Another noob

[duhgus]

Hello all!
I'm hoping you'll accept me into your world and take me under your wings.

I have been a long time admirer of lasers and the possibilities they posses.
As a young teenager in the late 80's I saved my hard earned cash from bagging groceries to buy my first red laser pointer. Later on, I bought a melles griot 5mW HeNe off of eBay. I even bought a "baby widow" after seeing one in a club, pulling over a chair and standing on it to read the model name/number! (That was the last time my friends would invite me along to a club.)

I've always been drawn to "visualization" programs and plug-ins for Winamp and Media Player. ...Very drawn... I don't have synesthesia, but still have felt very influenced my music visually and emotionally. (aren't most of us anyway?

I think I'm ready to take the next step into this curiosity and make it a hobby.

I am very tech savvy. I am a professional telecommunications engineer, so "geek" is practically printed on my business card.

There are a number of resources that I feel privileged to be around to start this hobby. #1 This forum. #2 I attend every MIT flea market. www.mitflea.com/ (I work in Boston and live 20 miles west) #3 Very experienced electrical engineers in my current and past companies. #4 A good friend of mine works at Cambridge Technology. www.camtech.com/ (I'm hoping to get the hook-up on some top of the line galvos for little expense)

My intent is to educate myself more on the systems and components needed to build an RGB projector. I've been lurking here for a while, reading and becoming increasingly jealous of the builds that I've seen. My goal is to build a very nice, budget projector for small displays in my garage/home. I enjoy the shows that are projected towards the audience over drawn graphics. "Best Demo", without the "dancing woman in red" is my goal. Although if I had the ability down the road to project video, I wouldn't complain.

I understand the basics of what goes into a system. PC with graphics software, case, a controller to control each laser's intensity and blanking, galvos, galvo amps (controllers?), dichros and most importantly the lasers.

I fully agree that there should be a noob guide. I'd also like to see a working system up close and in person. I'm also an avid homebrewer and while I know a case of beer isn't worth a 500mW 473nm, it may just convince someone that I'm willing to put in the time to learn.

Thank you in advance to everyone in the forum.

Mike

[soforene]

Hi Mike,
You'll find many kindred spirits here.
Mostly broke but happy.

[gottaluvlasers]

Hi Mike!

Welcome to the wonderful world of ridiculously expensive beams of light!

You are amongst one of the best places on the web for laser knowledge. just sit back and soak up as much as you can. Ask as many questions as you can and make as much extra money as you can! lol, trust us...youll need it!

A few things to get ya going...

1) lasers in the U.S. are regulated and you need special licensing and "variances" to perform shows legally for an audience.

you said that you will be begining with just home brew shows and home displays. that is perfectly fine. dont get caught up too much on the licensing aspects for home brew systems. Just be aware that when the time comes that you want to do public displays, you will need to get properly licensed and variances for your equipment.

2) decide what type of power output total you will be lookg for. most hobbyists will start at about 500mW total. maybe a little less. maybe a little more. depends on your budget.

500mW total output gets you a nice balance of brightness and white balance. This will usually consist of-

300mW 635 red, 650 red or 640 red.
100mW 532 green
100mW 473 blue

blue is the killer. it is VERY expensive. alot of people will also use 405nm blue to get them going. it is much much cheaper. but it is very dim to the eyes.

decide on how you want to control your system...

home brew DAC? or a little more professional? Pangolin's FB3 system is budget friendly and is an extremely powerful and easy program.

please ask as many questions as needed.

Again, Welcome.

-Marc

[Jem]

Hi Mike, and welcome to Photonlexicon

It's always nice to welcome another 'potential' addict

Any chance you could fill out your location profile as a reminder to those of us with short memories to show where you're from?

Cheers

Jem

[Doc]

Hi Mike, welcome to Geeks Anonymous

[flecom]

A good friend of mine works at Cambridge Technology.

dude, hook it up! lol

seriously welcome, sorry about your wallet

[duhgus]

I knew this would be a welcoming bunch! Thanks for the warm welcome and condolences for my wallet. (Luckily home brewing beer is a pretty inexpensive hobby that I'll always have to fall back on)

Honestly, I don't ever expect to take displays public. I say that now but if getting permits, inspections and licenses is anywhere near as difficult to open a micro-brewery...then the display will stay at home.

