I recently obtained a MTS 110 a3 vis AOM from gogu. Satisfied as I was, I ordered a second one and decided to write a review on its modulation characteristics. This AOM is suitable to modulate a CW laser that has no or poor modulation means by itself. I successfully modulated a 632 HeNe, a 543 HeNe, a 488 single line argon and a 532 dpss. It is driven by a matching AA driver.
An AOM in general is not a magic device that will cure all your modulation issues in an instant.
There are a few issues you will have to deal with:
-This AOM has a theoretical static extinction rate of 2000, so for display purposes you will need an additional shutter.
-The linearity has a slight S-curve.
-The positional and angular stability are critical. When a dichro gets de-adjusted by 1mrad, you'll get a slight error in the color representation in the far field. 1mrad de-adjustment of an AOM can cost you an efficiency drop of 25% or worse.
-The AOM is polarisation sensitive, resulting in bad modulation efficiency when used with random polarised sources.
The optical window is 3mmx3mm, allowing to modulate pretty fat beams. Inevitably, when using beams this big, you can't try and find the sweet spot on the crystal.
The deflection angle is 90mRad at 532nm, so a minimum distance of 80 mm has to be maintained between the AOM and the galvos. More distance is needed if you plan to terminate the 0th order beam into a light trap of some sort.
To implement a AOM successfully you will need at least:
A braggmount to meticulously adjust its position.
A optical power meter to optimise the efficiency of the AOM.
Preferably a quick photocell to optimise the RF-driver settings for a proper Uin to Pout curve.
The driver consumes 300mA at 24VDC. So a simple 10VA SMPS is sufficient to power this AOM.
The input is not balanced and its ground is connected to chassis, so you'll have to make yourself a differential receiver to connect it to ILDA pin 5 and pin 18. (Alternatively you could use pin 5 and pin 25)
I got best results by setting the driver at maximum power, then attenuating the input level to obtain the power level needed for optimal modulation.
Modulation results:
1 division equals 5mW
square wave 10Hz
square wave 100Hz
square wave 1kHz
square wave 10kHz
square wave 50kHz
square wave 100kHz
square wave burst 8x 500µS 10Hz repetition rate
square wave burst 8x 500µS 100Hz repetition rate
square wave burst 8x 50µS 100Hz repetition rate
square wave burst 8x 5µS 100Hz repetition rate
Vertical axis contains calculated efficiency
Analog input linearity response at 1kHz typical ramp sample
Analog input linearity response at 1 kHz average of 128 ramps
Analog input sine modulation 1kHz
Equipment used: Scope Tektronix TDS 210, Function generator HP 8116A-001, Photocell BPW 34, Powermeter Ophir AN2, 20 mW 632nm HeNe