Help need About Physiotherapy Laser Driver circuits

[Senthilkumar_rjpm]

Hi all...
Any1 Knows about Physiotherapy laser equipment. Here i desingng that. I want to interface Laser diode driver circuit with PIC Mc. Is there any special laser diode for Physiotherapy. Any Spl Driver circuit? Bcas usually machines are like to vary Power of laser diode. Is it possible to Adjust Power Of laser diode using Driver Cricuit? & abt Dosage Calculation?
Thanks in Advance

 

[pranam77]

As you may be deep in to the said field of Physiotherapy, you may first explain why a Laser is used in Physiotherapy and it uses, merits and demerits. The laser diode requires a current controlled driver which controls the current supplied to the device. Thus it all depends what diode you use and its power requirements. Drivers can then be fabricated which may be variable from lowest required power to the maximum possible power available from the used diode. Cheers

 

[keith1200rs]

I assume you know the wavelength and power levels required for physiotherapy? If so, you should read up on the drive requirements of the devices and also laser safety requirements. Normal laser diodes have a built in monitor photodiode and that MUST be used to control the power. There are dedicated ICs for driving lasers and I suggest you look at those. ic-Haus for example.

I have seen visible red lasers used for physiotherapy. Class 2 or 3a I think.

Keith

 

[Senthilkumar_rjpm]

Thanks for ur inetrest..
i m working in Physiotherapy equip manftr comp. as desing engg. So it may be in deep.
plz go threw this links
**broken link removed**

About Laser Therapy | eHow.com
It may help u to get idea about Physiotherapy laser.
Laser which is used for physiotharapy By machine manufacturers
like; 650nm to 685nm Power 30Mw to 200Mw max in Red laser diode.
830nm power 100Mw to 400Mw max in Infrared Laser Diode.
Plz visit Physiotherapy equipment - BTL
For clear details.
Can i make driver ckt with variable power? any samples? Plz...
Thanks in advance...

---------- Post added at 13:07 ---------- Previous post was at 13:03 ----------

I assume you know the wavelength and power levels required for physiotherapy? If so, you should read up on the drive requirements of the devices and also laser safety requirements. Normal laser diodes have a built in monitor photodiode and that MUST be used to control the power. There are dedicated ICs for driving lasers and I suggest you look at those. ic-Haus for example.

I have seen visible red lasers used for physiotherapy. Class 2 or 3a I think.

Keith

Thanks for ints Keith.
Its class 3b Lasers. I went threw ic-haus & more. But no 1 not exp clear about How to adjust power from Photodiode's feed back?
Thank u...

 

[keith1200rs]

You need an optical power meter to set the power. The built in monitor diodes are not accurate. You really need to read and understand the data sheets of both lasers and driver ICs. Be very careful with the lasers if you want to retain your eyesight. Protective eyewear should be worn.

Keith

 

[Senthilkumar_rjpm]

You need an optical power meter to set the power. The built in monitor diodes are not accurate. You really need to read and understand the data sheets of both lasers and driver ICs. Be very careful with the lasers if you want to retain your eyesight. Protective eyewear should be worn.

Keith

Thanks lot...
Do u have any idea about optical power meter? Its readyly available? How its work? Any spl sensors to measure optical power?

 

[keith1200rs]

You need to buy one with a large target area. Some are meant for fibre-optics so may not be suitable, although the more expensive ones have interchangeable heads. Have a look here for example

For driving the laser, look at iC-Haus Homepage - product: iC-WKN or iC-Haus Homepage - product: iC-WKP but you need to choose your laser first.

Keith.

 

[Senthilkumar_rjpm]

You need to buy one with a large target area. Some are meant for fibre-optics so may not be suitable, although the more expensive ones have interchangeable heads. Have a look here for example

For driving the laser, look at iC-Haus Homepage - product: iC-WKN or iC-Haus Homepage - product: iC-WKP but you need to choose your laser first.

Keith.

Now i m choose a red laser from laser components for testing purpose Details; https://www.cyfronika.com.pl/dok/rld_655.pdf. Becuz this laser diode 1ly bit cheap for testing purpose. & also i orderd ic-WKN for ic-haus. But My doubt is, there is no Adjustable external components in IC-WKN (iC-Haus Homepage - product: iC-WKN) circuit Diagram. Then How should i adjust power of laser diode. Or Can i make driver circuit with power adj? Any samples plz guide me....
Thx...

---------- Post added at 14:47 ---------- Previous post was at 14:44 ----------

You need to buy one with a large target area. Some are meant for fibre-optics so may not be suitable, although the more expensive ones have interchangeable heads. Have a look here for example

For driving the laser, look at iC-Haus Homepage - product: iC-WKN or iC-Haus Homepage - product: iC-WKP but you need to choose your laser first.

Keith.

Can i make simple Optical power meter? Or any other simple method. Bcz i think that meters or so much cost effective. My company ll not allow me to spend that much of money...

 

[keith1200rs]

But My doubt is, there is no Adjustable external components in IC-WKN

RM is adjustable - 80 ohms to 200k ohms.

You cannot easily make an optical power meter unless you have some means of calibrating it. If you overdrive the laser you will blow it up. If the company intends to make a laser based medical product they are going to have to spend some money! You may be able to find cheaper, locally made ones.

Keith.

 

[Senthilkumar_rjpm]

RM is adjustable - 80 ohms to 200k ohms.

You cannot easily make an optical power meter unless you have some means of calibrating it. If you overdrive the laser you will blow it up. If the company intends to make a laser based medical product they are going to have to spend some money! You may be able to find cheaper, locally made ones.

Keith.

