Undersea Visual Scanner Systems

  Our underwater scanner ideas were formulated after seeing poor
results from scans done in cloudy Loch Ness, which we have followed for
a long time.  A wide flank of boats moved abreast using sonar in a
loch-long sweep.  They came up empty, as you may know.  We then tried
observing various sonar fish-finder units here in Florida waters, but
were not impressed.  So we brainstormed.  Our first idea was to scan the
loch from above using wireless TV from a tethered helium blimp using
ultralight equipment.  We then built two types of tiny TV transmitters and
got three kinds of TV cameras.  These are working very well.  We have a
tiny vidicon B/W camera, a CCD B/W camera and a color CCD camera.  Another
idea was to have an observer in a towed parasail, possibly having the
observer even control the towboat from aloft. We went to Fort Myers to try
photos, videos, and just observing from a parasail, a great vantage point.
Another idea was to watch the surface of the loch from the bottom looking
up via cable-TV and robotics to silhouette the animals moving overhead.
Another idea was to have an U/W TV camera looking horizontally at night,
using a light from another boat to silhouette the animals.  We have not
tried this idea yet. Another option was to have lights on the loch bottom,
with a video camera just under water at the boat.  All the above ideas are
simple and appealing.  We need to determine which of all these will work
best before travelling. After seeing how far a 459 nm laser beam penetrates
sea water at night, we toyed with the idea of sweeping it mechanically,
receiving the reflected light in another boat using a photomultiplier. The
received light will modulate a laser diode that is swept by the same
spinning pentamirror that sweeps the power beam.  We got a scanning mirror
and motor and are using the B/W camera to convert the scanned image into
video for recording. The horizontal and vertical sweep rates are NOT synched
to the video rate.  The laser pointer beam shines into a Fresnel lens. The
B/W CCD camera is behind the Fresnel lens and upside down.  The sub-systems
work using a red laser beam.  We do not have a powerful 459 nm laser of our
own as of yet.  To be continued...