Noise Equivalent Flux

This table summarizes some characteristics and the expected performance of IRAS. The noise equivalent flux density and noise equivalent spectral density have been computed on the basis of a zodiacal emission of 3 x 10 W cm sr and a telescope temperature of 16K, while the orbital scan rate... 

The data of Figure 3 are converted to noise equivalent flux densities. 

There are important figures of merit (5) that describe the performance of a photodetector. These are responsivity, noise, noise equivalent power, detectivity, and response time (2,6). However, there are several related parameters of measurement, eg, temperature of operation, bias power, spectral response, background photon flux, noise spectra, impedance, and linearity. Operational concerns include detector-element size, uniformity of response, array density, reflabiUty, cooling time, radiation tolerance, vibration and shock resistance, shelf life, availabiUty of arrays, and cost. 

The Raman cross-section is proportional to v and to a. The molecular cross-section of Raman spectroscopy is some ten orders of magnitude smaller than that of IR spectroscopy. However, for a typical classical detector of Raman spectra, the photomultiplier (PMT), the number of photons to produce the noise equivalent power (NEP), which is the light flux necessary to produce a signal of the same magnitude as the noise, is up to ten orders of magnitude smaller than those of detectors employed... 

Noise equivalent power NEP The incident radiation power generating in the detector an output signal equal to the detector internal noise corresponds to the minimum detectable flux. Measured in W/Hz NEP = - ... 

Abstract. A liquid helium cooled midrinfrared ima ng Fabiy-Peiot ectiometei has been under development. A Si P 5x5 detector array is used for this instrument. Although the array system has small format, but conibination with JFET array will provide noise equivalent line flux of 1.0 x 10 TF/cm (1000sec,10[Pg.339]

Finally, it should be noted that with our present system and certain samples, background or analyte photon signal fluxes are large enough that measurements are flicker noise limited (noise proportional to the signal). In this case, the IDA already provides detection limits equivalent to that obtained with PMT detection. 

Air is prevented from entering the telescope where it would condense on the cold optics by a four micron thick polyethylene membrane. This system is being prepared for shipment to Palestine, Texas for launch in late June 1976. The potential sensitivity of this instrument flying at an altitude of 110,000 feet is rms flux equivalent noise of 34 Jy/y lz, 20 microns, 49 at 50 microns and 62 and 100 microns. 

These results imply that the extension of equilibrium theories to nonequiUbrium states is not always valid in a straightforward way. Particularly, the diffusion tensor is proportional to the components of the pressure tensor or equivalently to the velocity gradient Vvq, which implies that the amplitude of the noise in the dynamics of the tagged particle is not simply thermal as in equilibrium since the diffusion tensor cannot be characterized entirely by the thermodynamic temperature. In similar manner, Eq. (5) does not depend on the irreversible heat flux. This is an anomaly of the Maxwell potential, for other potentials there will be an additional contribution to the drift vector that would depend on the any temperature gradient in the fluid. 

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