Laser Light Source Divergence Control for Compact Projection Systems
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Solution Overview
Problem
Conventional light source systems for projection and display fields are large due to numerous optical elements, and separating 445 nm and 462 nm blue light beams is costly due to the need for a steep filter curve in wavelength-based light separation.
Innovation Solution
A light emitting device with a laser light source comprising a first and second laser array generating lights with different wavelength ranges, where the light collecting system controls the divergence angles of these lights to maintain a ratio less than 0.7, allowing for etendue difference-based separation in the downstream light path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wavelength-based light separation is used to separate 445 nm and 462 nm blue light beams, then the two light beams can be separated, but the filter plate requires a very steep light filter curve which increases cost
Solution Approach 1:
The patent changes the separation parameter from wavelength-based filtering to etendue-based spatial separation. By controlling the divergence angles of the two blue light beams to maintain a ratio less than 0.7, the system creates distinguishable etendue characteristics that enable separation without requiring steep wavelength-based filter curves, thereby reducing manufacturing cost and filter complexity
Solution Approach 2:
The patent segments the light collection and separation process into distinct functional regions. The light collecting system includes a first region for the first blue light beam and a second region for the second blue light beam, with different combined focal lengths. This spatial segmentation creates different etendue values for each beam, enabling cost-effective separation downstream without complex filtering
2Reliability
If multiple optical elements are used in the light source system, then light collection and homogenization are improved, but the system size becomes large
Solution Approach 1:
The patent merges the light collection and homogenization functions into a single integrated light collecting system. The system combines a condenser lens for light collection with a homogenizing rod for uniformity, creating a compact integrated unit that maintains high light collection efficiency while reducing overall system size compared to separate optical elements
Solution Approach 2:
The light collecting system is designed with multi-functionality, where the same optical elements serve multiple purposes: the condenser lens both collects light from the laser arrays and begins the homogenization process, while the homogenizing rod simultaneously uniformizes the light distribution and further compactes the optical path. This multi-functionality reduces the number of separate components needed
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 results in a compact light source system capable of effectively separating and utilizing the two light beams, improving excitation efficiency and reducing system size by leveraging the etendue difference between the light beams.
Implementation Method 1
The wavelength conversion device 30 includes a wavelength conversion layer, which includes a yellow phosphor, for absorbing the blue laser light from the first light emitting device 10 and generating a yellow converted light
Implementation Method 2
The light collecting system 40 includes a filter plate 401 and a collecting lens 402, where the filter plate 401 transmits blue light and reflects yellow light
Data Source
Figure 1~2A
Figure 2B~3
Figure 4A~4B
AI summary
A light-emitting device (1) and a related light source system. The light-emitting device (1) comprises a laser light source (11, 21, 31) and a light collecting system (12, 22). The laser light source (11, 21, 31) comprises a first laser array (111, 211, 311) and a second laser array (112, 212, 312) for respectively generating a first light and a second light with different wavelength ranges. The light collecting system (12, 22) is used for collecting the light emitted from the laser light source arrays. The ratio of the divergence angle of the collected second light to that of the first light is less than or equal to a predetermined value. The predetermined value is 0.7. The light-emitting device (1) is capable of generating two kinds of light beams with different etendues.