Modulation option on diode lasers

Greetings all,

The below specs are from a 445nm 1500mw diode system on ebay right now. I'm trying to understand the modulation option - another $75. What does it do? I'm guessing that it controls the output as one varies the applied voltage somehow? First of all, is this an additional electronic module on top of the diode plus the driver and PSU?

If I don't have the modulation, how much can I control the power output? I have a variable V and A DC power supply (Mastech HY1803D, with current limiter), can I not control the laser output using this?

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* Specs
* Emissions Indicator & FDA Key-switch Option added
* Matte Black Hammond Case # 1550D
* Aluminum (hammond page http://www.hammondmfg.com/pdf/1550D.pdf )
* MODULATION Optional - Add $75
* • Analog Input: 0-5.0V, clamped for protection. DC-155KHz NO OVERSHOOT!
• TTL input: 0-5V Off-On - YOU MUST HAVE 5VDC across terminals for Maximum output

* Output beam at aperture: 1mm x 3mm 2mRad divergence
* Color LCD LASER DIODE ASSEMBLY Thermometer in F or C (Please specify)
* Adjustable 3 element UV coated Glass lens ( fix focus yourself to suit your needs !)
* high power high stability
* compact configuration
* 1500mW (1.5 watt)CW Max
* Wavelength - 445nm blue
* Power Source 120/240VAC
* Separate Power supply

It has both analog and TTL modulation unless I'm reading it wrong. The two work very differently:

TTL: apply +5V and the laser turns on, anything below 4.8V and the laser remains off but powered up.

Analog: output power varies with input voltage, 5v for full power. How gradually it varies I have no idea.

Yep. TTL modulation is for laser show projectors and is used for color mixing and blanking.

Ash said:

Yep. TTL modulation is for laser show projectors and is used for color mixing and blanking.

Click to expand...

Ok so I though I understood Sigurthr's response (thank you, btw!) until yours. TTL is either on or off, so how is it good for color mixing? Wouldn't you need to vary the intensities to get different colors?

Achilleus said:

Ok so I though I understood Sigurthr's response (thank you, btw!) until yours. TTL is either on or off, so how is it good for color mixing? Wouldn't you need to vary the intensities to get different colors?

Click to expand...

In a RGB system with TTL modulation, 7 colors are possible. In a RGB system with analog modulation, millions of colors are possible. If all you want to do is burn stuff no modulation is needed. For a projector, TTL is required, analog is recommended.

Note: "TTL input: 0-5V Off-On - YOU MUST HAVE 5VDC across terminals for Maximum output." It looks to me like it is analog. If it was TTL, anything ~3V and above would give you max output. You can still feed an analog system a digital signal. However, if the digital signal is 4V instead of 5V, you won't get max output.

You're probably refering to this auction:
445nm Blue 1.5 Watt Diode Laser Lab industrial CW mode MADE IN USA !! | eBay
To be honest: the price for the module is a bit high, and $75 for the modulation option is REALLY expensive. The emission indicator and key switch is a $35 option apparently.
The holes in the front of the module do look funny btw.

Bluefan said:

You're probably refering to this auction:
445nm Blue 1.5 Watt Diode Laser Lab industrial CW mode MADE IN USA !! | eBay
To be honest: the price for the module is a bit high, and $75 for the modulation option is REALLY expensive. The emission indicator and key switch is a $35 option apparently.
The holes in the front of the module do look funny btw.

Click to expand...

That's the one. The holes are for the fan to blow through - would look better with a little grid or something instead.

But last time I looked into buying a laser, some years ago, that color and power would have cost $20K! Seems a good time to get back into things!

Achilleus said:

That's the one. The holes are for the fan to blow through - would look better with a little grid or something instead.

But last time I looked into buying a laser, some years ago, that color and power would have cost $20K! Seems a good time to get back into things!

Click to expand...

Yep... The reason:
Cas!o (electronics manufacturer) recently (early 2010) came out with a projector that has extremely powerful Blue (445nm) Laser diodes in it.
We are able to harvest the diodes from that projector at a cost of about $45 each diode. So, really a complete 1.5 Watt laser can be built for about $100 right now (if you DIY).