LASER EXCITATION LIGHT SOURCE

PROBLEM TO BE SOLVED: To provide a laser excitation light source in which failure of a laser oscillator due to return light is prevented, and whose luminous efficiency is high.SOLUTION: A laser excitation light source according to an embodiment includes: a laser oscillator 1 for emitting a non-polarized laser beam; a deflection beam splitter BS1 for splitting the laser beam from the laser oscillator 1 into S polarization light and P polarization light whose polarization directions are different from each other; and a condensing lens L1 for condensing the S polarization light and the P polarization light from directions different from each other on a focusing point of a bulb 2 in which a discharge medium is enclosed. The deflection beam splitter BS1 reflects the S wave having passed through the focusing point, thereby suppressing the quantity of return light returning toward the laser oscillator 1. A deflection beam splitter BS2 transmits the P wave having passed through the focusing point, thereby preventing the P wave from returning toward the laser oscillator 1.