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 fabrication becomes more difficult.

Certain combinations are unattainable, e.g. 3mm convex radius with 100mm length.

Certain configurations add significant fixturing costs, e.g. crossed axis cylinders, cylinders/spheres.

Interferometric testing of cylinders is somewhat case-specific. Aperture coverage is often limited by the range of diffractive nulls available.

Length is always the dimension along the plano axis and width is the dimension across the power axis.

During manufacturing, the lens is oversized in diameter. Be aware, forms well behaved within clear aperture may turn exotic or undefined just beyond the final diameter.

Manufacturing Limits for Cylindrical Surfaces Based on Manufacturing Method

Rod or Arbor

1Length (mm)3300
2Width (mm)2300
3Cylinder Radius (mm)10
4Concave sag to flat (mm)0.100²=Radius


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 at minimum radius and width. The part-specific minimum will grow in proportion to radius.
  2. Flat surfaces lead to scratching problems and polisher contact issues. For both practical and economic reasons consider plano here.

For more detailed information on any attribute, please contact