1st question: What is a good size base to start with? I'm going to look/ask around with some friends that are machinists to see if I can get a good sized aluminum base. 1" thick? 3/4" thick?

I'm judging by the pictures that something that will fit into a media-type pc case would be a good size? length and width. 16" x 16" ?

It's tough for me to just the size of the actual components since I've never seen or held any of them before.

2nd question: I've written down 650nm for red. I see 635 and 640 listed as well. I’m sure there are pros and cons of each. is 650nm the way to go?

3rd question: From what I understand there are 2 controllers for the system. Galvo controllers (one for each axis) and controller that will control the intensity of each color. this is done via TTL or DAC? TTL just turns the laser on and off at various frequencies and DAC actually varies the intensity of the light output of the laser by varying the output of the power supply to the laser?

Please bear with my repetition of what I think to be me understanding of the process. I've learned that the best way for me to understand new things is by repeating in my own words.

4th: Does each laser require a separate power supply? And is this power modulated by the TTL/DAC controller? Is there a main power supply for the whole case as well? Am I correct in assuming that TTL can be done directly with a PC but DAC needs a separate card in the projector?

I imagine then the Galvo-x amp, Galvo-y amp and DAC are connected to the PC? (25 pin...But I imagine with newer technology there could be a USB connection?)

I'm going to toss together a quick napkin sketch of how I think this all connects together.

[ChrisPriest]

I knew this would be a welcoming bunch! Thanks for the warm welcome and condolences for my wallet. (Luckily home brewing beer is a pretty inexpensive hobby that I'll always have to fall back on)

Honestly, I don't ever expect to take displays public. I say that now but if getting permits, inspections and licenses is anywhere near as difficult to open a micro-brewery...then the display will stay at home.

1st question: What is a good size base to start with? I'm going to look/ask around with some friends that are machinists to see if I can get a good sized aluminum base. 1" thick? 3/4" thick?

I'm judging by the pictures that something that will fit into a media-type pc case would be a good size? length and width. 16" x 16" ?

It's tough for me to just the size of the actual components since I've never seen or held any of them before.

2nd question: I've written down 650nm for red. I see 635 and 640 listed as well. I’m sure there are pros and cons of each. is 650nm the way to go?

3rd question: From what I understand there are 2 controllers for the system. Galvo controllers (one for each axis) and controller that will control the intensity of each color. this is done via TTL or DAC? TTL just turns the laser on and off at various frequencies and DAC actually varies the intensity of the light output of the laser by varying the output of the power supply to the laser?

Please bear with my repetition of what I think to be me understanding of the process. I've learned that the best way for me to understand new things is by repeating in my own words.

4th: Does each laser require a separate power supply? And is this power modulated by the TTL/DAC controller? Is there a main power supply for the whole case as well? Am I correct in assuming that TTL can be done directly with a PC but DAC needs a separate card in the projector?

I imagine then the Galvo-x amp, Galvo-y amp and DAC are connected to the PC? (25 pin...But I imagine with newer technology there could be a USB connection?)

I'm going to toss together a quick napkin sketch of how I think this all connects together.

Hi duhgus,

I can try and answer a few of your questions

With regards to the red, 640nm is excellent, the diameter on the beam is only about 2-3mm whereas the 635nm is about 5mm, much easier to combine with Green and Blue when the diameter is smaller, plus the mirrors on most scanners tend to be about 5mm or even 3mm, so you end up losing some power on the red with a 5mm beam as the beam doesn't fit the scanner mirror properly

With regards to a controller, pretty much all can handle the X & Y Galvo's and the colours as well, always try and get something that can do analogue modulation for the colours so that you can vary the intensity of the beam and mix colours, TTL is straight ON/OFF. As previously mentioned the Pangolin FB3 is a great interface to get started with, providing differential output for the galvo's and 3 channels for colour.

