Purple/blue laser for soap particle backscatter testing?

[Tony]

When I soap test I use boiling water to get rapid separation and a red laser pointer (the one on my IR thermometer) through the water to check for backscatter from soap particles.  If there is a little soap in the water then this shows as a beam through the water, even though just to the eye alone it may appear clear.  This is corroborated by NigelB's soap test kit.

But we know from the sky being blue that shorter wavelengths are more readily scattered by dust in the atmosphere, so perhaps a red beam is not a good choice.

Which got me thinking, what if we used a violet/blue laser directly through the biodiesel itself to look for soap?  But maybe green would be better as the eye is more sensitive to green light.

Shorter wavelengths are readily available up to 100mW for very little cost:

http://laser.ankaka.com/purple-blue-adjust-focus-laser-pointer-1-x-cr123a-100mw-405nm_p47057.html
http://laser.ankaka.com/wf501b-flashlight-style-green-laser-pointer-1-x-16340cr123a-50mw-532nm_p47537.html

...though at those kind of powers eye protection would be essential.

It appears that the import of lasers is not a problem, it is just public use of lasers that is restricted by law to lower powers.  So for the purpose of our private lab work this should not be an issue.

As an intermediate step I've got a 5mW green laser on the way to see how this performs (about £4 delivered, bonkers!)

It would be nice to have a quick test that doesn't involve water or titration - watch this space!

[Rotary-Motion]

should be plenty of the disco lasers about to buy...

[photoman290]

When I soap test I use boiling water to get rapid separation and a red laser pointer (the one on my IR thermometer) through the water to check for backscatter from soap particles.  If there is a little soap in the water then this shows as a beam through the water, even though just to the eye alone it may appear clear.  This is corroborated by NigelB's soap test kit.

But we know from the sky being blue that shorter wavelengths are more readily scattered by dust in the atmosphere, so perhaps a red beam is not a good choice.

Which got me thinking, what if we used a violet/blue laser directly through the biodiesel itself to look for soap?  But maybe green would be better as the eye is more sensitive to green light.

Shorter wavelengths are readily available up to 100mW for very little cost:

http://laser.ankaka.com/purple-blue-adjust-focus-laser-pointer-1-x-cr123a-100mw-405nm_p47057.html
http://laser.ankaka.com/wf501b-flashlight-style-green-laser-pointer-1-x-16340cr123a-50mw-532nm_p47537.html

...though at those kind of powers eye protection would be essential.

It appears that the import of lasers is not a problem, it is just public use of lasers that is restricted by law to lower powers.  So for the purpose of our private lab work this should not be an issue.

As an intermediate step I've got a 5mW green laser on the way to see how this performs.

It would be nice to have a quick test that doesn't involve water or titration - watch this space!

High quality and useful 405nm laser pointer is certain to bring convenience and joy to your life.

gosh!! will it do the washing up?

[Julian]

Tony, this could make a nice brief page in the "Safety and testing" section.

[Tony]

[photoman290]

nice to see that sign again. i know mike quite well. it was my big scary laser that prompted that sign. 2 5 watt lasers on one chassis. weighed 75 kgs.

[Tony]

How do you know Mike?  And what were your lasers for? I sense a story here

[photoman290]

i have known mike for about 13 years. he first met at a tesla coil meeting. i organised a meeting of tesla coilers until last year when i handing it over to someone else. too much paperwork for me. the laser came from a cambridge scrapyard. it was left in a factory owned by a big scary laser company, and was too old and big to move. i stripped the laser off the cabinet it was on with all the unwanted stuff like safety interlocks and stuff. the power supply was too heavy and expensive to get . remember this is in as scrapyard and i had already spent £75 quid on it. i  didnt do anything with it and sold it to mike. delivered it to his place and he managed to get it it working. he brought it up to a teslathon once. there is a picture of it on his site somewhere. it was originally a medical laser used as a light scalpel i think. 5 watt argon and 5 watt krypton. the krypton laser had degassed, but mike got the argon one working. the same model is used for light shows or was. the power supply is 240 volt 30 amps so easy to do. needed water cooling. 

[Tony]

Sweet.  I used to be a tesla coiler.  The biggest one I built was with two 3.3kW industrial microwave transformers with the secondaries in antiphase.  I think it was about 4.8kV @ 1.4A or thereabouts.

I built a Richard Quick sequential spark gap for it (in a tube with fan on the end to blow the arcs out).  First time I ran it it turned the spark gap to slag while emitting a pretty green light, then set fire to the grass.  Gave up on that one and returned to my 300W NST before I killed myself with those transformers

Mind you I did like that when they were turned on, it dimmed the lights in every third house down the street.

[Julian]

This thread is doing nothing to improve peoples opinion of your sanity!

[Tony]

Being sane is overrated 

[photoman290]

Sweet.  I used to be a tesla coiler.  The biggest one I built was with two 3.3kW industrial microwave transformers with the secondaries in antiphase.  I think it was about 4.8kV @ 1.4A or thereabouts.

I built a Richard Quick sequential spark gap for it (in a tube with fan on the end to blow the arcs out).  First time I ran it it turned the spark gap to slag while emitting a pretty green light, then set fire to the grass.  Gave up on that one and returned to my 300W NST before I killed myself with those transformers

Mind you I did like that when they were turned on, it dimmed the lights in every third house down the street.

 my biggest one was about 4 kw. 12 foot sparks. i kept it in a museum as that was the only place i could safely run it. do you know paul benham? he is somewhere near you. he has a nice dc coil using 4 MOTs and a voltage doubler.

[Tony]

It's possible I've met him, used to know a few coilers around here but forget their names.

One chap at one of the electric museums was going to try and source me a pole pig

[Chug]

I'll have a try wit me red laser pointer on the next batch.

and tesla coils is something I've been meaning to look into for ages and never got round to, probably coz electrics aint my strong point at the best o times. I've got a mate in London who has tinkered with some success.

[photoman290]

I'll have a try wit me red laser pointer on the next batch.

and tesla coils is something I've been meaning to look into for ages and never got round to, probably coz electrics aint my strong point at the best o times. I've got a mate in London who has tinkered with some success.

 i might build one for a bit of interest at the next BBB down here. a few people sounded interested. i have most of the bits lying around so wouldn't be too difficult. this will be after i finisher the processor of course.!!!