Wavelength measurement.

[dadamoid]

I recently purchased some 1W 660nm deep red led's singly.

I tried to find a supplier who could supply them on as flexible strip.

Infortunately as soon as it arrived, I powered it up and it was standard 630nm orangey red.

I shone my 660nm torch next to it and it was obvious.

I challenged the supplier who produced a graph showing a peak of 660m nm.

I then spent £175 haveing their strip tested and it came out at about 630nm. Suprise.

Now tthay are saying that the value depends on CCT temperature. Theirs is 140-0K, my testsa are 1000K.

Surely this makes no difference at all.

A dominant wave length is a dominant wavelength no matter how you measure it (unless you're in a black hope).

A m I right. Photometrics seems a complicate dsubjuect but surely physics says 660nm is deep red and 630nm os orangey red.

Some one p[leasde reassureme I am not an idiot. You can look at a colour chart and see the difference.

 

[Skogsgurra]

A simple wavelength estimation can be made with a grating and using a few known wavelength sources (a 660 red and a 550 green LED for calibration) and see where your unknown's line is in relation to the known. An extremely cheap, but good enough for comparison purposes, grating is a CD a DVD. Edmund Scientific is a good source for hardware and information.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

CCT is usually in the context of "white" lights, since CCT stands for correlated color temperature, and color temperature is a term applied to broadband sources, not monochromatic sources.

Nevertheless, 660 is indeed redder than 630, regardless of anything else.

TTFN
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[dadamoid]

THanks guys.

Exactly as I thought.

I had already made a little spectrometer with a slit and a DVD and my phone camera.

It took surprisingly good pics. Using this I could see a clear "space" between the sources, indicating to me it HAS to be a different wavelength.

The Chinese company are responding with doubts as to the capabilities of the professional test house I used.

I am now going to have to start an Alibaba official complaint. Armed with the facts I hope I get some joy.

I'm £650 down at the moment (£450 of useless goods + £200 for the testing). Grrrr.

One more thing, not totally related, but as far as I'm aware, don't ALL electronic components come with some form of datasheet/specification? Even the LED chips used on this flexible strip (which otherwise only has SMT resistors on it) MUST have a part number? And related spec sheet? NO?

They won't send me one or say they don't have it. This is nonsense isn't it?

Regards

Adam

 

[Skogsgurra]

Nice to hear that the DVD "spectrometer" worked for you!

I did so to look for Cu in a sample and then tested with sodium. The Cu green light and the double Na lines were very visible. Good luck!

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

"They won't send me one or say they don't have it. This is nonsense isn't it?"

Perhaps not, There's not guarantee that the supplier is a legitimate supplier in the sense of being the one that is actually manufacturing it. They could just be middlemen, sucking excess inventory away from someone else, or, the parts may be gray-market.

TTFN
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