1. An illumination source, comprising: an array of one or more light emitting diodes (LEDs) capable of emitting light at a first wavelength; a first light collecting/focusing unit to form at least some of the light at the first wavelength into a telecentric beam; a phosphor capable of generating light at a second wavelength when illuminated by light at the first wavelength, the telecentric beam being directed to the phosphor; and a reflective polarizer disposed to transmit light at the second wavelength, received from the phosphor, in a first polarization state and to reflect light at the second wavelength in a second polarization state back to the phosphor.