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175ma GH04850B2G 488nm Build

Arcygenical

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May 8, 2012
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So, I really wanted to get into some of the more interesting Blue wavelengths, and I decided that 488nm would be a perfect introduction to the 470nm<x<490nm wavelength range, well, without breaking the bank.

I don't have many build pics of the entire laser, as the build was rather straight-forward.

I had a case neutral diode, therefore I used the case as my -, and an old CREE 1w circuit board as the + (Stripped all the components off the board, obviously).

This is what I came out with:
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I thermal-epoxied the bottom of the Axiz module to the brass host plug, and soldered the - Driver input directly to the brass plug as well. Liberal use of epoxy to create the dielectric needed to ensure no shorting.

The host takes a single 18650, and I'm using an LDSE500 buck/boost driver, set to 175ma, which should give me around a 100mw output (sadly, I have no LPM on hand).

Here's a picture of the entire build, next to my 2 other DIY lasers. This build is on the far right, in the gunmetal host.
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Beamshot, "city dark" during a light foggy night:
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And finally, next to my 800mw 638nm, and ~500mw 520nm, unaided, no fog, natural city lighting at 11pm.
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Ignore the smudgy phone camera lens... I'm a chef by trade, my phone gets absolutely disgusting...

I suppose a real camera should be in the works next... Unless I spring for a nice 589nm pointer... My holy grail wavelength.

Thanks for looking!

Hands down my new favorite colour.
 
Last edited:



paul1598419

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I have several of these Sharp diode builds. All of mine are set to 275 mA and those are all >100 mW output. At 170 mA it likely won't get up to 100 mW. Probably closer to 80 mW. I noticed you have the modules seated out in your hosts. The heat transfers better if they are seated all the way into the hosts' heat sink.
 

Arcygenical

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Thank you for the reply. That helps a lot, as I have no LPM to measure output; I was just assuming that 175ma would yield around 100mw. I will modify it up to between 190-210ma and see if I can gain a few notches in visual output. If not, I will titrate back, to ensure temperatures are well within the norm. After 60s of lasing, the copper portion of the module reaches a relatively cool 31'c (VIA IR thermometer)

And yes, for this build specifically, I wasn't using a heat spreader between the mounting (axiz) module and the host body... I didn't feel it was necessary with a copper diode mount and a thermally epoxied module casing (to the slug). The other two lasers that I've built use a custom lathed aluminum shim between the host body and the mounting module... The 638nm laser was brazed and the 520nm laser was soldered, due to the differences in materials used. Both seem to have no issues running for normal pointer use, up to around 1m (where the 638 specifically, set to 1050ma, gets very warm).

Thank you for looking out for my diodes, though!
 

paul1598419

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All the Sharp diodes from 477nm to 505nm have fairly high Vf, forward voltages. This translates into higher heats to be dissipated. That is why I was concerned.
 

Arcygenical

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May 8, 2012
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Yes, this particular diode has a Vf of 6-7.5, so I can absolutely see why the waste heat could be a concern. P=IxV, yields me around 1.8w total draw from the cell, which is still a lot of heat to be dissipated by the driver and diode.

The driver IC has been heatsunk as well in every one of my builds, with a small copper heatsink.
 




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