Phosphor-Integrated Laser Light Source for Eye-Safe Brightness
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Solution Overview
Problem
Conventional light sources, such as incandescent bulbs, LEDs, and fluorescent lighting, suffer from inefficiencies, thermal instability, broad spectrum emission, and lack of directionality, while LED-based light sources face limitations like the 'droop' phenomenon, low spatial brightness, and internal polarization fields, making them unsuitable for high-brightness and focused applications.
Innovation Solution
A laser diode or superluminescent diode excitation source integrated with phosphor materials forms a compact, high-brightness, and highly-efficient white light source with inherent safety features to prevent laser beam exposure, using mirror configurations or electrical circuit modifications to maintain eye safety by ceasing lasing below a threshold condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional light bulbs are used, then they provide illumination, but they dissipate more than 90% of energy as thermal energy
Solution Approach 1:
The patent replaces the thermal radiation mechanism of conventional incandescent bulbs with a laser-based optical system. The laser diode generates coherent light that excites phosphor materials to produce desired wavelengths, eliminating the need for thermal heating and dramatically reducing energy loss as heat.
Solution Approach 2:
The invention changes the fundamental operating parameters from thermal radiation (broad spectrum) to stimulated emission (narrow spectrum). By controlling the laser wavelength and phosphor selection, the system achieves precise spectral control with minimal energy loss, converting inefficient thermal energy conversion into efficient optical excitation.
2Illumination intensity
If laser diodes are used for high brightness, then they provide focused directionality, but they pose eye safety hazards due to coherent beam exposure
Solution Approach 1:
The patent introduces phosphor materials as an intermediary between the laser diode and the final light output. The laser excites the phosphor, which then emits incoherent light with reduced directionality. This intermediary converts the hazardous coherent laser beam into safe incoherent illumination while maintaining high brightness through the phosphor's emission characteristics.
Solution Approach 2:
The invention converts the potentially harmful coherent laser beam into beneficial incoherent light. By using the laser only for excitation purposes and allowing the phosphor to emit the final light, the system transforms the hazardous property of coherence into a useful excitation mechanism, while the output light gains safety through incoherence and reduced directionality.
3Ease of operation
If conventional light bulbs are used, then they emit light in all directions, but this lack of directionality is undesirable for projection displays and optical data storage
Solution Approach 1:
The patent applies local quality by using optical elements (lenses, mirrors, or waveguides) to direct light only where needed. The laser-based system inherently provides directional emission, and additional optical components can further control the light path to achieve precise focusing for projection displays and optical data storage applications.
4Duration of action of stationary object
If LED-based light sources are used, then they offer long lifetime and low cost, but they suffer from the 'droop' phenomenon and low spatial brightness
Solution Approach 1:
The patent merges the advantages of laser diodes (high spatial brightness, directionality) with phosphor materials (long lifetime, efficiency). The laser diode provides the excitation source with superior brightness and directional control, while the phosphor materials convert this energy into the desired spectrum, combining the strengths of both technologies to overcome their individual limitations.
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
The solution provides a cost-effective, high-brightness, and eye-safe laser-based light source with reduced coherence and directionality, preventing accidental laser beam exposure, suitable for various applications including lighting, displays, and specialized uses.
Implementation Method 1
An LED is a two-lead semiconductor light source typically based on a p-i-n junction diode, which emits electromagnetic radiation when activated. When a suitable voltage is applied to the leads, electrons and holes recombine within the device releasing energy in the form of photons. This effect is called electroluminescence
Implementation Method 2
Fluorescent lighting uses an optically clear tube structure filled with a halogen gas and, which typically also contains mercury. A pair of electrodes is coupled between the halogen gas and couples to an alternating power source through a ballast. Once the gas has been excited, it discharges to emit light. Typically, the optically clear tube is coated with phosphors, which are excited by the light
Data Source
AI summary
The present invention provides a device and method for a laser based light source using a combination of laser diode or waveguide gain element excitation source based on gallium and nitrogen containing materials and wavelength conversion phosphor materials designed for inherent safety. In this invention a violet, blue, or other wavelength laser diode source based on gallium and nitrogen materials is closely integrated with phosphor materials, such as yellow phosphors, to form a compact, high-brightness, and highly-efficient, light source with closed loop design features to yield the light source as an eye safe light source.