Patent ID: 7821653

Claim:
A portable electronic device for measuring a distance (D 1 ) between two points (E 1 , E 2 ), the portable electronic device comprising: a visible and rotatable light emitter for generating a rotatable light beam capable of rotating from an initial direction to project to the point (E 1 ), the initial direction being substantially perpendicular to a line joining the points (E 1 , E 2 ), a perpendicular distance (H 1 ) between the light emitter and the line, and a distance (S 1 ) from the point (E 2 ) to the point of intersection of the line defined by the first and second points (E 1 , E 2 ) with the initial direction, being known; an angle computing unit for computing a first angle defined by the visible light beam projecting to the point (E 1 ) and the initial direction according to the rotatable light beam; a distance computing unit for computing the distance (D 1 ) based on the first angle, the distance (H 1 ) and the distance (S 1 ); and an output unit for outputting the distance (D 1 ).