LED Spectrophotometric Colorimeter with Integrating Sphere
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Solution Overview
Problem
Current spectrophotometric colorimeters face challenges in reproducibility due to non-uniform illumination and wavelength resolution, especially when measuring samples with non-uniform surfaces, and lack effective verification regulations, leading to suboptimal measurement results.
Innovation Solution
A spectrophotometric colorimeter based on an LED light source with an integrating sphere, a coupling light path, and a spectrometer, featuring a composite LED light source, a cone-shaped lower semi-sphere, and a rotating linear-array sensor, which improves reproducibility by ensuring uniform illumination and automatic wavelength calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional light source is used in the spectrophotometric colorimeter, then the spectral detection range can cover visible light, but the measurement reproducibility deteriorates due to non-uniform illumination
Solution Approach 1:
The patent employs an integrating sphere with a specific geometric configuration (upper semi-sphere and lower cone-shaped semi-sphere with 45-degree cone angle) to achieve uniform light distribution. The curved surfaces within the integrating sphere multiple-reflect and diffuse the light, transforming the non-uniform illumination from conventional light sources into uniform illumination across the measurement field, thereby resolving the contradiction between maintaining visible light spectral range and achieving measurement reproducibility.
2Measurement precision
If the spectral detection range is limited to 380-780 nm, then the instrument design is simplified, but the measurement accuracy deteriorates when measuring samples containing fluorescent matter
Solution Approach 1:
The patent extends the spectral detection range parameter from the conventional 380-780 nm to 300-1100 nm by selecting LEDs with appropriate peak wavelengths and configuring the linear-array sensor accordingly. This parameter change enables the detection of UV-induced fluorescence emissions while maintaining a relatively simple LED-based light source design, thus improving measurement accuracy for fluorescent samples without significantly increasing device complexity.
3Measurement precision
If the wavelength resolution is set to 10 nm, then the device complexity is reduced, but the wavelength accuracy deteriorates under temperature variations
Solution Approach 1:
The patent implements a temperature compensation mechanism that monitors temperature variations and adjusts the wavelength calibration accordingly. By establishing the relationship between temperature changes and LED peak wavelength shifts, the system applies feedback correction to maintain accurate wavelength measurement despite thermal effects, thereby achieving high wavelength accuracy without requiring overly complex hardware designs.
4Adaptability or versatility
If multiple LEDs with different peak wavelengths are used, then the spectral coverage is improved, but the illumination uniformity deteriorates
Solution Approach 1:
The patent uses the integrating sphere's curved reflective surfaces to multiple-reflect and diffuse the combined light from multiple LEDs with different peak wavelengths. This spherical geometry ensures that light from various spectral sources is thoroughly mixed and uniformly distributed throughout the measurement space, maintaining illumination uniformity while achieving broad spectral coverage from 300-1100 nm.
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 enhances reproducibility by achieving a reproducibility indicator of 0.92, meeting the verification requirements, and maintains wavelength accuracy despite temperature changes, thereby improving measurement consistency and accuracy.
Implementation Method 1
an inner wall of the integrating sphere is arranged with a composite light source consisting of eight LEDs; light emitted from each LED enters an interior of the integrating sphere through the incident aperture and is irradiated onto the inner wall of the integrating sphere
Implementation Method 2
the light enters the incident split through the coupling light path and is irradiated onto a linear-array sensor after being split by a spectral light path; different pixels of the linear-array sensor correspond to light radiation strengths at different wavelengths
Implementation Method 3
a composite light source consisting of eight LEDs; light emitted from each LED enters an interior of the integrating sphere
Data Source
AI summary
The present disclosure provides a spectrophotometric colorimeter based on LED light source, wherein the spectrophotometric colorimeter includes an integrating sphere, a coupling light path, and a spectrometer. An inner wall of the integrating sphere is arranged with a composite light source consisting of eight LEDs; a sphere wall of the integrating sphere defines an incident aperture; light emitted from each LED enters an interior of the integrating sphere through the incident aperture and is irradiated onto the inner wall. The coupling light path is configured to couple light at a measurement caliber such that the light can enter an incident split and to eliminate stray light from the inner wall. After emitting out from an observation aperture of the integrating sphere, the light enters the incident split through the coupling light path and is irradiated onto a linear-array sensor after being split by a spectral light path; and different pixels of the linear-array sensor correspond to light radiation strengths at different wavelengths.