Patent ID: 8654170

Claim:
An optical device comprising: a drive unit configured to drive a light source that outputs a laser beam; a detecting unit configured to detect the laser beam output from the light source; a converting unit configured to convert an output of the detecting unit into a value within a predetermined range; and a control unit configured to control the drive unit to switch a light quantity of the laser beam output from the light source from a first light quantity within an imaging light quantity range for forming an image to a second light quantity outside the imaging light quantity range, or vice versa, wherein when the control unit has switched the light quantity of the laser beam to the first light quantity, the converting unit converts an upper limit light quantity in the imaging light quantity range which is an output of the detecting unit into a maximum value in the predetermined range, and converts a lower limit light quantity in the imaging light quantity range which is an output of the detecting unit into a minimum value in the predetermined range.