Raman imaging of floating cells

Author(s): Caitriona Creely, Giovanni Volpe, Gajendra Singh, Marta Soler, and Dmitri Petrov

Abstract:

“Raman imaging can yield spatially resolved biochemical information from living cells. To date there have been no Raman images published of cells in suspension because of the problem of immobilizing them suitably to acquire space-resolved spectra. In this paper in order to overcome this problem the use of holographic optical tweezers is proposed and implemented, and data is shown for spatially resolved Raman spectroscopy of a live cell in suspension.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 16, pp. 6105-6110, 2005
DOI: 10.1364/OPEX.13.006105

Femtosecond pulse shaping using a liquid–crystal display: Applications to depth profiling analysis

Author(s): Ota Samek, Vanja Hommes, Roland Hergenröder, Sergei V. Kukhlevsky

Abstract:

“We report on a beam shaping technique for femtosecond laser pulses based on a liquid-crystal display. The system is capable of modifying femtosecond Gaussian beams to a flattop beam. A pattern projected onto liquid-crystal display modifies the incoming Gaussian beam intensity so that flattop intensity profile is obtained. The process is monitored online using a charge-coupled device camera so that the intensity distribution of each pulse is known. An experimental example of the depth profile of a Cr layer on a Si substrate obtained using such a modified beam is presented.”

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Publication: Review of Scientific Instruments
Issue/Year: Rev. Sci. Instrum. 76, 086104 (2005)
DOI: 10.1063/1.1994897

Spiral interferometry

Author(s): Severin Fürhapter, Alexander Jesacher, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“We present a surprising modification of optical interferometry. A so-called spiral phase element in the beam path of a standard microscope results in an interferogram of phase samples, for which the interference fringes have the shape of spirals instead of closed contour lines as in traditional interferograms. This configuration overrides the basic problem of interferometry, i.e., that elevations and depressions cannot be distinguished. Therefore a complete sample profile can be reconstructed from a single exposure, promising, e.g., high-speed metrology with a single laser pulse. The method is easy to implement, it does not require a spatially separated reference beam, and it is optimally stable against environmental noise.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 30, Issue 15, pp. 1953-1955 (2005)
DOI: 10.1364/OL.30.001953