) Images at 21cm-1, 75cm-1 and 111cm-1 depending on the time T between the two-pulse probing the vibrational refractive index transient. When T is equal to half the vibration period, the image disappears for this vibration.
Read more at: S. Shivkumar, D. Raanan, S. Metais, S. Suresh, N. Forget, R. Bartels, D. Oron, and H. Rigneault, “Selective Detection in Impulsive Low-Frequency Raman Imaging Using Shaped Probe Pulses,” Physical Review Applied 19, 054075 (2023).