What portable lightsource would you recommend for UVIVF?

[ulf]

Yes, in simple words, it's not worth it. For the cost of the modification one can buy an even bigger torch with more power, even if the efficiency is lower.

Exactly!

 

For higher power, at some point fan cooling will be needed and soon after it will not be practical with a battery powered light source.

You end up needing designs like the ones Colin has showed us here, that are stationary and depend on a mains sourced power supply.

 

Fan cooling of the LEDs might be needed first, but soon after you also might have to care for the filter that also will be warm due to the internal losses.

[Stefano]

Let’s take an extreme example. The IMALENT MS18, a 100,000 lumen-capable flashlight. It uses an active cooling system with a fan and can only sustain the maximum output for a short period of time. It uses 18 XHP 70.2 LEDs, those LEDs are rated for 29 W of input power each, so assuming they are all driven to their maximum they use 522 W. So I think we can say that the physical limit for a battery-powered torch with active cooling is around 500 W of input power (not sustained), and probably less than half of that sustained.

[Andy Perrin]

For fluorescence, this is where it becomes worthwhile to consider a laser. I’ve been having some success with that, by the way. 900mW 405nm laser spread into a line of 30 degrees wide is enough to light paint my mom’s garden in 30 sec.

[Stefano]

Wow, 900 mW is a lot for a laser. I don't know if it can be legally bought in most countries, it's the type of thing that can be considered almost like a weapon. But if you can and it gives you an advantage because of the high intensity, then that may be a good solution. You will need eye protection (900 mW will cause eye damage with a direct hit, although it may depend on how much the laser is focused) and you will need a way to scan the area evenly.

[Andy Perrin]

Stefano, spread into a 30 degree line, 900mW is not very bright a few meters away. I wouldn’t want to shine it in my eye (not ANY laser) but I don’t think it’s as dangerous as you are imagining. The same 900mW will easily burn things focused to a point, but shining the laser line on my arm produces no sensation— you can’t even feel the warmth unless it’s really close.

 

I’m actually thinking about going even higher because I can’t detect the fluorescence over the streetlights even by subtracting.

 

(Also, I’m not sure how much of the original 900mW actually escapes the laser with my optical setup. I have no way to directly measure the beam. I bought the laser from a trusted member of the laser pointer forum so it should not be mislabeled, but my modifications have probably affected the final output.)

 

Laser eye protection is of course required, but as you know, I have described that already in the multiple threads I’ve written on the topic.

[dabateman]

Andy you're not training sharks with lasers now?

Oh wait that was already done

https://www.google.com/amp/s/www.wired.com/2012/05/wicked-lasers-shark/amp

[Cadmium]

I think you meant the same number of batteries when you said "Both same battery"

 

If you compare the Nemo's bigger 26650 battery with the four 18650 in parallel in the Alonefire, there are one advantage:

The internal resistance in a good battery is lower for the bigger one, but by putting four smaller in parallel the total serial resistance might get even lower.

There are also four times as many contact points between torch and batteries, also lowering that contact resistance.

 

If the Alonefire consumes more current like David describes above, the total design situation could be a bit better in this respect for the Alonefire.

 

You said "both same battery", I said it with a "?", I was questioning your statement, because they don't have the same battery.

[dabateman]

Cadmium,

That was me and my error. Not exact same battery but one battery. However the Nemo can use the exact same battery as the convoy and I will do that in a pinch as I only have 2 of the big fat ones.

 

The Alonefire uses 4 in parallel, as reported by Enrico.

 

Andy,

Now I am researching line lasers. There are some for UV in 193nm, 248nm, 308nm and 355nm to cover all my desires.

But not too portable. Look at the man for scale:

https://www.coherent.com/machines-systems/uv-lasers/linebeam

[Andy Perrin]

Haha, UV laser diodes are not common. On the laser pointer forum there have been some 375nm diodes, but you basically have to know someone to get them (or join the forum and be fast when someone offers them for sale). It’s very easy to find powerful 405nm laser diodes, however, which is fine for fluorescence work.

 

Most of the work I’ve done is on finding appropriate Powell lenses and figuring out how to mount them. You don’t want to buy a line laser with a cylindrical lens because they aren’t uniform.

[Stefano]

375 nm laser diodes can be found on eBay occasionally if one knows where to look. I already posted this, but Youtuber styropyro got one for $80:

 

Bought new from Thorlabs they cost about $4500, way more their weight in gold.

[Andy Perrin]

We are talking about the same people, Stefano. There is only one large laser forum, and yes, they are the ones who post them on eBay sometimes after offering them to members. Much like our vendor members do here.

 

Apparently the way it works is these people who get the UV laser diodes are on various mailing lists with especially good prices sometimes. I am not sure if it is because it is surplus or manufacturing seconds or what.

[Stefano]

Nice, they all come from the same place. That’s interesting.

[Andy Perrin]

Nice, they all come from the same place. That’s interesting.

