Reflective Diffractive Grating for Compact Laser Beam Combining
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Solution Overview
Problem
Laser scanning projection systems face challenges in compactly combining red, green, and blue laser beams into a single beam due to the size constraints of pico-projection systems, as existing solutions like dichroic and polarizing mirrors and dispersive optical elements are volumetric and require multiple optical elements, making them bulky.
Innovation Solution
A compact beam combining device using a reflective diffractive grating surface with an optimized profile for high diffraction efficiency, which reduces the number of optical elements needed by efficiently combining three light beams into one, eliminating the need for additional devices like dichroic mirrors or prisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dichroic mirrors or dispersive optical elements are used to combine laser beams, then beam combining effectiveness is improved, but device size increases
Solution Approach 1:
The patent combines multiple beam combining functions into a single optical element - a reflective diffraction grating that simultaneously combines red, green, and blue laser beams into one beam. This eliminates the need for separate dichroic mirrors or dispersive elements, reducing device volume while maintaining beam combining effectiveness
Solution Approach 2:
The reflective diffraction grating performs multiple functions: it acts as both a beam combining element and a wavelength-separating element, replacing what would traditionally require multiple specialized optical components. This multi-functionality reduces the overall device size while achieving the same beam combining results
2Measurement precision
If multiple optical elements are used for beam combining, then combining precision is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple beam combining operations into a single reflective diffraction grating element that handles all three laser wavelengths simultaneously. This reduces device complexity from multiple separate optical elements to one integrated component while maintaining the precision needed for accurate beam combining
3Measurement precision
If traditional dispersive elements are used, then beam separation accuracy is improved, but energy loss increases
Solution Approach 1:
Instead of using transmissive dispersive elements that absorb or scatter light, the patent employs a reflective diffraction grating that redirects light through reflection. This inverted approach maintains beam separation accuracy while reducing energy loss, as reflective surfaces generally have higher efficiency than transmissive dispersive materials
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 achieves high diffraction efficiency, allowing for a more compact device size and improved energy efficiency by using a single reflective diffractive grating surface, enabling the creation of a compact laser scan pico-projector that effectively combines red, green, and blue laser beams into a mixed-color light beam.
Implementation Method 1
a reflective diffractive grating surface configured to combine a first, a second and a third incident light beam having different colors to a single diffracted mixed-color light beam when impinging on the reflective diffractive grating surface
Data Source
AI summary
The present application discloses a beam combining device, which includes a reflective diffractive grating surface configured to combine a first, a second and a third incident light beam having different colors to a single diffracted mixed-color light beam when impinging on the reflective diffractive grating surface, wherein a profile of the grating surface is configured according to an optimization criterion with respect to a diffraction efficiency.