Lasers - Electronics Blog

Archive for the ‘Lasers’ Category

DIY CNC Laser Cutting: what *doesn’t* work

The idea to document a failed project is not mine. When I read this post by Hackaday, I realized that I do have a project that failed which I don’t want to simply trash. Some valuable insights have been gleaned while working on it and I am planning to reuse many of the parts and the software in a different project. I have so many DVD drive parts now that it would be silly not to make another attempt at building a DVD CNC laser cutter, but it will definitely be designed differently, thanks to the lessons learned. So, that’s how this post came about.
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Laser Diode Driver with TTL Control. PCB V2.0 is ready.

Laser Diode Driver with TTL control. PCB V2.0, populated

Laser Diode Driver with TTL control. PCB V2.0, populated

This is another one of my belated updates. It has been about 3 months now since I’ve received the boards for the updated version of the laser diode driver from Olimex. However, I haven’t had a chance to work on any project that required a laser driver until just recently and so the boards were not populated and tested for the longest time. Finally, I can report that the design works, here are some pictures and there’s the Eagle board file for the PCB later in the post. Read the rest of this entry »

TTL-controlled Laser Diode Driver. Updated schematics. TTL-Controlled Laser Diode Driver TTL-Controlled Laser Diode Driver

During the course of my DIY laser cutter project I needed a laser diode driver that I could control with a CNC software, such as EMC2. I’ve already made an attempt to build one based on Linear Technology’s LT1121 voltage regulator with Enable input but the driver design that came out was not exactly successful :(
So, I took another stub at it … Read the rest of this entry »

Blu-Ray Teardown – HP CT10L BD-ROM / DVD Rewriter

HP CT10L BD-ROM/DVD R/W drive , ready to be disassembled

HP CT10L BD-ROM/DVD R/W drive , ready to be disassembled

Even though it takes me much longer than I anticipated, I’m still collecting parts for the laser cutter based on broken CD/DVD/Blu-ray drives. This time I decided to open a Blu-ray drive for the first time, never had a working 405nm laser diode harvested from a Blu-ray drive before.

This time the broken drive teardown is performed on an HP CT10L BD-ROM/DVD Rewriter drive (HP part number HP nPC P/N:491775-6CO). This is an older drive (manufactured in October 2008) and I expected it to have some useful parts – my experience has been that the most useful for disassembly parts are usually from 2003-2008 time frame. I was surprised to find not only two useful laser diodes inside but also an interesting part I did not expect to be in there … Read the rest of this entry »

Laser Diode Driver Based on LT1121 Voltage Regulator – schematic and PCB

Laser diode driver based on LT1121.  PCB version 1.2,  populated.

Laser diode driver based on LT1121. PCB version 1.2, populated.

01-12-2012 Update
This post is kept alive just to hold the old comments – please see the corrected circuit design here:

I’m having some issues with overheating of both the LT1121 IC and the R1 potentiometer, so I advise you to approach this design with caution. I will be revising it in near future. I would love to hear any suggestions for improving this design from the site visitors!

I’ve been using an off-the-shelf laser diode driver for my CNC laser cutting projects and came to realize that I need a different driver. Maybe not so small as to fit inside the laser diode enclosure but capable of driving both red diodes in 100mA-200mA range and blue diodes in 75mA-130mA. In fact, having the driver inside the laser diode housing proved to be inconvenient for this application because it is hard to monitor the current and also both the driver and the diode emit considerable amount of heat and I see no good reason to put them together to double that heat up inside a small enclosed space. Read the rest of this entry »

Laser Diode Power Output Based on DVD-R/RW specs

Unknown red laser diode - what performance can we expect? -

Unknown red laser diode - what performance can we expect? -

I’ve opened about a dozen different types of CD and DVD drives so far (of both read-only and burner varieties) and every time it’s a thrill to find a working red laser diode in there. But it would be useful indeed to know what performance can be expected from the laser diode once it’s free of its mounting hardware (AKA “sled”) – if it’s the laser diode you’re after, the drive may not even be worth opening. It would be nice to know that before wasting some time on opening it. Although it would be hard to know the exact specs of the diode down to the part number, some of the specs can be found rather quickly doing an Internet search. Here is how I do that.
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Laser Diode Housing from Hardware Store Parts

Laser Diode Housing, MacGyver'ed

Laser Diode Housing, MacGyver'ed. The focus is not THAT horrible, the camera picked up too much splatter.

I never seem to be able to finish my laser engraver/cutter from broken DVD-RW drives project (inspired by Groover’s pocket laser engraver) because I keep opening new DVD drives and keep finding reasons to go on tangent mini-projects. Most of those mini-projects are brought about by my admiration of the amount of useful parts a DVDs has (even a broken one, apparently) and some are caused by specific challenges each new opened drive brings. So, at some point I opened an HP SDVD8821H DVD R/RW/RAM Drive and found this laser diode inside:

Laser diode on a chip with PD arrays (front)

Laser diode on a chip with PD arrays (front)

Laser diode on a chip with PD arrays (back)

Laser diode on a chip with PD arrays (back)

It’s a weird looking laser diode (LD) that is mounted in the same case with the photodiode arrays which makes for simplified optics but I did not have any housing for this shape/size diode. By the way, if anyone reading this knows a professionally made housing for this type of LD, please post a comment with the reference, I would greatly appreciate that. The diode is just slightly smaller than your more standard 9mm LD – it’s smaller diameter is 6.50mm and the larger diameter is 8.25mm so it fits neither 5.6mm nor 9mm standard size housings.
This made me think that I may not be the only one stuck without a proper housing for a laser diode and I decided to see what it would take to build a housing for a laser diode out of parts available only in the disassembled drive itself and in a local hardware store. Here is what came out
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Laser Cutting DIY

I should have said “laser diode cutting” but did not want to spoil a great looking title :) I had this CNC setup for about a year now and and have been tinkering with different setups for the laser diode but only recently have made any progress.

Please make a note that if you are going to do this yourself, you owe it to yourself to buy a pair of nice ($35 or so) color filter safety glasses designed for the particular wavelength of the laser you are going to use. Mine is 650nm – red. I specifically wanted a laser in the visible part of the spectrum – if it’s going to burn my eye I want to at least know about it and give my reflexes a fighting chance to blink and shield my eye(s) from more damage. An infrared might have been more efficient and less picky about colors (with red laser forget about cutting any light colored material) but it requires more safety discipline.

The CNC machine it’s based on is Sable-2015 which I bought in the Summer of 2009 from eBay seller Luke-Chen in China. I have also bought the controller and the 24V DC power supply from Luke-Chen and had it running within hours after the package came in the mail. Read the rest of this entry »


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