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Sphere Limits

SpheresBelow are manufacturing limits and tolerances specific to spheric lenses. For more detailed information on any attribute, please contact

General Comments on Manufacturing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • As requirements move closer to a min or max shown, the more challenging the part will be.
  • During manufacturing, the lens is over-sized in diameter.

Manufacturing Limits for Spherical Surfaces

Based on Form Error Tolerance

Diameter (mm) 3 400
Radius (mm) ±1 2
Aspect Ratio (Diameter/Center Thickness) <1:1 30:1
Included Angle (°) 0 2103

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 be made prior to choosing any value below.
  • Robust sensitivity analyses will help yield the most cost effective tolerancing.

Tolerancing Limits for Spherical Surfaces

Sphere Tolerancing Limit
Glass Quality (nd, vd) Melt Rebalanced and Controlled
Diameter (mm) +0, -0.010
Center Thickness (mm)4 ± 0.020 
Sag – Concave (mm)  ± 0.010 
Clear Aperture  100%5
Radius (mm)6 ± 0.0025 or 1 HeNe fringe7
Irregularity (HeNe fringes)8 0.059
Wedge Lens – ETD (mm)  0.00210
Bevels – Face Width @ 45° (mm)  ± 0.0511
Scratch – Dig (MIL-PRF-13830B)12 <10 – 5 
Surface Roughness (Å RMS)  313,14

1Limited by machine envelope
2Metrology dependent. Avoid 3-10 meter radii when possible, choosing to stay plano instead. It will be less expensive too.
3This represents highest values possible. Actual value possible depends on finished and metrology options available plus tolerance range available for a given part.
4This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerances ranges.
5Of full aperture (FA)
6In addition to irregularity
7Whichever is correspondingly larger over the clear aperture
8Coverage dependent, stitched or otherwise, and also subject to system error
9As geometry requirements move closer to a min or max shown the less likely this is possible
10This specification is extremely tight and expensive. For a more economical limit, please consider using 0.005mm.
11Subject to measurement uncertainty
12Crystals and reflective materials will receive 40W inspection
13This represents lowest values obtained. Actual values for crystalline, especially polycrystalline materials, will be higher.
14With scan length and filter appropriate for the selected spatial period.