Cross-talk absorption

Absorption regions of HgCdTe are formed at regions between detector elements in the invention of JP-A-63043366. The design reduces the problem of cross-talk. 

Cross-talk is reduced in US-A-5376558 by forming a three layered light absorption structure in the areas between the photodiodes of the array. The second layer has a refractive index which is greater than that of the first layer and the third layer is a metal layer. 

The amount of cross-talk is reduced in JP-A-4313267. Individual detector elements are separated by grooves in which an absorption layer of HgCdTe is formed. 

Utoguchi N, Watanabe Y, Shida T, Matsumoto M (1998) Nitric oxide donors enhance rectal absorption of macromolecules in rabbits. Pharm Res 15 870-876 Uzzau S, Fasano A (2000) Cross-talk between enteric pathogens and the intestine. Cell Microbiol 2 83-89... 

Two-thirds of the energy acquired from the absorption of the photon remains in the opsin protein. From this energy-rich state rhodopsin passes through several intermediate states on the way to the signalling state which is able to bind and activate the G protein, transducin. The 9-methyl group of retinal is the allosteric trigger that opens the cross-talk... 

Table I, provided yet another instrumental approach for balloon experiments intended to measure the extinction of solar radiation by stratospheric aerosol. Spectrometer 4, Table I, based on the use of a pyroelectric vidicon image device, was developed to measure the strong absorption bands of non-isonuclear molecules ( 2-5 ym range). Recently we have developed spectrometer 5, Table I, based on the use of a self-scanned solid state pyroelectric array sensor. The main advantages of this sensor, over the pyroelectric vidicon, are its improved sensitivity and reduced channel-to-channel cross-talk.

Figure 5 Cross-talk. Fluorescence generated In a 1 mm spot area is detectable from an outside area. It spreads by scattering processes and will be reshaped by absorption processes. Monte Carlo simulations and measured data show that haemoglobin absorption in tissue affects emission intensities at 580 nm more than at 600 nm. Adapted with permission from Keijser M, Richards-Kortum RR, Jacques SL and Feld MS (1989) Fluorescence spectroscopy of turbid media Autofluorescence of the human aorta. Applied Optics 28(20)-. 4286-4292.

In addition to cross-talk, we can also take into account the effects of absorption in arrays. This is useful in the study of visual photoreceptors, which in many animals are absorbing fibers, often single moded and weakly guiding [2,3], The image encoded by a photoreceptor array is determined by the distribution of absorbed light across the array. Here we examine the image deterioration due to cross-talk when the photoreceptors have the alternate illumination of Fig. 29-3. 

We assume a uniform power absorption coefficient a throughout the array, in which case the power attenuation coefficient y for each fiber satisfies y = a, as we showed in Section 18-8. Thus, by analogy with Eq. (29-21), the power in each fiber is given by the product of Pj (z) or P2 (z) of Eq. (29-39) with exp (—az). We define P+ (z) and P (z) to be the power absorbed over length z of fibers with illumination -f and —, respectively. If there were no cross-talk, then P+(z) - P,(0) and P (z) - P2(0) as z - 00, i.e. each fiber of the array would absorb all of the power illuminating it. However, because of cross-talk, this situation is degraded. If we define a normalized difference in absorption... 

For creating patterns of more than one type of molecule, the two fluorescent dyes must be chosen with spectrally separated absorption peaks. The two beams must be aligned collinearly, and it is essential to avoid cross-talk between channels, i.e., each laser should only... 

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