Laser Diode Information
I am working on one project in which laser should be travel maximum 500 meters distance,for leveling ,At reciver side their are no of photo diode of the similar range for detection this laser baem.
I am using Red visible range class 3a Laser diode but i am confused about power at which laser should travel maximum 500 meters.
Now there are lots of laser diode which working on 620-680nm range and also available in 1-several hndred mili watts.
But which kind of laser diode full fill my distance travel issue,
Is that related with power of laser diode ? or any thing elese.
Please guide me for this .
Regards,
Heena
If the laser is pointing directly at a photodiode then you only need a tiny laser power. There will be very little atmospheric loss, but the laser will have significant divergence over that distance so it will be tricky to get high accuracy unless you design the laser optics for a small spot at 500m.
You could have the laser and receiving circuitry together if you use a corner cube as the target.
Keith
Maybe you can take a look at the laser measurements equipment to get an idea what they are using. For 500m distance the optical power is about 0,95W on the FSL series from Dimetix and the spot size at 30m is defined as 15mm. Take a look at the technical data on page 15 of the datasheet http://www.dimetix.com/downloads/Man...al_V204_en.pdf . It contains also the definition of laser safety classes. For laser diodes and laser driver you could look at Roithner Roithner Lasertechnik - Laser Diodes Overview and Drivers for Laserdioden . Of course the sensitivity of the receiver is as well import and as Keith said it is important to look at the total set. By the way the optic for focusing the laser beam is a challenge.
Enjoy you New Year celebration!
In my view 500meter is really long distance....and one need to think about two aspect.....first one is output light divergence....bcz over such distance the power of laser light singal may be get affect in case the laser have high value of divergence and ....second point is laser safty....if you are using high laser power diode then one need to make sure that it should not come in contact with any of human beings eye contact directly....it may harm human eye....
Good Luck
The Dimetix is 0.95mW not 0.95W! i.e. Class I.
Keith
hi all,
Thank you for your suggestion,
thanks HTA ,your Links are very use full for me.
But i have one question is that in general laser diode's power and beam divergence this both parameter's are important for long distance range.
In my project i wants my laser beam dimensions would be minimum 3-4mm at this 500 meter.
I already selected photo diode for this red visible range and its works [properly ,
So if i will use 50 mW laser diode of 660 nm wave length .
Please tell me it would be OK or not...
does laser power depends on laser diode and its driver circuitry ?
Please guide me for this.
Regards,
Heena
Your laser spot size at 500m will be a lot more than 3mm - it is more likely to be 1m unless you do some very good optics design.
50mW is not going to be eye safe!
Keith
Hi,
It means i have to choose a very low beam diameter due to the effect of beam diavergence ?
right
Please see at once this laser module may be it will work ?
http://www.roithner-laser.com/datash...dl-66503tl.pdf
Also you said that 50 mw is harmful for human Eye if its from Class 3a or 3B and for if ray is directly contacted with eye..
i am not confirm about above laser diode is from which class ..
So please let me know if i goes wrong .
Regards,
Heena
The class of your design depends on many aspect of the design, not just the laser diode power. The optics design has a large impact as well.
Spot size depends on several things such as the lens diameter, laser source size, laser astigmatism, optics design, lens focal length...
You need to study optics to optimise the design.
Keith