Filters acousto-optic

Accelerator mass spectrometry Acousto-optical tuneable filter Acousto-optical tuneable spectrometer/scanning Atom probe... 

Acousto-optic Filters. The newest type of spectrometer to become commercially available is the acousto-optic tunable filter (AOTF). An AOTF is a sohd-state, electronically tunable bandpass filter based on the diffraction of optical waves by acoustic waves in an optically anisotropic crystal. 

Fig. 2. Stmctures of acousto-optic tunable filters (a) collinear and (b) noncollinear.

P. J. Treado, I. W. Levin, and E. N. Lewis, Near-infrared acousto-optic filtered spectroscopic microscopy A solid-state approach to chemical, Imaging. Appl. Sped. 46, 553-559 (1991). 

Because NIR was initially used for food and agriculture products, it has evolved as a technique for complex matrices. Many types of hardware have become available for NIR work interference filters, gratings, interferometers, diode arrays, and acousto-optic tunable filters. And, as it was originally developed for complex mixtures, chemometrics has been an integral part of any NIR analysis for the last few decades. NIR practitioners are quite comfortable with multivariate equations and development of equations for complex matrices. 

The acousto-optic tunable filter (AOTF) analyzer... 

AOTF acousto-optical tunable filter CPAC Center for Process Analytical... 

Monmayrant, A., Joffre, M., Oksenhendler, T., Herzog, R., Kaplan, D., and Tournois, P. 2003. Time-domain interferometry for direct electric-field reconstruction by use of an acousto-optic programmable filter and a two-photon detector. Opt. Lett. 28(4) 278-80. 

Verluise, R, Laude, V., Cheng, Z., Spiehnann, C., and Toumois, P. 2000. Amplitude and phase control of ultrashort pulses by use of an acousto-optic programmable dispersive filter Pulse compression and shaping. Opt. Lett. 25(8) 575-77. 

IR spectroscopy is not a very sensitive analytical tool and is, therefore, not well suited to the detection of small amounts of material. If, however, intermediates have intense and well-resolved IR absorptions, the progress of their chemical transformation can be followed by IR spectroscopy [83,88,91-93], Near-infrared spectroscopy, in combination with an acousto-optic tunable filter, can be sufficiently sensitive to enable the on-bead identification of polystyrene-bound di- and tripeptides, even if the peptides have very similar structures (e.g., Leu-Ala-Gly-PS and Val-Ala-Gly-PS) or differ only in their amino acid sequence (e.g., Leu-Val-Gly-PS and Val-Leu-Gly-PS) [94]. Special resins displaying an IR and Raman barcode have been developed, which may facilitate the deconvolution of combinatorial compound libraries prepared by the mix-and-split method [48]. 

It should be noted that the transmission of the acousto-optic filter is only about 50%, while the transmission of the liquid crystal filter is about 20-40%. By contrast, a dielectric filter passes 80-90% of the incident light. The differences arise because both the AOTF and LCTF operate on linearly polarized light. In most Raman microprobes, both polarization components of the Raman scatter are collected, even when the exciting laser is linearly polarized. 

There are several measurement techniques that can be considered for use in IR-based instrumentation in the NIR and the mid-IR spectral regions, and these are summarized in Table 4.1. Some of these techniques are classical, as in the case of optical filter-based instruments and scanning monochromators. Others, such as acousto-optically tunable filter (AOTF), have been considered for 15+ years, but are mainly applied to NIR... 

Wang, X. Soos, J. Li, Q. 8t Crystal, J., An Acousto-Optical Tunable Filter (AOTF) NIR Spectrometer for On-line Process Control Process Contr. Qual. 1993, 5, 9-16. 

Wang, X., Acousto-Optic Tunable Filters Spectrally Modulate Light Laser Focus World 1992, 28, 173-180. 

Fig. 1 Schematic drawing of a wide-field single-particle tracking fluorescence microscope equipped. Several lasers are used as excitation source for different fluorophores with fast selection hy an acousto-optical tunable filter (AOTF). The collimated laser light is coupled into the objective such that only the observed area is illuminated. The emission light is separated from the excitation light by a dichroic mirror. In the case of multi-color imaging, the emission light is separated by...

Fig. 2. Set-up of the ILP laser system. Intracavity frequency-doubling is realized with a KTP crystal which, together with a Brewster plate, serves as a Lyot filter. This allows to frequency time the laser by more than 500 GHz by changing the temperature of the KTP crystal. The 532 nm laser radiation, after passing an acousto-optical modulator (AOM), is directed into an external I2 fluorescence cell. A photomultiplier (PM) detects the fluorescence signal over a solid angle of almost 0.2 n. The photodiode D is used to detect a fraction of the 532 nm laser beam to power stabilize the 532 nm light via the AOM...

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