Rayfoss/Mitsubishi 638nm 300mW laser diode

These are available on ebay or from their site. See this thread for a lengthy discussion on them.

Various members donated money so that two diodes could suffer in the name of science. Thanks, guys!

The main drawback is the large emitter size of ~40x2 microns. For comparison, 445nm diodes are 1x15 microns. This means they have a nasty fast axis. More on this later.

Equipment used for testing:

• Gentec TPM-310 power meter
• Science-surplus spectrometer
• Mastech bench power supply

Aixiz glass lens (for red) was used for these tests. Acrylic provided a marginal increase of power of about 3%. If you decide to use acrylic, keep the lens in collimation-mode at all times when the laser is on. If the lens is any further out, the wide beam will start melting the sides of the lens. Other members have claimed up to 40% power increase can be had by a G1 lens (I did not test this). A 445 aixiz lens resulted in a 10% drop in power. Anywho, several hundred datapoints later:



Both of the diodes still live. I didn't push them past 1.85A, because there's no point I initially thought the diode degraded, because it was making 30% less power than it did before. This turned out to be due to the slight warming of the heat sink. They appear to be very sensitive to heat.

I was going to try a prism pair to correct the fast axis, but for some reason, one does the job. :thinking: I'm not sure why.

at 6 meters with glass lens, divergence is ~3.3mRad and has some nasty wings:



At 6 meters with glass lens and uncoated glass prism, divergence is ~0.9mRad! wings are almost gone, too:





The problem is that this prism drops 50% of the power. It's just for proof of concept. I have several coated prisms on their way from surplus shed.

Awesome. Thanks for doing the hard work.:beer:

I was planning on building one in a Ehgemus host tonight @ 1A and that looks to be about the sweet spot. Hoping to get about 900mW. Also still in the 640's @ 1A for the wavelength. That is just down right awesome.:beer:

sweet nice write up :thanks:

EDIT: i'm glad my $5 contributed to this really fine job

Awesome...Thanks for the nice review!

Edit: And thanks to all that have donated for this test to be done! :thanks:

Simple and clean. Just the way test results need to be presented. Good job mate :beer:

Thank you for the review ! :gj:

Wow I guess these multimode diodes are just plain tough as nails!

Thanks for the testing! :beer:

Lots of good info there, +1 for you sir! :beer:

That emitter is MASSIVE. You will unlikely ever see a COD death on one of these. If you look at the data sheet, they are indeed very temperature sensitive. Throw a big TEC on your setup, and you will only see power increase will current- no more of these goofy power "peaks".

Thank You so much for the detail testing.:gj:

This is what i was saying how sensitive to heat change they are even though they have a stable reading.

The Wavelength shift is not all that bad as Long as you Keep it <1A. Best to keep it ~700mA if you want the true 63Xnm.

Really happy with these Results.

Cant wait for the 500mW ones. Will we see 1.5W stable and Safe.:eg:

Thanks Alex.


+:beer:

Alex... as usual, great testing!!!

also, i have a spare tec alex, if you want to do some more testing with cooling the diode. let me know and i'll send it to you.


michael.

These diodes are really something else. Thats some nice data plots

Thanks for the info :beer:

Ra1nfade said:

These diodes are really something else. Thats some nice data plots

Thanks for the info :beer:

Click to expand...

He is the Best Out there.

So I have a question.

current isn't killing them. But that doesn't mean that the current won't cut the life expectancy on them, does it?

Do we have any way to test that? (I thought someone had a rig for something like that)

There was a torturer testing rig someone had. I remember seeing a thread about it when the 445's first came out. It may be a member that is not active here anymore.:thinking:

Awesome work:wave:, thank you so much for the information Cyparagon!