|
APPLICATIONS
Measurement of distance is fundamental to hundreds of
industrial, defense, and consumer needs. Of course, the measurement of level
is a distance measurement.
With ranges extended up to a mile or
more or as short as small fractions of an inch,
they typically find applications in such disparate fields as collision avoidance systems,
military target ranging, tanker car load-out, truck positioning, robotics, laser
measuring tapes and industrial level control.
HiTECH's
expertise and emphasis is level measurement, however, we can and do address a
wide range of laser applications.
To accurately measure
distance, the time required for light to make a round trip between the measuring device and the
object is measured. HiTECH
offers two
different laser measurement methods.
The right choice for your
application is dependent upon a variety of parameters.
The simplest, conceptually, is the time-of-flight
approach that measures the elapsed time between when a short pulse of light leaves the
instrument and when the returning reflected or scattered pulse is detected.
Conceptually more complex, but electronically
simpler, is to measure the phase of a modulated light beam when it leaves the instrument,
and then compare that phase to the phase of the return light.
VARIOUS
LASERS OFFERED
PRINCIPLES OF OPERATION
There are three physical properties of laser light that
can be exploited in the measurement of distance:
This property makes
feasible a variety of possible geometric methods for measuring distance, most of which
depend on some form of triangulation. These methods are limited in that they require at
least two spatially separate reference points.
The use of diffraction
(destructive and constructive interference) of the light is an excellent method for
measuring very short distances (inches or less) with sub-micron accuracy. The technique,
however, is not easily usable for greater distances.
In principle, this offers an extremely accurate way
to determine distances of any required length. It is technically difficult, though, to
accurately time the departure/return of a light pulse traveling ~ 1 ft/ns. Resolution of
1/8 in., e.g., requires a temporal accuracy of ~ 10 ps.
   
| 
