Multi-Channel Modulators (AOMC)
Acousto-optic multi-channel modulators (AOMC) allow multiple beams to be modulated or deflected independently by integrating an array of transducers with a single acousto-optic crystal. We have minimized crosstalk through proprietary optical and electrical designs to allow concurrent operation of up to 48 channels for modulation, and up to 8 channels for beam deflection. Our multi-channel modulators are known for their reliable operation and high performance.
Multi-channel modulators are most often used for high speed applications like micromachining and direct-write lithography, as each beam can be modulated independently. They are also used to increase throughput when writing large media by writing multiple beams at the same time.
An acousto-optic multi-channel modulator (AOMC) operates on the same principles as a typical acousto-optic (AO) modulator, but is fabricated using an array of electrodes on the transducer substrate so that a parallel array of beams can be simultaneously controlled. A different acoustic wave diffracts each input beam independently to modulate its intensity or to deflect a portion of the beam into the 1st order mode.
As the number of channels incorporated into a single device increases, so does crosstalk. Either as electrical crosstalk in the circuitry and electrodes, or as acoustic crosstalk between the various modulation channels. Thermal crosstalk can also arise as a channel is turned on, inducing thermal strain in the adjacent channels and altering the acousto-optic effect. These effects often limit the number of channels possible, the contrast ratio of those channels, or their spatial resolution.
Careful placement of electrodes and the optical aperture optimizes performance. Design of the associated RF driver is equally important to minimize crosstalk and ensure easy interfacing for control by a larger system. Multiple beams or a sheet of collimated light may be manipulated.
A typical multi-channel modulator has parallel beams as input, each operated on by a different transducer to modulate its intensity. We offer 2 to 48 channels for UV through NIR wavelengths, with rise times as short as 7 ns for apertures < 1 mm. Multi-channel RF drivers are available with analog or digital modulation.
A multi-channel deflector generates multiple diffracted beams from a single input beam at specific locations by simultaneously applying multiple frequencies to a single transducer. Each individual channel is a deflector that can either scan the beam or produce multiple spots. This makes it possible to create a two-dimensional grid. For example, if a four channel deflector were configured so that each channel diffracted three spots, the result would be a 4x3 grid.
Our multi-channel modulators match the variety of performances available with our single channel modulators, and can be customized for large aperture applications as well as high speed small aperture applications.
High laser damage threshold is achieved using low-scatter materials inspected to rigorous quality standards. We draw our own tellurium oxide (TeO2) and source high quality fused silica and crystalline quartz to ensure low insertion loss and excellent optical power handling.
Applications of multi-channel modulators
Marking, material processing, micromachining, printing
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