General Comments on Tolerancing 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 Aspheric Surfaces

wdt_IDAttributeAsphere Tolerancing Limit
1Glass Quality (nd, vd)Melt Rebalanced and Controlled
2Diameter (mm)+0, -0.010
3Center Thickness (mm)⁶± 0.010 
4Sag – Concave (mm) ± 0.010 
5Clear Aperture 100%⁷
6Vertex Radius⁸± 0.1% or 3 HeNe fringes⁹
7Irregularity – Interferometry (HeNe fringes)¹⁰0.11¹¹
8Irregularity – Profilometry (μm)¹⁰± 0.5 
9Wedge Lens – ETD (mm) 0.002¹²
10Bevels – Face Width @ 45° (mm)¹³± 0.05 
11Scratch – Dig (MIL-PRF-13830B)¹⁴10 – 5 
12Surface Roughness (Å RMS)¹⁵10 
  1. This is for the most well-behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc) will need larger tolerance ranges
  2. Of full aperture (FA)
  3. In addition to irregularity
  4. Whichever is correspondingly larger over the clear aperture
  5. A vertex radius tolerance is required in addition to irregularity
  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.

For more detailed information on any attribute, please contact