Patent ID: 8645081

Claim:
A light absorption examining device that examines pulse laser beam absorption when a measuring object is irradiated with a pulse laser beam and the pulse laser beam is transmitted through the measuring object, the light absorption examining device comprising: a laser light source that emits the pulse laser beam according to a supplied driving pulse; a measuring unit that retains the measuring object and irradiates the measuring object with the pulse laser beam to cause the pulse laser beam to transmit through the measuring object; a light receiving unit that receives the pulse laser beam transmitted through the measuring object and outputs a light receiving signal; a pulse generator that produces a single rectangular pulse of an electrical signal at a time when a signal magnitude of the light receiving signal output from the light receiving unit becomes equal to or higher than a set threshold value; a laser driver that supplies the produced rectangular pulse as the driving pulse to the laser light source in order to drive the laser light source to emit the pulse laser beam from the laser light source every time the produced rectangular pulse is supplied to the laser light source, and drives the laser light source to emit a single pulse laser beam; and a control/processing unit that measures and determines an accumulated delay time and examines absorption of the pulse laser beam by the measuring object using the measured accumulated delay time, the accumulated delay time representing a delay in a production timing of the rectangular pulse caused by reduction of light intensity due to absorption of the pulse laser beam during a period between a start-up driving pulse and a latest rectangular pulse of an electrical signal that is produced when the pulse generator repeats to generate the rectangular pulse no less than predetermined repetition times, after the start-up driving pulse for starting the emission of the pulse laser beam is supplied to the laser driver to drive the laser light source to emit the pulse laser beam and the rectangular pulse is supplied a plurality of times from the pulse generator to drive the laser light source to emit the pulse laser beam the plurality of times.