Acousto-Optic Devices Acousto-Optic Devices A piezoelectric element is bonded to an acousto-optic medium consisting of single crystal such as tellurium dioxide (TeO2) and lead molybdate (PbMoO4) or glass, and when an electrical signal is applied to this piezoelectric element to generate acoustic waves, which are propagated in the medium, a laser beam passing through the medium is diffracted (Acousto-Optic effect). This diffraction includes Bragg diffraction and anisotropic Bragg diffraction. Using the former is an acousto-optic light modulator, and using the latter is an acousto-optic light deflector and acoustooptic tunable flter. The acousto-optic light modulator can modulate laser beam intensity by means of amplitude modulation at a fixed frequency. The acousto-optic light deflector is capable of angle modulation (position modulation) and intensity modulation for laser beam by means of frequency modulation and amplitude modulation. The acousto-optic tunable filter can select diffracted light wavelength by means of frequency modulation and can modulate output intensity by means of amplitude modulation. Some specifications of AO devices can be optimized according to the needs/purpose of customers. Please contact us for further details. Safety Precautions (Common precautions for Acousto-Optic Devices) ◊ When using our products, no matter what sort of equipment they might be used for, be sure to make a written agreement on the specifications with us in advance. ◊ Do not use the products beyond the specifications described in this catalog. 1. Falling Shock As single crystal or glass is used as medium for acousto-optic devices, care shall be taken not to give a falling shock to prevent breakage of the devices. 2. Electrical Input (Driving Power) The electrical input power shall not exceed the specified maximum driving power to prevent breakage of the crystal. 3. Laser Input Beam Polarized light conditions of laser input beam differ in accordance with the input equipment types. Operate at the specified polarized light. Exercise caution as the light input of 1 W/mm2 or more can not be applied in some cases. 4. Dewing Dewing on optical surfaces of the medium causes stain, thus deteriorating the light transmittance. 5. Installation Use fixing screws and bragg adjusting rotating axis with the allowable depth of the fixing taps or the rotating center hole specifed in the product diagram or more. 6. Environmental Conditions The AODs shall not be operated and/or stored under following environmental conditions: a) To be exposed directly to water or salt water b) Under conditions of dew formation c) Under conditions of corrosive atmosphere such as hydrogen sulfied, sulfurous acid, chroline and ammonia. 7. Long Term Storage The AODs shall not be stored under severe conditions of high temperatures and high humidities. Store them indoors under 40 °C max. and 75 %RH max. with no dew formation. <Package markings> Package markings include the product number, quantity, and country of origin. In principle, the country of origin should be indicated in English. Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use. Should a safety concern arise regarding this product, please be sure to contact us immediately. 00 Dec. 2014 Acousto-Optic Devices Definition of Terms Terms Definition Center Frequency: fo Driving frequency at light modulator and the center frequency of deflection bandwidth at light deflector. Modulation Bandwidth: Δ fi This is calculated via following equation using response (tr) Δ fi=0.35/tr Diffraction Efficiency Ratio of the first-order diffracted light intensity (I1) and the 0th diffraction intensity with no driving power (Transmitting light intensity) (I00) I1/I00 (%) Rise time at pulse modulation (10 to 90 %) With the pulse response of electric system (te) included, the total response time (ts) is ts=√ te2+tr2 (%) 90 Pulse Response: tr 10 tr Extinction Ratio Ratio of the maximum first-order diffracted light intensity and the optical intensity in the same direction with no driving power. Number of Resolvable Spots: N Ratio of the deflection angle Δ q=l Δ f/u and the extending angle of optical beamΔ qb=l/D D 1 1 Δq 1 = · Δf · = · Δf · t N= · u g g Δqb g l : Optical Wavelength D : Diameter of input laser beam Δ f : Defection Bandwidth g : Coefficient in accordance with optical beam shape u : Acoustic Velocity of medium t : Access Time Access Time: t Time for acoustic wave to pass optical beam t=D/u Deflection Bandwidth: Δ f Driving frequency range where first-order diffracted light intensity is half of the maximum value (–3 dB). Deflection Angle: Δ q Diffraction angle in accordance with deflection bandwidth Δ q=l Δ f/u Resolution Extention of filter light wavelength with the constant driving frequency at acousto-optic tunable filter. Dispersion of Deflection Angle Wavelength dispersion of diffracting direction(angle) in the range of optical wavelength at acousto-optic tunable filter. Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use. Should a safety concern arise regarding this product, please be sure to contact us immediately. 00 Dec. 2014 Acousto-Optic Devices Application Examples (Light Modulator) Cleaning Laser Laser Charging Polygon Lens u Lens Photo Detector Transferring f·q Lens Lens Light Modulator Beam Splitter Sensitive Drum Flow Cell Slit mirror Light Modulator Fixing Lens High Freq. Signal Developing Signal Processor Laser Doppler Velocity Meter Laser Printer (Light Deflector) AOD AOD Laser Beam Laser Beam Diffracted Light Diffracted Light 0 th.Light Stopper 0 th.Light Stopper Amp Amp VCO VCO Input Signal Input Signal Laser Beam Random Access Scanner Laser Beam Sweep Scanner AOD Lens Image Sensor Laser Beam Computor 0 th.Light Stopper Amp Input Signal Mixer Local Oscillator Spectrum Analyzer (Acousto-Optic Tunable Filter) Color Original Drum Monochromatic Light Electrical Signal Acousto-Optic Tunable Filter EFL-F20 Photomultiplier Amp. Changing-Over Switch Memorized Standard Signal RF Amp. Differential Amp. White Light Source Sweep Oscillator Trigger Gate Circuit Color Analyzed Signal Schematic Diagram of a Color Analyzer System Using Acousto-Optic Tunable Filter Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use. Should a safety concern arise regarding this product, please be sure to contact us immediately. 00 Dec. 2014