Truth in advertising....

[Shiraz (Ray)]

re the longevity of multilayer dielectric mirrors with Al base coat, according to Orion Optics:
"there is no reason Hilux coatings will not last 25 years or even longer. ...We have had a small mirror outside in all weathers now since 2003 and if we wipe it carefully, it looks as good as the day we coated it. It has had, rain, snow, hail, everything the elements could throw at it."

I think we might be arguing about angels and pins

[Kunama]

Originally Posted by RobF

You SCIENTIST you! Is that going to be flame photometry or ISE Peter!?
Direct or indirect? Actually, I'm expecting ICP-MS for all my sodium estimations please.

Err, sorry. Back to mirrors now.....

I would think inductively coupled plasma mass spectroscopy would be overkill, salt or no salt.
As for the OP's first post, I think one would be within their rights to expect such a claim to have a basis in fact. But then again I have seen people advertising items made from FPL51 and 53 as CaF2.

[LewisM]

Originally Posted by Kunama

But then again I have seen people advertising items made from FPL51 and 53 as CaF2.

They don't anymore - too much criticism here and elsewhere A little bit of BS can only fool a certain type.

Hang on, W.O still claims some of their FPL53 scopes are fluorite... (which they aren't)

[Peter.M]

Originally Posted by RobF

You SCIENTIST you! Is that going to be flame photometry or ISE Peter!?
Direct or indirect? Actually, I'm expecting ICP-MS for all my sodium estimations please.

Err, sorry. Back to mirrors now.....

Sodium method of choice is OES. Call me when you want rare earths or something

[Peter Ward]

Originally Posted by Shiraz

re the longevity of multilayer dielectric mirrors with Al base coat, according to Orion Optics:
"there is no reason Hilux coatings will not last 25 years or even longer. ...We have had a small mirror outside in all weathers now since 2003 and if we wipe it carefully, it looks as good as the day we coated it. It has had, rain, snow, hail, everything the elements could throw at it."

I think we might be arguing about angels and pins

If it has a Al base coat its not a dielectric mirror.

Dielectric mirrors use the interference of light reflected from the different layers of dielectric stack.

If Orion are calling their mirrors dielectric...they are equally guilty of mis-representing their coatings.

Suggest you Google "Bragg mirror" .

P.S.
Just had a look at Orion's HILUX info...while they claim excellent reflectivity, I did not see any bogus
claims about them being dielectric.