Freeform lens for an efficient wall washer

Adrien Bruneton; Axel Bäuerle; Peter Loosen; Rolf Wester

doi:10.1117/12.896803

21 September 2011 Freeform lens for an efficient wall washer

Adrien Bruneton, Axel Bäuerle, Peter Loosen, Rolf Wester

Proceedings Volume 8167, Optical Design and Engineering IV; 816707 (2011) https://doi.org/10.1117/12.896803
Event: SPIE Optical Systems Design, 2011, Marseille, France

Abstract

LEDs are a promising alternative to existing illuminants for a wide range of lighting applications. Besides efficiency and high durability, the small light source dimensions compared to conventional light sources open up new possibilities in optical design. In many lighting setups, it is desired to realize a prescribed intensity distribution, for example homogeneous irradiance on a given area on a wall or floor. This can be realized using LEDs in combination with specially designed freeform lenses and/or mirrors. For high efficiency, it is necessary to collect at least 70 - 80 degrees half-angle (measured against the z axis) of the light that the LED emits into a 90 degree half-angle. This results in a lens that resembles a hemisphere. The numerical design problem thus requires a mathematical description that can handle such strongly curved surfaces with strongly varying surface slopes. Surface parametrizations with a rectangular topography, like e.g. Cartesian tensor product B-splines, have severe drawbacks when handling such surfaces. We report on the use of an alternative surface approximation scheme that uses a triangular mesh. We describe an algorithm that optimizes the two surfaces of a lens for a wall washer that generates homogeneous irradiance on a wall area of 2.8 × 2.8 m² while mounted to the ceiling. The homogeneity is better than 80% and the optical efficiency including Fresnel losses is about 85%.

Citation Download Citation

Adrien Bruneton, Axel Bäuerle, Peter Loosen, and Rolf Wester "Freeform lens for an efficient wall washer", Proc. SPIE 8167, Optical Design and Engineering IV, 816707 (21 September 2011); https://doi.org/10.1117/12.896803

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available