SERVO FEEDBACK CONTROL BASED ON DESIGNATED SCANNING SERVO BEAM IN SCANNING BEAM DISPLAY SYSTEMS WITH LIGHT-EMITTING SCREENS
Scanning beam display systems that scan one servo beam and an excitation beam onto a screen that emits visible light under excitation of the light of the excitation beam and control optical alignment of the excitation beam based on positioning of the servo beam on the screen via a feedback control.
1 . A scanning beam display system, comprising:
an excitation light source to produce at least one excitation beam having optical pulses that carry image information;
a servo light source to produce at least one servo beam at a servo beam wavelength that is invisible;
a beam scanning module to receive the excitation beam and the servo beam and to scan the excitation beam and the servo beam;
a light-emitting screen positioned to receive the scanning excitation beam and the servo beam and comprising a light-emitting area which comprises (1) parallel light-emitting stripes which absorb light of the excitation beam to emit visible light to produce images carried by the scanning excitation beam, and (2) stripe dividers parallel to and spatially interleaved with the light-emitting stripes with each stripe divider being located between two adjacent stripes, each stripe divider being optically reflective;
an optical servo sensor positioned to receive light of the servo beam scanning on the screen including light reflected by the stripe dividers and to produce a monitor signal indicative of positioning of the servo beam on the screen; and
a control unit operable to, in response to the positioning of the servo beam on the screen in the monitor signal, adjust timing of the optical pulses carried by the scanning excitation beam based on a relation between the servo beam and the excitation beam to control the spatial alignment of spatial positions of the optical pulses in the excitation beam on the screen.