How do you interpret the transparency figure in lens material?

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Someone says "Lexan is 87%" specialy glass referred to as ultra clear lens is "98%".

The glass/plastic obviously absorbs more light the thicker it is, but what is the thickness and other factors used for transparency spec?
 

NewBie

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0.125" (which is 3.175mm)

From the creator of Lexan, General Electric's own datasheet:
http://www.molalla.net/~leeper/lexan.pdf

Roughly 8% of that is due to a lack of AR coating.

There are ultra pure high end grades that reach up to the 90% range, but they are rather uncommon.


Thus, making it thinner is mostly a game of futility in the overall scheme of things, as reducing the thickness to 1/2, into the MagLite lens range, will only gain you 2% or so.


High quality lights usually use AR coated acrylic or glass, with some even using glass that is water clear when looking at it edge on. Window glass (aka soda lime float glass), will look greenish edge on. Low iron soda lime float glass will look yellow edge on.

Not all AR coatings are created equal.

A good manual for coating basics is found here:
http://www.molalla.net/~leeper/ar_coa~1.pdf


Even some low cost flashlights use AR coated lenses, such as is found in high end flashlights, most of the Fenix line is a good example.

Unfortunately, Maglite is more interested in profit, than quality or performance, so they do not use AR coated lenses. One will also find that Maglite does not even use a hard coat on their plastic lenses, which results in the easy scratching of the lens.

It is possible to use a hard coat on plastic, which can resist scratches from even steel wool, and an AR coating at the same time, and still get excellent results. In volume, such as something like the Maglite, the cost is very minimal.



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