Compact and efficient spectrometers are of great interest for biological and environmental sensing. In this paper, we
describe a new class of spectrometers that work based on diffractive properties of spherical beam volume holograms
(SBVHs) and cylindrical beam volume holograms (CBVHs). The hologram in these spectrometers acts as a spectral
diversity filter (SDF) that maps different input wavelengths onto different locations in the output plane. The main
properties of these holographic SDFs and new techniques for removing the ambiguity between incident wavelength (or
the input channel) and incident angle (or the input spatial mode) are discussed. By using CBVHs, we show that the
spectral mapping of the input beam can be obtained in one direction and the beam can be independently modified in the
perpendicular direction. Using this unique property, we demonstrate a spectral wrapping technique to considerably
increase the operation spectral range of spectrometers, without sacrificing their resolution. Finally, it is also shown that
by combining CBVHs with a Fabry-Perot interferometer, a true two-dimensional spatial-spectral mapping can be
formed, and an ultra-high resolution of 0.2 nm with large spectral bandwidth is demonstrated for this tandem
spectrometer.
We present a class of spectrometers that work based on diffractive properties of spherical beam volume holograms. The hologram in these spectrometers is recorded by a plane wave and a spherical beam and acts as a spectral diversity filter (SDF), which maps different input wavelengths into different locations in the output plane. The experimental results demonstrate that the spherical beam volume holograms have the capability of separation different wavelength channels of a collimated incident beam. For the analysis of the spherical beam volume hologram, a new theoretical method is introduced and used. It is shown that the experimental results are in good agreement with the theoretical study. Using these results, we demonstrate a Fourier-transform volume holographic spectrometer formed by a Fourier-transform lens, a spherical beam volume hologram, and a CCD. We show that this spectrometer can operate well under spatially incoherent light illumination without using any spatial filter (i.e., slit) in the input. We finally introduce a new implementation of a spectrometer for diffuse source spectroscopy by using only a volume hologram, recorded by two spherical beams, and a CCD. The proposed spectrometer is very compact, inexpensive, less sensitive to optical alignment, and has potentially high throughput that can be widely used in biological and environmental sensing applications.
The kinetics of the recording, compensating, and developing processes in two typical thermal fixing procedures (L-H-L and H-L procedures) are analyzed. The optimum condition (in terms of the fixing temperature, compensation time and material parameters) for each fixing procedures are obtained under the boundary condition of shot-circuit. Experimental results are shown which are in qualitative agreement with the theory in L- H-L procedure.
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