A sneaky peak... ! 27.06.10

[HaloBlu]

Re: A sneaky peak... ! (Updated 20.06.10)

May not be fully aligned but its still a really nice sight no?

Interested in how your cutting of the dichros goes. How small would you like to get them?

 

[Meatball]

Re: A sneaky peak... ! (Updated 20.06.10)

You forgot to include the little green dot! He's left behind on the vice!

I think your setup is a win for the sake of simplicity.

I might add a small stress relief for those wires coming off the (diode pins?) connection on top. Wouldn't want to break those!

It's been awhile since we've seen some more DIY white beams!

 

[Benm]

Re: A sneaky peak... ! (Updated 20.06.10)

That seems to work out really well for a design that compact - cool!

I would not be too concerned about the splash - once you use it as a scanner those problems are much less obvious compared to looking at a static dot.

I'd love to see some detailed schematics on how you set it all up - the adjustable laser modules are a sure win, but do the dicro mounts also feature some degrees of freedom?

 

[Morgan]

Re: A sneaky peak... ! (Updated 20.06.10)

May not be fully aligned but its still a really nice sight no?

Interested in how your cutting of the dichros goes. How small would you like to get them?

It's a beautiful sight to be sure! I am literally loving it. The dichros only need to be as big as the face they sit on so about 7mm x 8mm. I've got one half of each of the dichros in the Casio projector so enough for 2 sets. That means I can build a spare! I'm going to score them with a glass engraving tool and snap underwater, (I heard this is a good way to get a clean break).

You forgot to include the little green dot! He's left behind on the vice!

I think your setup is a win for the sake of simplicity.

I might add a small stress relief for those wires coming off the (diode pins?) connection on top. Wouldn't want to break those!

It's been awhile since we've seen some more DIY white beams!

Don't worry there's a friendly yellow spot hanging back to keep old greenie company. He's not as fast as he used to be you know!

It seems to work reasonably well. I would have made the baseplate twice as thick as I think this one is vulnerable to knocks and flexing but 3mm plate was all I could get before breaking for summer. When it's installed into a housing this may not be so much of problem. Heat expansion worries me a little but it's not like I'm going to be doing parties so I can live with that I think.

Don't worry about the wires, this is still in development stage at the moment. They will all be heatshrinked, fixed and tucked neatly away.

That seems to work out really well for a design that compact - cool!

I would not be too concerned about the splash - once you use it as a scanner those problems are much less obvious compared to looking at a static dot.

I'd love to see some detailed schematics on how you set it all up - the adjustable laser modules are a sure win, but do the dicro mounts also feature some degrees of freedom?

Whilst I'm disassembling I might as well give everything a clean up to see if it helps but I take your point and will worry no more. Thanks.

The dichros are fixed but after initially lining the lasers up to leave the baseplate perpendicular and parallel. I had another baseplate across the room to line each laser up on it's respective hole to ensure the right geometry. Then I applied the dichro mounts and secured each one as I went. After that it was just a matter of a little tweak here and there for the modules again. I will eventually fix these with a resin or some permanent compound. The O-rings, although they do give some good adjustment, just don't give me enough confidence. (The ones for the green module are harvested from disposable lighters if you can believe that!)

I didn't know if I was supposed to line the near field for the first two lasers and then the far field for them both and THEN install the last one? I figured it didn't matter too much so fixed all three then lined up all the dots with the green. I can now see that if they were well out of line then this could affect where I put the last dichro. I will follow the described procedure next alignment.

I will explain a little better just how it went together when I work out the best way to go about it so it's repeatable and when I work out the best way to explain it! It's not to keep any secrets, merely to keep the edits to a minimum!

There is one little gem that I know you will like though. I got it from the dentist! I'll leave you with that one for now... (Don't worry, all will be revealed and you probably know it anyway. A man of your calibre!)

M

 

[flecom]

Re: A sneaky peak... ! (Updated 20.06.10)

very neat compact unit! I like it a lot!

if you want to get rid of that splatter you could put a pin-hole in front of your last dichro... would also get rid of some of the blue (bigger beam it looks like?) since you seem to be heavy on the blue anyway

 

[millirad]

Re: A sneaky peak... ! (Updated 20.06.10)

Really great results, from a well thought out design. We will be waiting for the next step, towards that more complete build. Kudos!

