Creating a Freeform Lens Based on an Irradiance Target

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

Note: The Freeform Lens based on an irradiance target definition 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 Irradiance Target type.
  8. Define the axis system of the target:
    1. Click and select a point to define the Origin of the Target.
    2. Click and select a line to define the horizontal axis of the sensor.
    3. Click and select a line to define the vertical axis of the sensor.
  9. In Type, define the uniformity of beam pattern:

    • Select Uniform for a uniform light spread on the Target, and set X half size and Y half size to define the size of the target.

      Each half size is generated from the target origin. A X half size of 100 mm means the X size of the target is 200 mm.



    • Select Gaussian for a Gaussian distribution and define:

      • X half size and Y half size to define the size of the target.

        Each half size is generated from the target origin. A X half size of 100 mm means the X size of the target is 200 mm.

      • the FWHM for X and Y.
    • Select Image to define the light spread based on an image, and define:

      • X half size and Y half size to define the size of the target.

        Each half size is generated from the target origin. A X half size of 100 mm means the X size of the target is 200 mm.

      • the image file (*.png, *.jpg or *.bmp file).

      • 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.

      • 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 Image File target to allow to better design the Backface of the Freeform Lens.

  10. Click Compute to build the feature.