Detector, acousto-optical

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. 

Abbreviations AOD, Acousto-optical deflection BCB, bisbenzyocyclobutadiene CCD, indirect contact conductivity detection CL, chemiluminescence ECD, electron capture detector FCS, fluorescence correlation spectroscopy FRET, fluorescence resonance energy transfer ICCD, integrated contact conductivity detection GMR, giant magnetoresistive LED-CFD, light emitting diode confocal fluorescence detector LIF, laser-induced fluorescence LOD, limit of detection MALDI, matrix-assisted laser desorption ionization PDMS, poly(dimethylsiloxane) PMMA, poly(methylmetha-crylate) SPR, surface plasmon resonance SVD, sinusoidal voltammetric detection TLS, thermal lens spectroscopy. 

Figure 1 Apparatus of Oxford experiment [6]. LI, L2 tunable dye lasers. UV ultra violet radiation (243 nm). RF radiofrequency dissociation of flowing molecular hydrogen. PI signal photomultiplier (Lyman-a detector). P2 photomultiplier for cavity locking and signal normalisation. SI cavity length servo-control. C conrouter. AOM acousto-optic modulator. T heated quartz cell containing tellurium. S2 laser frequency servo-control. D fast photodiode...

A modification of the Debye-Sears effect, i.e., the modulation of the refractive index by acoustical waves functioning as tunable grating, is now applied to fast scanning NIR spectroscopy The Acousto-Optic Tunable Filter (AOTF), (Harris and Wallace, 1969 Chang, 1981). In combination with array detectors, chemical imaging is possible (Treado et ah," 1992). 

Numerous styles and brands of instruments and sample cells have been used for the analysis of tablets. The authors currently use several brands of instrumentation for tablet analysis, including filter-, diffraction grating-, and acousto-optic tunable filter-based instrumentation. Detector configurations are evolving slowly toward an optimal design however, the designs of most manufacturers are suitable for many applica-... 

Select an appropriate dichroic mirror to reflect the 514-nm excitation light to the specimen. Select and an appropriate bandpass filter in the emission filter wheel (550/40, Chroma). In addition to the emission filter, we place a 514-nm notch filter (Semrock) into the emission filter slot of the dichroic mirror cube to block unwanted excitation light from reaching the detector, and we use a 514-nm excitation filter to clean up unwanted wavelengths from the argon gas laser that are not blocked by our acousto-optical tunable filter. 

The first term represents the shot noise, the second is the dc term, and the third term gives the heterodyne beat spectrum with the difference (co — coq) and sum (o) -h coo) frequencies. The detector is not fast enough to detect the sum frequency. The output signal of the third term therefore contains only the difference frequency (co — ct)o)- If this difference frequency lies in an inconvenient frequency range, the local oscillator can be shifted with an acousto-optic modulator to the frequency COL Act) in order to bring the difference frequency 0)+ Acd — cog into an easily accessible range [947]. 

Microscope with Multichannel Detection In this scheme, an unfocused laser beam illuminates the area of the sample. An optical filter isolates the selected Raman line, and the multichannel detector produces a picture of the sample. At the time of this publication, the optical filter was a monochromator used as a filter. [Since then, this same concept has been implemented with dielectric filters [57], AOTFs (acousto-optic tuning filter) [58], and LCTFs (liquid-crystal tuning filter) [59,60] these technologies will certainly be covered in later chapters on microscopy and imaging.]... 

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