The Complete Guide to Non-Imaging Optics

by | Mar 17, 2021 | Optics explained

Non-imaging optics, also known as anidolic optics, is the branch of optics concerned with optimal light transference between a source and a target. Unlike imaging optics the techniques used for non-imaging optics do not form an image of the source. Non-imaging optics systems are focused on optimal radiative transfer from a source to a specified target.

In this article we will take a closer look at non-imaging optics, in particular non-imaging optics for illumination applications. We will end this article with advice on how to order prototypes and custom non-imaging optics.

What is non-imaging optics?

Non-imaging optics is the theory of thermodynamically efficient optics, as such it depends more on thermodynamics than on optics. Non-imaging optics have been discovered through heuristic ideas as “simultaneous multiple surface”, “edge ray involutes” and “string method”.

In short, non-imaging optics is:

  • The field of optics concerned with transfer of light between a source and an object.
  • Involved with techniques which do not form an optimized image of the source.
  • Optimized for radiative transfer from source to a target.

There are two major factors for each non-imaging optics system, namely:

  • Concentration: the amount of energy that lands on the target.
  • Illumination: controlling the distribution of light.

A brief history of non-imaging optics

In the 1930’s the field of non-imaging optics got started in the United States, at lighting companies like General Electric. It was not before 1970 that the field really began to take hold. Around 1970 Roland Winston and Walter Welford began to formulate principles, theory and mathematics of non-imaging optics.

Examples of non-imaging optics

Examples of this type of optics include:

  • Optical light guides
  • Reflectors
  • Non-imaging lenses
  • LCD backlights
  • Fiber optics

Applications of non-imaging optics

Non-imaging optics are used in two fields:

  • Solar energy concentration
  • Illumination

For this article we will focus on non-imaging illumination optics.

Non-imaging optics for illumination

There are numerous examples of non-imaging optics, such as non-imaging reflectors and non-imaging lenses. Modern applications for non-imaging optics include automotive headlamps, LED lights, projection display systems, luminaires and much more.

When compared with traditional design techniques, non-imaging optics have a couple of advantages for illumination:

  • It delivers more compact optics
  • It is better with handling of extended sources
  • It offers color mixing capabilities
  • Can combine light sources and -distribution to different targets
  • Can be used with LED light sources

Designing non-imaging optics

Non-imaging optics are mostly designed using one of these different methods:

  • Flow-line (Winston-Welford) design method
  • SMS (Miñano-Benítez) design method
  • Miñano design method using Poisson brackets

Most commonly used is the flow-line design method, but the SMS design method has also proven very versatile and can be used for designing a wide variety of optics. The Miñano design method using Poisson brackets has thus far remained in the realm of theoretical optics and has not been used for real life applications.

Flow-line design (Winston-Welford) method

The flow-line, or Winston-Welford, design method is used to design optics which guide light by confining it between two reflective surfaces. A well-known device for this is the Compound Parabolic Concentrator.

SMS method

The Simultaneous Multiple Surface (SMS), or the Miñano-Benítez, design method enables the simultaneous design of multiple optical surfaces (hence the name). The design method was initially developed in 2D by Miñano (and later also by Benítez). The first generalization to 3D geometry came from Benítez. The design procedure is related to the algorithm used by Schulz as used for the design of aspheric imaging lenses.

This design method is very versatile and many types of optics can be designed with it. The 3D version allows for the design of freeform optics which may not have any kind of symmetry.

Miñano design method using Poisson brackets

This design method, also developed by Miñano, is based on Hamiltonian optics. The Hamiltonian formulation of geometrical optics shares much of the mathematical formulation with Hamiltonian mechanics. This design method allows for the design of optics with variable refractive index and as such solves some of the problems that are not solvable using other methods. However, manufacturing of variable refractive index optics is not yet possible. As such, this design method did not yet find a real world application.

Prototyping and manufacturing of non-imaging optics

As an optical engineer you are looking for ways to design tailor-made custom optics while keeping costs low. With Addoptics’ unique approach this is possible. We offer smart manufacturing of optics, which allows you to scale prototyping and production with affordable, industrial-quality optics.

With our unique manufacturing method we are able to deliver a physical prototype of your optical design within 6 working days, no matter how complex it’s geometry (even freeform optics are possible).

We offer strong, heat resistant optics that can withstand the rigours of thorough usage. Our solution is competitively priced and we offer a significant discount when ordering multiples.

Check our datasheet for our most up-to-date capabilities and material properties. Or, if you are interested to discuss the prototyping and manufacturing of your non-imaging optics, please reach out to us. We’d be happy to help!