Patent ID: 7471712

Claim:
A laser irradiating device for condensing or focusing a processing laser beam (a) from a laser oscillator through a lens, and irradiating an object to be irradiated with the processing laser beam (a), wherein a first mirror is located at a reflection position (I) at which an optical path between the lens and the object to be irradiated is blocked and the processing laser beam (a) with a given reflectivity is reflected and at an open position (II) at which the optical path between the lens and the object to be irradiated is opened is arranged between the lens and the object to be irradiated, and a second mirror that reflects the processing laser beam (a) with a given reflectivity is arranged perpendicularly to an optical axis (L) of the processing laser beam (a) which is reflected by the first mirror located at the reflection position (I), and wherein the first mirror is located at the reflection position (I) so that the processing laser beam (a) that is transmitted through the lens is sequentially reflected by the first mirror and the second mirror, and an intensity of the processing laser beam (a) that is again reflected by the first mirror is made to coincide with an intensity of the processing laser beam (a) that is reflected from the object to be irradiated in a state where the first mirror is located at the open position (II), and the lens is heated when the processing laser beam (a) is transmitted through the lens and irradiated on the object to be irradiated.