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Leslie Wright and Samuel Goldwasser
(Original version: March 8th, 2007)
(Last Update: October 1st, 2011)
This is an investigation in progress, and is by no means complete, especially regarding the functions of the rest of the assembly, any updates, warnings or new links, will hereafter be in RED type!There is always new data being added to the pages, as more people are e-mailing me with specs for their particular diode. So if you have a PS3 laser on order, visit again before extracting or testing the diode, in case there have been any developments!
Thanks go to those people, who have mailed.
The original page had become quite large. I never expected to be writing an essay on a Disc reader, so it has now been split into three parts, and are indexed as follows:
- Main Page (you are here! has now been stripped of technical details, which are on the following two pages. Some of the original text is still here, since other sites have linked to images etc).
- Diode Page (All of the information currently available on the special PS3 diode can, if you want to build one of these, then this is where you need to be!)
- Optics Page (Since the optics also turned out to be very special, and useful, they have now got a page to themselves.)
I recently purchased, for the princely sum of £40 UKP / $80 USD, a SONY PlayStation 3, replacement laser reader assembly, with the sole intent of taking it apart, for the Blu-ray laser diode.
Here is the drive unit itself, part number KES-400AAA, as I received it. The optical carriage is almost twice the size of conventional carriages.
The pin-out was determined by eye, at first. I extracted the laser diode, and looked through the end window, with the aid of a microscope, to determine, where the internal wires went. Then tested my conclusions with the multimeter. The case is negative with respect to ALL THREE laser diodes. (Yes, there are THREE individual laser diodes in the same can – hence the weird pin out!)
Carefully read all the related material in Sam’s Laser FAQ, especially in the chapters starting with: “Diode Lasers”. The information there is invaluable, and extremely important!
- GND: Negative return for LDs and PD cathodes (-ve).
- VLD: Violet (~405 nm) diode anode (+ve).
- RLD: Red (~650 nm) diode anode (+ve).
- IRLD: IR (~780 nm) laser diode anode (+ve).
- PD: Photodiode anode.
- Black: LD and PD cathodes (GND, -ve).
- Blue: VLD anode (+ve).
- Red: RLD anode (+ve).
I ran a series of tests on my diode this afternoon, and have determined the following parameters. (these are a guide only, and are the specs for my particular diode, your Ith may vary, and as a consequence, your operating current will vary!)
- Threshold current = ~28 mA.
- Working voltage = ~4.5 V.
- Operating current = 30 to 40 mA; *** see WARNING at the bottom of the page!
Note: On this graph, the final real measurement was made at 45.7 mA (13.9 mW). The line from 45.7 mA to 50 mA is extrapolated.
I have tested and run mine at settings of 4.4 V and 40 mA MAX! The output is VERY bright. It works, and it stays cool!
The PSU at the moment is a simple 6 V battery with a current limiting resistor in series (47 ohm). There is a better driver, at the bottom of the page! If you intend to build one of these visit the Diode Page first! There is new, updated and more accurate information there!
This is the Laser diode mounted on a heatsink with the red emitter powered.
And now, this is what you have all been waiting for…..
In the above picture the Laser and its little mount, were just glued to the large heatsink, no heat transfer compound was used,(the heatsink was used, because it was convenient) I figured there was enough metal in the mount to dissipate any heat. The laser stayed cool throughout its operation.
The diode can is standard 5.6 mm dia, and could be easily integrated into the collimating assembly of a dead red module.
The optical output is confirmed by Rob as being 10 to 20 mW, there will be more info about this, as soon as he completes his measurements.
** Note: It has been suggested that this may cause heat dissipation issues, by running two diodes at the same time!
***** WARNING *****
Yesterday (12 March 07) after running some tests (plotting light output against drive current) I (Leslie) noticed a diminished brightness of the beam, and erratic output. During the tests, the current had been increased to 52 mA. Upon examining the beam today it has become apparent that damage has been caused.A picture of the expanded beam is shown below:
This shifts the reasonable range of operation for this diode down to 30 to 40 mA, for a decent diode lifetime. Or if your diode has a lower or higher threshold, adjust according to the simple equation:
Where Ith is the threshold current for your particular diode, and IopM is the maximum suggested drive current.
As the saying goes “you have to break a few eggs, to make an omelette”. I have broken mine so you don’t have to break yours! Fortunately, I already have another unit in the post. Since this one still lases, (although at diminished brightness) I have made a Blu-ray laser pointer out of it!
Below are pictures of a module I have designed. They will occasionally be on sale on eBay, as will violet laser pointers, and other laser related Items. Please check HERE to see what is available.
CHECK that whatever you connect it to is actually 9 V off load! I have lost count of the number of times I have checked 9 V adaptors, to find they put out more than 15 V under light load!
The Rest of the Assembly
Violet Laser Diode Myths Exploded!
I have read in various places on the internet, articles with reference to this site, that some of the PS3 diodes are recording or “burning” diodes! I have NEVER observed this, in any assemblies that I have taken apart, and think it is doubtful that any exist!While the violet laser diodes, are obviously of a much higher power than one would expect to find in a reader, you must consider the losses apparent in Sony’s optical system, and remember that scattering is much more of a problem at short wavelengths.
Some people have commented that “it must be a burner because you can see the beam in the dark” and “wow that spot is bright for its wavelength so it must be a burner!”
These are the reasons for both of those comments:
- You can see the beam in the dark because, at this short wavelength, the light will scatter forward, even off the gas molecules in the air! (the reason the sky is blue – Rayleigh scattering).
- As for the spot appearing exceptionally bright for it wavelength, well at say 695 nm (deep red), the eye is fairly insensitive, and you would expect at the other end of the spectrum, that 405 nm would appear just as dim! However, at these short wavelengths, most things (read: almost everything in the universe!) are quite fluorescent! If you actually find a surface that isn’t as fluorescent, such as (very clean) Teflon, you will find that the spot is indeed quite dim!
- If it truly was a “burner”, I would expect the voltage drop to be considerably larger, and Ith to be considerably higher too.
- The output of the violet laser diode may vary by as much as 10 mW only because Nichia’s processes are far from perfect yet, and whilst the diode is capable of being pushed to at least 20 mW, I advise that you only run at Iop of Ith+10mA max, for reasonable life! The lifetimes are quoted as 5,000-10,000 hours when run at its lowest operating current, so pushing it higher, will result in shortened life!
For More Information
There have been extensive discussions on the USENET newsgroup alt.lasers, and the Internet forums Photon Lexicon and Laser Pointer Forums. Checking the archives for those will probably turn up more than you ever wanted to know. You can contact Leslie at: firstname.lastname@example.org and Sam through the Feedback form at RepairFAQ.org. For a wealth of information about Laser related stuff, and plenty of diagrams, go to Sam’s Laser FAQ.