Hard (hot MgF2?) AR coatings on glass in Los Angeles?

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salmonegg@sbcglobal.net - 13 Aug 2005 02:29 GMT

I have just ordered a pair of uncoated glass eyeglasses. From what I can
tell, it is very difficult or impossible to find a Los Angeles supplier of
hot deposited quarter-wave magnesium fluoride coatings on glass. Does anyone
have a suggestion along those lines? Does anyone have a suggestion for AR
coatings of similar durability?

Bill

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William Stacy - 15 Aug 2005 04:48 GMT

I don't know why it would be tough, since anyone who coats glass will
use that technique on glass. Fairly common. Maybe the people you're
talking to don't know what you're talking about. Try saying
"anti-reflection coating". You will get the 1/4 wave MgFl coating...

w.stacy, o.d.

> I have just ordered a pair of uncoated glass eyeglasses. From what I can
> tell, it is very difficult or impossible to find a Los Angeles supplier of
[quoted text clipped - 3 lines]
>
> Bill

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salmonegg@sbcglobal.net - 15 Aug 2005 06:53 GMT

On 8/14/05 8:48 PM, in article
DgULe.2338$Hn3.1580@newssvr23.news.prodigy.net, "William Stacy"
<wstacy@obase.net> wrote:

> I don't know why it would be tough, since anyone who coats glass will
> use that technique on glass. Fairly common. Maybe the people you're
> talking to don't know what you're talking about. Try saying
> "anti-reflection coating". You will get the 1/4 wave MgFl coating...

I talked to the "dispensing optician" at the ophthalmologist's office where
I got refracted by an optometrist. She called their supplier who said that
they bake their glass and plastic coatings. I have no idea what that really
means. I cannot imagine plastic getting baked at a temperature high enough
to give truly hard MgF2 coatings. Earlier, when I contacted salespeople at
Lenscrafters, they also had no idea of what hard MgF2 coatings were. On
Monday, I will calling a place that has been around for a long time. In the
end, I ordered glasses without AR coatings.

By the way, the optometrist did a fine job of determining my prescription.
She also did not give me a hard time about my desires for computer glasses.

Bill

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cbf - 15 Aug 2005 09:52 GMT

I have tried to order computerglasses, but the glasses I received do
not work.
Do I need a special eye examination to determine the right focal
length?
What is normal focal length for computerglasses?
I am nearsighted, how much do they have to add to my -2.75 and -3.25.

Chris

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salmonegg@sbcglobal.net - 16 Aug 2005 01:44 GMT

On 8/15/05 1:52 AM, in article
1124095925.238142.86940@o13g2000cwo.googlegroups.com, "cbf"
<cfredk@gmail.com> wrote:

> I have tried to order computerglasses, but the glasses I received do
> not work.
[quoted text clipped - 4 lines]
>
> Chris

I am not a vision professional, but figuring out how to modify your distance
prescription is neither rocket science or brain surgery.

1. Measure the distance from your eye to where your monitor screen will be
in meters.

2. Take the reciprocal of that distance. That is 1/distance. That is the
additional power in diopters required for your computer glasses.

3. Get a prescription that is the same as you distance prescription except
that number of diopters gets added algebraicly to your distance spherical
diopter value.

4. If you use bifocals, the add for bifocals is algebraicly reduced by the
number of diopters you calculated above.

That should be a simple calculation for optometrist or ophthalmologist to do
and measure.

Bill

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William Stacy - 16 Aug 2005 02:08 GMT

Not so much a special eye exam, but during the exam the doc has to know
what your desired working distance is, because there is no "normal focal
length". In your case, the Rx below will be reduced by an appropriate
amount based on that working distance and other factors such as the
amount of your amplitude of accommodation and your near phoria
(binocularity). It's not complicated, but it must be done correctly, or
as you found out on the first try, don't bother...

w.stacy, o.d.

>I have tried to order computerglasses, but the glasses I received do
>not work.
[quoted text clipped - 6 lines]
>
>

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