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An Effective Freeform Optics Design Method for Advanced Illumination

Modern illumination and laser technologies depend on freeform tailored optics. A pre-proof study in Optik offers an effective and streamlined optics design method to overcome illumination challenges.

Study: Freeform optics design method for illumination and laser beam shaping enabled by least squares and surface optimization. Image Credit: Andrey Armyagov/

The researchers combine freeform surface optimization capabilities into commercial optical design software with ray-mapping least squares computations. Modifying a built-in merit function reduces the complexity of freeform illumination and laser beam shaping design.

The viability of this technique is shown through the use of three custom irradiance distribution design examples. The outcomes demonstrate the freeform optics design method's effectiveness, simplicity, and adaptability, which can be used in various setups.

Importance of Freeform Tailored in Advanced Illumination

Modern light-tailored optics are used for lighting and laser system technologies.

Light-tailored optics effectively distribute and shape light into uniform intensity distributions for illumination applications such as LED illumination, automobile luminaries, or street lighting.

Top-hat beams are uniform distributions designed on the Gaussian intensity distribution in laser technologies such as material processing or additive manufacturing.

Laser beam shaping can enhance precision and energy efficiency in laser processing technologies.

Modern laser and lighting systems require freeform optics tailored. The geometrical requirements for illumination applications differ from circular symmetries. The geometry of tailored freeform optics is constrained to do so as well.

Rotational-symmetric laser beam shaper optics are prevalent. However, the development of new laser manufacturing forms and the requirement to rectify experimental elliptical Gaussian beams have prompted the progress of customized tailored freeform optics.

Potential Advantages of Tailored Freeform Optics

Refractive and reflective freeform optics are prominent in light-tailored techniques for their high energy efficiency, reduced sensitivity to misalignments, low wavelength dependence, and low input source changes.

Tailored freeform optics are easier to fabricate than their counterpart technologies, such as diffractive, aperture, and beam integrators. Integrating this tailored freeform optics in existing illumination and laser technologies has become more practical with the rapid development of measurement and fabrication capabilities of freeform optics.

Tailored freeform optics is an appropriate and appealing solution for many applications owing to these features.

Limitations of Tailored Freeform Optics Designing Methods

There are numerous approaches for designing tailored freeform optics. These methods can be divided into two major categories. A Monge-Ampere (MA) type equation is solved in the first method to determine the freeform surfaces.

The irradiance and geometries attained by freeform optics developed using these methods demonstrate the best nominal performances. Freeform irradiance distribution is constructed after addressing the MA problem.

These approaches are challenging to apply to illumination and laser beam shaping as the solutions depend on complicated computations. Most involve derivations that depend on the quantity of freeform optics surfaces and the irradiance distributions. The MA solutions demonstrate minimal designs without apparent plans or research.

Using local optimization techniques, a second method finds the optimal freeform optics surface to divert light rays towards a collection of target points. Surface optimization-based approaches compute ray-mapping functions to direct the optimization algorithms through merit functions to establish the target placements.

These methods have produced tailored freeform optics with excellent built-in performance in lighting and laser beam reshaping applications. However, these methods have only been linked to solutions with rotationally symmetric geometries and smooth distributions because of the few ray-mapping generators in use.

Development of Innovative Design Strategy for Tailored Freeform Optics

The restricted availability of practical, efficient, and reliable design methodologies that a larger technical community can access is hampered by the limited availability of specialized freeform optics tailored solutions in lighting and laser technologies. It is crucial to combine the versatility and applicability of surface optimization-based approaches with the resilience and efficacy of Monge-Ampere-like methods to attain wider usability.

Madrid-Sánchez et al. presented the design strategy to extend freeform optics tailored to practical use in illumination and laser beam shaping applications through surface optimization algorithms built into (commercial) optical design software. The researchers suggested using a least squares optimization algorithm employed in MA approaches for calculating freeform surfaces.

Research Findings

An effective design strategy for customized freeform optics has been presented. The design was developed using a combination of freeform surface optimization and optimal mass transportation (OMT) algorithms.

Such a strategy highlights the possibility of building illumination and laser beam shaping optics with high efficiency and minimal uniformity faults.

The researchers created three custom freeform optics systems that demonstrated the adaptability of the design methodology using highly variable source and wavefronts, target distributions, and optical circumstances.

The majority of direct freeform tailored procedures are difficult and time-consuming to implement. In contrast, by combining the mapping functions produced by a least square Monge-Ampère algorithm and the optimization methods built into (commercial) optical design software, the design of a freeform optics system can be simplified.

The optimization technique is guided by a mapping function-based merit function that also permits the introduction of physical and tolerance restrictions to facilitate the design of as-built tailored optics.


Madrid-Sánchez, A., Duerr, F., Nie, Y., Thienpont, H., & Ottevaere, H. (2022) Freeform optics design method for illumination and laser beam shaping enabled by least squares and surface optimization. Optik, 269, 169941.

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Usman Ahmed

Written by

Usman Ahmed

Usman holds a master's degree in Material Science and Engineering from Xian Jiaotong University, China. He worked on various research projects involving Aerospace Materials, Nanocomposite coatings, Solar Cells, and Nano-technology during his studies. He has been working as a freelance Material Engineering consultant since graduating. He has also published high-quality research papers in international journals with a high impact factor. He enjoys reading books, watching movies, and playing football in his spare time.


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