Physics of why to use metallic (surface) reflectors for UV

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Physics of why to use metallic (surface) reflectors for UV

Postby kingofnobbys » Wed Aug 21, 2019 10:26 pm

Reflective in visible light doesn't infer reflective in UVA and UVB bands.

Unless the reflector has a polished metal or "vapor deposited" aluminium surface , I'd be reluctant to use it as there is a very good chance the surface of the "painted" / powder coated surface will actually absorb UVA & UVB and perhaps reemit the light in the visible bands thereby defeating the purpose of using a reflector / reflector hood partly or even entirely ( all the UVA & UVB may actually be absorbed and fluoresced as visible light ) , see below for basics :
Image

In short - if the reflector is not designed to reflect better than 80% of the UVA & UVB that falls on it's front surface , it's not suitable for use in a reptile enclosure. This means the reflective surfaces are restricted to copper, aluminium, gold or silver.

See this for specular reflectivities of some reflective surfaces :
Image
Ref : Evaluation of reflectivity of metal parts
InfraMation 2010 Conference Proceedings p210-p243, Z. Sarosi

Reminder :
UVA, or near UV (wavelengths 315–400 nm)
UVB, or middle UV (wavelengths 280–315 nm)

This is why I'd be looking for a polished aluminium reflector or a vacuum aluminized surface on the reflector.
The substrate behind the reflective surface is irrelevant ( it only forms the focusing shape and holds the reflective surface in place ).
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : , Fluffy (F) rescued injured by lawnwacker 14Nov17, Gutzy (F) rescued 27Sep19 - RIP 3Aug20 (est 12 yo), Wriggles (F) - injured rescue, over 8 yrs old, RIP 2Feb16 old age. Lucky juvenile (M) - cat attack rescue (lost r-eye, broken r-lower jaw), fatal SI RIP 21Jul2010.
kingofnobbys
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Re: Physics of why to use metallic (surface) reflectors for

Postby kingofnobbys » Fri Aug 23, 2019 5:14 pm

Interesting note :

There is an paint that is highly reflective in the range 300 - 400 nm designed to hide aircraft and vehicles and artillery in snow country .
It's general composition is :
essentially of 40 parts by weight of calcium carbonate,
l0 parts by weight of highly viscous chlorinated rubber,
6 parts by weight of chlorinated diphenyl,
and 44 parts by weight of xylene.

Ref United States Patent O 3 300,325
CAMOUFLAGE PAINT REFLECTING ULTRAVIOLET LIGHT FOR USE IN SNOWY COUNTRY Filed April 1, 1965
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : , Fluffy (F) rescued injured by lawnwacker 14Nov17, Gutzy (F) rescued 27Sep19 - RIP 3Aug20 (est 12 yo), Wriggles (F) - injured rescue, over 8 yrs old, RIP 2Feb16 old age. Lucky juvenile (M) - cat attack rescue (lost r-eye, broken r-lower jaw), fatal SI RIP 21Jul2010.
kingofnobbys
BD.org Sicko
 
Posts: 12562
Joined: Tue May 12, 2015 10:56 pm
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