Prism-Based Infrared Spectrographs Using Modern-Day Detectors

Abstract

A comparison of prism-based spectrographs to grating-based spectrographs is made when each of the systems is coupled to a modern-day liquid-nitrogen-cooled photovoltaic array detector. A comparison of the systems is also made using a room-temperature microbolometer array detector. Finally, infrared microspectroscopy of samples whose size is approximately 10 micrometers will be demonstrated using a prism spectrograph outfitted with both types of detectors. The results of the study show that prism-based spectrographs offer an economical alternative to grating-based systems when spectral coverage is more critical than spectral resolution. The results also demonstrate that spectra with good signal-to-noise ratios can be collected on any of the systems with a total integration time of 10 seconds or less.

Rapid Molecular Imaging Using Attenuated Total Internal Reflection Planar Array Infrared Spectroscopy for the Analysis of Counterfeit Pharmaceutical Tablets

“…Once the data is collected, the corresponding infrared spectra from the 256 3 256 image can be converted from pixel numbers to wavenumbers using a previously reported process. 25 To explain briefly, an infrared spectrum was collected on a sample both interferometrically and also with the PA-IR system. The pixel number absorptions obtained from the PA-IR spectrum were plotted against wavenumber absorptions from the FT-IR spectrum.…”

“…PA-IR spectroscopy is gaining acceptance as a viable alternative to FT-IR spectroscopy for many applications. [20][21][22][23][24][25][26][27][28] The emergence of PA-IR spectroscopy can be attributed to its sensitivity, rugged nature (no moving parts), and multichannel detection capabilities for imaging. Most of the current PA-IR systems incorporate either grating or prism-based macro sampling accessories and employ mercury cadmium telluride (MCT) focal plane array detectors.…”

“…In an effort to lower the cost of PA-IR imaging systems, Keltner et al demonstrated the use of a room temperature microbolometer array and an infrared prism-based spectrograph. 25 Keltner pointed out that the room temperature arrays are larger, in both size and number of pixels, than their liquid nitrogen cooled counterparts; as a result, either larger areas can be observed or the same area can be investigated with superior pixel resolution. The focus of the current investigation involves construction of a prism-based ATR-PAIR spectrograph using a 256 3 256 MCT array detector (40 lm pixels).…”

Clinical instrumentation and applications of Raman spectroscopy

“…There has recently been renewed interest in reflective and prism-based approaches to dispersion. 54,55 Reflective gratings can usually cover a larger range of the spectrum at high spectral resolution, but often result in a longer integration time due to lower efficiency and movement of the grating position. Some devices circumvent this issue by including versatile options for either static or full-range spectral measurements, or include gratings with different dispersion elements to achieve high resolution.…”

Concept for a single-shot mid-infrared spectrometer using synchrotron radiation

“…Generally, prism-based spectrographs have the advantage of a higher optical transmission when compared to grating spectrographs, although optimized grating structures [30] can reach diffraction efficiencies up to 80%. Prisms are deployed when spectral width rather than spectral resolution is demanded [31]. In addition, they do not suffer from order effects and stray light.…”