Post-objective scanning beam systems
View Patent ↗Scanning beam systems, apparatus and techniques in optical post-objective designs with two beam scanners for display and other applications.
1. A scanning beam system, comprising:
an optical module operable to produce a scanning beam of excitation light having optical pulses that carry image information; and
a fluorescent screen comprising parallel fluorescent stripes that are displaced from one another along a first direction perpendicular to the parallel fluorescent stripes which are elongated along a second direction, the parallel fluorescent stripes absorbing the excitation light and emitting visible fluorescent light to produce images carried by the scanning beam,
wherein the optical module comprises:
a light source to produce the beam of excitation light;
a horizontal polygon scanner to scan the beam of excitation light along the first direction on the screen;
a vertical scanner having a single mirror that scans back and forth to scan the beam of excitation light from the polygon scanner along the second direction on the screen;
a 1-dimensional scan lens placed between the polygon scanner and the vertical scanner to direct the beam of excitation light from the polygon scanner along a line on the vertical scanner and to focus the beam of excitation light onto the screen; and
a controller that controls modulation of the beam of excitation light and adjust timings of the optical pulses, in response to displacements in position of the optical pulses along the first direction on the screen caused by scanning of the beam of excitation light along the second direction by the vertical scanner, to reduce the displacements in position of the optical pulses.
2. The system as in claim 1 , further comprising:
a beam focusing element placed between the light source and the horizontal polygon scanner to adjust a focus of light on the screen;
an actuator coupled to the beam focusing element to adjust a position of the beam focusing element, in response to a control signal, to adjust the focus in synchronization with a scanning position of the vertical scanner.
3. The system as in claim 2 , wherein:
the beam focusing element comprises two lenses separated from each other, and
the actuator is engaged to at least one of the two lenses to adjust a spacing between the two lenses.
4. The system as in claim 1 , wherein:
the light source includes one or more diode lasers that produce the beam of excitation at an excitation wavelength, each diode laser being directly modulated to produce a modulated beam of optical pulses that carry image information under a control of the controller.
5. The system as in claim 1 , wherein:
the vertical scanner includes a galvanometer engaged to the single minor to scan the single mirror back and forth.
6. The system as in claim 1 , wherein:
two adjacent parallel fluorescent stripes are made of different materials that emit visible light of different colors.
7. The system as in claim 1 , wherein the san lens is a f-theta lens.
8. The system as in claim 1 , wherein:
the screen is located near the vertical scanner; and
the system includes a reflector positioned above the plane defined by positions of the horizontal polygon scanner, the scan lens and the vertical scanner, wherein the reflector is oriented and positioned to receive the beam reflected from and scanned by the vertical scanner and to reflect the beam to the screen along a folded optical path between the vertical scanner and the screen.
9. The system as in claim 8 , wherein:
the screen is located, along with the reflector, on one side of the horizontal polygon scanner, the scan lens and the vertical scanner.
10. A scanning beam system, comprising:
a light source to produce a beam of light having optical pulses that carry image information;
a horizontal polygon scanner to scan the beam along a first direction at a first scanning rate;
a vertical scanner located downstream from the horizontal polygon scanner in a path of the beam of light and having a single mirror that scans back and forth to scan the beam from the polygon scanner along a second direction different from the first direction at a second scanning rate less than the first scanning rate;
a 1-dimension scan lens placed between the polygon scanner and the vertical scanner to direct the beam from the polygon scanner along a line on the vertical scanner and to focus the beam onto a reference surface;
a beam focusing element placed between the light source and the horizontal polygon scanner to adjust a focus of the beam on the reference surface; and
an actuator coupled to the beam focusing element to adjust a position of the beam focusing element, in response to a control signal based on a variation in beam size with scanning of the single mirror in the vertical scanner, to adjust the focus in synchronization with a scanning position of the vertical scanner to reduce a variation in beam size of the beam on the screen with the scanning of the vertical scanner.
11. The system as in claim 10 , wherein:
the beam of light is at one wavelength.
12. The system as in claim 10 , wherein:
the beam of light comprises light of at least two different wavelengths.
13. The system as in claim 10 , wherein:
the beam focusing element comprises a first lens and a second lens that are spaced from each other in an optical path of the beam of light, and
the actuator is engaged to at least one of the first and second lenses to adjust a spacing between the first and second lenses.
