Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Hello Vienna is calling for help to modulate a Laser on 38kz carrirerfreq.

wranox

New member
Joined
Nov 30, 2018
Messages
6
Points
1
Hello from Austria , and sorry for my english.
i search for help on a project.
I like to puls a 523 nm Laser to transmitt a ID ( one startbyte 3 times ID Byte and one Stopbyte )
A easy way by to use same protocol as a IR remote control . Carrier freq. 38hz carrirer.jpg
Switch on and off for differed timing is a 1 or 0 bit .
I am plan to using a Arduino Uno R3 to build the 38kz carrier and the 1 and 0 bit or bytes , but how can i switch the laser so fast and precise on and off or better what kind of laser or lasermodul ar the best for this. In case that i like to see the beam on daylight it soud by a 532nm green one.
Thanks for help.
PS: Hello Santaclaus, this ar my wishes for Christmas " Freedom on would and ideas for my project" LOL
 

Attachments


diachi

Well-known member
Joined
Feb 22, 2008
Messages
9,634
Points
113
Guessing you mean 38kHz... Anyway...

532nm is not a good choice for this as it does not modulate well, the rise and fall times are terrible, especially on cheap 532nm modules. Just a result of how the light is produced. 532nm is produced by "pumping" a set of crystals with an 808nm laser diode, which then gets converted in 532nm light.

If you want fast modulation go with a direct diode laser, such as a 520nm laser diode.

What's the purpose of your project?
 

wranox

New member
Joined
Nov 30, 2018
Messages
6
Points
1
Guessing you mean 38kHz... Anyway...

532nm is not a good choice for this as it does not modulate well, the rise and fall times are terrible, especially on cheap 532nm modules. Just a result of how the light is produced. 532nm is produced by "pumping" a set of crystals with an 808nm laser diode, which then gets converted in 532nm light.

If you want fast modulation go with a direct diode laser, such as a 520nm laser diode.

What's the purpose of your project?
O yes it is 38 khz . Thanks for the idee to use 520nm . I dinent now the differenziertes betwin 532 and 520. So a 520 mm diode drive whit a mosfet from a pin of the Arduino must by good for 38 kHz. Du have a idea whot diode i shut take ( not more or less then 5 mw output )It is not easy to explane the purpose in case of some patens but so far it is part of a game idea.
 

Immo1282

Well-known member
LPF Site Supporter
Joined
Sep 4, 2018
Messages
548
Points
63
O yes it is 38 khz . Thanks for the idee to use 520nm . I dinent now the differenziertes betwin 532 and 520. So a 520 mm diode drive whit a mosfet from a pin of the Arduino must by good for 38 kHz. Du have a idea whot diode i shut take ( not more or less then 5 mw output )It is not easy to explane the purpose in case of some patens but so far it is part of a game idea.
Correct me if I misunderstood you - but you CANNOT drive a laser diode from the pin of an arduino, and you certainly shouldn't drive such a device by using a microcontroller pin to switch a MOSFET on and off alone. Laser Diodes require careful current regulation - if you just stick one across the power rails (i.e. a constant voltage supply), it will draw far too much current and just die immediately.

Look for a laser diode driver that has TTL input for modulation - that way you can drive the TTL input of said driver with your arduino all day - and the driver circuitry will handle the proper current regulation for the laser diode. I'm not sure if such a driver exists but you have to be smarter about driving LDs, or you'll have a neat pile of dead ones.
 

Encap

Well-known member
Joined
May 14, 2011
Messages
4,723
Points
113
You are not going to see the beam in daylight. Forget about that aspect of you imagined device.
 

paul1598419

Well-known member
Joined
Sep 20, 2013
Messages
14,778
Points
113
I have driven a 532nm DPSS laser driver's TTL with KHz frequencies, but have not tried it at 38 KHz. I know that it can be done, however. Why are you limiting the optical power to 5 mW? It certainly isn't necessary unless your project needs such a low power for a reason I don't know. You can get a direct diode lab laser ~505nm at 60 mW for around $65.00. This might also be a good laser to chose for your project.
 

wranox

New member
Joined
Nov 30, 2018
Messages
6
Points
1
Correct me if I misunderstood you - but you CANNOT drive a laser diode from the pin of an arduino, and you certainly shouldn't drive such a device by using a microcontroller pin to switch a MOSFET on and off alone. Laser Diodes require careful current regulation - if you just stick one across the power rails (i.e. a constant voltage supply), it will draw far too much current and just die immediately.

