Re: [PSUBS-MAILIST] One more reason to use acrylic windows.

["James" <james@whototake.com>]

I remember hearing somewhere that Graham Hawks Deep Flight canopy was
manufactured to couple with seawater so well that it seemed to disappear
when the sub was placed in the water.  My question is, does the conical
shape and thickness of the dome or viewport effect the refractive index?
And if so, is there a specific radius or cone that is "best" for underwater
viewing?

James

----- Original Message -----
From: "Sean T. Stevenson" <sts@telus.net>
To: <personal_submersibles@psubs.org>
Sent: Thursday, May 30, 2002 3:45 PM
Subject: Re: [PSUBS-MAILIST] One more reason to use acrylic windows.


> The "optical erasing" that you refer to is the result of the refractive
index
> of acrylic being closer to the surrounding water than other materials.
>
> For reference, some approximate values are:
>
> vacuum          1.0
> fresh water     1.33
> sea water       1.37
> acrylic         1.49
> glass           1.52
> polycarbonate   1.58
>
> -Sean
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