TITLE:
Signal Efficiency in Gradient Index Lens Based Two Photon Microscopy
AUTHORS:
Axel Wingert, Henning Seim, Sebastian Schürmann, Rainer H. A. Fink, Martin Vogel
KEYWORDS:
Second Harmonic Generation; Gradient Index Lens; Multi Photon Microscopy; Multi Harmonic Microscopy; Micro-Endoscopy
JOURNAL NAME:
Open Journal of Biophysics,
Vol.3 No.1A,
February
27,
2013
ABSTRACT: Gradient index (GRIN) lenses are often used as an optical relay to a
sample at a location that is not accessible for a standard microscope. This capability
is turning them into an important enabling technology that extends many optical
imaging modalities like harmonic laser scanned imaging with micro endoscopic in vivo capabilities as needed in research and diagnostics. These micro endoscopic imaging
variants however rely on the light scattering capability of the underlying tissue.
Further complications arise from an increased number of optical interfaces and the
overall optical performance of a GRIN rod. We have therefore performed a quantitative
comparison of the back-scattered second harmonic generation (SHG) signal intensity
generated in skin and low-scattering muscle tissue, both obtained with a standard
two photon laser scanning microscope (LSM) and a GRIN lens based LSM. We report
that the GRIN lens based system sees approximately 1/4 of the net two photon signal
detected by the standard LSM. We expect that this value can be generalized to other
LSM techniques enhanced by GRIN technology and encourage its use in experimental
situations with standard LSM signal to noise ratios of four or higher.