Patent ID: 8428092

Claim:
A laser unit comprising: a laser output commanding part configured to generate a laser output command based on a predetermined program or a user input; an excitation energy commanding part configured to generate an excitation energy command transmitted to a laser power supply based on the laser output command; a laser power monitor configured to measure laser output obtained by excitation energy which is output by the laser power supply; an output correcting part configured to determine a correction coefficient for correcting command output included in the laser output command so that the command output coincides with laser output measured by the laser power monitor; a preliminary laser outputting part configured to carry out a preliminary laser output for a predetermined duration time on plurality of preset preliminary laser output conditions, wherein a preliminary laser output command for the preliminary laser output is different from a laser output command for determining the correction coefficient; and a correction laser outputting part configured to output a correction laser output for a duration time, after the preliminary laser output, on a laser output condition for determining the correction coefficient, wherein the plurality of preliminary laser output conditions include a command for sequentially outputting the laser from a high laser output to a low laser output only when the correction laser output is lower than a predetermined value, and wherein the output correcting part determines the correction coefficient based on a measurement result of the correction laser output.