Question about Acousto-optic devices.

[Laser Electronics Ltd]

AO's can only handle one frequency and the RF harmonics have to be tuned to the specific frequency at the correct timing.
PCAOM's can deal with several frequencies dependant upon the cycle frequency in the RF modulation, the draw back is PCAOM's cause an ablation of the beam when the RF gain is to high and the modulation frequency is within the division of the switching frequency versus the RF gain.
To use either an AO or PCAOM you need a TEM00 beam and the correct polarisation.
Both AO's and PCAOM's have a 2.5 degree deflection angle, any higher drive causes ablation of the light source.
When used in XY configuration the use of a polymorphic dampening field is required.

[swamidog]

what about something like this:

http://www.physikinstrumente.com/en/...?sortnr=300710

[krfkeith]

AO's can only handle one frequency and the RF harmonics have to be tuned to the specific frequency at the correct timing.
PCAOM's can deal with several frequencies dependant upon the cycle frequency in the RF modulation, the draw back is PCAOM's cause an ablation of the beam when the RF gain is to high and the modulation frequency is within the division of the switching frequency versus the RF gain.
To use either an AO or PCAOM you need a TEM00 beam and the correct polarisation.
Both AO's and PCAOM's have a 2.5 degree deflection angle, any higher drive causes ablation of the light source.
When used in XY configuration the use of a polymorphic dampening field is required.

Yeah, that's the main problem. So my question is whether one can use optics to expand the deflection angle without causing the beams to diverge.

[krfkeith]

what about something like this:

http://www.physikinstrumente.com/en/...?sortnr=300710

Those certainly look interesting. However, you're still dealing with rather low angles, only 5.7 degrees maximum.

[Laser Electronics Ltd]

5.7 degrees deflection, these are piezo devices and unlike AO or PCAOM don't have the resonant stability of a crystal.
Piezo devices are great provided you design a resonant field clamping to compensate for overshoot from the resonant magnetic field generated.

[mixedgas]

Modern AOs have a 20 Mhz or so typical bandwidth. A typical scanning AO will range something from 70 to 130 Mhz. Typically much wider bandwidth at 400 Mhz or 1 Ghz. Transducers and array transducers have greatly improved in the last 15 years.

What, may I ask is a Polymorphic Damping Field? A Google search results in a reference to Star Trek.

Steve

[Laser Electronics Ltd]

It's a PCAOM/AO resonant damping design that uses several resonant frequency inductance fields placed around the crystal( Hence Poly) that helps reduce overshoot, it limits the diffraction of the primary beam entering the crystal so the output beam doesn't exhibit diffraction.

[krfkeith]

Unfortunately we seemed to have gotten a little side tracked. To summarize my question:

With an acousto-optic deflector and lens to expand the angle, what you get is this: http://i.imgur.com/0amCac0.png

My question is how to design a system to instead get this: http://i.imgur.com/6Xz0ng7.png

[mixedgas]

We're not sidetracked.

The answer is a series of lenses upstream of the AO cells, and there will be more then one AO.

I sent you a PM on Korpel's book. Its selling for 13$ at ABE books, used. I suggest you start there.

To achieve decent deflection resolution, you need a wide aperture AO, such as the one pictured, for each axis. You have to fill the whole slit with the beam. This requires Anamorphic optics to compress the first deflected axis to fill the second cell. Ie sets of seven to nine cylindrical optics. The AOBD has a side effect of acting as a variable focus lens, so the output stage lens has to be a "field flattener" to counteract the variable focus. This is why AOBDs are very un-popular, the required lenses are very expensive and cost several times the cost of the AOBD itself.

Attached picture of a AOBD cell for one axis of deflection.




Steve

[Laser Electronics Ltd]

In short you can't, AO deflection is 2.7, to Achieve greater in one axis would require a cross phase dampening field.
Modulate two devices in an XY config and then apply a resonant field that is applied to the given movement for the deflection .
X/Y *c2.