Getting Nichia LEDs

I requested samples of the infamous NSPW500BS from Nichia, specifying color rank "B1", brightness rank "S". I was told that I could specify color rank, but not brightness.

So how exactly does one go about getting "S" rank brightness Nichia's, anyway?

-XCN-

It's essentially the luck of the draw and you may need to order a bundle of them. Nichia seems to bag lots by 100 and 500 pieces and I would guess that one of these bags would be open at all times for filling small quantity orders. You might order one LED and get the rank S if the current open bag was rank S. If it's an open bag of rank Q, you might need to wait a long time.I have a couple spare NSPW500BS of S brightness but they're B2 color. You might go to the for sale/trade and query for what you want.

You can look at www.techt.ch (No problems with your french??), they sell the Nichia S rank LEDs (Don't know wich color rank...)

Do you know if its normal for a nichia LED to contain a secondary blueish ring arround the center hotspot?

I recently got some NSPW500BS-B1S and they have a faint but distinct blue ring at the outer edge of the hotspot.

Also, if you look carefully, the hotspot is not entirely uniform.

It consists of a bluish colored round area which is slightly off centered when compared to the hotspot.

Surrounding about 270 degrees of this bluish portions is a more greenish yellow crescent moon shaped area. At its widest point, this "moon" is about 10% the width of the hotspot.

Together, the round blue area and the moon shaped yellow area form an almost circle which is surrounded by the blue ring.

From what little I know about LEDs, I figure the the blue is where the light from the LED dominates, the yellowish color is where the light from the phosphor predominates, and the ring is from some optical effect associated with the "dome". I believe that if the dome was PERFECTLY alligned with the active portion of the LED, there would be no "crescent yellow moon".

I don't intend all of this to sound worse that it is. The irregularities are almost negligible unless a single LED is projected onto a white wall, and become nothing when multiple LED are used. These are very good
LEDs - the best 5mm I've ever seen.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Wim Hertog:

Do you know if its normal for a nichia LED to contain a secondary blueish ring arround the center hotspot?<HR></BLOCKQUOTE>

Probably, I would think it depends on the particular model of Nichia. The 310 has some distinct yellow as well as blue areas. It's the same die in all the white Nichias (3 and 5 mm) so it's mostly a function of how well the integrated epoxy lens disperses the light. I would think that Craig would have a difinitive answer on this...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Wim Hertog:
Do you know if its normal for a nichia LED to contain a secondary blueish ring arround the center hotspot?<HR></BLOCKQUOTE>

From what I've read, it would appear so. Nichia seems to produce many of the white LEDs available -- of both the good and not-so-good variety. The Radio Shack 276-320 is believed to be a Nichia, and it's an obnoxiously dim piece of work with a massive blue ring. Guess all those non-B1S rank LEDs have to go somewhere ...

Even with the higher quality LEDs, there's quite a bit of variability between individual samples. I have no idea why that is.

-XCN-

I suspect the blue ring is associated with the "lens" of the LED and that it can never be completely eliminated.

Camera lenses exhibit similar problems (although not to this extent) - so it seems reasonable to expect some optical anomolies on a 2 dollar LED.

So, a ring... then I have the B1S's!!!, just like I ordered.

Quick follow-up: just got my 4 LED samples from Nichia today -- and despite them saying that I couldn't request the brightness rank, I did anyway and they sent me B1S for all the samples! Woohoo!!!

Downside: At $5 per LED, a $20 minimum order, and $8 (!!!) shipping, it ain't cheap. Ah well. =)

-XCN-