Multiplex recording

Comparison between heat-mode and photon-mode processes is given in Table I. The main differences are the superior resolution and the possibility of multiplex recording in photon-mode systems. Because of the diffusion of heat, the resolution of heat-mode recording is inferior to that of photon-mode systems. Furthermore, photons are rich in information such as energy, polarization and coherency, which can not be rivalled by heat-mode recording. 

In infrared spectroscopy, the detector noise is usually much higher than the noise from other sources. In this case, multiplex recording provides an additional advantage. An interferogram contains the detector noise only once, independently of the number of spectral channels. Fourier transformation produces a spectrum where the SNR) of each spectral element is related to that of one line, SNR by ... 

Figure 16.24 shows the polarization-multiplexed recorded data X, Y, and Z at the respective recording polarization angles 0 , 60 , and 120 . Each pattern was recorded with the same exposure time. The lateral distance between bits in the plane was 3 /xm. The expected refractive-index change was estimated as about 0.01. 

Comparisons between heat-mode and photon-mode processes are given in TABLE 1. The main differences are the superior resolution and the possibility of multiplex recording in photon-mode systems. 

FIC. 16.24 Readout results of the polarization-multiplexed recorded data at the respective recording polarization angles 0°, 60°, and 120°. 

Fig. 9. Holographic pattern recognition system, (a) Recording an angularly multiplexed hologram (b) forming correlation outputs using arbitrary input...

Another possible advantage of the PHB method is its potential multiplexing characteristics by synchronous recording and read-out, exceptional data transfer rates can be achieved. These high transfer rates are of equal importance in practical data technology as high storage densities. 

Screening of compound libraries with medium throughput is only possible if the spectra can be recorded in a short period of time, and if one measurement gives simultaneously a number of answers. In practice, several ligands are usually measured in one protein sample, depending on the problem [5]. Mostly 10-20 ligands are combined to multiplexes, which need to be deconvoluted if a positive answer, as shown in Fig. 1 is obtained. The hits obtained maybe analyzed automatically or by hand through manual inspection of the spectra. 

An application for multiplexed diode-laser sensors with a potentially large impact is for measurements of important parameters at several locations in a gas turbine combustion system. In this example, illustrated schematically in Fig. 24.1, the multiplexed diode lasers are applied for simultaneous absorption measurements in the inlet, combustion, afterburner, and exhaust regions. For example, measurements of O2 mass flux at the inlet may be determined at the inlet from Doppler-shifted O2 absorption lineshapes near 760 nm. Measurements of gas temperature and H2O concentrations in the combustion and afterburner regions may be determined from H2O lineshape measurements near 1.4 pm. Finally, measurements of velocity, temperature, and species concentrations (e.g., CO, CO2, unburned hydrocarbons) may be recorded in the exhaust for the determination of momentum flux (component of thrust) and combustor emissions. 

Multiplexed diode laser sensors have also been applied for measurements of gas temperature, velocity, and H2O partial pressures in hypervelocity air flows at the Calspan University of Buffalo Research Center s (CUBRC) Large Energy National Shock Tunnel (LENS Tunnel) in Buffalo, New York [12]. The sensors were developed to provide quantitative characterization of the facility operation and, in particular, the freestream flow properties as a function of time. The measurements were recorded using a hardened probe, which contained critical optical components and photodetectors, that was installed directly into the hypersonic shock-tunnel near the nozzle exit to minimize complications due to boundary layers and facility vibration. 

Nal(Tl) crystals. The sample to be counted is mounted between Mylar sheets on a 1/4-inch thick X 5-inch diameter plastic ring. This system is presently used with a four quadrant, multiplexed, 4096-channel, multidimensional analyzer. The multidimensional y spectrum in coincidence with the proportional counter events is recorded in one quadrant, and the anticoincident multidimensional y spectrum is recorded in another quadrant thus, no data are lost. The various background y spectra obtained with this detector assembly are compared in Figure 12. The y-y coinci-... 

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