Post by thread:[EE] Simple to use 650nm (red) laser diode modules

Does anyone know where I can get some very simple to use red laser diode module units? Essentially I want a off the shelf laser pointer that I can power with 5v. (or some other easy to produce voltage) The application is for a clock that will point the laser at a wall to show what time it is. The laser will be run continuously so a lifetime of at least 10,000 hours (1 year) is required, though a lifetime comparable to an LED (1 million hours) would be much appreciated. I'm quite willing to turn down the brightness to achieve this, the laser dot only needs to be visible in indoor lighting. Furthermore it would be nice if there is a way to PWM the laser light for brightness control, but that'd be icing on the cake! I've already tried the two modules from http://www.us-lasers.com/ (ordered through digikey, 38-1010-ND and 38-1003-ND) They are almost exactly what I need except for two annoying issues. First of all they require very precisely regulated voltage to them, I spoke to one of their engineers and he said that their input voltage must be exactly 3.0V +- about 0.1 of a volt, doable, but a pain. Secondly the quality of the laser dot is rather poor, it's an unfocused oval rather than a tight round point. Something like one of those modules but that can accept less tightly regulation power and has a good quality dot would be perfect. Anyone here dealt with this sort of thing before? -- spam_OUTpeteTakeThisOuTpetertodd.ca http://www.petertodd.ca

On Tue, Dec 20, 2005 at 10:08:22PM +1300, Jinx wrote: > > > Does anyone know where I can get some very simple to use red > > laser diode module units ? > > Why not just hack a laser pointer ? Dirt cheap Oh I would, but this is an art project that I've beeen comissioned to make. So I have a budget of about $100US for the laser module but also I have to think about the long-term maintanance of the project. Unfortunately that means that potentially unreliable things like hacking a laser pointer are out. It's gotta be off the shelf and documented, so that in 10 years when the laser craps out it'll be easy to replace with another one. -- .....peteKILLspam@spam@petertodd.ca http://www.petertodd.ca

> > Why not just hack a laser pointer ? Dirt cheap > > Oh I would, but this is an art project that I've beeen comissioned > to make. So I have a budget of about $100US for the laser module > but also I have to think about the long-term maintanance of the > project Well, far be it from me, but ........ ;-) You're making an assumption about what will be available in 10 years time. US Lasers could be long gone by then. I daresay something else will be available, but according to Sod's Law it will be just different enough to be annoying > Unfortunately that means that potentially unreliable things like > hacking a laser pointer are out Reliability is the responsibility of the workman !!! ;-)) If you build within spec and have a good margin there's no reason to think any unit would fail prematurely. And you document it yourself so that someone in 10 years time will have no trouble fixing it > It's gotta be off the shelf and documented, so that in 10 years > when the laser craps out it'll be easy to replace with another one Seriously, what makes "off the shelf" so dependable ? I've had my share of garbage OTS, and I'm sure everyone else here has. If you're considering PWMing the one you get, is that any less "hacking" than taking a cheap pointer and doing the same ? I've looked at modules available from RS and their prices are way higher than you'd pay at a stationary supplier for basically the same thing sold as a pointer. Eventually I got some LM3s from Oatley in Australia and they work great http://www.oatleyelectronics.com/lasers.html Oatley also sell lenses (collimating and line, plastic, they're OK) I wonder though if 5mW is going to be enough. (I notice Digikey describe the 38-1010-ND as "4.8MW" but I'm guessing that should be mW !!!). 20mW might be more like it if the display starts getting big and the dot has to move around a lot

On Tue, 20 Dec 2005 04:14:05 -0500, you wrote: >Does anyone know where I can get some very simple to use red laser diode >module units? Essentially I want a off the shelf laser pointer that I >can power with 5v. (or some other easy to produce voltage) Have a look at http://www.roithner-laser.com/ There are plenty of manufacturers of OEM laser modules at pretty much every price & performance point. If you want good beam shape you are probably looking at something a bit better engineered than a laser pointer, but may be significantly more expensive. If you want really good beam quality, don't rule out a surplus helium-neon tube - these are available pretty cheaply >I've already tried the two modules from http://www.us-lasers.com/ >(ordered through digikey, 38-1010-ND and 38-1003-ND) They are almost >exactly what I need except for two annoying issues. First of all they >require very precisely regulated voltage to them, I spoke to one of >their engineers and he said that their input voltage must be exactly >3.0V +- about 0.1 of a volt, doable, but a pain. Secondly the quality of >the laser dot is rather poor, it's an unfocused oval rather than a tight >round point. What's so hard about a 3V regulator..? 0.1V is trivially easy with a regulator chip.