 

[kiyoukan]

Re: A sneaky peak... ! (Updated 20.06.10)

as far as your splash problem goes you can make a peep hole.
A hole just the size of your beam it help cut the splash away from your projections.

 

[Morgan]

Re: A sneaky peak... ! (Updated 20.06.10)

Thanks guys!

Here's an update that addresses and in some way solves some of the issues mentioned. This is a fluid build right now, as you've probably guessed, and improvements are made all the time.

I've since swapped out the Laserwave dichros for some out of a Casio projector som before the photos, some of you may be interested in some figures. Bearing in mind this is an experimental setup, and this being the first time I've recorded this type of data there is room for error. Therefore, these results should be taken with a pinch of salt but I'll give you all the data I have and if there are any clear anomalies then we can talk about them and narrow them down.

The first thing to say is that I'm pretty impressed with these dichros! The first time I set this combiner up I got a raw beam measurement, prior to any optics installation, of ~500mW, and a total of only 300mW after all optics. A huge loss of some 40%. This may have been down to clipping beams and not just optics but that is still a lot of losses.

The second time I've done much better. Raw beam measurement was 566mW total after a good optic clean and focus, (Blue - 198mW, Red - 248mW, Green - 120mW). Total output now was measured at 464mW! Only 18.4% losses total. Much happier!

I changed the setup to run in reverse order to previously due to the reflect/pass of the dichros. I.e. Blue first, then Red, then Green.

Blue - 198mW raw: After FS mirror 143mW, (28% loss!): After 1st dichro 130mW, (91% pass): After 2nd dichro 120mW, (92% pass).

Red - 248mW raw: After first dichro 240mW, (97% reflected): After 2nd dichro 237mW, (99% pass)

Green - 120mW raw: After dichro 105mW, (87.5% reflected)

Even just working on the figures I was expecting 462mW total output and came within 2mW of this so I'm confident my maths and alignment were pretty successful. As mentioned before, there is room for error as this is the first time I've built something like this but... Practice makes perfect!

I hope thos figures come in useful to others. The dichros show the reflective side quite clearly as it is the metallic side. Looks like a spacemans visor! If you're dealing with these then you'll quickly know what I mean!


So, on with some more pics then...


The dichros cut to fit. 8 x 11.5mm cut with a tiny diamond engraving wheel set in a pillar drill! The dichros were held in a hand vice and moved slowly across the drill bed. I was pretty worried they'd shatter!

The new setup! Much tidier than the first attempt. The dichros are just the right size and look great in the pics, the near field alignment is much better, (I'm still not totally satisfied, but that's just me because it's not absolutely, positively perfect! Arghhhh!), and the far field alignment is much more stable, (focus of the lasers is to around 50 feet but the dot stays white well beyond that!). There have been a couple of changes to the way the heatsinks are fixed too. Remember I was concerned with flexing and heat expansion issues? Well, I harvested some more cigarette lighters for their tiny silicon washers because the large o-rings were causing the case plate to flex as I tightened the Allen screws. This has meant less adjustment but no warping at all, and a firmer fix. This knocked on to requiring a better first fix of the dichros. A bit longer to achieve but well worth the time and effort.

These are all macro shots so no beams yet but I did bouce off a nice defraction mirror I got from Hak and they looked lovely last night!

I just noticed the hair in this shot! How ugly! Sorry folks.

If you're wondering what I used to fix the dichros and mounts... It's a truly brilliant compound! If any of you have had white fillings at the dentist then you have some of this stuff in your mouth. It's great. You can put it on and it doesn't rush you while you are getting everything, 'just so', as it doesn't cure in air. When all is in the correct position, zap it with 100mW of BR for 40 seconds and it's as hard a teeth! Give it something to key into and it's rock solid. The accuracy in this build would not have been posible without it as a normal air cured or epoxy resin would move whilst setting and be much, much harder to work with.

I hope you're liking the updates. I have some components now to at least build this into something I can hold in my hand and select the colour I wish from the 7 standard settings. This whole setup draws 1070mA at the moment at 4.2V so I'm hoping for a nice little number in the end. More pics as and when they're ready...

