AOTF

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. 

AOT, could form w/c RMs in the presence of the commercially available perfluoropentanol (F-pentanol) as a co-surfactant, and the RMs formed could provide polar micro-aqueous for highly ionic chemicals[4,5]. Herein, we present the synthesis of crystalline nanoparticles of Ag, Agl, and Ag2S (which have potential application as photoelectric and thermoelectric devices) in the polar micro-aqueous domains of the w/c RMs stabilized by the AOT/F-pentanol (AOTF) surfactant/co-solvent combination, suggesting the possibility of the commercial utilization of SCCO2 in nanomaterials synthesis. 

AOTF w/c RMs bearing the silver, silver iodide and silver sulfide nanoparticles were depressurized slowly and the nanoparticles in the cell were collected and re-dispersed in ethanol. Finally, the sample grids for the TEM (FEl TECNAl G ) measurements were prepared by placing a drop of ethanolic dispersion of nanoparticles on the copper grid. The morphology and size distribution of the silver, silver iodide, and silver sulfide nanoparticles were determined by TEM at an operation voltage of 200kV. The crystallinity of the silver, silver iodide, and silver sulfide nanoparticles was studied by electron diffraction techniques. 

The Ag nanoparticles were synthesized by the reduction of Ag ions in the water core of the AOT/F-pentanol (AOTF) w/c RMs using NaBH(OAc)3. The acidic nature of the water core due to the formation of carbonic acid makes conventional reagents such as NaBH4 and... 

A modern spectrophotometer (UV/VIS, NIR, mid-IR) consists of a number of essential components source optical bench (mirror, filter, grating, Fourier transform, diode array, IRED, AOTF) sample holder detector (PDA, CCD) amplifier computer control. Important experimental parameters are the optical resolution (the minimum difference in wavelength that can be separated by the spectrometer) and the width of the light beam entering the spectrometer (the fixed entrance slit or fibre core). Modern echelle spectral analysers record simultaneously from UV to NIR. 

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

So far a modulator device has been described, not a filter. In order to understand how an AOTF device goes further than this, it is necessary to look at the effect of Bragg regime diffraction and the impact of the anisotropy of the AOTF crystal medium. 

In an AOTF analyzer the input optical beam to the crystal is polychromatic from a broadband source. For a given acoustic frequency and angle of incidence, only a very narrow band pass of wavelengths from the... 

The raw band pass of an AOTF has a sine squared function lineshape with sidebands, which if ignored, may amount tol0% of the pass optical energy in off-centre wavelengths. This apodization issue is normally addressed by careful control of the transducer coupling to the crystal. 

Although there are no slits associated with an AOTF device, there are some necessary compromises regarding throughput. First, there are physical restrictions on the size of available crystals, and in the case of the normal noncollinear arrangement where the inpnt beam direction is traversed by the acoustic wave front, then the open beam apertnre needs to be limited so that the transit time of the aconstic wave front across the crystal is limited, in order that a narrow optical band pass can be maintained. Typically this is of the order of a few millimeters. 

The temperature tuning coefficient of TeOa is 0.025 nm/°C, so it is clear that in order to combat the effects of thermal heating of the crystal due to incident optical and aconstic power, as well as environmental considerations, a good level of thermal control is needed. This can be in the form of a thermo-electrically cooled enclosure. This will deal to a certain extent with the need to achieve analyzer wavelength repeatability. However, it does not address the issue of wavelength reproducibility between AOTF modnles, which impacts the transportability of calibrations and datasets between analyzers. 

Broadband tunable filters (examples AOTF, LCTF) X ... 

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

TF Systems A TF is a device whose spectral transmission can be controlled by applying a voltage or acoustic signal. There are two main TF devices acousto-optical TF (AOTF), based on diffraction, and liquid crystal TF (LCTF), based on birefringence. An AOTF is a transparent crystal in which an ultrasonic wave field is created,... 

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