Rangefinder and range finding method

A method for determining the distance to an object using a rangefinder that includes:

• a lens system including a number of lenses, which are arranged so that their optical axes are parallel to each other and which are integrated together;
• an imager, which has a number of image capturing areas that face the respective lenses and which transforms light that has been incident on the image capturing areas into an electrical signal;
• a light-transmitting flat plate, which is arranged between the imager and the optical system and which has substantially the same thermal expansion coefficient as the lenses;
• and a number of markers, which are provided on the light-transmitting flat plate for the respective lenses and each of which casts its shadow on an associated one of the image capturing areas,
• the method comprising the steps of:
• (a) receiving the electrical signal from the imager, thereby generating a plurality of image signals representing images that have been produced in the respective image capturing areas;
• (b) determining the locations of the markers' shadows on the respective images to be detected marker locations;
• (c) calculating the magnitude of parallax detected based on a difference in the object's location between the respective images;
• and
• (d) correcting the positions of the optical axes of the lenses based on initial marker locations and initial optical axis positions that have been detected in advance and the detected marker locations and determining the distance to the object by performing a triangulation based on the corrected optical axis positions and the magnitude of the parallax detected.