Design of Freeform Illumination Optics

Abstract

Freeform optics constitutes a new technology that is currently driving substantial changes in illumination design. It liberates designers and engineers from restrictions of optical surface geometry, enabling them to achieve compact, lightweight, and efficient illumination systems with excellent optical performance. Freeform optics is currently used widely for both fundamental research and practical applications. This Review focuses on the design of freeform illumination optics, which is a key factor in advancing the development of illumination engineering. The design methods of freeform illumination optics can be divided into two groups: zero‐étendue algorithms based on ideal source assumption and design algorithms for extended light sources. The zero‐étendue algorithms include ray mapping method, Monge–Ampère equation method, and supporting quadric method. The algorithms for extended sources include illumination optimization, feedback design, and simultaneous multiple surfaces method. The characteristics and limitations of these design methods are illustrated and a summary of these methods with future outlooks is also given.

Simplified Geometric Approach to Freeform Beam Shaper Design

“…Beam shaping is the process where well-defined input beam is transformed into the desired output beam. It has numerous applications in all the fields where spatial light distribution plays vital role in illumination design [1], solar concentration optics [2], material processing [3], laser active media pumping [4], laser output wavefront correction, semiconductor lasers beam forming [5], lidar [6], military optronics [7], and many others. Beam shaping process can be realized by a variety of optical methods, based on refractive, reflective, diffractive, and adaptive components [8].…”

“…In this work, following the purely ray-tracing methodology, the problem described by (12) is not solved mathematically, but geometrically. In the first step, in order to obtain initial ray mapping, we take into account the rays positions at B and C planes obtained from (7) and denote them as (x B,ij , y B,ij ) (1) and (x C,ij , y C,ij ) (1) . e corresponding initial ray mapping M (1) is thus nonintegrable and does not fulfil (12).…”

“…e corresponding initial ray mapping M (1) is thus nonintegrable and does not fulfil (12). is equation can be used however to determine an error function є defined for initial ray positions (x B,ij , y B,ij ) (1) and (x C,ij , y C,ij ) (1) as follows:…”

“…e scalar potential ѱ (1) , which appears in (13) is obtained simply from integrating the mapping M (1) as it is. In the next step, the error function є (1) is added to I (1) B , producing slightly changed irradiance distribution at plane B, denoted by I (2) B . en, the whole loop is repeated K-times until є (K) is minimized below certain predefined threshold, which means that the obtained ray mapping corresponding to I (K) B ⟶ I C transformation is "nearly" integrable.…”

Reflector design and study via conformal mappings

“…The field of illumination optics has seen great progress [1][2][3] in both numerical and analytical implementations of the irradiance and/or intensity calculations given any source and a target. Early work designed reflectors through source-target maps, i.e.…”