Phase-Suppression Imaging

One then subtracts the two phase sensitive images. By a series of trigonometric rearrangements, one can show that the intensity in the difference ima is zero for components which display a phase angle of 

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McGofwn, E. id Bn R. 1984, Phase-icsdved ftiocescence spectmoopy.An Chan. 6 140fl-14I5. 

B flett,J. D., and Mattbds.J.IL. 1984, Pfiase feso lution in spectrofloorometric measuremaits Ap icaliona to o-chemica systems, BioTedu tts 1984(Mi9 iM)tl74-I80. 

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Phase-sensitive images and difference images of these NADH solutions are shown In Figure 22.22. In the nonprocessed image, all the samples display a positive nonzero intensity. Phase-suppressed images are shown in the middle and lower panels, where the suppressed lifetimes are 0.37 and 0.47 ns, respectively. Also shown are... 

Quadrature images in the Fi dimension can be suppressed by expanding the 8-step phase cycle to 32 steps or 16 steps, respectively, using CYCLOPS [20] or 2-step CYCLOPS [21]. In the CYCLOPS scheme, the phases of all pulses are simultaneously incremented by 90°, 180° and 270°. In the 2-step CYCLOPS scheme, the incrementation of the pulse phases is limited to the 90° step. 

We first review the essentials of the phase distribution of the electric fields at the focus of a high numerical aperture lens in Section II. After discussing the phase properties of the emitted signal, in Section HI we zoom in on how the information carried by the emitted held can be detected with phase-sensitive detection methods. Interferometric CARS imaging is presented as a useful technique for background suppression and signal enhancement. In Section IV, the principles of spatial interferometry in coherent microscopy are laid out and applications are discussed. The influence of phase distortions in turbid samples on phase-sensitive nonlinear microscopy is considered in Section V. Finally, in Section VI, we conclude this chapter with a brief discussion on the utility of phase-sensitive approaches to coherent microscopy. 

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