Broadband LED  - Page 1
Forum section: electronics / projects

author: LaserSteve
author_rank: Super Contributor
timestamp: May 31, 2018, 04:33:07 pm
content: Anyone knows who makes the LED with this broad spectrum or a similar one.I love Thorlabs, but I need ~ 20 small leds with a full spectrum roughly 445 nm to 800 nm...That price for one die is shocking.I need a legitimate US distributer such as Digikey, and low cost pricing. This project to is get used USB spectrometers out to students who need them in local schools, as a loaned tool, and to have a cheap source for undergraduate labs.Halogen lamps need a lot of heat sinking and are a lot of grief for us. Everybody here wants to replace Halogens with LEDs for the obvious reasons. Especially on our Spectrophotometers with the custom, hard to get, twenty year old GE bulb, that burns out regularly.For what I pay for bulbs each semester, I could buy some other useful instrument for the classroom.I've ordered a few of the 380-850 Ebay "Bridgelux" clone lamps out of personal cash, but I can't deal with "Fly by Nite" sellers using the University P-Card.I have some beautiful lamps by Soraa, which are pricy, but your workstation absolutely glows like sunshine when you use them. However, no IR or UV. I'd endorse the Soraa lamps wholeheartedly.I only need a T1 and 3/4 or small SMD package, a few milliwatts of total light.Application is a spectrometer light source for undergraduate experiments.Steve

author: JohnG
author_rank: Frequent Contributor
timestamp: May 31, 2018, 04:57:53 pm
content: Maybe these will fit the bill. I have heard good things about them, but no personal experience.https://www.yujiintl.com/high-cri-led-lightingJohn

author: JohnG
author_rank: Frequent Contributor
timestamp: May 31, 2018, 05:03:42 pm
content: 100 for ~$50:https://store.yujiintl.com/collections/vtc-series/products/vtc-series-high-cri-led-smd-2835l-100-pcs?variant=18341122951#tabs-4Look at the 5000K and 5600k spectra:https://cdn.shopify.com/s/files/1/0344/6401/files/YJWJ004-1.2_YJ-VTC-2835-G01.pdf?7088009637272241372John

author: LaserSteve
author_rank: Super Contributor
timestamp: May 31, 2018, 05:19:44 pm
content: John, Those are a beautiful device. Google is not always my friend these days.Thanks,Steve

author: JohnG
author_rank: Frequent Contributor
timestamp: May 31, 2018, 05:35:39 pm
content: No problem. I used to dabble in lighting, pre-LED, but always have kept track of things. They don't quite make it to 800 nm, but maybe are good enough.I'm interested in your spectrometer project. Do you have a link or two that you can share?John

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 31, 2018, 05:42:40 pm
content: What about a UV LED illuminating some phosphors?

author: ajb
author_rank: Super Contributor
timestamp: May 31, 2018, 06:33:25 pm
content: Thorlabs have their own semiconductor facilities (just up the road from where I am, in fact), so it's entirely possible they make that LED entirely in house. At the very least it's quite likely they use their own secret phosphor sauce to get that spectrum.If you can make two separate sources work, there are broadband IR LEDs that pick up where white LEDs leave off and give a nice spectrum out to 1050nm.Here's one, although its spike at 445 is truly impressive, in a Burj Khalifa kind of way.

author: LaserSteve
author_rank: Super Contributor
timestamp: May 31, 2018, 06:44:21 pm
content: Unless you get them direct from China, buying small quantities of precision phosphors in the US can be an "interesting" task... They get really pricy if you need less then a 55 gallon drum. Then sometimes Homeland calls and asks why you requested a sample of the material..Evidently the nice folks at Homeland grabbed a large amount of the US cheap phosphor production post 911 and has continued to do so.At least that is what one major vendor told me, some years ago.A few microscopy places sell ZNS:Cu or a blue sulfide phosphor at low costs. The other colors however, unless you like the strontium based Ebay materials, can be difficult to get, especially the IR materials.It got to the point that I downloaded the "Phosphor Handbook" , an older version with the Sylvania recipes in the front, and started making them in house when needed. There are a few that can be made at 800'C instead of 1100+ 'C from common chemicals, but you have purify theinitial ingredients very well, except for Zinc Sulfide. A few parts per million of the wrong dopant can ruin your day. The newer reactions that make a phosphor by burning two precursors are a lot easier.When you are the sole technologist for 330 undergrads and 127 grads, and 22 profs, some times it is just easier to buy. I actually would rather make stuff like this, and spend my time soldering and machining, but time is of the essence. I literally can not walk down the halls around here without a request, or a "is it done yet?, Is it done yet, when will it be done?"Steve

author: ajb
author_rank: Super Contributor
timestamp: May 31, 2018, 07:11:13 pm
content: Quote from: LaserSteve on May 31, 2018, 06:44:21 pmDo those materials actually have nefarious applications, or is it just 'scary chemical' syndrome?

author: LaserSteve
author_rank: Super Contributor
timestamp: May 31, 2018, 07:45:15 pm
content: They have applications in tracing materials , persons, securing documents, tracers in bullet cartridges, tracing explosives, X-ray systems, detecting radiation. If its a radiation detecting strategic material, Homeland and their Contractors seem to snap it up. Try to buy some Helium 3, for example. Then again, she could have just been trying for any excuse she could have to avoid packing a sample and paperwork, but I doubt it.The black flat LED is awesome. I think an order will go out ASAP. 7.20 each at Digikey... That and a bit of phosphor salvaged from a CFL lamp or a COB led...Steve

author: LaserSteve
author_rank: Super Contributor
timestamp: May 31, 2018, 07:59:19 pm
content: JohnG. Check your PMs...Steve

author: analogo
author_rank: Regular Contributor
timestamp: May 31, 2018, 08:20:48 pm
content: According toxiphmont, Nichia USA sells good and acceptably pricey "exotic" LEDs. But you won't find them on Digikey.