How to make a working super pulsed laser module or device?

[ozgur85]

Hello everyone

I joined the forum today and really appreciated the knowledge sharing with each other and helping out.

Can someone please help me? This question is giving my brain throbbing

I want to make a super pulsed 905 nm laser device. I want 5 laser modules in one box. I found a laser diode for this job. I attached it.

Question is, what driver should i use to make this laser diode work? What should i do? I have little electronic knowledge so can someone please give me information that i can understand.

Thank you very very much already!

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By the way the specifications should be like this:

905 nm GaAs laser diode
60 mW average power
50 W "peak" power
200 ns flashing (50 W power for this period of time)
6000 Hz

 

[keith1200rs]

Your two main choices are to use an avalanche transistor or MOSFET. The Osram application notes are quite useful.



Keith

 

[ozgur85]

Thank you keith!

I will look at that. I hope i can figure it out..

Luckily, if i need to ask sth, there are electronic geniouses like you on this forum

 

[keith1200rs]

If you are interested in avalanche transistor drivers then the Zetex (now Diodes Inc.) application notes might be useful.

Keith

 

[ozgur85]

Keith, that's very helpful! Thank you very much

 

[ozgur85]

Hello everyone again:smile:

I read the documents Keith gave me:smile: I saw that the best way for me to build a small sized SP laser device is to use an "OEM, small sized high power laser diode driver board".

I looked on the internet but couldn't find a web store selling one. Can someone please give me a link to a selling store? (I want to buy just one or two drivers with a credit card)

(I want to use SPL PL 90-3 laser diode with the driver)

Thank you!

 

[keith1200rs]

I don't know of any OEM pulsed driver boards although there are plenty of modules for CW lasers up to a few hundred mW. Have you seen a board somewhere?

Keith

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I guess there is this one: http://www.eodevices.com/main_etx_10a_frameset.htm but I don't think you will find things like that in web shops. Drop them an email. They are $149 each which actually isn't bad.

Keith

 

[ozgur85]

Keith, thank you very much! This board has also an integrated high voltage power supply which is good for me.

149 dollars seemed a little pricy though

I found some boards. I'm attaching them. But i couldn't see an option like "add to cart". You said it's hard to find that option so i will e-mail them. I hope they sell 1-2 pieces.

But, after buying the diode and the driver, who know what should i do next I have a lot to learn. But at least i'm learning

 

[keith1200rs]

They are specialised products so don't tend to be sold on web shops. While you may think $149 is expensive, prices for modules from companies like Laser Components are often a lot higher, but there is no harm in asking.

Be very careful when using high power lasers. Until you can verify that they are eye safe (based on power, pulse width and repetition rate) I would suggest you wear protective goggles/glasses. What are you planning to do with the driver when you have it?

Keith

 

[ozgur85]

Thank you Keith for your concern!

I see, so 149 dollars is a pretty good price ha? I know someone who can build these specialized drivers "by himself"! His name is Engin Hüküm. He has this blog: Please take a look at that:
https://polyhobby.blogspot.com/

He builds his own laser therapy devices which contain superpulsed lasers! He doesn't want to sell to me, he only sells to other countries (other than Turkiye).

I want to build a laser device like him but he won't give me any information:sad: So i'm trying to learn it by myself.

In fact, i too build my own laser devices. But my devices contain only continuous wave (CW) laser modules. But superpulsed 905 laser has much better penetrating capability. I want to use it for my mother. She has 3 herniated lumbar discs and also spinal stenoz..

We achieve success with CW lasers but partly. There is some 904 nm GaAs laser study for this illness and it's very positive.

I know lasers which have more power than 5 mW are dangerous for eye so i pay attention to it. After i learned every thing about making a SP laser module and feel confident, then i will get down to business.

But this forum is a very important source for me. I'm certain many of you guys have a very good knowledge. In fact, maybe some of you guys could make the work for me and then explain it to me and i will pay gladly.. And after that i can make another one more easily.

Also, i made contact with a medical company. We're in the process of determining the plastic molding. And company owner wants super pulsed lasers in the devices. So it's essential for me to learn.

Sorry, i had to give a long answer


His device on e-bay: (English description)
**broken link removed**

 

[keith1200rs]

Hmm - that is expensive! I know some of the lower power CW lasers are used in therapy. I didn't know about using pulsed ones though.

I can try to help if you want discrete designs but I have never bought any modules as my designs are for incorporating in products so modules would be too expensive. Laser Components have good prices on 75W lasers and the Osram ones are similar prices. Excilitas ones seem a lot more expensive. As you aren't making a laser rangefinder driving it shouldn't be an issue - you can make do with a 60ns to 100ns pulse. A lot of the laser rangefinder applications want pulses below 10ns so the drive gets more difficult. Package inductance makes it quite tricky to get down to 5ns pulses which is why high voltages are used.

