Frequently Asked Questions: Optics

Q: 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.

Optics: Frequently Asked Questions