Patent ID: 8186835
Filing Date: 2012-05-29
Classification: G01M,G03B,H04N

Abstract:
1. A method of measuring a zoom ratio of a projection optical system adapted to project image light representing an original image on a projection screen, the method comprising: (a) projecting and displaying a measuring image including a measurement point on the projection screen so that the measurement point is displayed at a position with an offset from an optical axis of the projection optical system; (b) capturing a portion of the measuring image that contains a projected measurement point, which is the measurement point projected and displayed on the projection screen, from a measurement point detection position having a fixed position relative to the projection optical system; (c) detecting the projected measurement point based on the portion of the measuring image that is captured at the measurement point detection position; and (d) determining the zoom ratio using position information of the detected projected measurement point and a predetermined correspondence between the position information and the zoom ratio.