Narrow-bandpass

Boron implant with laser anneal. Boron atoms are accelerated into the backside of the CCD, replacing about 1 of 10,000 silicon atoms with a boron atom. The boron atoms create a net negative charge that push photoelectrons to the front surface. However, the boron implant creates defects in the lattice structure, so a laser is used to melt a thin layer (100 nm) of the silicon. As the silicon resolidihes, the crystal structure returns with some boron atoms in place of silicon atoms. This works well, except for blue/UV photons whose penetration depth is shorter than the depth of the boron implant. Variations in implant depth cause spatial QE variations, which can be seen in narrow bandpass, blue/UV, flat fields. This process is used by E2V, MIT/LL and Samoff. 

It should be noted that when we compare the brightness of a LGS to a NGS, the result depends on the spectral bandwidth, because the LGS is a line source, whereas the NGS is a continuum one. The magnitude scale is a logarithmic measure of flux per spectral interval (see Ch. 15). This means that a (flat) continuum source has a fixed magnitude, no matter how wide the filter is. In contrast, the magnitude of a line source is smaller for narrower bandpasses. It is therefore advisable to use the equivalent magnitude only for qualitative arguments. The photon flux should be used in careful system analyses. 

The 2 emission at 394 nm and the HPO emission at 526 nm are selected by means of appropriate narrow bandpass filters and the lower half of the flame is shielded to reduce background... 

The instruments used in X-ray emission spectrometry reflect the principles set out in Chapter 7. Radiation characteristic of the specimen is produced by electron or radiation bombardment. Monochromatic radiation is then presented to the detector by a diffraction device or by use of a series of narrow bandpass filters. Alternatively pulse height analysis (p. 465) can be applied to a series of pulses which have been generated with a size proportional to the radiation energy. Typical X-ray spectrometry arrangements are shown in Figures 8.40 and 8.41. 

Effect of bandpass and choice of wavelength on a Beer s law plot. Curve A represents a calibration curve using a narrow bandpass monochromator at k. Curve B represents a calibration curve using a wide bandpass filter at X or a narrow bandpass monochromator at. ... 

Figure 2. Experimental set-up for Raman spectroscopy. The desired laser line is isolated from other plasma lines by a narrow bandpass filter or broadband prism monochromator, then focused onto a sample in a capillary tube. A collecting lens placed at a 90° angle to the incident beam focuses the scattered light onto the entrance slit of a monochromator with output to a photomultiplier tube (in the case of a scanning instrument) or a diode array detector.

Therefore, in order to minimize the overlap between G+( ) and Fj+ oo) for general gapped baths, and thereby the transfer infidelity (4.198), we will design a narrow bandpass filter centered on the gap. Since G ( ) has a narrower gap than G+( ), we optimize the filter Fj o)) under the variational E-L method. We seek a narrow bandpass filter, whose form on time domain via Fourier transform decays as slowly as possible, so as to filter out the higher frequencies. This amounts to maximizing Fj- (t) = ( )e (f subject to the variational... 

Figure 7. The effect of ambient temperature changes on the transmission of narrow bandpass optical filters of different design on separate substrates.

It is also possible to partially alleviate the problem of chemical insensitivity by incorporating narrow bandpass filters into the optical setup.20 Thus, by choosing an appropriate frequency region, it becomes possible to detect the presence of a particular reactant or product species. While this adds some measure of chemical sensitivity to the thermography approach, it is only capable of monitoring one species at a time. Additionally, the success of this approach relies upon the fact that the spectral bands of the desired species do not overlap with any other species and that unexpected reaction products that have spectral contributions in the region of interest are not present. 

These are highly selective and among the most sensitive of detectors. They are based on filter fluorimeters or spectrofluorimeters (p. 376) but are usually purpose-designed for hplc or capillary electrophoresis (p. 168). The optical arrangement of a typical detector using filters is shown in figure 4.30. Excitation and emission wavelengths are selected by narrow bandpass filters. 

So far in this discussion of diffraction, we have assumed that the periodic object is illuminated by coherent light, such as that produced by a small laser of the type used in the Porter experiments. However, the light produced by a thermal source (e.g., a sodium vapor lamp or a heated filament coupled with a narrow bandpass filter) is never strictly monochromatic even the sharpest spectral line has a finite width. Moreover, such a source has finite extent, and the light is emitted by many independent radiators (atoms). These two characteristics of thermal sources are directly related to what are usually referred to as temporal and spatial coherence, respectively. 

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