Spectral filtering

Note that parameters ft and 5 depend on signal amplifications in the utilized detectors and on the elements in the optical path (optical filter, spectral detection bands) only, while a and y are additionally influenced by relative excitation intensity. This is usually a fixed constant in wide-field microscopy but in confocal imaging laser line intensities are adjusted independently. Furthermore, note that the a factor equals 5 multiplied by y (see Appendix for further detail). 

When using the fast-Fourier-transform algorithm to calculate the DFT, inverse filtering can be very fast indeed. By keeping the most noise-free inverse-filtered spectral components, and adding to these an additional band of restored spectral components, it is usually found that only a small number of components are needed to produce a result that closely approximates the original function. This is an additional reason for the efficiency of the method developed in this research. 

Light emission was recorded with an IP 21 R.C.A. photomultiplier tube in the range 3000-7000 A. Interference filters (spectral bandwidth A A = 100-140 A.) showed that the light emission of the pic darret arises from the same emitter as that from the slow reaction—probably excited formaldehyde (16). The pic darret appears as a clear pulse on the record of light intensity vs. time (Figure 1). 

Wang, X., Acousto-Optic Tunable Filters Spectrally Modulate Light Laser Focus World 1992, 28, 173-180. 

Output Filtered spectral information leads to a score for each component... 

Finally, DOEs can serve as various optical spectral filters, including low-, high-, or bandpass filters, spectral transformers, notch-filters, etc. All of these features can be used to enhance photodetectors. 

Filter, spectral - An optical element, usually transmissive) used to restrict the spectral band of energy received by the detector. 

And a rotation of the emitter-receiver transducer around the "object" (or a rotation of the object) gives a annulus of center O and radii [Km, Km] [2]. The situation is identical to that of X-ray tomography (slice-by-slice spectral coverage), but with a band-pass spectral filter instead of a low-pass spectral filter. ... 

McMorrow D and Lotshaw W T 1990 The frequency response of condensed-phase media to femtosecond optical pulses spectral-filter effects Cham. Phys. Lett. 174 85-94... 

Wall M R, Dieckmann T, Feigon J and Neuhauser D 1998 Two-dimensional filter-diagonalization spectral inversion of 2D NMR time-correlation signals including degeneracies Chem. Phys. Lett. 291 465... 

Mandelshtam V A and Taylor H S 1997 Spectral analysis of time correlation function for a dissipative dynamical system using filter diagonalization application to calculation of unimolecular decay rates Phys. Rev. Lett. 78 3274... 

A computer-controlled bandpass filter system controls the size of the acquired spectral window. Typically, this is set to about 120% of the desired sweep width. Only frequencies within these limits are allowed to reach the ADC. Those frequencies outside the limits would only contribute to the noise in the final spectmm. The need for this system is dictated by the nonselective nature of the excitation rf pulse. 

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