Project 2 - Infra-Red Projector
The project shown is the previous
generation of our infra-red projector. This system projects a "virtual"
image, which appears to the IR detector as if it were at infinity.
It is basically a virtual reality display for instruments that see in the
infra-red range instead of seeing regular light.
The IR information projected can
come from several sources, including internally generated fixed and moving
patterns, externally computer generated full motion video, and video from
a conventional video camera or VCR. Control can be from the local
control panel, or from an external computer through an IEEE-488 interface.
This makes it possible to integrate it into a suite of test equipment to
use it for fully automated testing of devices with IR sensors.
The new generation system is under
development. No, I won't show any pictures. No, I cannot say much
about it. Why tell potential competitors what we are up to?
Let's just say that it is well worth the wait.
Figure 1. This is the outside of the projector shown
from the control panel side. The IR Port is on the opposite side
of the chassis. The local control is through the pushbutton interface
in the upper left. Vacuum system monitoring and control is in the
upper right. Power and signal interfaces are in the lower left.
The cooling system air outlet is the black square in the lower right.
Figure 2. This is a side view of the projector with
its cover removed, shown with an IR camera in the position from which it
can view the virtual image. Note that the normal IR sensor position
is well outside the projector opening.
Figure 3. This is a view of the IR source on its support
board. You cannot see the source itself since it is hidden in a small
vacuum enclosure behind a silicon window. Silicon is transparent
in the IR spectrum, but does not pass visible light.
Figure 4. This is the IR Optical chassis, removed from the
projector. Note that the optical system is a fully-reflective, offset
system comprised of several diamond-turned mirrors.
Figure 5. This is another view of the IR optical chassis,
shown from behind the IR source. The IR source is temperature controlled.
Note the fan and heatsink assembly, which is attached to a thermoelectric
cooler. This is controlled by a closed-loop system which maintains
a very constant source temperature.
Figure 6. This view of the inside of the IR projector
with the IR optical chassis removed gives an idea of the electronic complexity
which was required to control the IR source. All that complexity
on the inside is required to make the unit easy for the user to use.
Figure 7. This shows the simplicity of the local user
interface. Many of the common user functions can be controlled through
a flexible menu-driven pushbutton interface. More complex functions
can be controlled through the IEEE-488 computer interface.
Figure 8. The electronics package is composed primarily
of a backplane which can hold four large printed wiring boards. The
card rack is shown here during bench testing of the prototype. The
board on the top is the control and system housekeeping board. The
board on the extender is the high-speed image digital signal processing
board.
Figure 9. This view of the electronics package shows
the wire-wrap backplane which was used in the prototype system. Each
of the connectors has 540 pins to insure that the system could be expanded
without running out of pins.
Figure 10. This view shows the back side of the front
panel. Note that all connections are modular, to reduce the cost
of production. The liquid crystal display and the vacuum display
meter are purchased items.
Figure 11. This view shows the IR projector during a demonstration,
with a Tektronix TSG-95 video test signal generator as a video source,
and a laptop computer with a IEEE-488 controller PCMCIA card to control
the system.
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