• Deformable mirror drive
• MEMS/NEMS device drive & test
The AmpArray™ is a simple 32-channel amplifier unit capable of driving adaptive mirrors with actuator load capacitances in the 10pF – 10nF range, at the frequencies typically required to correct atmospheric turbulence. It contains no internal digital-to-
analogue converters, and is intended to be
|driven by an external source of analogue control signals.|
This analogue in–analogue out configuration was created to allow a deformable mirror to be controlled directly from high-level data acquisition and instrument control software, without requiring additional device driver software. The AmpArray would typically be driven by a PC multi-channel DAC card supported by the user's preferred high-level software. The input specification matches the output characteristics of many popular DAC cards offered with the leading instrument control software packages.
This simple yet versatile device comes in a compact enclosure and requires only a single +5V dc power supply input. It offers a convenient and economical way to control a variety of modern MEMS-based and bimorph deformable mirrors. A variety of output options can be offered as semi-custom drive solutions.
|Number of amplifier channels||32|
|Amplifier Gain||+19 ± 5%|
|Input Voltage Range||0V to +10V|
|Output Voltage Range||0V to +190V|
|Output Drive Current Limit||45μA ± 40%|
|Small Signal Bandwidth||4kHz @ -3dB corner|
|Slew Time with Capacitive Load
(2.2nF load, 100V step)
|3.9ms typ. (10% to 90% of step)|
|Enclosure Dimensions||126mm(D) × 106mm(W) × 34mm(H)|
|Power In||+5V dc regulated, @ 0.2A|
The AmpArray has a unipolar output range, but it can also be used to drive mirrors requiring a bipolar drive signal. Application Note 1 explains how.
The 32-channel AmpArray is matched to the channel
count of popular DAC cards, and can be used to
drive a wide range of deformable mirror sizes.
Several of the compact AmpArray units can be combined to form higher channel-count drive systems. The image to the left shows a 128-channel configuration formed from four AmpArray units. The maximum channel count is typically limited by the DAC I/O capacity of the host computer.
Each amplifier channel's current limit is set to a nominal 50µA. There is a ± 40% spread in this value. The current limit is a safety feature of the amplifier, it is not the normal operating mode. The amplifier should be operated in the linear regime, not the current-limited regime.
The plot below shows the large signal step response for a low capacitance load (15pF) and for a high capacitance load (2.2nF). These values are typical of MEMS mirrors and bimorph mirrors, respectively. A 100V pk–pk square wave is applied, the voltage swing is between +20V and +120V.
For the 15pF load, the rise and fall times are about 80µs, determined by the 4kHz low pass filter. For the 2.2nF load, the large signal step response is quasi-linear, with a 3.4ms rise time and a 2.5ms fall time, determined by the current limit. There is a 2V overshoot on exit from the current limited mode.
|Signal Input Connector:||44-way HD22 (density-and-a-half) 'D'-type socket.|
|HV Output Connector:||37-way HD20 'D'-type socket.|
|Power Supply Connector:||0.1" pin miniature power jack. (Power supply is included).|
Pin assignment on the input (44-way) and output (37-way) 'D'-type connectors:
|Input Connector: 44-way||Output Connector: 37-way|
|Pin No.||Signal||Pin No.||Signal|
© 2002–2011 Starpoint Adaptive Optics Limited