Multi-stripe Laser Diode for Scanning Projector Brightness
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Solution Overview
Problem
Scanning projectors face limitations in brightness due to maximum power constraints from laser light sources, particularly in bright environments, and traditional solutions require bulky and expensive optical elements to combine light from multiple lasers.
Innovation Solution
The use of a multi-stripe laser with multiple laser elements on a single semiconductor die, where at least one scanning mirror reflects the laser light beams in a raster pattern, allowing for improved brightness and resolution without the need for complex optics by independently controlling each laser element to generate pixels simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate laser sources are used to generate multiple wavelengths, then the laser display system can achieve full-color capability, but the device complexity and cost increase significantly
Solution Approach 1:
The patent segments a single laser source into multiple wavelength outputs by using nonlinear optical crystals that divide the laser's output into different color components (blue, green, yellow, orange, red), allowing full-color laser display from one laser source rather than requiring multiple separate lasers
Solution Approach 2:
The patent changes the wavelength parameter of the laser light through nonlinear optical conversion processes, transforming a single wavelength (blue laser at 450nm) into multiple wavelengths through frequency doubling, sum-frequency generation, and other nonlinear optical effects in crystals like BBO, LBO, and KTP
2Adaptability or versatility
If multiple separate laser sources are used to generate multiple wavelengths, then the laser display system can achieve full-color capability, but the alignment precision requirements become extremely difficult to maintain
Solution Approach 1:
The patent segments the wavelength generation function into nonlinear optical crystals positioned within the laser cavity, where each crystal generates specific wavelength components through controlled nonlinear optical interactions, eliminating the need for precise alignment of multiple independent laser sources
Solution Approach 2:
The patent nests multiple nonlinear optical crystals within the single laser resonant cavity, allowing sequential or simultaneous wavelength conversion processes to occur within the same optical path, thereby maintaining precise alignment through the shared cavity structure rather than requiring alignment between separate lasers
3Adaptability or versatility
If multiple separate laser sources are used to generate multiple wavelengths, then the laser display system can achieve full-color capability, but the system reliability decreases due to multiple potential failure points
Solution Approach 1:
The patent merges multiple wavelength generation functions into a single integrated laser system where nonlinear optical crystals convert the blue laser output into multiple colors (green, yellow, orange, red) within or outside the cavity, reducing the number of independent laser sources from multiple to one, thereby improving reliability by eliminating multiple potential failure points
4Duration of action of stationary object
If traditional laser cavities are used, then the laser can operate continuously, but the threshold pump power is too high for practical laser display applications
Solution Approach 1:
The patent employs periodic pulsed pumping instead of continuous pumping, where the laser diode delivers short high-power pulses that excite the gain medium above threshold, allowing the laser to oscillate and generate the desired wavelengths with much lower average pump power compared to continuous operation of traditional cavities
Solution Approach 2:
The patent transforms the static continuous-wave laser cavity into a dynamic pulsed oscillating system where the resonant cavity is periodically activated above threshold during pump pulses, enabling efficient energy conversion and lower threshold requirements through transient high-gain conditions rather than steady-state continuous operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances image brightness and resolution without increasing scanning frequency or using bulky optics, resulting in a more compact and efficient scanning projector.
Implementation Method 1
a blue laser is used to generate green, yellow, orange and red wavelengths through nonlinear optical interactions with crystals
Implementation Method 2
photons bounce back and forth between the two mirrors, stimulating atoms in the gain medium to emit more photons
Implementation Method 3
photons bounce back and forth between the two mirrors
Data Source
Figure 1
Figure 2A~2B
Figure 3A~5B
AI summary
A scanning projector (100) and method is provided that uses at least one multi-stripe laser (102) to generate the laser light for the scanned image. Specifically, the multi-stripe laser includes at least a first laser element and a second laser element formed together on a semiconductor die. The first laser element is configured to output a first laser light beam, and the second laser element is configured to output a second laser light beam. At least one scanning mirror is configured to reflect the first laser light beam and the second laser light beam, and a drive circuit is configured to provide an excitation signal to excite motion of the at least one scanning mirror. Specifically, the motion is excited such that the at least one scanning mirror reflects the first laser light beam and the second laser light beam in a raster pattern of scan lines.