Sharp 490nm GH04850B2G 55mW Laser Diode

[Alaskan]

All we need is a 1/4 wavelength multiple strand fiber optic light guide to collect all of the output from those LED's and we could have a collimated output, probably lower divergence than our laser diode outputs, if they existed.

 

[RedCowboy]

Aren't the LED's side emitters, I know there's a couple of options as to the angle of emission but it's the reflector that makes them project forward and these are multi element to reach 5W

Still if we could lens it all into a fiber coupler, but the coupler has an acceptable angle of entry and the multi element led will likely be not well collimated.....but if it could be done that would be awesome.

---edit---

Ok I see, you were talking about collecting from all the individual LED's LOL

Maybe a really big MM fiber ? Or a big fiber that tapers down with an OC mirror at the input ?

 

[paul1598419]

If you are going to try collimating LED light you have more problems than lining up the emitters. They give off a wide band of wavelengths and like any large band of WL can't be collimated. You might be able to focus them to a point if you try hard enough, but not a beam any better than a flashlight beam.

 

[RedCowboy]

I know this 485-495 yellow isn't but some LED's are single wavelength.

I just found this site, looks interesting > https://www.mightexbio.com/products/bioled-sources/fiber-coupled-leds/

LOL apparently this is not a new idea > http://www.qphotonics.com/Fiber-Coupled-LEDs-c-20/

p.s. We know there are all LED data projectors and we have seen flash lights built with the high output LEDs, I think the problem is the LEDs are multi element and multi mode, it's a shame as there's a lot of light there.

Here's some reading that I have not done yet, I just found this > https://preserve.lehigh.edu/cgi/vie...ng.com/&httpsredir=1&article=1165&context=etd

Here's a video by Lazeerer, just look at all the light.

 

[WizardG]

I want to put this diode in a two 18650 host, but my driver can't take 8.4 VDC, anyone know where to buy some dummy batteries which cost less than 10 dollars delivered? That's all I can find on Amazon.com so far, eBay has one listed, but it doesn't have DC pass through, like what good is it?

Add a few rectifier diodes in series with the input side of your driver. Count on ~0.7 volt loss per diode. And the reverse polarity protection comes free!

 

[RedCowboy]

They will waste 0.7 to 1.0 volts at full load, but much less at startup, ( non linear ) it could result in the driver getting too much voltage at startup, I don't know if that would be an issue or not but I assume it's a boost driver with a max in of 4.5 -5v ?

 

[WizardG]

They will waste 0.7 to 1.0 volts at full load, but much less at startup, ( non linear ) it could result in the driver getting too much voltage at startup, I don't know if that would be an issue or not but I assume it's a boost driver with a max in of 4.5 -5v ?

Yep, you'll lose ~0.5 volts at zero load (<1uA) and ~0.7 volts under load and you also lose a great deal of efficiency. What you gain is the ability to use the batteries you wanna use and protection against putting the batteries in backwards. I'm not saying it's the best way, but it works.

 

[paul1598419]

For a fully charged battery that is 6 rectifiers. I'd still go with a dummy battery.

 

[Alaskan]

Add a few rectifier diodes in series with the input side of your driver. Count on ~0.7 volt loss per diode. And the reverse polarity protection comes free!

Just saw this, and I knew that but didn’t consider it for some reason. Thanks.

E: Thinking more on this, that is a lot of diodes, I wonder if someone sells a string of them all inside one little axial package. I did however order a dummy battery. This could be a nice solder bridge addition to a driver, if someone would add the ability to route the battery through some onboard diodes.

 

[RedCowboy]

We all know that our brain plays a role in how we perceive colors, well I had been noticing how in my work room with black walls my sharp 490 looks bright blue but out my window at night in the bushes and grass it looks blue/green.

Well try this, I looked at the 490 in a fog filled room and it looked blue, then a ndb7875 that's 445nm alone and that 445 looks down right purple, so I turn on the 490 next to the 445 and the 490 looks green/blue, turn off the 445 and the 490 looks blue, turn on the 445 along with the 490 and the 490 looks green/blue, 445 off and the 490 looks blue.

It's really something to see it change in real time...well my perception changes in real time because of the surrounding contrast, try it

----edit----

Always set up your lasers with your proper laser safety glasses on, then you can conduct your experiment with everything safely secured, don't take any risks with your vision as there is still so much that can NOT be repaired, a moments mistake can last a lifetime.

It should go without saying but I will anyway, I terminate a high power laser such as a ndb7875 into a beam stop that blocks my view of the spot in the above mentioned experiment, I am only observing the beam.

 

[paul1598419]

Yeah, I have done this many times with wavelengths even closer to each other. It is interesting to see how we perceive colors when they are being compared side by side. I have a <1 watt 445nm laser I use with the blue ones sometimes. It can look like a 405nm by comparison.

 

[CurtisOliver]

There are so many factors involved in how we perceive colour. It is rather fascinating.

 

[RedCowboy]

Yes, in this pic A and B are the same color.

 

[CurtisOliver]

I made this to show how bad our eyes are at telling apart colour when in between bands.

All the inside dots are 490nm, and the surrounding are close neighbours.

Note: I am viewing on a sRGB monitor.
For me I can see very subtle differences.

 

[paul1598419]

Yeah, no matter what you try to show how these lasers look to other people, it is always going to fail as the true single wavelength color cannot be reproduced using combinations of colors. You can only experience it in person.

 

[RedCowboy]

Yes, I expect most people here know how monitors work.

I still enjoy looking at peoples beam shots.

Here's a tip, mix just a little smoke into the room air to bring out a nice looking beam, again for enjoyment and a rough idea of color.