Filters spectral

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... 

Fig. 25-2. Double-beam, double-pass transmissometer for measuring smoke density in stacks. A[, chopper wheel A, beam gating wheel A3, aperture D, detector Fj, spectral filter F2, solenoid-activated neutral density filter L, lamp M, half-mirror/beam splitter Rj, solenoid-activated zero calibration reflector R2, retroreflector (alignment bullseye not shown). Design patented. Source Drawing courtesy of Lear Siegler, Inc.

Figure 10-10. (a) Semilogarillnnic plol of ihc stimulated emission transients for various excitation pulse energies measured for LPPP on glass. The excitation pulses have a duration of 150 fs and are centered at 400 nm. The probe pulse were spectrally filtered (Ao=500nin, Aa=l0nm). (b) Emission spectra recorded for the same excitation conditions. The spectra are normalized at the purely electronic emission baud (according lo Ref. [181). 

Straightforward application of OCT as described above often results in a quite complicated pulse shapes and may especially introduce some high frequency components, which are difficult to realize experimentally, into the pulse. It is thus highly desirable to find an optimized pulse with spectral components within a predefined frequency range. With this end in view the projected search direction is subjected to a spectral filter... 

Dakin J.P., Spectral filtering optical fiber sensors, Anal. Proceed. 1985 22 214. 

The characteristics of the laser system and SHG apparatus have been described earlier. The fundamental wavelength was obtained from a Q switched Nd+3/YAG laser operating at 1.064 fim and the harmonic was detected by a photomultiplier tube monochrometer combination with spectral filtering at 532 nm. 

C02-IR detection systems for example contain a light source emitting infrared light ideally at wavelengths around 4.2 pm (often a simple light bulb), an absorption path (the so called cuvette), a spectral filter and a detector (thermopile). The filter is normally integrated into the detector housing. 

A detailed description of LES filtering is beyond the scope of this book (see, for example, Meneveau and Katz (2000) or Pope (2000)). However, the basic idea can be understood by considering a so-called sharp-spectral filter in wavenumber space. For this filter, a cut-off frequency kc in the inertial range of the turbulent energy spectrum is chosen (see Fig. 4.1), and a low-pass filter is applied to the Navier-Stokes equation to separate the... 

Figure 4.1. Sketch of LES energy spectrum with the sharp-spectral filter. Note that all information about length scales near the Kolmogorov scale is lost after filtering. 

The filtering process used in LES results in a loss of information about the SGS velocity field. For homogeneous turbulence and the sharp-spectral filter, the residual velocity field5... 

A. Vijay, J. Chem. Phys., 118, 1007 (2003). A Lorentzian Function Based Spectral Filter for... 

Spectral Filters in Quantum Mechanics A Measurement Theory Prospective". 

H. Berends, DBR grating spectral filters for optical waveguide sensors, PhD thesis, (University of Twente, The Netherlands, 1997). 

The experimental setup for observing this effect, as seen in Figure 8, is identical to that for the quadratic response, except that the PLZT plate is prepoled to saturation remanence before using. Applications include modulators and spectral filters however, no devices have yet emerged utilizing this effect. 

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