Ultrahigh-speed multiplex coherent anti-Stokes Raman scattering microspectroscopy using scanning elliptical focal spot.

We present a beam-scanning multiplex coherent anti-Stokes Raman scattering (CARS) microspectroscopy system using parallel excitation and parallel detection schemes based on an elliptical focal spot, which enables highly efficient signal acquisition even for short exposures. The elliptical focal spot was used to simultaneously observe the CARS signals of an enlarged region and reduce the peak irradiance. The developed system realized an acquisition rate of 34 139 spectra/s and enabled ultrahigh-speed acquisition of a vibrational spectroscopic image, covering the fingerprint region of 930-1 830 cm-1 with 256(x) × 256(y) × 512(spectrum) pixels in 1.92 s or with 128(x) × 128(y) × 256(spectrum) pixels in 0.54 s. We demonstrated ultrahigh-speed hyperspectral imaging of a mixture of polymer beads in liquid linoleic acid and living adipocytes using the developed system. All of the present demonstrations were performed with a low-peak irradiance excitation of ∼19 GW/cm2, which has been reported in previous studies to cause less photodamage to living cells. The label-free and ultrahigh-speed identification and visualization of various molecules made possible by the present system will accelerate the development of practical live-cell investigation.