General Comments on Manufacturing Limits

This represents a general list of soft limits and is intended for reference only.

Reducing tolerance range increases costs.

Optimax advises a close consideration of budget (tolerance, delivery, or dollar) versus need to be made prior to choosing any value below.

Robust sensitivity analyses will help yield the most cost-effective tolerancing.

Tolerancing Limits for Spherical Surfaces

wdt_IDAttributeSphere Tolerancing Limit
1Glass Quality (nd, vd)Melt Rebalanced and Controlled
2Diameter (mm)+0, -0.010
3Center Thickness (mm)⁴± 0.020 
4Sag – Concave (mm) ± 0.010 
5Clear Aperture 100%⁵
6Radius (mm)⁶± 0.0025 or 1 HeNe fringe⁷
7Irregularity (HeNe fringes)⁸0.05⁹
8Wedge Lens – ETD (mm) 0.002¹⁰
9Bevels – Face Width @ 45° (mm) ± 0.05¹¹
10Scratch – Dig (MIL-PRF-13830B)¹²<10 – 5 
11Surface Roughness (Å RMS) 3¹³˒¹⁴
  1. This is for the most well-behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerances ranges.
  2. Of full aperture (FA)
  3. In addition to irregularity
  4. Whichever is correspondingly larger over the clear aperture
  5. Coverage dependent, stitched or otherwise, and also subject to system error
  6. As geometry requirements move closer to a min or max shown the less likely this is possible
  7. This specification is extremely tight and expensive. For a more economical limit, please consider using 0.005mm.
  8. Subject to measurement uncertainty
  9. Crystals and reflective materials will receive 40W inspection
  10. This represents lowest values obtained. Actual values for crystalline, especially polycrystalline materials, will be higher.
  11. With scan length and filter appropriate for the selected spatial period.

For more detailed information on any attribute, please contact