LED Light Radiation Measurement via Optical Diffuser
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring light radiation from light-emitting diodes (LEDs) at the wafer level suffer from deviations due to different coupling-out efficiencies and emission behaviors caused by variations in thin-layer materials and surface structuring, leading to measurement errors and yield losses when LEDs are encapsulated in casting materials.
Innovation Solution
A method and apparatus that use an optical device, such as a diffuser or microlens array, to redistribute the light radiation emitted by LEDs into a larger angular region before it enters an optical fiber, ensuring more precise and reliable measurements by converting the light into a diffuse form, thereby reducing the influence of different emission behaviors and surrounding effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a free end of an optical fibre is positioned at a relatively large spaced interval above a wafer to measure light radiation, then the measurement setup is simple and fast, but the measurement precision deteriorates due to different emission behaviors and small angular detection region
Solution Approach 1:
An optical device is introduced as an intermediary component between the light-emitting diode and the optical fibre. This optical device redistributes the light radiation into a larger angular region, enabling the optical fibre to capture light from multiple emission angles simultaneously. This resolves the contradiction by maintaining the simplicity and speed of the optical fibre method while improving measurement precision through enhanced light collection capability.
Solution Approach 2:
The optical device transforms the light radiation angular distribution from a narrow cone to a broader angular region. By changing the angular dimension of light propagation, the system can detect light radiation more effectively without requiring the optical fibre to be positioned extremely close to the wafer, thus maintaining productivity while improving measurement precision.
2Measurement precision
If an Ulbricht sphere is used to collect larger proportion of light radiation and reduce emission behavior influence, then the measurement precision improves, but the device complexity and calibration requirements increase
Solution Approach 1:
The invention extracts the essential function of the Ulbricht sphere (collecting light radiation from multiple angles) and implements it through a simpler optical device combined with an optical fibre. Instead of using the complex spherical geometry with diffuse reflective inner surface, the optical device redistributes light angularly, achieving similar precision improvements without the associated complexity and calibration requirements.
Solution Approach 2:
The optical device serves as a simple, replaceable component that can be easily manufactured and positioned. Unlike the expensive and complex Ulbricht sphere requiring meticulous calibration, the optical device provides a cost-effective solution that achieves comparable measurement precision with minimal setup complexity.
3Measurement precision
If an Ulbricht sphere with calibration is used to correct measurement deviations, then the measurement precision improves, but the measurement time increases considerably due to auxiliary light measurements
Solution Approach 1:
The optical device performs preliminary redistribution of light radiation into a larger angular region before the light enters the optical fibre. This preliminary action ensures that the measurement is less sensitive to emission behavior variations from the start, eliminating the need for time-consuming auxiliary calibration measurements that would otherwise be required to correct deviations.
Solution Approach 2:
The optical device automatically compensates for emission behavior variations through its light redistribution function. The system becomes self-correcting, as the optical device inherently handles the variations in emission characteristics without requiring external calibration procedures, thus maintaining high measurement precision while minimizing measurement time.
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 allows for more accurate and insensitive measurement of light radiation, enabling reliable comparison of LEDs with varying roughening or surface structuring at the wafer level, while eliminating the need for complex Ulbricht sphere calibration and reducing measurement errors, thus improving measurement throughput and precision.
Implementation Method 1
The optical device causes the light radiation passing through the optical device to be emitted in diffuse form in the direction of the end of the optical fibre
Implementation Method 2
A portion of the light radiation is coupled via the free end into the optical fibre and is guided further to a suitable measuring device
Data Source
AI summary
The invention relates to a method for measuring a light radiation (300) emitted by a light-emitting diode (210). In the method, an end (121) of an optical fiber (120) which is connected to a measuring device (130) is irradiated with the light radiation (300), which is emitted by the light-emitting diode (210), through an optical device (140), so that a portion of the light radiation (300) is coupled into the optical fiber (120) and is guided to the measuring device (130). The optical device (140) causes the light radiation (300) passing through the optical device (140) to be emitted in diffuse form in the direction of the end (121) of the optical fiber (120). The invention also relates to an apparatus (100) for measuring a light radiation (300) emitted by a light-emitting diode (210).