Patent ID: 8053713

Claim:
A light source device comprising: a semiconductor light-emitting element that emits, according to an input value, light having a first wavelength; a wavelength converting element that converts, with a nonlinear optical effect, the light having the first wavelength emitted by the semiconductor light-emitting element into light having a second wavelength; a light-amount measuring unit that measures a light amount of the light having the second wavelength emitted from the wavelength converting element; an equivalent-light-amount calculating unit that calculates, on the basis of the measured light amount measured by the light-amount measuring unit, an equivalent light amount equivalent to a light amount of the light having the first wavelength; a light-amount correcting unit that corrects an emitted light amount of the semiconductor light-emitting element using the input value and the equivalent light amount; and a current supplying unit that supplies a driving current to the semiconductor light-emitting element according to the input value and a command value outputted by the light-amount correcting unit, wherein the light-amount correcting unit calculates an equivalent light amount error as a difference between the equivalent light amount and a target equivalent light amount that should be emitted by the semiconductor light-emitting element with respect to the input value, calculates, using an integrated value of a product of the equivalent light amount error and the input value, differential efficiency defined by an amount of change in the equivalent light amount with respect to an amount of change in the driving current, calculates, using an integrated value of the equivalent light amount error, a threshold current value of the semiconductor light-emitting element, and corrects the command value according to the differential efficiency and the threshold current value.