Generation of uniform light by use of diode lasers and a truncated paraboloid with a Lambertian scatterer (original) (raw)

Reflector design for illumination with extended sources: the basic solutions

Applied Optics, 1994

The goal of the optical design of luminaires and other radiation distributors is to attain the desired illumination on the target with a given source while minimizing losses. Whereas the required design procedure is well known for situations in which the source can be approximated as a point or as a line, the development of a general analytical design method for extended sources began only recently. One can obtain a solution for extended sources by establishing a one-to-one correspondence between target points and edge rays. Here the possible solutions in two dimensions (cylindrical sources) are identified, based on only one reflection for the edge rays. The solutions depend on whether the "image" on the reflector is bound by rays from the near or the far edge of the source. For each case there are two solutions that could be called converging and diverging by analogy with imaging optics. Counting the topological choices for the boundaries of the "image" we obtain a complete classification of the buildingblocks from which luminaires can be designed. One can construct interesting hybrid configurations by combining these building blocks. Thus one can gain a great deal of flexibility for tailoring designs to specific requirements. The differential equation for the reflector is shown to have an analytical solution. Explicit results are presented for symmetric configurations with the target at infinity.

Compact illumination system with variable beam direction and beam divergence

Lighting Research & Technology, 2020

Countless approaches to optimise lighting conditions for indoor and outdoor applications are described in the literature by adaptive dimming schemes or control algorithms. Those methods rely on adapting the emitted flux of individual luminaires in order to adjust lighting conditions to varying circumstances. Complex illumination requirements are tackled by controlling the output of every independent luminaire. In this case, the innovation is rather in software than in hardware, and such approaches are limited by how the LED fixtures can be manipulated. Lighting fixtures with a tuneable radiation pattern are rare, or these fixtures are rather large. This paper introduces a compact lighting system with a collimated light beam of which the beam direction and beam divergence can be adjusted electronically. To realise this optical functionality, a focus tuneable lens and rotatable mirror are combined with two custom-made aplanatic lenses in front of a compact, high-brightness LED. This p...

Low Cost High Intensity LED Illumination Device for High Uniformity Laboratory Purposes

Uniform illumination is a key requirement in different research fields. However, this requirement is often difficult to achieve when high intensity is required at the same time. Recent advancements in LED lamps allow nowadays for compact and economical solutions. In this work we present a suitable solution for various laboratory purposes requiring stable, uniform and high intensity illumination. The system is composed of four identical high power white LED arrays of 30 mm diameter each, placed on a supporting and cooling structure having a minimum volume of 26 cm x 26 cm x 8 cm. A numerical model has been developed, based on a ray tracing software, in order to simulate the performances. These have then been experimentally validated with measurements of the power density map, carried out with a 1% uncertainty pyranometer. Data show that the built system is very stable over time and provides an illumination uniformity higher than 98%, on a surface of 50 mm radius, which reduces to 95%...