Acousto-Optic Tunable Filters (AOTFs)

The acousto-optic filter system offers flexible control of the laser intensity and is designed to meet specific demands for all of the Olympus FluoView^TM confocal microscope systems.

The acousto-optic tunable filter (AOTF) is a specially designed element that controls light intensity by directing acoustic waves through a dense crystalline matrix. The principal feature of the AOTF is the high speed control of laser light intensity and wavelength. The ultrasonic wave introduced into the AOTF crystal forms a compression wave and acts as a diffraction grating due to the re-distribution of the refractive index within the crystal. The grating separates incident laser light into zeroth order and first order diffraction waves. The first order diffraction wave is used, and its wavelength and intensity are controlled by the frequency and intensity of the ultrasonic wave. The AOTF system employed in the FluoView^TM uses multiple acoustic frequencies to control each laser wavelength independently.

Benefits of the FluoView^TM AOTF Include:

• Minimal Specimen Fading - The laser exposure will be limited within the scanning area by default. Also, there will be no laser exposure in the flyback motion of the galvanometer mirrors. These features minimize unnecessary photobleaching of the specimen.

• Sequential Line Scanning for Reduced Crosstalk - Individual lines can be scanned sequentially, minimizing the time difference between each wavelength and producing images with less crosstalk.
• Region of Excitation Mode - Providing any laser intensity level for any excitation area, the AOTF enables users to designate several different areas on the specimen and apply different laser intensities to each. Laser intensities can be set in 0.1 percent increments for each designated area. There is no limit to the number of areas that can be designated.

• Multiple Laser Applications - Adding the time course software to the FluoView^TM palette enables sequential time-lapse observations in which several application area patterns are combined in a single experiment. The freedom of bleaching an area and controlled intensity add even more variety to fluorescence recovery after photobleaching (FRAP) experiments.

• Ease of AOTF Controller Configuration - The FluoView^TM AOTF controller has input/output trigger terminals on the rear of the instrument and can synchronize laser application with the experiment being performed. The controller also enables the user to monitor laser intensity levels.

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