Technical Specifications - Glass
Teleprompter Mirror - 70% Transparency
Scope
This specification applies to the above coating when it is applied
to glass with an index of refraction of 1.523.
Materials and
Workmanship
- The coating
process shall cause no injury to the glass surface which would
cause rejection of the optical element under other applicable
specification. Any optical element which has met the
requirements of other applicable specifications prior to coating
shall not be rejected after coating because of fine hair lines
or other defects in such optical element which are made more
visible by the coating.
- The coating
shall have negligible absorption of visible light.
Reflection
The coated element shall reflect from the
front surface 32 plus or minus *3% of the total incident light in
the visible region as defined by a Viscor filter, when using an
incandescent tungsten filament lamp light source.
Transmission
The coated element shall transmit 68 plus or
minus *3% of the total incident light of above type in the visible
region defined by the Viscor filter.
Adherence
No visible part of the coating shall be
removed by the cellulose tape test described here:
Test:
The tacky surface of cellulose tape shall be carefully placed in
contact with a portion of the coated surface and firmly rubber
against that surface. It shall then be quickly removed with a
snap action that exerts the greatest possible stripping action
on the mirror surface.
Hardness
No evidence of film removal or film abrasion
shall be visible to the eye when any one or all of the following
test are applied:
- The coated
optical element shall be carefully washed first in a solution
consisting of one (1) ounce of sulphated alcohol, one (1) ounce
15 Baume normal ammonium hydroxide, and one (1) gallon water;
then cleaned in acetone or grain alcohol and dried with lens
tissue or soft cloth.
- A thick past of
U.S.P. precipitated chalk and water shall be applied to the
coating and allowed to dry, and then wiped off with a soft
cloth.
- A pad of clean
dry cheese cloth (previously laundered) 3/8 inch in diameter,
1/2 inch thick, bearing with a force of one pound on the coating
shall be rubbed across the coated element in any direction 150
times.
Note:
During the above tests, care should be exercised to prevent
contaminating abrasives contacting the coated surface causing slight
sleeks.
Durability
No evidence of film removal of film abrasion
shall result from one or both of the following tests:
- The coated
element shall be placed in a thermostatically controlled cabinet
with a salt atmosphere at a temperature of 95° F. plus or minus
4° F for 48 hours. The salt atmosphere shall be obtained by
allowing a stream of air bubble through a salt solution
containing about 1 1/2 pounds of sodium chloride per cubic foot
of water.
- The coated
element shall be placed in a thermostatically controlled
humidity cabinet with an atmosphere of at least 95% relative
humidity and at a temperature of 120° F. plus or minus 4° F. for
a continuous period of 24 hours.
Water Resistance
No evidence of film deterioration visible to
the eye shall result from the following test:
A drop (0.05
milliliter) of distilled water shall be permitted to dry at room
temperature on the coated surface and the coated surface shall
then be cleaned with acetone or grain alcohol.
Effect of
Temperature
The coating shall function satisfactorily and
shall not be damaged by exposure to an ambient temperature of minus
60° F. and plus 500° F.
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All original text
and images Copyright 2008
Reflective Security LLC
