Optical throughput,

In the infrared spectral range in general Fourier transform (FT) interferometers are used. In comparison with dispersive spectrometers FTIR enables higher optical throughput and the multiplex advantage at equivalent high spectral resolution. In... 

Special Problems Reflection Losses Result in Low Optical Throughput Limiting Signal to Noise Highly Susceptible to Airborne Noise and Build-inq Vibrations... 

The pyroelectric DTGS detector is a very useful low-cost, general purpose, wideband NIR detector well suited for use in FT-based analyzers. It is not normally used in scanning monochromators where higher sensitivity detectors are needed to match the lower optical throughput and discrete wavelength scanning requirements. 

First, the availability of high optical throughput in an FT-NlR analyzer means that lower-cost, more robust and also more linear DTGS detectors can be used routinely. These in turn allow (through the choice of suitable beamsplitter materials and source characteristics) a wider range of operation than the conventional... 

Also, for parallel multichannel devices, the source image can be divided, and injected simultaneously into a number (for example up to eight) of output fibers. Alternatively for more demanding diffuse reflectance or diffuse transmission applications with much lower optical throughput, the whole source image dimension can be used, but injected into micro- or macrobundle fiber optics. 

The use of hber optics and hber-optic multiplexing can increase the number of analysis points, and hence can reduce the overall costs related to a single analyzer. This approach has been used successfully with NIR instrumentation, where typically up to eight points can be handled. As noted earlier, the use of hber optics with IR Fourier transform instruments has in the past been limited. New hber materials with improved optical throughput are available, and also with the considered use of IR lasers, the role of hbers for IR applications is expected to increase. Although in the past commercial multiplexers have been available for mid-lR hber systems, their use has not been widespread. 

Deconvolution of spectra, such as infrared absorption spectra, provides researchers with a tool that they can use to carry out a particular experiment. It provides an extra measure of flexibility in the design of experiments and in the observation process. In dispersive infrared spectroscopic systems, Blass and Halsey (1981) have shown that effective resolution-acquisitiontime trade-offs may be made, owing to the fact that dispersive infrared spectroscopy is usually detector noise limited. Acquisition rates are therefore optical throughput dependent, which is equivalent to saying that acquisition rates are resolution dependent. Blass and Halsey (1981) show that, for a constant signal-to-noise ratio,... 

Thus, a 1pm diameter fiber would support one mode of green (X = 500 nm) light. Obviously, optical throughput (energy) of such a fiber is very low. A typical fiber of d < 10pm supports thousands of modes. 

Flat optical waveguides offer the possibility of increasing the optical throughput but maintaining the monomode internal reflection. This is achieved in the... 

The second fundamental advantage of an FT spectrometer over a grating spectrometer is often called Jacquinot s advantage and derives from the increased optical throughput of an interferometer compared to a grating monochrometer. 

The maximum optical throughput for a Michelson interferometer, 0 is given by max 6... 

The argument for the applicability (or lack of it) of the above factors in FTIR-based NIR applications centres on the issues of optical throughput and detector responsivity. NIR sources are comparatively very bright, and detector responsivities may be many orders of magnitude better than in the mid-IR. Hence in order to avoid detector... 

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