How would you build a laser pointer?

[leglez]

I recently bought a 5mW green laser pointer. But I want more power. I found These, and I was wondering if it is possible to build one. I think all I would need is a power source, and a circuit with a switch to turn the laser on and off, and possibly a cooling device. Is this right? Are there any guides out there that show you how?

 

[Heisenberg]

Well, first of all, 808nm is infrared, so you most likely wouldn't be able to even see the beam. Secondly, 200mW is easily enough power to cause permanent eye damage. Thirdly, I'm not sure a controller for a diode like that could be small enough and be battery powered. My advice: stick with a store-bought pointer.

 

[Rubycon]

This really depends on your electronics and laser knowledge, skills, and abilities. (KSA)

Frequency doubled solid state lasers (DPSS) are much more complex than direct diode injection sources such as the common red variety.

Text

Sam's Laser FAQ is a great place to start. Since you're interest is in class IIIb devices >5mW you may want to read through the safety parts first. 🙂

Oh but there's soooo much info on that site! You may want to skip to this section which focuses (pun not intended!) on small DPSS lasers. 🙂

 

[So]

Originally posted by: Heisenberg
Well, first of all, 808nm is infrared, so you most likely wouldn't be able to even see the beam. Secondly, 200mW is easily enough power to cause permanent eye damage. Thirdly, I'm not sure a controller for a diode like that could be small enough and be battery powered. My advice: stick with a store-bought pointer.

Wouldn't he need a lasing cavity as well? Or is one built in to the housing of the diode?

 

[Raiden256]

This thread is SO about light sabers.

 

[mb]

Just buy one of these http://www.wickedlasers.com/ 🙂

Check out the videos http://www.wickedlasers.com/videos.php

 

[silverpig]

Originally posted by: Heisenberg
Well, first of all, 808nm is infrared, so you most likely wouldn't be able to even see the beam. Secondly, 200mW is easily enough power to cause permanent eye damage. Thirdly, I'm not sure a controller for a diode like that could be small enough and be battery powered. My advice: stick with a store-bought pointer.

A controller for one of those is stupidly simple. Just apply 70-80 mA at 1.9-2.3 V and it works. I've got a 60 W (yes 60 watts) diode laser and while the controller is more complicated, all it really does is supply 60 amps at 1.8 volts across the laser and it works.

But seriously, lasers like that can be pretty dangerous. Also, make sure you look at the divergence. You've got a 3 degree divergence on those diodes so take that into consideration.

 

[mugs]

Originally posted by: supafly
Just buy one of these http://www.wickedlasers.com/ 🙂

Check out the videos http://www.wickedlasers.com/videos.php

I know what I'm getting for Christmas.

 

[silverpig]

Originally posted by: So

Originally posted by: Heisenberg
Well, first of all, 808nm is infrared, so you most likely wouldn't be able to even see the beam. Secondly, 200mW is easily enough power to cause permanent eye damage. Thirdly, I'm not sure a controller for a diode like that could be small enough and be battery powered. My advice: stick with a store-bought pointer.

Wouldn't he need a lasing cavity as well? Or is one built in to the housing of the diode?

The diode itself is the laser. 🙂

 

[Rubycon]

Originally posted by: silverpig

A controller for one of those is stupidly simple. Just apply 70-80 mA at 1.9-2.3 V and it works. I've got a 60 W (yes 60 watts) diode laser and while the controller is more complicated, all it really does is supply 60 amps at 1.8 volts across the laser and it works.



But seriously, lasers like that can be pretty dangerous. Also, make sure you look at the divergence. You've got a 3 degree divergence on those diodes so take that into consideration.

Not for long though. 😉 LD's are much more susceptible to ESD damage than the most sensitive device in your PC. This damage isn't always immediately apparent until the device becomes an LED. :Q Most diodes have three leads because they have an internal photodiode to monitor the backside radiation that escapes through the (non egress) mirror coating. This is important as the laser output will "run away" as the temperature increases. Without these kinds of protective steps, the facets will be quickly destroyed.

Larger (bars) emit a stripe of light that must be shaped and then collimated for practical use. A single diode also has a large diverging beam that must be "treated" as well. Many novices simply give up (cost aside hehe) when they cannot get green output. Alignment is VERY tricky.

The wicked lasers are OK given the price. Just don't expect a precision instrument. 🙂

Originally posted by: silverpig

Originally posted by: So

Originally posted by: Heisenberg
Well, first of all, 808nm is infrared, so you most likely wouldn't be able to even see the beam. Secondly, 200mW is easily enough power to cause permanent eye damage. Thirdly, I'm not sure a controller for a diode like that could be small enough and be battery powered. My advice: stick with a store-bought pointer.

Wouldn't he need a lasing cavity as well? Or is one built in to the housing of the diode?

The diode itself is the laser. 🙂

Actually I believe they are referring to the KTP/Vanadate part. If you use discrete components instead of an MCA (definitely not recommended for the beginner!) the output coupler (OC) requires alignment to get peak 532 output. Never operate a DPSS laser without an IR filter in place either. A relatively harmless 5mW pointer operated without an IR filter can have well over 100 mW of 808 and a few 10's of 1064 mixed in the beam - all completely invisible to the eye!