Keith

 

[ozgur85]

Keith, you're an excellent, helpful moderator. Thank you

So, at this point i learned that laser diodes are very sensitive. I should be very careful handling them. After i get the diode, i should put it in a heatsink. Then i should make connections between the diode and the driver. Then i should make the driver's configurations like voltage adjustment. I should do these as recommended.

Then i will power the module with correct adapter.

But i'm wondering if it's possible to wire more than 1 laser diodes (for ex 5) with just one driver (etx-10a)? I learned that HLD 500 series can do that. (attached)

By the way, "please forgive me" that can you give me some details after i got the driver and the diode? I assume you know how to make a good connection. The instruction on the sheets seem a little hard for me to understand. At least it takes time and gives me headaches..

Very grateful to you Keith

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I want 60 mW average power
6000 Hz
100 or 200 ns duty
50-60 W peak power

 

[keith1200rs]

You can certainly put laser diodes in series - some of the high power devices are exactly that - multiple lasers in one package. You just need to make sure you have enough drive voltage.

The high power lasers aren't that sensitive. Use normal static handling precautions. I would recommend you put a protection diode across them - they don't like much reverse voltage. You might not need a heatsink - do the calculations to check. For example, 50A at 20V (across the laser) is 1000W but with <0.1% duty cycle (which is typical) that is only 1W average. I use some of the plastic packaged devices and they have no heatsink and never get warm.

You will blow them up if you overdrive the current so start off low and adjust slowly upwards.

Keith

 

[ozgur85]

I'm noting down your recommendations! Thank you

 

[ozgur85]

Hello everyone again:smile: (and especially to helpful Keith..)

I learned lots of things about high power laser drivers but i'm in some trouble again:-( Luckily i have you guys

I want to buy ETX-10A driver but in the pdf document (i attached) it says it has a 8 pin FFC connector. In simple, standart CW laser diode drivers, only 2 cables (+ and -) are connected to the driver and the driver is connected to the wall adapter but can i ask that

What am i going to do with this board? How am i going to run my laser diode? I'm guessing only a 5V wall adapter won't be enough..

Thank you very much already

 

[keith1200rs]

You need two things - a power supply and something to generate the pulses. Usually the pulse width on laser drivers is determined by the capacitor value, laser current and voltage. So, you don't need to generate a really short pulse. A 74AHC123 dual monostable should do fine.

You need a power supply. The average power is quite low so a simple wall wart should be fine (look at the current graph in the datasheet).

The FFC is a nuisance. You can buy pre-made FFC cables but then you still end up with an FFC at the other end. The board can be purchased without the FFC fitted so maybe that is a better option - you can then solder to the pads where the FFC connector would have gone. You need to be fairly adept at soldering as these are 1mm pitch and you don't want to damage the PCB.

Keith

 

[ozgur85]

Keith, i don’t know what would i do without your help! You’re kind and a pro and your explanations are very nice. Thank you very much:smile:

Since you’re very kind, can i ask you one more question?

Can you please look at the images i attached? (I will get the pulse generator component you recommended. )

 

[keith1200rs]

You need proper operating instructions for the board to find out exactly what to do with the signals and how to set the voltage/current/capacitance and resistance. It might be worthwhile seeing if you can get them to email that to you before you buy it.

Some of the signals are to give flexibility in a system design such as the shutdown input. Other than power and tying the shutdown pin so the unit is ON, the only other signal you need is a pulse train. The width should ebay.co.uk short, say 1us or less, but the manual for the board should give limits. You need to repeat the pulse to suit the laser limits and the therapy effect. It is likely to be 100Hz to 10kHz. An LMC555 might be good enough. There are probably lots of example circuits on the internet, or you can look at the datasheet https://www.ti.com/product/lmc555 You need ASTABLE operation and choose the resistors/capacitor to give the required pulse width and repetition rate.

Keith

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Sorry I cannot draw any diagrams at the moment as I am doing this with my mobile phone so my facilities are limited at the moment

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It would be worthwhile checking the maximum trigger pulse width with them. It says 200ns in the datasheet but I cannot see why a longer one will no work. It prevents the capacitors recharging until the trigger pulse is over but at low repetition rates that shouldn't matter. Otherwise you need something faster than an LMC555 to generate the short pulses.

 

[ozgur85]

Thank you very much Keith! I will follow your instructions

I wish it wasn't that hard to make my laser diode just pulse.. But with your critical information i'm getting closer to victory

(By the way, i gave away all of my points to you )

 

[keith1200rs]

It will be a lot easier using a pre-built board like that than by designing your own from scratch!

Keith