[PSUBS-MAILIST] LED Lights, a.k.a. Submersible History Article Link

["Jens Laland" <laland@artematrix.org>]

I read something very interesting about homemade LED lighting in the
pdf-document Steve just recommended,

http://www.doermarine.com/files/Vol43-No5_Part_1.pdf

[quote, pages 93-94]

"However, we needed another light to illuminate the launcher internally in
order to check for proper function, including observing the vehicle and
its docking unit, the core sampler, and the water sampler. The vehicle
must be equipped with a light on its roof because we need to keep visual
track of the vehicle from the launcher when the vehicle is undocking.
However, lights are expensive and the budget was limited.

For such a purpose, a rod-type light composed of a number of LEDs was
deemed suitable. To keep costs down, rather than use a pressure hull
structure, we tried to make an oil-filled pressurebalanced LED light. We
immediately found some white LEDs that work at a pressure of 110 MPa. One
of these LEDs was the surface mount type 1 W LED. This LED has a lens that
gives a beam angle of about 30°. We made the first prototype of the
pressure-balanced LED array using 20 LEDs. The prototype worked well for a
week or so, but a problem occurred after several weeks. A few LEDs blew
out. This is because oil dissolved the bond between the LED body and the
lens. We tested the relation between the bond and various oils (silicon
oil, mechanical oil, high voltage insulating oil, paraffin oil, etc.). As
a result, all industrial oils were found to dissolve the bond, but castor
oil did not affect the bond. Castor oil is a vegetable oil obtained from
the castor bean. It has good low temperature viscosity properties and is
slightly soluble in petroleum solvent.

We made 10 LED arrays, and the ABISMO system is equipped with these light
arrays. The lights were put to practical use in the Marianas Trench."

Thank you, Steve...

Best regards,
Jens Laland




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