Patent ID: 7054046

Claim:
A method of doubling an optical scanning frequency, comprising: disposing a mirror with a reflection point in an equilibrium position such that a line passing through the reflection point and orthogonal to a direction of the mirror in the equilibrium state divides a region into a light incidence area and a light reflection area; emitting light from the light incidence area toward the reflection point of the mirror along a light incidence path at an angle θ to the mirror's equilibrium position; oscillating the mirror about the equilibrium position between angles −δ 1 and +δ 2 at a predetermined frequency and scanning through reflection the incident light into a light scanning area of the light reflection area with an angular range corresponding to δ 1 and δ 2 , the light scanning area being divided into a feedback scanning region and an output scanning region; feeding the light that enters the feedback scanning region directly back into the vicinity of the light incidence path of the light incidence area; and reflecting the light fed back into the light incidence area toward the reflection point of the mirror and scanning through reflection the reentered light into the output scanning region.