>> Why not just hack a laser pointer ? Dirt cheap > >Oh I would, but this is an art project that I've beeen >comissioned to make. So I have a budget of about $100US >for the laser module but also I have to think about the >long-term maintanance of the project. Unfortunately >that means that potentially unreliable things like >hacking a laser pointer are out. It's gotta be off the >shelf and documented, so that in 10 years when the laser >craps out it'll be easy to replace with another one. To me this is all the more reason to hack a laser pointer. If you go out and buy a specific laser unit then replacement is all the more awkward in 10 years, as technology moves on and things are done in a different way. But a Laser Pointer in a pen type barrel will probably still be available - for the same use as laser pointers are now. If you can fit a laser pointer by mounting the barrel with minimum modifications and supply a suitable voltage to it to replace the batteries, then whenever it fails the same can probably be done with whatever is available then.

On Tue, Dec 20, 2005 at 11:21:10PM +1300, Jinx wrote: > > > Why not just hack a laser pointer ? Dirt cheap > > > > Oh I would, but this is an art project that I've beeen comissioned > > to make. So I have a budget of about $100US for the laser module > > but also I have to think about the long-term maintanance of the > > project > > Well, far be it from me, but ........ ;-) > > You're making an assumption about what will be available in > 10 years time. US Lasers could be long gone by then. I daresay > something else will be available, but according to Sod's Law it > will be just different enough to be annoying Definetely one of my worries. I mean, by asking for such modules, what I'm really thinking is are they commonly available? Because if they are now, there's a good chance that they'll be available in 10 years, even if not specifically from US Lasers. > > Unfortunately that means that potentially unreliable things like > > hacking a laser pointer are out > > Reliability is the responsibility of the workman !!! ;-)) If you > build within spec and have a good margin there's no reason > to think any unit would fail prematurely. And you document > it yourself so that someone in 10 years time will have no trouble > fixing it You're right for sure, but I guess my point is that that $1 laser pointer you get from a surplus place doesn't *have* specs to follow. > > It's gotta be off the shelf and documented, so that in 10 years > > when the laser craps out it'll be easy to replace with another one > > Seriously, what makes "off the shelf" so dependable ? I've had > my share of garbage OTS, and I'm sure everyone else here has. As I say above, at least the OTS stuff *has* specs to follow, even if they lie and the hardware doesn't meet the specs. Makes me look less bad too! > If you're considering PWMing the one you get, is that any less > "hacking" than taking a cheap pointer and doing the same ? Not if the datasheet mentions PWM and I check it over with one of their engineers. :) > I've looked at modules available from RS and their prices are > way higher than you'd pay at a stationary supplier for basically > the same thing sold as a pointer. Eventually I got some LM3s > from Oatley in Australia and they work great > > http://www.oatleyelectronics.com/lasers.html Thansk for the tip, looks like a decent module, and nice price! > Oatley also sell lenses (collimating and line, plastic, they're OK) > > I wonder though if 5mW is going to be enough. (I notice Digikey > describe the 38-1010-ND as "4.8MW" but I'm guessing that > should be mW !!!). 20mW might be more like it if the display > starts getting big and the dot has to move around a lot It's going to be stationary actually. See, what I'm doing is mounting the laser to the shaft of a stepper motor. Then I *very* slowly pan it across a wall. Each 12 hour period the laser dot will make one trip from one side of the wall to the other. The whole assembly is mounted into the ceiling of a room and some control lines and power is run behind the wall to a control panel somewhere. The only tricky part is microstepping the motor for a sufficiently high resolution, I have a 400 step/rev motor I'm using with 64x microstepping. Actual realised resolution seems to be maybe 1600steps/rev. -- peteKILLspampetertodd.ca http://www.petertodd.ca

On Tue, Dec 20, 2005 at 12:28:22PM +0000, