PURPOSE: To optically compensate an accuracy limit of a mechanical component by supplying a signal for indicating a position of an image on a surface of an optical table, comparing an image position measured by receiving an optical beam feedback signal and a position signal with a designated image position to determine a displacing error, and optically displaying the image along the table signal in response to an optical beam control signal.

CONSTITUTION: The optical photoplotter comprises an interferometer 22 for providing a signal for designating a position of an image to each axis to a controller 24. The controller 24 calculates a position of an optical beam on a surface of an optical table, and gives a signal to a shutter mechanism in an exposure head 26 to selectively expose a board. The controller 24 gives a position command signal to a control signal to the mechanism to motors 18, 20 to form a desired board pattern. In order that an optical compensator 44 gives a displacement of a plotted image, it is disposed in an optical path of the optical beam 16. An optical photoplotter control system decides an accurate position of the table, and compares the position with a designated position. If an error is discovered between the designated position of the beam 16 on the board and the measured position, the controller 24 generates a signal for displacing the image and removing an error of the position.