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General laser facts FAQ: A Summary

Wolf11

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Hi guys, i am making this post as a response to all the useless threads out there, so you (us ^^) newbies can find out what we want to know without clogging up the rest of the forum :) Alot of these questions will be obvious to many, but not so much to others. If i have made an error, please correct me. I know there is already an FAQ section, but i thought it wasn't thorough enough when it came to the technical aspects. If you have any other questions, feel free to add them!

So here we go:

Q. I see alot of people talking about a driver in my laser, why can't i just hook up my diode to some batteries?
A. This is the worst question ever, but easily answered - a driver regulates current and sometimes steps up the voltage, this is needed so your diode doesn't fry in a matter of minutes, or even seconds depending on your diode/batteries. Also, to make use of it's full potential you will need a lens in the form of an Aixiz housing or other such things otherwise all you will have is a pretty red/blue/green light.

Q. Why is an 8x diode more powerful than a 16x burner diode?
A. This one's straightforward, when people use the terms '6x' or '8x' they usually refer to BLU-RAY burners, these are much more powerful than regular burners, i think i read that an 8x burner is nigh on equivalent to a 22x regular dvd burner!

Q. Can i mod my low-power laser pointer into a high-power burner?
A. No, this would require a larger power source, driver, and new diode - even more problems occur when dealing with green lasers.

Q. What's the difference between a buck/boost driver and a linear driver?
A. A boost driver allows a lower input voltage to be used when making a laser, much like a step-up transformer, while also regulating current - whereas a linear driver just regulates the current.

Q. I took apart my green laser, but when i put it back it doesn't seem to work, what happened?
A. As far as i know, most green lasers use infra-red light and convert it into green light by doubling the frequency (nm) via a crystal, you probably misplaced it or damaged it.

Q. What's the difference between an open can diode and a closed can diode?
A. An open can diode has no 'cover' or 'roof' and is larger so it can be used at about 250% current as it will not overheat as easily, a closed can diode is more susceptible to overheating and the like, but is less easily damaged and recommended for people new to the hobby.

Q. I built my laser, but it doesn't burn anything - help!
A. There could be a multitude of problems including; overheating; too much resistance on the pot (potentiometer); diode is not powerful enough; voltage is not high enough; some solder has been misplaced and is connecting two things where they should not be; you don't have a lens; you bought an under-spec laser from an unreliable website.

Q. I want to get into the laser hobby, but don't know where to start, what should i do?
A. To start with you will want to pick up any old LD (laser diode) and connect the correctly connect the wires to a driver (Phazonxl made a great tutorial on how to make a driver easily for very little money using a breadboard here : YouTube - DIY: How to build a laser diode driver), doesn't have to be a micro one or anything - just good enough to not blow your diode, with an appropriate power source. It has to work, of course. (Do not use it for long, just check it works, otherwise it may overheat)

Once you can do this quickly and understand the processes involved you will be well on your way to knowing how lasers work. After this you will be able to make a proper laser (no offense :) ) with a host, heatsink and driver (the rckstr driver or flexdrive are great micro drivers which can fit into almost any host). Jayrob makes great kits!

Q. I heard about back reflection damage to my diode, what can i do to prevent this?
A. This is more of a problem in open can diodes as the small wires are exposed and be burnt by the reflecting laser light, to stop most of this you will want to buy the best lens you can, Jayrob sells glass lenses for all colours, not only will they increase the longevity of your diode, but will also improve performance by >20%! Alternatively for lower budget hobbyists, aixiz glass lenses do the job.

Q. I watched loads of videos, why do people always colour the place they point the laser at black?
A. When you want to burn something with a laser, it helps alot to colour it black, this is because black absorbs the most light as opposed to colours like green, blue or red, and since a laser heats using light, it is appropriate to increase heat absorption in the burning area.

Q. I've seen lots of people put the driver in a different place in their host, does it matter where i put mine?
A. Usually you should just follow what it says on the tips (if it does), if not then it's easy to say that it doesn't matter, a driver is a driver, but sometimes excess metal in the host is drilled out to create extra space for components and the like.

Q. People say i need goggles, can't i just be careful?
A. That's ok if you want to put the fate of your eyes in your hands, but people don't realise that even a reflection from a mirror, shiny tile or floor can hit your eye and cause permanent blindness, if not the whole eye, you will have a permanent blind spot. The hazard becomes greater the higher the power of your laser.

Q. I think I overheated/overused my laser - is it damaged?
A. I know from experience that this can be a daunting question, you just got your new kit, but in your excitement accidently left it or kept it on too long. It really depends what kind of laser, in most cases it works, or it won't come on at all, but as daguin mentioned to me, if you have a violet you may have started the inevitable slow degradation process. If it is a particularly powerful laser ( 300mw+ ) then you will have a higher chance of damaging it. Just make sure to keep it in the correct heatsinking and don't overuse it again!

I will be updating this thread regularly as i can't post the whole lot in one go, please post your replies, comments and suggestions.

Thanks for reading, i hope this helped you!
Wolf11
 
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Just bookmark this page into your Browser...
I just did...


Jerry
 

HIMNL9

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Could you post a link for that?

I suppose it's an LM317 or an LM1117 based linear driver, you can find a lot about them here, using the search function.

Oh, ok ..... just as examples ..... :D

http://laserpointerforums.com/f42/diy-homemade-laser-diode-driver-26339.html

or
17371-meta-topic-pinout-performance-actual-ld-quick_ref_sheet_1.jpg


and so on :D
 
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Ok... I didn't expect the usual LM317 linear DDL driver, cos that's so common.
So no other cheap alternatives I suppose?
 

HIMNL9

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Some sites, rayfoss, o-like, so on, have pre-builded cheap drivers, but not all are good, it depend from your diode.

As linear, if you use an LM1117, instead an LM317, you have a better driver with low dropout (LDO) ..... pins are identical, just use one instead the other.

Flexdrive is a good choice for miniature mounts, also if a bit expensive ..... or you can build a boost driver yourself with an LM3140XMF, if you know how to work with SMD components (til 600mA it work good, with a 3,3uH coil and a 0,33 ohm RI).

I'm also doing tests with other IC's, but i'm far from the end, cause lack of free time :p
 
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...
Q. I see alot of people talking about a driver in my laser, why can't i just hook up my diode to some batteries?
A. This is the worst question ever, but easily answered - a driver regulates current and sometimes steps up the voltage, this is needed so your diode doesn't fry in a matter of minutes, or even seconds depending on your diode/batteries. Also, to make it lase (burn stuff/focus) you will need a lens in the form of an Aixiz housing or other such things otherwise all you will have is a pretty red/blue/green light.
...
Hey Wolf, nice FAQ. This should be useful to those of us who are just starting to fiddle with the laser hobby.

And I'm not trying to be obnoxious, but I just thought I'd point something out. Technically, the verb "lase" is defined as "to emit coherent light", which we know to be a requirement for laser light (well, most lasers). The light must (usually) be not only of the same wavelength, but also have the same wave phase. Whether or not the beam is focused doesn't affect whether the laser is lasing.

Thanks again for the FAQ!
 

Wolf11

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Sep 25, 2009
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Wow, thanks for the replies guys - definitely didn't expect such good feedback!

As for your suggestions, i sure will get a link to that straight away and change 'lase' to 'burn' or something of the like :)
 




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