Ascension laserBIRD, Инструкция по установке и эксплуатации

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3: Configuration and Basic Operation
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Basic Operation
The laserBIRD tracks position and orientation of its sensor through an optical scanning technique.
Fan-shaped laser beams are scanned throughout a pyramid-like motion region, and are detected by
photodiodes mounted in the laserBIRD sensor. Information from these detectors is used to
compute the sensor position and orientation. This is reported serially to the host computer
through an RS232 interface.
Scanner
The laserBIRD Scanner is the main electronics unit for the system. It utilizes digital signal
processors (DSPs) to process data events returning from the sensor and to calculate position and
orientation. In addition it contains the opto-mechanical sub-assembly that generates the required
laser beams and scans them across the operating region.
The beams are scanned across the motion region by reflecting them off a rotating shaft. This single
shaft is designed with polished mirrored facets that reflect all four beams during a single rotation. A
small DC motor spins the shaft at 3600 RPM (60Hz), thus providing the required data for a 240Hz
measurement rate.
Lasers
The four beams generated by the Scanner electronics for tracking are produced using laser diodes
with a typical operating wavelength of 785 nm. This places the light in the near infrared region, and
eliminates the possibility of visual distractions.
In addition, each beam is modulated at a high frequency. This ensures that the sensor event data,
demodulated using the same high frequency, has decreased sensitivity to interfering light sources.
Because each tracking laser is diverged into a fan-like beam and then scanned, the energy radiated
outside the windows (apertures) of the Scanner is well below the Class I limit. (EN 60825-1 and
CFR-1040.10-11) This means that the unit cannot emit laser radiation at known hazard levels and is
eye safe when used as designed.
An interlock is designed into the laserBIRD Scanner which disables the lasers if the scanner shaft is
not rotating appropriately. This is a safety feature, and cannot be disabled.
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CAUTION!
Attempts to
adjust/alter the
internal Scanner
components, may
cause hazardous
levels of laser
radiation. Never
attempt to open the
Scanner unit.