Yep, like this (not posting a direct link because I'm not sure I want traffic from that forum to come here...):

https://laserpointerforums.com/threads/375nm-ushio-200mw-hl37013mg-diode.107917/

By the way someone else at the bottom of the thread had an interesting remark:

Regarding mine, I ran a small group buy for 5 over on the discord. First 5 were lost in transit, so their remaining stock - 2 diodes - were sent to me and once they get more they will be sending me the remaining 3, likely after the Chinese new year. Not sure if 15 per year is from the manufacturer or from Phillip's supplier. Also... Based on the price difference, I'd like to think we have different suppliers.

 

Since more of these were available than I expected, any prospective buyers should really look at and consider the operating temperature, 20-30C, which is really tight considering what most of us are used to here. I can't stress it enough.. UV diodes are a bit notorious for dying early... as such I do not run mine for more than 5-10 seconds at a time. These cannot be abused like we abuse our more familiar diodes.

 

I don't think I would buy a UV diode at this time. Between the price and the likelihood of a premature death, seems like it's best to wait.

[ulf]

Laser diode modules are often used for lighter engraving and cutting.

The more powerful are often 445nm, but some are 405nm:

https://www.ebay.com...AkAAOSwSONcVOsY

I have no idea if those can be adjusted to give a reasonably parallell beam usable like in Andy's setup

[Andy Perrin]

Laser diode modules are often used for lighter engraving and cutting.

The more powerful are often 445nm, but some are 405nm:

https://www.ebay.com...AkAAOSwSONcVOsY

I have no idea if those can be adjusted to give a reasonably parallell beam usable like in Andy's setup

Most likely yes, but I would be hesitant to use one that powerful. I'm getting used to the 900mW level still. Of special concern at 405nm is that the beam is visible, but our eyes are not very sensitive to that wavelength, which gives rise to the paradox of having a beam that doesn't LOOK very bright, but in reality is quite strong enough to do damage to eyes or skin, especially if you stand there staring at the pretty purple dot like an idiot. In theory, the operator knows better than to stare at the beam without protective eyewear, but you really want to make sure nobody else is around when you do your experiment. Spreading the beam into a line does decrease the intensity quite a lot, but with a 7 watt laser, I'm not sure how far back people would have to be to be safe. Most of the safety charts assume the beam is focused to a dot.

[Stefano]

A 7 W laser dot is well into the IV class, it is powerful enough that looking at the dot on a wall (diffuse reflection) can cause eye damage. This is a 7 W blue laser:

This Youtuber said he keeps it without batteries because it is scary to use it, it's a fire hazard, he has to be very careful when using it. It is a dot and not a line, but at that output one must be really careful.

 

I kind of miss my 405 nm laser pointer (the diode died). I have a 405 nm LED, so I can see this color again (and more safely), but really, the violet color 405 nm light has is beautiful. it's like a pure violet. The violet dot really is pretty.

[ulf]

Most likely yes, but I would be hesitant to use one that powerful. I'm getting used to the 900mW level still. Of special concern at 405nm is that the beam is visible, but our eyes are not very sensitive to that wavelength, which gives rise to the paradox of having a beam that doesn't LOOK very bright, but in reality is quite strong enough to do damage to eyes or skin, especially if you stand there staring at the pretty purple dot like an idiot. In theory, the operator knows better than to stare at the beam without protective eyewear, but you really want to make sure nobody else is around when you do your experiment. Spreading the beam into a line does decrease the intensity quite a lot, but with a 7 watt laser, I'm not sure how far back people would have to be to be safe. Most of the safety charts assume the beam is focused to a dot.

Those engraving lasers are possible to modulate to a lower intensity.

Not sure if it is done by an analog input or with a fast PWM.

That could be a way for you to start at a lower intensity and increase the power when needed, instead of getting gradually more powerful lasers.

[ulf]

For a blue alternative these might be interesting:

https://www.ebay.com...UBM31T&_sacat=0

 

It would be fun to design a sweeping illuminator with this beast.

[Stefano]

A video on this laser:

[dabateman]

A video on this laser:

 

But can it heat up a giant ball of popcorn in a house from space?

[Andy Perrin]

Spreading an array into a line would be hard I think. Keep in mind that for photography we care about things like even illumination which don’t matter if all you want is to burn the tops off soda bottles.

[ulf]

Spreading an array into a line would be hard I think. Keep in mind that for photography we care about things like even illumination which don’t matter if all you want is to burn the tops off soda bottles.

There will be a need for more optics, but I think it is doable with some effort.

It is interesting to speculate about the best way to do it, but a way too powerful laser to deal with alone.

The final design must have some really good safe simple interlock devices to make the usage safer.

[Stefano]

But can it heat up a giant ball of popcorn in a house from space?

Probably not, but I am sure it can be seen from the ISS:

 

I bet you can see it from the Moon, maybe with the help of a telescope but also with the naked eye in ideal conditions.

[dabateman]

Probably not, but I am sure it can be seen from the ISS:

 

I bet you can see it from the Moon, maybe with the help of a telescope but also with the naked eye in ideal conditions.

 

You might be too young, but this was my joke from Real Genius:

 

 

 

[Stefano]

I understood it was a joke, but I never saw that movie. I am probably too young.