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Analog vs Digital ? Can some one explain

baddspella

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Hey, iv been reading threads dayly, but im not much of a poster, so be easy on me lol.

I have a few lasers and im planing on investing on stepping up the collection.
Im thinking about getting this 500mw dpss but One says "ANALOG" and costs more expencive than the exact same one that dosnt say it.

500mw dpss

500mw ANALOG dpss

Also in the tech specks

in the Analog one
Modulation ANALOG Level |10k​

In the other one
Modulation TTL Level | 0~10k​

Can enyone expalin what this is, why and if its worth the extra few bucks?
:thanks:
 

Things

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TTL and Analog are ways of allowing you to control the laser. TTL means you can turn the laser on and off, analog means you can vary it's power. This means you could connect it to a microcontroller, and use the TTL wires to turn the laser on and off instead of using a relay, or connect it to a DAC or potentiometer and vary the power for analog.

If you're just going to have it always at full power, and don't need power adjustment, get the TTL one.
 

LarryDFW

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baddspella;

I am experimenting with some TTL RGB laser systems currently.

Just to add a little more information:

TTL can be used to vary power by PWM (pulse width modulation).

If the frequency is high enough, you will not see the on/off cycles.

Processors usually can handle PWM very efficiently.

It would ultimately depend on the lighting control software you plan to use.

LarryDFW
 

hakzaw1

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All analog are also TTL --ttl only means, at best, seven colors in a RGB or RGV pj-
any ads saying 'full color' are either analog modulated modules or ( very unlikely for cheap Chi-Jectors) they are mistaken and they should be saying 7 color- Analog costs more than ttl only.
my rule of thumb is any RGB PJ under say $800 will most likely be seven color ttl even tho they will tell you its full color-

Two color PJs like RGs make only three colors- R/G and a combined yellow..unless they are analog.
hope this helps

hak
 
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Jacob32123

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baddspella;

I am experimenting with some TTL RGB laser systems currently.

Just to add a little more information:

TTL can be used to vary power by PWM (pulse width modulation).

If the frequency is high enough, you will not see the on/off cycles.

Processors usually can handle PWM very efficiently.

It would ultimately depend on the lighting control software you plan to use.

LarryDFW
Interesting. Have you tried it with a set of galvos to see if you see a dashed line as the beam moves?
 

baddspella

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Oh thats awsome, so i could verry easly controll it with an Arduino and a POT or get fancy and have it PWM increase with time on its own.

I think the analog is all i need. hopefully ill have photos of this new bad boy over the next month or two when i get some cash together :)

thank you all so much.
 

baddspella

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Dose the laser im buying seem alright ? its not my first dpss, but its my first 500mw.
dose it all look legit and stuff?
 

Benm

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baddspella;
TTL can be used to vary power by PWM (pulse width modulation).

If the frequency is high enough, you will not see the on/off cycles.

Processors usually can handle PWM very efficiently.
There is a bit of a problem with that: While you can make a processor produce a pwm signal fast enouh, the laser driver may not be able to follow it.

Usually laser units (or their drivers) are rated to a modulation frequency of 30 kHz or so, in the same order as the galvo's can move. When using analog or ttl, that is all fine since you can switch the laser as quickly as you can move the mirrors.

Now try PWM: To get reliable PWM dimming, your switching speed should be considerably faster than the movenment speed of the galvo's. If you are scanning a pattern at, say, 20 kpps, a driver that can take 30 kHz TLL would not be fast enough to accurately dim each point scanned.

As long as you're just drawing some lines this will average out to the eye nicely, but if you plan on projecting something complex and need reliable intensity control, the only options are to either go analog, or use a driver that has a much faster response time.

The latter isn't overly difficult to design, but most commercially available drivers just arent that fast. Neither is designing an analog driver, and if required integrating the pwm signal to get analog control, so all of it can be solved with good planning.

In the case of DPSS laser all of this may be moot, however: The delay between applying power to the pump diode in a typical 532 is so large it has to be compensated for at 'normal' 20-30 kHz scanning speeds already. Perhaps the laser itself would integrate faster PWM to some degree, though i doubt the whole conversion would be all that linear.
 




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