lpfthings
Posted: Tue Jun 22 2010, 07:28AM
IntraWinding wrote ...

LPF screwed up losing you!

What happened? If you let me know the banned nick, I can probably unban it for you if you'd like

I bought one of these diodes the other day, and now the flexmod laser drivers are out of stock for about a month! :(


Killa-X
Posted: Sat Jun 19 2010, 10:28PM
RickLaser, sorry didnt know you were talking about his IR engraver!
So the info below is for people who didnt know then!

I have no issues seeing a 5mw green laser IR dot through my laser glasses with my camera. I dont see any IR passing through the glasses from my 200mw violet or my 455nm running at 980mA. These lasers do not emit any IR. If it was a DPSS blue, it would...But these are diode based, not pumped.

Not sure if this is what you ment, but I'm just tossing it out for you that these do not emit IR. Its easy to see my 5mw green IR emmisions, but nothing come up for my blue, and my glasses are 200-540nm!

Here is my 445nm running 900mA into my glasses pointed at my hand. Nothing at all passes, my hand just glows orange because these glasses are designed to absorb and reflect light.

THESE ARE OD-4


RickLaser
Posted: Sat Jun 19 2010, 06:27PM
Conundrum wrote ...

interesting..

might be worth starting a new thread about homemade IR engraver setups, as the hazards are different to visible lasers.


A always use 808nm goggles, becareful with 808nm! It is at the edge of the visible spectrum and can fool you quite easily. It appears as a faint dim light even though it can be very intense in power. 808nm is in the retinal hazard zone


...
Posted: Sat Jun 19 2010, 06:02PM
I am using a pair of 'sand wind dust' googles that I got off ebay, they are relatively commonly available and meet mil spec MIL-PRF-31013 (note they come in 2 types, green lenses and brown lenses, the green ones do not block blue/green wavelengths but the brown ones do). I haven't measured the OD, but they block well enough that I feel safe around high amounts of 445nm light running around. I wouldn't trust them to save me from a shot to the eye however, if only because they would melt in short order!

The photodiode I just took a closer look and your are right the PHR-803T only has a huge multi-element array in it which would make it pretty unwieldy. I was thinking of the older CD-rom sleds which often had a separate power monitor photodiode which was quite large (probably 2mm on a side)
Conundrum
Posted: Sat Jun 19 2010, 04:22PM
interesting..

might be worth starting a new thread about homemade IR engraver setups, as the hazards are different to visible lasers.

-A


RickLaser
Posted: Sat Jun 19 2010, 02:48PM
Hi all,
i´m new at site, i work with Co2 lasers since 1983 , now i´m searching about laser diodes, i got a 2.4W 808nm module , it came with a C-mount diode and a positive meniscus lens, but the c-mount beam is not round but flat, with a mescus it gave me a 1.5mm spot, it can make a hole in a 3 1/2" disc drive and burn things, nothing usefull.... so i place a cylindrical lens between diode and meniscus, it give me a 0.4mm spot ( laser diodesarray is so hard to focusing..) so i rook the module in my laser machine with rubberbands..( don´t laught about...) well now it can cut some thin materias like paper, fabric, artificial leather..... i can´t compare it with my co2 lases but is a good start to undestand diodes... here a tube link to a video.


Conundrum
Posted: Sat Jun 19 2010, 01:37PM
yeah, that should work. Didn't realise the '803T had a built in photodiode but it should work.

re. attenuators, another idea could be to use two crossed polarisers with the angle adjusted to block most light.

the only issue here is that you might run into problems with them melting at this power level..

... what goggles are you using? i bought some off ebay for about £35 which are not ideal but have confirmed the OD to be at least 5 so they are safe for at least low power NUV and blue.

one of my friends also suggested mounting the whole setup in a light tight box, with an indirect viewing setup (mono video camera) and external red LED laser power indicator that can be seen through the goggles.

-A

"Bother" said Pooh, as England got pwned by Algeria...


...
Posted: Sat Jun 19 2010, 01:45AM
Using the detector out of a blueray sled (the PHR-803t specifically) is a great idea, I can draw up a calibration for one fairly easily. The only issue I see is that most photo diodes are very sensitive, and will saturate with more than 1-2mw of power, so some kind of standardized attenuator will probably be necessary, although it should be possible to calibrate your attenuator based on the detector from your drive.

On the bright side (haha) the diode I am testing seems to be holding steady at 1.5W (measured after a stock projector lens); the test has been running for just over 15 hours so far and the power just keeps increasing (presumably due to temperature variations in my garage). Link is same as in my previous post.
Conundrum
Posted: Fri Jun 18 2010, 07:15PM
Sam G (of RepairFAQ and LaserFAQ fame) suggested using a silicon solar cell as a sensor. the main problem with these is that they aren't optimised for blue light but as long as it is spread out over a large area of the cell the calibration should hold.

i've also found that the sensors built into PS3 BRIR diodes work very well indeed as they are already able to detect the 395-405nm light from the blue diode. Usually this sensor survives even if the diode is totally frazzled..

to use, find the appropriate pins and short all others to ground (including the IR) to prevent spurious photovoltaic output from the diodes from affecting the readings.

someone will need to draw a calibration table for these.

Obviously you will want to run it at well under its maximum power and/or use a known attenuation or the makeshift detector will not survive.


-A

#include "Never_overcurrent_tunnel_diodes.h"