5 PICOSCALE HARDWARE
Figure 5.9: Setup of a
PICO
SCALE
sensor head.
The open port of the beam splitter cube is the SmarAlign window. In specific sensor heads (for
example sensor head type C01) it can be used as a monitor to superimpose the beams re
fl
ected
from the reference and target mirr
or, respectively, using the visible pilot laser beam that is dif-
fusely scattered at this surface. All standard components are mounted in a titanium sleeve.
5.5 Environmental Module
Figure 5.10: Environmental Module
To measure the environmental parameters (temperature, pressure, humidity), an environmental
module can be connected to the
PICO
SCALE
Controller. Since the measurement of the environ-
mental conditions is most meaningful close to the sensor head, the environmental module has a
small chassis to make it possible to place it in close vicinity of the heads. The environmental mod-
ule is contained in an aluminum housing as small as 32x50x16 mm³. A microprocessor collects the
data of the individual sensors and sends them to the FPGA for further processing. The measure-
ment bandwidth is
1 Hz
which is su
ffi
cient to detect variations in the environmental conditions.
The accuracy of the environmental module is:
•
temperature:
±
200 mK
•
pressure:
±
2 mbar
•
relative humidity:
±
2%
These measurement uncertainties result in a position accuracy of typically <1 ppm.
41
PicoScale User Manual
