Results are in...635nm new diodes feeler.

Re: 635nm new diodes feeler.

rhd said:

A reasonable point - but these (8.5, 35) are actually WORSE than 445s (12, 40)

$45 for 35mW, with really really bad divergence, doesn't make sense to me.

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So you are saying the divergence is worse even though the specs say they are better?

Re: 635nm new diodes feeler.

I could be wrong, but for our purposes, isn't it the differential between the two numbers that creates a challenge? (because the axes) diverge at a greater rate difference?

Re: 635nm new diodes feeler.

That is quite possibly true. Even then, the difference between the two numbers for the 635 is less, 26.5 compared to 28.

Re: 635nm new diodes feeler.

True, but I believe that for our purposes, focusing these with a single lens, the absolute value of the difference between the two is less important than the ratio.

IE, if the two numbers were 40 & 50, this would be preferable to the two numbers being 3 & 6.

Even though 40 & 50 is a difference of 10, while 3 & 6 is a difference of just 3, the 40 & 50 will have axes that diverge at a RATE that is more even.

So while a divergence of 50 on one axis is 25% larger than the divergence of 40 on the other, that's better than the divergence of 6 on one axis being 100% larger than the divergence of 3 on the other.

I'm not 100% on my understanding being accurate, and I'm also not sure I explained it well. But essentially my thinking is that we're focusing these diodes no matter what. So better to have the axes diverge at a rate that is closer to each other, as opposed to a rate that is any specific value itself (within reason)

So 8.5 & 35 would translate to something like 12 & 49 (worse than blues)

Again though, my math/science may not be correct here.

Re: 635nm new diodes feeler.

i will be sending 2 diodes to cyparagon for testing. he has an LPM and a spectrometer.

i am only concerned with 2 tests... 1- wavelength @ rated 30 mw. 2- wavelength when overdriver and warmed @ 40mw. oh, i will ask if he can check divergence too.

michael.

Re: 635nm new diodes feeler.

ok results are in and they are less than stellar.

We can thank Cyparagon for doing the tests. He checked wavelength, voltage, and mw.

Cyparagon said:

Initial results are in. The powers are too low to register on my thermal meter properly, so I had to use just the lasercheck.

Code:

Ambient: 63F
Driver:  LM317 Constant Current
Case:    Aixiz 12mm
Lens:    Aixiz Acrylic 
 
Power Meter:  Coherent Lasercheck
Spectrometer: Science-Surplus Fiber-coupled CCD Spectrometer
 
Diode1:
mA       V         mW      nm
50       2.51      0.1      
60       2.58      1.3      639
70       2.66      5.5      640
80       2.73      7.9      641
90       2.8       10       641
100      2.87      13       642
110      2.94      16       642
120      3         20       643
130      3.1       LED
 
Diode 2:
mA       V         mW      nm
50       2.32      1       638.5
60       2.4       4.2     639
70       2.45      7.5     639.5
80       2.52      10      640
90       2.59      13      640
100      2.65      16      640.5
110      2.7       19      640.5
120      2.73      22      640.5

The first died at 130mA, so I stopped short of that on the second, just in case. :undecided:

Something must be wrong. Are they normally this inefficient? Maybe the first was defective and the second will go higher. It does drop less voltage. What are other people getting for these values?

As for the wavelength, this is typical of most 635nm diodes. They are only 635 when near freezing.

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So much for being 30mW diodes. I wonder how much farther the 2nd one will go.

chipdouglas Thanks for taking the Plunge and testing these diodes. All tough its not what we expected, you still are a good man for Dropping 150$ just to test 3 diodes out for us.

Thank You.:beer:

not sure how far the second will go. while it looked more efficient it got to 22mw but @ 640nm. either way no bueno... and a big thanks to cyparagon for doing the tests.

Its a bit sad indeed... I'm puzzled by the big differences between the two tested diodes though. Especially looking at the voltage for a given current, the variation is much bigger than what you'd normally expect.

As for the increase in wavelength with current: I reckon thats due to the laser heating up?

yes it is sad. but i am in communications with the american distributor about this issue. i havent aske them yet, but i hope they are in communications with the mfg.


michael.

Was the power output posted before or after lens?

Humm, even those cheapo DL-6353TL diodes seem to fare better than those.