In the paper, an optical design for a standard light source is proposed and demonstrated to perform high stability, high angular CCT (correlated color temperature) uniformity, and adjustable light pattern from a Lambertian-like pattern to a narrow light pattern with a full-width at half-maximum (FWHM) angle of 60°. The optical module contains a color-mixing cylinder, a diffuser, and an absorbed cylinder. The simulation well predicts the corresponding measurements and the angular CCT deviation can be kept a certain low level, which is much lower than a general phosphor converted white LED. In addition, we apply a pcW-LED of CREE XML as the light source to the optical module to show the general adoptability of the optical module. The measurement shows that the similar behavior, with adjustable light pattern from 120° to 60°. In addition, the angular correlated color temperature deviation (ACCTD) is always kept an extremely low level.
- Fluorescent and luminescent materials
- light-emitting diodes (LEDs)
- wavelength conversion devices