Prototype Optics in One Week

request a quote

Cylinder Limits

cylinders-insetBelow are manufacturing limits and tolerances specific to cylinder lenses. For more detailed information on any attribute,  please contact sales@optimaxsi.com.

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.

Manufacturing Limits for Cylindrical Surfaces
Based on Manufacturing Method

Rod or Arbor
Attribute
Minimum
Maximum
Length (mm) 3 5001
Width (mm) Radius dependent 2 < 2x Radius
Cylinder Radius (mm) – Convex Only 2 150
X-Y
Attribute Minimum Maximum
Length (mm) 3 300
Width (mm) 2 300
Cylinder Radius (mm) 10
Concave sag to flat (mm) 0.1002 =Radius

 

General Comments on Tolerancing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • Reducing tolerance range increases costs.
  • Robust sensitivity analyses will help yield the most cost effective tolerancing.

Tolerancing Limits for Cylinder Surfaces

Attribute
Cylinder Tolerancing Limit
Glass Quality (nd, vd) Melt Rebalanced and Controlled
Length and width (mm) +0, -0.020
Center Thickness (mm)3 ± 0.020 
Sag – Concave (mm)  ± 0.020 
Clear Aperture  100%4
Radius5 ± 0.1% or 3 HeNe fringes6
Irregularity – Interferometry (HeNe fringes)7 0.18
Irregularity – Profilometry (μm)  ± 0.5 
Plano Axis Wedge – ETD (mm)  0.00512
Cylinder Axis Decentration – TIR (mm)9 0.01010
Axial Twist Angle (arcminutes)  3 
Bevels – Face Width @ 45° (mm)11 0/0mm max
Scratch – Dig (MIL-PRF-13830B)12 10 – 5 
Surface Roughness (Å RMS)13 5 

1This is at minimum radius and width. The part-specific minimum will grow in proportion to radius.
2Flat surfaces lead to scratching problems and polisher contact issues. For both practical and economic reasons consider plano here.
3This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerance ranges.
4Of full aperture (FA).
5In addition to irregularity.
6Whichever is correspondingly larger over the clear aperture.
7Typical metrology is Zygo MetroPro plots for interferometry.
8As geometry requirements move closer to a min or max shown the less likely this is possible.
9Optimax measures total indicated runout (TIR) as part is rotated. Actual decentration varies with focal length.
10This specification is extremely tight and expensive. For a more economical limit, please consider using 0.0100mm.
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.
X