How does visible light color difference occur
How is visible light produced to the naked eye
The color visible to the naked eye is the visible part of the UV-C LED emission spectrum, which comes from electronic transitions between various deep energy levels and conduction band energy levels such as oxygen substitution sites and lattice mismatch dislocations in semiconductor materials. Due to the higher position of defect energy levels relative to the quantum well valence band, the photons emitted by electronic transitions have a longer wavelength, typically around 450nm, which is visible light
Why should visible light appear in different colors
UV-C LED chips, similar to IC semiconductor devices, are cut from a single wafer. Due to the limitations of semiconductor equipment accuracy, the concentration and types of material defects vary slightly among chips in different regions and batches on the wafer. This difference leads to differences in the position of deep energy levels that emit visible light, resulting in the emission of visible light of different wavelengths and presenting different colors. Although the wavelength difference is small, it is noticeable to the naked eye
Does the color difference affect the UVC sterilization effect
The conclusion is that it does not affect. Specifically, take four light beads of different colors (returned by a customer), as shown in Figure 1. The UVC band optical power was tested using an integrating sphere, and the specific data is shown in Table 1, all of which are within the nominal range. This data indicates that regardless of the visual color, the photoelectric performance of the UVC band meets the requirements, thereby ensuring the consistency of the sterilization effect. If deemed necessary, you can also send your company's products with color differences to our company for optoelectronic parameter review
Figure 1 Two LED beads with significantly different colors to the naked eye
Table 1 Integral sphere test results of four LED beads with different emission colors (@ 40mA, nominal 4-6mW, 270-280nm)
Can the color difference be effectively controlled
Due to the extremely weak visible light and the small difference between the main wavelengths of visible light. It is basically impossible to perform bin control on its color using traditional spectroscopic equipment. Of course, with technological advancements, (1) the improvement of LED efficiency will reduce the proportion of visible light energy, thereby reducing color differences; (2) The advancement of spectroscopic equipment has improved the sampling resolution of visible light, enabling bin based control; (3) The improvement of consistency within and between batches of epitaxial equipment has reduced the color difference of light beads
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