Hello. semi new member.

[buffo]

I got banned here my first day. i would direct you to the thread but when you get banned here they completely take you out LOL...

Actually, as far as I can remember, that's only the second time Spec has done that (delete significant portions of a thread following a banning). In fairness though, it was a lot of needless drama that didn't need to be here. (And yes, I carry some guilt in that, because I perpetuated some of that drama, to my shame.)

So let's call this a do-over, yes?

as for pangolin fb3 it is pricey. i already have my sound card and op amp. i'm in no way looking for a professional solution. so isn't exactly available in an affordable package.

Might want to give Spaghetti a try then. It's more affordable, and it will get you going. Later on, if you really want to get serious, you might consider selling your sound card DAC (with the correction amp) and your copy of Spaghetti so you'll have some funds to put towards Pangolin's FB3/Quickshow package.

I gotta tell you though, once you see what you can do with Quickshow, you'll be hooked...

On LPF i was recommended to use some drawing program and another program by dr.lava.

That would be Adobe Illustrate and Dr Lava's ILDA-SOS software. Basically, you do your designing in Illustrate (or any other structured drawing program or CAD program that supports the proper file format), and then you wash the files through ILDA-SOS and it converts the vector artwork into ILDA frames. It handles things like point optimization, blanking jumps, etc all by itself.

Though I haven't tried DR Lava's software personally, the people I've spoken to that have used ILDA-SOS have said that it's extremely powerful. Unfortunately, you still have to be able to draw the frames (or have a huge collection of pre-made artwork in the proper file format ready to convert). Since I can't draw to save my life, I haven't tried his software yet.

One thing: you didn't mention your location, but if you're in the US, understand that there are some pretty serious legal issues involved with using your projector in public. If you plan to do that, we can help you through the process of getting it certified, but it will help a lot if you design the projector ahead of time with certification in mind. (Assuming that this is your goal, of course. If you only plan to use it in your home or garage for your family and friends, then certification isn't an issue.)

And welcome to PhotonLexicon! Be sure to fill out your profile information so we know where you're located. There are several LEM's coming up, so there may be one close enough to you that you could make a road trip and have some fun.

Adam

[chipdouglas]

thanks for all that advice buffo. i do plan on my projector being just for me. but if the variance process isn't too hard, maybe i can try that as well. i am in souther california. i'll update my profile as well.

now remember i have not built this yet so my question is based off of observation only...
i read on multiple forums that you need way more red than green and blue. but in reality i can't remember seeing any people actually doing this. how come?

[buffo]

i read on multiple forums that you need way more red than green and blue. but in reality i can't remember seeing any people actually doing this. how come?

It has to do with the way our eyes see color. As it turns out, our eyes are far from perfect when it comes to color perception. They are more sensitive to some colors (wavelengths), and less sensitive to others.

The peak of human color perception for daylight-adapted vision is around 555 nm, which is right in the middle of the green spectrum. That's why green lasers appear brighter than red or blue lasers of the same power level. Our eyes are simply more sensitive to green.

Now, as the light levels go down, this peak starts to shift towards the blue end of the spectrum. Thus, in a very dark room (think: nightclub), a deep blue laser (like the new 445 nm blues, for example) will appear almost as bright as a DPSS green laser (at 532 nm) of the same power.

When you design your laser projector, the idea is to select the power of the red, green, and blue lasers so that you get very close to a perfect white when they are all operating at max power. Of course, "white" is subjective, because everyone has a different idea about what white should look like. But as a general rule, you can use the color response curves for human vision to calculate how much of each wavelength you need.

Tocket released a free program called "Chroma" that will do these calculations for you. However, remembering that white is subjective, you have to understand that just because Chroma says a certain combination is an ideal white doesn't mean it will look white to you. Also, Chroma assumes daylight-adapted vision. If you are in a dark environment, the balance shifts towards blue. So Chroma will get you in the ball park, but you'll probably want to tweak the color balance a bit using your software when you're all finished.

The largest variable in your projector design will be with the red laser, both because there are several different wavelengths to choose from and because our eyes have a lot of variability on the red end of the spectrum. The longer wavelength reds (650 nm and 660 nm) are much harder for the eye to see, so you need more power to compensate. Conversely, the shorter wavelength reds (642 nm and 635 nm) are closer to the color peak for our vision, so you can use less power with those wavelengths and still get the same apparent brightness.

Selecting a blue laser is easier, both because of the limited choices (445 nm and 473 nm, basically), and because there is less variability in our eyes at the blue end of the spectrum. So if you plan to use 445 nm for blue, you will probably be OK with a 1:1 power ratio between blue and green. Thus, if you have 200 mw of green, you will probably need around 200 mw of blue. But if you want to use 473 nm for blue, then you'll be better off with a 1.5:1 or 2:1 ratio of blue to green.

With red, these numbers change depending on which wavelength red you use. For the shorter wavelength reds, a 2:1 or 3:1 ratio of red to green will be good, but with the longer wavelength reds you'll probably want a 4:1 ratio or higher.

Because color perception is so subjective, some people simply pick a ratio that sounds about right and go for it. Other people spend a lot of time tweaking the numbers in Chroma first. But in the end, as long as you are in the ball park, your projector will look great. (And remember, you can always tweak the balance in software once everything is running.)

I've even seen projectors with a 1:1:1 ratio that still looked pretty good. (Granted, that was a projector with 445 nm blue and 635 nm red though.) But the closer your actual power balance is to an ideal color balance, the less power you'll waste when you tweak your software to get your "white" dialed in.

Adam

[dnar]

A good post buffo.

I guess at the end of the day, the appearance of your white beam is less important than how individual primary colours work together, ie. a fan of red green and blue should look balanced with no one colour dominating or looking weak.

I am also guessing mismatched divergence modules plays in to this argument also.

[buffo]

the appearance of your white beam is less important than how individual primary colours work together, ie. a fan of red green and blue should look balanced with no one colour dominating or looking weak.

In theory, if you've selected your lasers properly for a good white balance, then the color blending between individual colors will also be correct. (But again, it's all subjective...)

Where this often breaks down though is when people decide to add a little extra power in one color (usually green, but lately it's been extra blue, since 445 nm has become so affordable). The justification is that "I want some extra power in case I need more punch..." I did this with my projector, in fact. I have twice as much green as I need.

Now I wish I hadn't done this. I never run my green laser at full power, because when I do, everything looks green and I don't like how it looks. So my green laser is always running at 50% power or less. And the modulation response *sucks* when I do this. I have one of DZ's color boards installed, and that helps a lot, but I would have been better off installing a smaller green laser to start with.

I am also guessing mismatched divergence modules plays in to this argument also.

Yes, that's another piece of the puzzle, but they have less of an effect on your color balance. Ideally you want all of your lasers to have the same beam diameter and divergence, but that rarely happens in real life. Still, as long as they are close to the same, you won't really notice it.

If you will have a particularly long throw, however, the differences in beam characteristics will become more apparent - especially with graphics shows.

Adam