Electronics Weekly
The technology inside is a blue-emitting GaN die and phosphor converter, specially developed for spectroscopy, that converts the blue light into radiation across 650 to 1,050nm.
“By making improvements to the phosphor material, developers at Osram Opto Semiconductors have succeeded in increasing the intensity of the light by 60% compared with the predecessor component,” said the firm, comparing it to the Oslon Black Flat SFH 4735, introduced at the end of 2016.
Spectroscopy allows certain chemical bonds and groups of atoms to be identified, which allows the presence of certain molecules to be inferred. And according to Osram, near-infrared spectroscopy enables such things as the water, fat, sugar and protein content of food to be measured. “If a defined light spectrum is directed at a sample it is possible to determine the presence and quantity of certain ingredients from the wavelength distribution of the reflected light,” it said.
The firm is aiming the new led at phone-based spectrometers for technology-based fitness monitoring and electronic aids. “Consumers will soon be able to use their smartphones to check how fresh supermarket food is, measure the calories in canteen meals and verify whether the tablet in their hand really is a painkiller,” claimed Osram.
Dunno about IR emitting phosphors but I did turn up a paper from 1970 where someone produced blue light from an IR pumped phosphor.
Ah ha, I think that works by absorbing two photons and emitting a higher energy photon
Reality warning – this guess relies on a belief in photons, which is a deceit I will slavishly follow until someone actually finds out what is going on.
this is probably a pretty basic question.. considering that IR and red were some of the earliest and easiest wavelengths to produce, why use a blue LED and phosphors to generate IR?
I’m going to assume that it is more efficient than producing it directly, which prompts the next question: why?
I’ll have to poke around the web a bit and see if I can find a quick explanation. Otherwise, I really should open up my enormous solid state physics text from the early 90’s and see if it can shed any light on the issue. It was printed well before blue LEDs were on the market, so I’m not expecting much.
Because it’s “broad spectrum”?
It’s covering 650nm to 1050nm.
IIRC the typical IR led has a much narrower bandwidth than that, maybe a 50nm spread.
Hi Steve and zeitghost
That phosphor technique is so valuable for broadening spectrum – although a beast* to go the other way – hence nano-particle quantum-dot phosphors.
* that did say bugger, but I edited it
good point about the broad spectrum being the requirement for phosphors as opposed to finding a material with the appropriate bandgap… I wasn’t thinking about that aspect.
How long have people been using phosphors to generate IR? Pretty amazing that phosphors are available to emit such a range of wavelengths!