POLARIZED, MULTICOLOR LED-BASED ILLUMINATION SOURCE

摘要

Light emitting diodes (LEDs) emit light at a first wavelength. A phosphor material close to LEDs converts at least some of the light to a second wavelength. The light at both wavelengths passes through a light collecting unit. A reflecting polarizer transmits both wavelengths in a first polarization state and reflects light at both wavelengths in a second, orthogonal, polarization state. Light reflected by the reflective polarizer is directed back towards the phosphor material without any substantial increase in angular range. The resulting output light beam contains polarized light at the first and second wavelengths. In some embodiments, an array of LEDs includes LEDs that emit light at a first wavelength and others that emit light at a second wavelength. The phosphor material is disposed on the LEDs emitting the light at the first wavelength.