14. The system as in claim 10 , comprising:
a screen located near the vertical scanner and oriented to be perpendicular to a direction from the horizontal polygon scanner to the scan lens and the vertical scanner, the screen having a screen surface as the reference surface; and
a reflector positioned above the plane in which the horizontal polygon scanner, the scan lens and the vertical scanner are located and oriented to receive the beam reflected from and scanned by the vertical scanner and to reflect the beam to the screen.
15. The system as in claim 14 , wherein:
the reflector is oriented to have
a first end located close to a first end of the screen away from the vertical scanner to direct the beam from the vertical scanner to the first end of the screen, and
a second end to direct the beam from the vertical scanner to a second end of the screen that is close to the vertical scanner.
16. The system as in claim 14 , wherein:
the screen is located, along with the reflector, on one side of the plane in which the horizontal polygon scanner, the scan lens and the vertical scanner are located.
17. The system as in claim 10 , comprising:
a controller that controls modulation of the beam of light and controls timing of the optical pulses in the beam of light, in response to a distortion in positions of the optical pulses on the reference surface caused by scanning of the beam along the second direction by the second scanner, to correct the distortion.
18. A method for scanning a beam of sequential optical pulses in time along two directions on a target surface, comprising:
scanning the beam with a first scanner to scan the beam along a first direction at a first scanning rate;
directing the beam out of the first scanner into a second scanner to scan the beam along a second direction different from the first direction at a second scanning rate less than the first scanning rate;
using a 1-dimension scan lens placed between the first and the second scanners to focus the beam onto the target surface;
controlling a focus of the beam in synchronization with a scanning position of the second scanner to control focusing of the beam on the target surface to counter a variation in beam size on the target surface due to scanning of the second scanner; and
controlling timing of the optical pulses in the beam, in response to displacements in position of the optical pulses along the first direction on the target surface caused by scanning of the beam along the second direction by the second scanner, to reduce the displacements in position of the optical pulses.
19. The method as in claim 18 , comprising:
using two lenses spaced from each other in an optical path of the beam to adjust a relative position of the two lenses in controlling the focus of the beam.
20. A scanning beam system, comprising:
a plurality of diode lasers to produce beams of excitation light at an excitation wavelength, each diode laser being directly modulated to produce optical pulses that carry image information;
a controller that controls the diode lasers to directly modulate driving currents of the diode lasers in producing the beams of excitation light;
a screen comprising parallel light-emitting stripes that are displaced from one another along a first direction perpendicular to the parallel light-emitting stripes which each are elongated along a second direction, two adjacent parallel light-emitting stripes being made of different materials that emit visible light of different colors by absorbing the excitation light to produce images carried by the beams of excitation light;
a horizontal polygon scanner in an optical path of the beams of excitation light between the diode lasers and the screen to scan the beam along the first direction on the screen at a first scanning rate;
a vertical scanner located in the optical path of the beams of excitation light between the horizontal polygon scanner and the screen and having a galvanometer and a single mirror engaged to the galvanometer, the vertical scanner scanning back and forth to scan the beams of excitation light from the polygon scanner along the second direction on the screen at a second scanning rate less than the first scanning rate;
a 1-dimension scan lens placed between the polygon scanner and the vertical scanner to direct the beams of excitation from the polygon scanner along a line on the vertical scanner and to direct the beam onto the screen;
a beam focusing element placed between the diode lasers and the horizontal polygon scanner to adjust a focus of the beam on the reference surface;
an actuator coupled to the beam focusing element to adjust a position of the beam focusing element, in response to a variation in beam size on the screen caused by scanning of the single minor in the vertical scanner, to adjust the focus in synchronization with scanning of the vertical scanner to reduce a variation in beam size of the beam on the screen; and
means for controlling timings of the optical pulses, in response to displacements in position of the optical pulses along the first direction on the screen caused by scanning of the beam of excitation light along the second direction by the vertical scanner, to reduce or offset the displacements in position of the optical pulses.
21. The system as in claim 20 , comprising:
a relay optics module located in the optical path between the diode lasers and the horizontal polygon scanner to reduce spacing of the beams of excitation to form a compact set of the beams of excitation that spread within a facet dimension of the horizontal polygon scanner.
22. The system as in claim 20 , comprising:
a reflector positioned above a plane defined by the horizontal polygon scanner, the scan lens and the vertical scanner, wherein the reflector is oriented and positioned to receive the beam reflected from and scanned by the vertical scanner and to reflect the beam to the screen along a folded optical path between the vertical scanner and the screen.
23. The system as in claim 22 , wherein:
the screen is located, along with the reflector, on one side of the horizontal polygon scanner, the scan lens and the vertical scanner.