Open AccessHyper-numerical aperture (NA = 28) microscope using λ = 156 µm femtosecond source for multi-photon imaging
Author(s) -
YoungSik Kim,
Phat Lu,
Tom D. Milster,
Khanh Kieu
Publication year - 2013
Publication title -
biomedical optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.362
H-Index - 86
ISSN - 2156-7085
DOI - 10.1364/boe.4.001786
Subject(s) - optics , materials science , femtosecond , microscope , microscopy , numerical aperture , silicon , colloidal gold , two photon excitation microscopy , photon , optoelectronics , nanoparticle , laser , nanotechnology , physics , fluorescence , wavelength
A new microscope is discussed, where the scanning illumination has a numerical aperture of 2.8 with λ = 1.56 µm femtosecond fiber laser. Samples are placed or grown on a silicon substrate. Multi-photon emission is imaged in transmission on a cooled CCD. Two-photon and three-photon effects are observed from the silicon/water interface and gold nanoparticles. Images of cells, reference spheres and gold nanoparticles illustrate imaging properties of the microscope. Spectral characteristics of individual particles are achieved with a blazed transmission grating. Emission properties of differently sized gold nanoparticles are studied in detail, which indicate that their emission is a two-photon effect due continuum generation. Interestingly, spectral shape and emission power are similar for 20nm, 40nm and 60nm diameter gold nanoparticles for the cases studied.