The optical sensor for detecting NO₂ and O₃ using a white GaN LED

Abstract

This article describes the scheme and principle of operation of an optical sensor for detecting nitrogen dioxide (NO2) and ozone (O3) based on the effect of optical absorption spectroscopy. A distinctive design feature of the proposed technical solution is that it is proposed to use an inexpensive powerful white led based on GaN as an optical radiation source, which has two relatively wide radiation peaks at wavelengths λ from 420 to 440 nm and λ from 525 to 650 nm. To separate the light streams and form separate measurement channels, three multilayer optical coatings were synthesized: a broadband beam-splitting coating and two narrow-band reflective coatings.

The application of phosphor Sr4La(PO4)3O:Ce3+,Tb3+,Mn2+ on the white-LEDs: luminescence and power transmission characteristics

“…Due to various properties such as extended duration, minimal energy usage, compact size, and environmental safety, people utilize white light-emitting diodes (WLEDs) which attracted tremendous potential attention like solid-state illumination industry [1]- [3]. At this time, the producing white color light that is very popular method of is merging the InGaN chip in blue color and the yellow color phosphor Y 3 Al 5 O 12 :Ce 3+ (YAG: Ce) [4], [5]. Nevertheless, owing to the shortage in the red-light component, this kind of white color illumination output has small hue rendered indice (CRI≈70-80) as well as great correlating colour temperature (CCT≈7500 K).…”

Application of dual-layer phosphor geometries for enhancing the optical properties of white-light LEDs

“…If this task is not completed, lumen efficiency will be lost. To resolve such drawback, we can enhance the geometries or the attributes of the distant phosphor motes in order to boost the lumen efficiency with patterned or shaped layers of phosphor [10], [11], poly-layer phosphor [12]- [14], nanoparticle-blended phosphor [15] and advanced phosphor substance [16]. Another way to overcome the disadvantage is to combine the LED's emissions with a reflecting lens for increased lumen efficiency [17], [18].…”