Creating a Freeform Lens Based on an Intensity Target

This procedure shows how to create a freeform lens based on an intensity target. The spread type allows you to control the light distribution on the target you define.

Note: The Freeform Lens based on an intensity target is in BETA mode for the current release.

To create a Freeform Lens:

Prerequisites: A surface corresponding to the front face of the lens must already be created.
  1. From the Design tab, click Freeform Lens .
  2. In the Global section, select the Spread Type.
  3. In the 3D view, click and select a point to define the Source point.
  4. Define the Refractive index of the lens.
    The Refractive Index of a material is a pure number that describes how light propagates through that medium. Most transparent materials have refractive indices between 1 and 2. Here the refractive index refers to the index of the lenses' material.
  5. In the 3D view, click to select the front face of your lens (any freeform shape).
    Note: Only one non-trimmed surface with exactly four sides should be selected for the freeform lens' front face. The selection of multiple surfaces is not supported.
  6. In Minimum thickness, define a thickness threshold to be respected between the lens' front and back face. The thickness is measured along the optical axis.
    Note: This value is a target value. This means the algorithm tries to generate a thickness that is the closest possible to the one defined but might not reach the exact value.
  7. In the Target section, select the Intensity Target type.
  8. Define the axis system of the target:
    1. Click and select an optical axis to define the direction of the light.
    2. Click and select an orientation axis for the target.
  9. In Type, define the uniformity of beam pattern:
    • Select Uniform for a uniform light spread on the Target, and set X half spread and Y half spread to define the size of the target.

    • Select Gaussian for a Gaussian distribution and define:

      • X half spread and Y half spread to define the size of the target.
      • the FWHM for X and Y.
    • Select Intensity file to define the target intensity distribution based on an intensity file, and:

      • load a *.ies, *.ldt, *.xmp intensity file

        Note: SAE XMP (non-conoscopic) are not supported as intensity file. If you want to use it, make sure to open SAE XMP map in the IESNA LM-63 Viewer and convert it to IES.

      • define the Contrast ratio with an integer value equal or superior to 2.

        The Contrast corresponds to the ratio between the minimum illuminance value (associated in RGB=(0,0,0)) and maximum illuminance value (associated in RGB=(255,255,255)) on the photometric map.

      • define the Maximum threshold.

        The Maximum threshold corresponds to the percentage of the maximum value of the intensity file. Defining this threshold means that all values of the intensity file below it are not considered. This helps you concentrate on the useful part of the light distribution by removing the unimportant part of it.

      • The Resolution factor with an integer value equal or superior to 1.

        The goal of the Resolution Factor is to densify the number of rays launched from the Intensity File target to allow to better design the Backface of the Freeform Lens.

  10. Click Compute to build the feature.