Defining an Automatic Face

This procedure helps you define an automatic back face or an automatic front face during a projection lens creation.

To create an automatic face:

Prerequisites: You must have set the Back face type or Front face type to Aspherical.


  1. In the Back / Front Face section, define the Aperture diameter of the lens' back / front face in mm.
  2. Define the Refractive index of the lens' material.

    The refractive index impacts how the face of the lens is constructed. Combined with the specified Focal point, and the specified Back Focal Length, it automatically adjusts the shape and curvature of the lens face.

    Note: This face type results in a lens without spherical aberration that focuses all rays of a collimated beam on the specified point regardless of whether they are paraxial or marginal. Accordingly, it perfectly collimates all the diverging rays originating from a point source.
  3. If you want to create a Fresnel lens, from the Fresnel mode drop-down list:
    • Select Constant step to create grooves of the same length.

      1. In Back/Front face step, define the step size.
      2. In Back/Front face draft angle, define a draft angle in the range [0° ; 15°] that takes into account the manufacturing constraints and ensure a safe removal of the lens from the mold.
    • Select Constant height to create grooves of the same height.

      1. In Back/Front face height, define the height of the grooves.
      2. In Back/Front face draft angle, define a draft angle in the range [0° ; 15°] that takes into account the manufacturing constraints and ensure a safe removal of the lens from the mold.
The automatic face has been defined.
If not yet defined, define the plan or aspherical characteristics of the other face.