Thanks,

M

 

[flecom]

wow! very nice! I am really impressed with how clean it looks now... seriously I would be really proud of that... get some small scanners and you could have a nice handheld projector

 

[Morgan]

The scanners and colour mix control are next on the list! Then there's an enclosure...

I'm going for tiny steppers. I know this is primitive but for the size and power requirements, and relative simplicity compared to full on galvos, I feel this is the best way. A big wow! for a tiny scanner will make up for limited patterns etc.

I did a test run the other night and it gets a little too warm after 10mins at full throttle but I had anticipated that. The enclosure will form part of the heat management system and with PWM control for colour, I'm hoping it will just about stay cool enough. It would be tricky to squeeze anymore mWs out of a build this size but I keep thinking of little improvements. Since using thermal paste between the heatsinks and modules this not only gets rid of more heat more quickly but also seems to have reduced the current draw by nearly 200mA but I still can't quite understand why as I'd expect the current draw to reduce with more heat, not less. Anyone electronics experts got any ideas here?

One thing I didn't mention in my post from last night is that the colour match is actually a lot better now I've increased the losses from the blue after changing the position. This will all be irrelevant anyway when the colour control is in place and I've changed over to Microboost drivers using TTL.

There's still heaps to do but we move forward... However slowly!

M

 

[flecom]

why not go for some galvos with a small driver pcb like this?

12Kpps Galvo System laser galvo scanner - eBay (item 180526889341 end time Jul-29-10 07:50:25 PDT)

your really limiting yourself by using steppers... even at 12k those galvos can do decent simple animations (say using a USB sound card dac or something) and you can run it standalone from that dmx board thingie or a micro controller or something depending on what direction you want to go in

 

[Morgan]

Thanks for the link but that is WAY too big. The steppers I'm looking at are the ones from GGW sleds. Only a few millimeters in diameter.

Everyone I mention this to says the same thing and I'm getting used to it so don't feel bad but there just aren't galvos small enough. Not to mention the power needed. I'm looking at battery powered. Just not enough in it for a proper galvo setup, from what I understand.

Is there a real purpose to building so small? Probably not but that's just the sort of thing I like to do.

Early indications for simple patterns are to go the DMX route but I'm not offa with what is required here. PICs are also in mind for research but I've been leaning towards Arduinos and the like as I can probably find it easier to programme and at least there will be simple tutorials regards colour mixing to start with. Like I said, loads to do but it keeps me out of trouble. Any knowledge of DMX is gratefully received.

M

 

[flecom]

well DMX is just RS485 data... you have channels and then values for those channels... you need something to turn that into an analog singal that makes some kind of pattern (oscillators for example)... you could probably do this with a pic or micro controller of some kind...

theres also another option, using small DC motors (ex cell phone vibrator motors) and make a tiny spirograph projector... that would be a lot easier

 

[Morgan]

Yep, it would be easier but...

... Been there, done that! This was my first ever build after getting a working laser so my skills and knowledge have moved on quite a bit since this untidy build.

http://laserpointerforums.com/f47/2-mirror-spiro-cute-box-32642.html

Ok, DMX may be just another level I don't need. This part of the project is not my strongest as I'm more mechanical than electronic but the old cogs are in motion. Thanks for the info.

M

 

[Things]

Thats a very creative way of mounting the dichro's. I'd imagine the alignment would have been a bit of a PITA. Whats your far field alignment like? Any pics?

Cheers,
Dan

 

[Morgan]

^Thanks! It's not all that bad to be honest. You just have to be patient. I don't see any reason why the alignment can't be spot on doing it this way but it might be a different matter if I was projecting a shape for finer tuning. There are a few things to keep an eye out for which I spotted and took into account the second time I aligned and would be improved on when done again. It's only the second time I've tried aligning anything so because the dichros end up fixed then adjustment later is reduced and compromises have to be made, but get it right the first time and it turns into a really good result.

In short, far field alignment should hold up beyond 50 feet with this setup but could be even better with the next one. As I've had to recycle the drivers at this time it is sitting and waiting for some TTL controlled Microboosts to be installed for some colour control. Pics will come then and I'll make a point of getting a long distance far field shot.

M