Acousto-Optic Devices
Charts showing the characteristics of acousto-optic scanning devices, acousto-optic figures of merit, and solutions for common problems with acousto-optic processor devices.
ACOUSTO-OPTIC SCANNING DEVICES: CHARACTERISTICS
MODULATORS
|
Material |
|
Bandwidth
(MHz) |
|
Rise Time
(ns) |
|
Acousto
Input Power (W)
(Saturation) |
|
Material
Wavelength
Range (µm) |
|
Efficiency at
Maximum Bandwidth
(633 nm) |
| |
|
|
|
|
|
|
|
|
|
|
|
| |
Glass |
|
5 - 10 |
|
50 |
|
1 - 6 |
|
0.4 - 25 |
|
>70% |
| |
PbMoO4 |
|
>80 |
|
4 - 6 |
|
0.5 - 1.5 |
|
0.42 - 5.5 |
|
>70% |
| |
TeO2 |
|
>80 |
|
4 - 6 |
|
0.5 - 1.5 |
|
0.35 - 5 |
|
>70% |
| |
Germanium
|
|
10 |
|
70 |
|
20 - 30
|
|
2 - 20
|
|
>50% at 10.6 µm
|
| |
GaP |
|
100 - 1500
|
|
10 - 0.7
|
|
0.5 - 2 |
|
0.6 - 1
|
|
>80% |
| |
GaAs |
|
50 - 200 |
|
20 - 5
|
|
0.5 - 2
|
|
1 - 1.6 |
|
>30% at 1.5 µm |
DEFLECTORS
|
Type
|
|
Resolution
|
|
Scan Speed
(Spots/µs) |
|
Acoustic Power
(W) |
|
Wavelength Range
(µm) |
| |
|
|
|
|
|
|
|
|
|
| |
PbMoO4 |
|
>1500 |
|
15 |
|
<5 |
|
0.42 - 5.5 |
| |
TeO2 |
|
>2000 |
|
20 |
|
<5 |
|
0.35 - 5 |
| |
Glass |
|
<1000 |
|
10 |
|
<5 |
|
0.4 - 2.5 |
| |
Germanium |
|
600 - 800 |
|
5 |
|
100 - 150 |
|
2 - 20 |
| |
TeO2 chirp |
|
~2000 |
|
>20 |
|
<1 (avg.) |
|
0.35 - 5 |
| |
Gap |
|
~2000 |
|
1000 |
|
<1 |
|
0.6 - 1 |
| |
GaAs |
|
~400 |
|
200 |
|
<1 |
|
1 - 1.6 |
ACOUSTO-OPTIC FIGURES OF MERIT
| |
Material |
|
Acoustic Mode
|
|
Figure of Merit (M2)
(S3/kg) |
|
Acoustic Velocity
(mm/µs) |
| |
|
|
|
|
|
|
|
| |
Flint glass (SF 4) |
|
Longitudinal |
|
4.51 x 10—15 |
|
3.63 |
| |
TeO2 |
|
Longitudinal |
|
34.5 x 10—15 |
|
4.2 |
| |
TeO2 |
|
Shear |
|
793 x 10—15 |
|
0.617 |
| |
PbMoO4 |
|
Longitudinal |
|
36.3 x 10—15 |
|
3.63 |
| |
GaP |
|
Long |
|
30 x 10—15 |
|
6.32 |
| |
GaP |
|
Shear |
|
16 x 10—15 |
|
4.13 |
| |
GaAs |
|
Long |
|
104 x 10—15 |
|
5.15 |
| |
GaAs |
|
Shear |
|
46 x 10—15 |
|
3.32 |
ACOUSTO-OPTIC PROCESSOR DEVICES:
PROBLEMS AND SOLUTIONS
| |
Problem |
|
Cause
|
|
Solution |
| |
Limited bandwidth |
|
Transducer impedance
mismatch |
|
Acoustic impedance matching (quarter-wave layers) |
| |
|
|
|
|
|
| |
Quadratic phase error |
|
|
|
Quarter-wave matching, frequency plane phase filter |
| |
|
|
|
|
|
| |
Limited bandwidth |
|
Acousto-optic interaction |
|
Birefringent diffraction
Beam steering
|
| |
|
|
|
|
|
| |
Frequency distortion/ frequency blurring |
|
Acoustic dispersion |
|
Increasing interaction length
(limited bandwidth)
Optical beam apodization
Increasing transducer height
Acoustic Beam apodization
Birefringent diffraction
Material selection |
| |
|
|
|
|
|
| |
Limited resolution
slide lobes |
|
Optical diffraction |
|
Increasing aperture
Optical beam apodization |
| |
|
|
|
|
|
| |
Fresnel pattern distortion |
|
Acoustic diffraction |
|
Frequency plane filtering
Acoustic beam apodization
Material selection |
Source: Isomet Corp. and Brimrose Corp. of America
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