Look for a laser diode driver that has TTL input for modulation - that way you can drive the TTL input of said driver with your arduino all day - and the driver circuitry will handle the proper current regulation for the laser diode. I'm not sure if such a driver exists but you have to be smarter about driving LDs, or you'll have a neat pile of dead ones.
Thanks ,you ar right i need a driver board to ttl the laserdiode. Du you now some driverboars for 532 or 520 nm diods max 5 mw and powert by 5 V . in case it is a mobil Applikation and i like to use akkus from mobilphones or Rc models so small as possible.
 

wranox

New member
Joined
Nov 30, 2018
Messages
6
Points
1
I have driven a 532nm DPSS laser driver's TTL with KHz frequencies, but have not tried it at 38 KHz. I know that it can be done, however. Why are you limiting the optical power to 5 mW? It certainly isn't necessary unless your project needs such a low power for a reason I don't know. You can get a direct diode lab laser ~505nm at 60 mW for around $65.00. This might also be a good laser to chose for your project.
Hello thanks for reply . How fast du you puls your 532nm diode . Some papers that i found
I have driven a 532nm DPSS laser driver's TTL with KHz frequencies, but have not tried it at 38 KHz. I know that it can be done, however. Why are you limiting the optical power to 5 mW? It certainly isn't necessary unless your project needs such a low power for a reason I don't know. You can get a direct diode lab laser ~505nm at 60 mW for around $65.00. This might also be a good laser to chose for your project.
hello . Thanks for reply. How fast puls your 532 nm diode . Diachi tell me ,532 nm Diode ar not so fast in case the have some cristalls inside the pump . 520nm ar straight .
 

wranox

New member
Joined
Nov 30, 2018
Messages
6
Points
1
You are not going to see the beam in daylight. Forget about that aspect of you imagined device.
Hello , thanks for reply .yes i cant see the beam self . I need only see the dot on a taget. And on daylight gren is better for this.
 

Immo1282

Well-known member
LPF Site Supporter
Joined
Sep 4, 2018
Messages
548
Points
63
Wranox - do try to avoid double/triple posts - you can reply to multiple people in one comment and it'll get exactly the same visibility on the forum.

It's been said before - but why do you specify <5mw? Is the application something that could pose an eye-hazard?
 

paul1598419

Well-known member
Joined
Sep 20, 2013
Messages
14,778
Points
113
I have driven the TTL of a 532nm laser at ~5 KHz. I know it's not close to 38 KHz, but I had no problems at that frequency. I no longer have a frequency generator or I'd try to run one at 38 KHz for you. Sorry.
 

Singlemode Laser

Active member
Joined
Jun 25, 2017
Messages
293
Points
43
I modulate laser diodes with frequencies up to the GHz range without any problems. If your current driver doesn't have a wideband modulation port, use can use a simple bias-tee to couple your AC signal in.

Singlemode
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,115
Points
113
The problem is using DPSS here. These things do have a lag in both turning off and on between electrical input and optical output.

This already gives notable issues when scanning at 20 kHz or so, but you can compensate for that in software by delaying the movement of the galvo's and power up times of the non-dpss lasers in a system making it look pretty good in the end.

Just use a direct laser diode if you need speed, without the dpss process you can modulate them in the MHz to GHz regime if your drivers are up for that.
 

paul1598419

Well-known member
Joined
Sep 20, 2013
Messages
14,778
Points
113
Since the OP isn't using this in a projector the fact that there is some amount of lag in the solid state laser shouldn't matter. I don't know specifically what this project is, but it seems to be for communication as the OP is using it to send a binary code.
 

Singlemode Laser

Active member
Joined
Jun 25, 2017
Messages
293
Points
43
The OP don't gave us more information about his project and not a lot other informations either. If lag is important (active feedback scheme o s.e.) than other laser types than dpss are a suitable choice. If not, every led will do the job, kHz modulation was perfected decades ago.

Singlemode
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,115
Points
113
It's not lag as such. These DPSS lasers average out rapidly changing power levels of 808 nm light going into then, and the actual solid state laser makes them too slow to transmist 38 kHz signals.

Any LED or direct lasser diode would have no problem with this, probably you can modulate those into the gigahertz range as they do in fibre optics for internet connections ;)
 




Top