Femtosecond Laser Phase Scanner for SHG Microscopy
Researchers from Institut National de la Recherche Scientifique and Axis Photonique have developed a new Interferometric Second Harmonic Generation (ISHG) Microscope that combines interferometry and SHG microscopy techniques. By recording the SHG signal as well as its phase, this laser microscope allows a better imaging accuracy when studying biological tissues, like cartilage and muscular tissues.
The microscope scans the phase within each pixel of the sample, using a kHz CPA laser and an ultrafast electro-optical phase scanner from Axis Photonique.
In conventional laser-scanning microscopy, images are formed by acquiring the signal from pixel to pixel. Using the new single-scan interferometric SHG microscope, one can obtain more than one order of magnitude reduction in acquisition time by scanning the phase within each pixel, to characterize the relative polarity of various samples. Using the AXIS Femtosecond Laser Phase Scanner, the phase-shift patterns required for interferometry can be applied at each pixel during the scanning of the sample, allowing single-scan I-SHG (1S-ISHG) measurements. Requiring exposure times comparable to standard SHG intensity images, the additional phase information of the signal can thus be retrieved in parallel to its amplitude at the time-scale of seconds. Moreover, slower modulations can be used to enhance the precision of the phase measurement, without any spatial or temporal shift between interferograms, in contrast to conventional frame phase-shifting I-SHG (standard I-SHG).
“Single-scan interferometric second harmonic generation microscopy using a kHz phase-scanner”
M. Pinsard, L.P. Belley, J.M. Piau, C.Y. Côté, H. Ibrahim, F. Légaré,
Opt. Express 27, 38435-38450 (2019).