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Frequently Asked
Questions
Questions
Optics: Frequently Asked QuestionsQ: What's the difference
between your PBF02A and PBS02A ?
A: PBF02A
is 3 waves/inch flat and is 1.6+/-0.1mm thick.
PBS02A is not optically flat and is 0.7+/-0.07mm thick. The
flatness of the PBF allows it to be used as a fine optical component.
The PBF can be used with confidence in the imaging path without
any distortion.
Q: What is the difference
between the PBS series (PBS and PBF) and the PPL series?
A: PBS02A
and PBF02A are both optimized for AOI=45 degree, and PPL is
optimized for AOI close to 0 degree.
Q: What's the smallest size your
PBF/PBS/PPL can be cut into? What's the tolerance?
A: 7x7mm
is the smallest size with a tolerance of +/-0.2mm for both
the X and Y directions.
Q: Do you offer only 1.6 mm thickness
for PBF02A?
A: Yes
Q: Can the flatness be better
than 3 waves/inch?
A: Yes, but
it becomes much more expensive, since it would be a non-standard
part. We have found that 3waves/inch achieves a nice balance
between cost and performance.
Q: On one of Moxtek presentation
files, you say PBF/PBS/PPL works well under “moderate light
level ". What does "moderate"
mean?
A: Only the
PBF needs to be operated in "moderate light levels." "Moderate
light levels" basically mean the light level that will
maintain the flatness of the PBF and will not cause a distortion
in the image because of thermal expansion. There have
been no problems, however in any applications so far with thermal
expansion induced distortion.
Q: On the same file, a Moxtek
PBF (with another PPL as pre polarizer) shows 10000:1 contrast
when working with mirror/QWP combination instead of with LCOS
panel. Is there any type of analyzer you applied? (I don't see
anyone on the drawing)
A: Here's
the short answer - We originally did this with a customer
and the analyzer was the PBS, however to obtain high levels
of contrast we do recommend using some type of analyzer.
Q: If the above statement is true,
then it means in reflection mode, PBF features around 20:1 contrast.
Then the contrast of reflected light twisted by QWP can become
10000:1.after passing through the PBF, with no analyzer. Is
this right?
A: No, it
is necessary to analyze the reflected image.
Q: When will PBF move to MP phase?
A: We need
60-90 days lead time for volume orders of PBF. This is
necessary for ordering the PBF substrates.
Q: What's the lead-time if I want
to order some ( 20 to 100 ) Moxtek samples ?
A: 12-16
business days.
Q: What's the lead-time of MP
pieces?
A: Same as
above.
Q: If the quantity is huge, is
it a must that we deal with you through such a complex
hierarchy? (Moxtek --> Polatechno -->
Taiwan Nippon Kayaku Co.)
A: Yes. We
have had customers in production in Taiwan and it is not
as confusing as it seems.
Q: Can we customize the AR coating
(or other types of diachronic coating) spec we want? Or is it
possible for you to cooperate with coating houses we assign?
A: Anything
is possible. However, anything that is non-standard will
be more expensive. It is possible to work with other coating
houses, but it is easier for us to work with companies in the
US.
Q: Does the cost relate to the
thickness (0.7 mm or 1.6 mm)?
A: Partially.
The thick flat substrate is substantially more than the 0.7mm
substrate for several reasons (the biggest reason is the thick
substrate is polished).
Q: What are the definitions of,
and differences between optical grade 0/1/2/4? Is grade 1 good
enough for imaging area application?
A: The difference
is the size of the defects. The defect size ranges
from 1mm for optical grade 4 and 150 microns
for optical grade 0. It depends on how close the parts
are to the image plane.
Q: Any recommendation on the most
optimized cutting size from cost viewpoint?
A: The smaller
the better, but leave at least 1-2mm edge exclusion around the
part.
Q: Please help to fill in attached
cost due diligence table, based on normal AR coating requirements.
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