Aerotech Final DR 2/3/10 12:45 Page 13
Vendor Application
techniques may also lead to the ‘holy grail’ of
producing complete active switching circuits for
optical computing.
Direct Write
As opposed to more traditional
photolithography mask processing methods for
these types of devices, the direct write approach
Issue I 2010
benefits from single-step integration and is
square4
consequently much faster and very adaptable for
.com
rapid prototyping/short production runs at
reasonable costs. The basics of the direct writing
process involves modifying the core layer
material by manipulating the substrate under the
focussed UV laser, so clearly the precision and
dynamic performance of the positioning system
is fundamental and an intrinsic ‘enabling
oasiasemiconductor
technology’ for the success of the process.
.eur
The high power UV laser is directed through
www
an interferometer to produce an intense dual
beam interference pattern at the target area.
13
During the writing process, its focal length is
held constant and the overall positioning system
flatness, derived from pitch, roll, yaw and Abbe
errors from both X and Y axes, must maintain
sub-micron tolerances. Furthermore, the writing
process needs to be continuous as the core
materials are adversely affected by heating, so
the control of the UV lasers’ power and firing
pattern is completely synchronised with the on-
the-fly compound translation of the X and Y
axes. This synchronisation is another key factor
for the process and is carried out within the
Aerotech controller by an advanced software
feature called PSO or Position Synchronised
Output. 300 mm x 300 mm travel range, this brushless Dual UV laser beam
PSO triggers the UV laser in real time during linear servomotor driven, ultra-high precision for Bragg grating
continuous motion, processing high speed stage features a balanced air-on-air preload writing
encoder feedback in conjunction with XY system for maximum stiffness and glass scale
position array information for the particular encoder feedback with an encoder resolution of Image courtesy of
feature being written. In this way, not only is just one nanometre. University of
each feature held to nanometre level tolerances The H-bridge design maintains both axes Southampton ORC
in all planes, but the accuracy and repeatability and their respective encoders at the same level
from feature to feature and the distance which co-locates the centrelines of mass, force
between them is also realised with fantastically and feedback - effectively ensuring that errors
high precision. are minimised for best performance straightness
The positioning system used at the ORC is and flatness. With dual linear motor driven Y
an Aerotech ABL9000 series air bearing stage axes and active yaw control, the ABL9000 is able
complete with the A3200 Digital Automation to produce perfectly parallel scans, straight lines
Platform motion control system with FireWire and interpolated curves over its entire working
networked Ndrive linear stage amplifiers. With a surface. Each axis is also factory calibrated by
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36