Generally each laser comes with it's own PSU and driver board, I would recommend not attempting to combine them as each is usually setup to match it's laser head. It is better to have seperate supplies and drivers for each laser.

DAC is just Digital to Analogue Conversion, this can be done using a modified sound card DAC, there is another thread on the forum which details how to do this, at the end of the day, all controllers are DAC's in one shape or another.

Galvos' usually run at -10v - 0v - 10v, so anologue control is definitely required here to position them correctly.

I'm quite new here myself too, but you'll find that everyone on here is friendly, helpful and all round good people Don't be afraid to ask questions. and if I have made any errors, I'm sure I'll be shot down for it and corrected

Best Regards
Chris

[drlava]

Welcome dughus, it's a pleasure to have you here.

For the baseplate, 3/8" should be fine for a small to medium build up to a foot and a half or two feet wide, where 1/2" would be better for a 'large' build.

When you look at the red wavelengths, keep in mind that 640nm is visually about twice as bright as the equivalent 650-658nm power. However, 658nm diodes are much more readily available from DVD burners so are less expensive to build into lasers.

As Chris said, the DAC, or Controller, drives the galvos and the color modulation signals. Most modern controllers have analog modulation for the lasers, which can be used to drive both 'ttl' (off/on) lasers and 'analog' (dimmable) lasers, the latter being more desirable.


The galvos usually come with their own power supply, and the power supply needs for the lasers varies, so you can decide on it after you have chosen which lasers to buy.

The 'standard' for projector connection to the DAC/Controller is via the ILDA interface:
http://www.laserfx.com/Backstage.Las.../ISP-DB25.html
If you built a projector you'll have to wire this up yourself.
However some pre-made projectors might have a DAC built-in in which case you can connect to it via USB or sometimes ethernet, depending on the sophistication of the controller inside.

[Insanity]

Hi and welcome to the forum,

Here is a quick guide for you:

Lasers:
The lasers themselves usually come with a power supply, driver and laser head. The driver can be TTL or analogue. Best to go for analogue as you have 16.8 million colours, tones and hues. TTL only gives 7 colours. As Chris says, it is best to have individual power supplies, if you have only one and it fails, you loose all lasers, individually if one goes, you still have the other two.
A note on red lasers:
Red lasers typically have fat beams and not always round, such as 635nm which tend to have rectangular beam profiles. The best red laser is 640nm which has a small 3mm beam and is pretty round. Also being a short wavelength it is bright and you don't need masses of power. 650nm is much darker in colour and requires more power output than 640nm. 635nm is the brightest of all, but also has the worst beam specs.

Galvo's:
Again, galvo sets come with galvo's, mounting block, driver amps and a power supply. 30K is the standard, but 20k would be fine for beam shows and simple graphics. Obviously the faster your scanners, the sharper your images. But it sounds like you may be already hooked up with Cambridge, lucky you

Optics:
You will probably need a first surface mirror on a kinematic mount to steer the green into the galvo's. You then use a dichro to pass the green and reflect the red, again on a kinematic mount and finally you need a reflect blue dichro with the same setup as the rest. This will mix your coloured lasers into a white beam.

DAC:
The DAC (Digital Analogue Converter) is the link between your PC and Laser projector. It takes digital signals from the PC and converts them to analogue voltages to control brightness of the 3 lasers and positioning of the galvo's. The DAC usually comes with software to run on the PC. The Pangolin FB3 is a really good buy and now comes with QuickShow, which is a very pro and easy to use software package. The FB3 connects to your PC via USB and to the projector via DB25 cable. Of course like the others say, you can cut costs by using a modified soundcard as your DAC and then use Spagetti or LaserBoy software.

Baseplate:
Really an 8mm thick ally baseplate should be fine for what you want to do. You could even get away with 6mm, but as your projector grows, your baseplate needs to get thicker, as you can imagine keeping all the optics in line is critical, so flexible baseplates are not good.

Check out my build here for ideas: http://www.photonlexicon.com/forums/...ead.php?t=8485

Hope that helps
Mark