Sampling

An optical systems is defined with a model that represents a physical reality where there are infinitely many rays of light emanating from light sources.

In practice, when simulating, we need to decide how many rays we use for computation. This is called sampling and the number of rays is the number of samples.

Sampled rays can follow a particular distribution, like wavelength can be between 400 and 600nm only, angular distribution can be restricted to ±10°, and so on. But those distributions are continuous, and samples are a discrete realization.

• pupil dimension: Dimension along which we sample when all other variables are fixed.

  • If the light source is at finite distance, the pupil dimension is angular along the angular size of the emitted light beam.
  • If the light source is at infinity, the pupil dimension is linear along the diameter of the emitted light beam.

• field dimension: Dimension that represents the object size. The coordinate of a ray along the field dimension is the coordinate of its origin point on the light source.

  • If the light source is at finite distance, the field dimension is linear along the object size.
  • If the light source is at infinity, the field dimension is angular along the object apparent angular size.

• wavel dimension: This dimension represents wavelength.

Sampling configuration

Sampling configuration is defined by parameters of the light source element and is specific to 2D or 3D. You can also use set_sampling2d and set_sampling3d utility functions directly:

optics.set_sampling2d(wavel=10)
optics.set_sampling3d(pupil=10, field=150)