OSLO Tolerancing

To evaluate how system performance will be affected by manufacturing tolerances, and help you to find the best balance between cost and performance, OSLO includes state of the art tolerancing tools:

Surface Tolerances describe the quality of each surface:

  • Radius of curvature
  • Conic Constant
  • Surface form error
  • Irregularity surface form
  • Thickness
  • Axial Surface Shift
  • Refractive index
  • X, Y and Z surface tilt
  • X and Y surface decenter
  • Default tolerances according to ISO 10110

Component Tolerances describe the positioning of surfaces relative to one another:

  • X and Y decentration
  • X and Y tilt about free aperture
  • X and Y tilt about center of curvature

Group Tolerances allow you to set up subsystems or elements of your overall design:

  • User defined groups
  • Group axial shift
  • Group decenter
  • Group tilt (x, y and z) about an arbitrary point

User-defined tolerancing
Allows you to specify an error function to characterize system performance. This method provides the greatest flexibility for tolerancing, but has the slowest performance. Since this method is based on an error function, you can select which terms to display, so that only relevant data is shown.

Change table tolerancing
This tool tells you how specific performance aspects of your system (see list below) will be affected by tolerances. It has the advantage of not requiring an error function to be defined.

MTF/Wavefront tolerancing
This method uses the Hopkins-Tiziani algorithm, which allows you to tolerance a system based on an MTF or RMS wavefront evaluation. Although defining an error function and using User-defined tolerancing can also achieve this, MTF/Wavefront tolerancing may be as much as 100 times faster.
Features include:

  • Direct or inverse sensitivity
  • Perturbation coefficients or direct output
  • Tolerancing over all field points
  • Tolerancing over all configurations
  • Compensators over all configurations
  • Simultaneous T&S tolerancing
  • Statistical performance estimate

Monte Carlo Tolerancing
It is the closest thing to real world simulation. A number of systems are statistically generated and evaluated, giving you an accurate idea of what your rate of success is going to be.

  • User defined error function
  • Statistics available for individual operands
  • Specify number of systems to evaluate
  • Select default, end-point, RSS, or Gaussian distributions
  • Save generated systems

Compact Custom Output

OSLO includes features that simplify the interpretation of tolerance data:
A grade table (A, B, C, D), establishes ranges for which a tolerance is considered Very Tight (A), Tight (B), Standard (C), or Loose (D).

A display threshold can be used to suppress unimportant output.

Sorting routines allow you to find out at a glance which tolerances are critical.

Tolerancing Analysis and Design

OSLO allows you to chose from different tolerancing methods. Each method can be used for either analysis (“sensitivity”) or design (“inverse sensitivity”), with the exception of Monte-Carlo (sensitivity only):

  • Best focus, back focus, focal length
  • Magnification
  • Transverse spherical
  • Distortion, transverse distortion, shear
  • Axial and field D-d
  • Meridional and central coma
  • Axial and field sags
  • Axial and field RMS OPD
  • Direct or equal RSS contribution