Yes Thanks Now 1ly i saw RM.. It seems nice.. Can i Use Ic-WKN to drive any laser(ie. RED 200Mw & INFRARED 400Mw)? bcaz i m not able to find any power limitations from Ic datasheet...

I m searching local make for power meter.
THX....

 

[keith1200rs]

It will drive up to 300mA but you are limited to 150C junction temperature so you need to check your supply voltage & laser volts drop to make sure the temperature rise isn't too high.

Keith.

 

[Senthilkumar_rjpm]

It will drive up to 300mA but you are limited to 150C junction temperature so you need to check your supply voltage & laser volts drop to make sure the temperature rise isn't too high.

Keith.

Okay thax...

 

[Senthilkumar_rjpm]

Now i m choose a red laser from laser components for testing purpose Details; https://www.cyfronika.com.pl/dok/rld_655.pdf. Becuz this laser diode 1ly bit cheap for testing purpose. & also i orderd ic-WKN for ic-haus. But My doubt is, there is no Adjustable external components in IC-WKN (iC-Haus Homepage - product: iC-WKN) circuit Diagram. Then How should i adjust power of laser diode. Or Can i make driver circuit with power adj? Any samples plz guide me....
Thx...

---------- Post added at 14:47 ---------- Previous post was at 14:44 ----------



Can i make simple Optical power meter? Or any other simple method. Bcz i think that meters or so much cost effective. My company ll not allow me to spend that much of money...

Hi All... (Once again)
Here now i have a ic-WKN(ic haus) & red laser diode. (still i dont have optical meter). i am checking it now. its working right...

https://www.cyfronika.com.pl/dok/rld_655.pdf
iC-Haus Homepage - product: iC-WKN

but now i have some doubts...
1.Is there any relationship between(in red laser) LASER brightness Vs laser power. (if i adjust Rm of ic-WKN red laser bright ness also vary. its more brighter if i put Rm=22k than Rm=100k)
2.May i know the relationship between Rm Vs Power.? (Which resistor value i put for LASER maximum power)
3.Can i use this same ic(ic-WKN) for IR LASER diode which is i hv purchased? (https://www.farnell.com/datasheets/43673.pdf)

Please help me & share your knowledge with me...
Thanks in advance...

 

[FvM]

I see, that you selected a 200 mW infrared laser. I'm quite sure that nobody would use such a device in physiotherapy due to the serious safety risk. Hopefully, you know what you're doing?

P.S.: You may want to to consult IEC 60825 for an overview of safety requirements. I assume, that they have been also adapted for the national regulations in your country.

 

[Senthilkumar_rjpm]

I see, that you selected a 200 mW infrared laser. I'm quite sure that nobody would use such a device in physiotherapy due to the serious safety risk. Hopefully, you know what you're doing?

P.S.: You may want to to consult IEC 60825 for an overview of safety requirements. I assume, that they have been also adapted for the national regulations in your country.

Thanks for your reply FvM.... Actually there is lot of company using more than 200mw infrared laser for physiotherapy...
here link for 1 sample...
Physiotherapy equipment - BTL
Physiotherapy equipment - BTL
Physiotherapy equipment - BTL

 

[FvM]

O.K., I see. But the safety requirements are rather strictly. Eye protection means for staff and patient are obligatory. Safety trainings must be held and a safety representative has to be named in a physiotherapy shop using these devices.

The drive current for a high power semiconductor laser usually can't be adjusted without a calibrated power meter, at least if you want to achieve rated output. Otherwise the laser diode can be damaged by the radiation power. Thermal conditions have to be kept in addition.

P.S.: The operation current of the laser diode is within the rated current of the ichouse chip, so it can be used without additional current amplification.

 

[Senthilkumar_rjpm]

Thanks FvM.... Here i have bit knoledge of safty points... here i am desingning such equipment... we are using safty googles while playing with lasers...
i think i might be burn some laser diode...

 

[keith1200rs]

You cannot set the power without some means to measure it!

The range of monitor current of the ADL-6575 is 0.1mA to 0.3mA at 7mW so without a power meter you cannot set it.

The WKN chip has a nominal 500mV reference voltage (see page 5 of the datasheet and diagram on page 1). So the resistor Rm would be chosen to develop 500mV at the required monitor diode current, so 5k ohm to 1.67k ohms for the ADL6575. So, you might pick a 10k potentiometer, for example, depending on how low you want to be able to adjust the power.

Keith.

 

[Senthilkumar_rjpm]

You cannot set the power without some means to measure it!

The range of monitor current of the ADL-6575 is 0.1mA to 0.3mA at 7mW so without a power meter you cannot set it.

The WKN chip has a nominal 500mV reference voltage (see page 5 of the datasheet and diagram on page 1). So the resistor Rm would be chosen to develop 500mV at the required monitor diode current, so 5k ohm to 1.67k ohms for the ADL6575. So, you might pick a 10k potentiometer, for example, depending on how low you want to be able to adjust the power.

Keith.

Thanks keith.... bit confusion with theory & practical sir... ie. First i put Rm=100k fixedly. the lase will glow with some medium power. Secoundly i put Rm=50k now laser glow some more brighter. & finally i put Rm=22k now laser is so so bright but turn off with in seconds. i thought laser is burn (but there is no heat on both laser & ic).. But, after some time i switch ONN with Rm=100k .it works well... i didnt come any conclusion wether laser problem or ic shut down?????? can you explain me more? Thanks...

 

[keith1200rs]

7mW is bright! The real value for Rm for 7mW will be 5k ohms or less. With 100k you are probably only around 350uW.

You need a power meter.

And I hope you are wearing safety goggles at all times.

Keith.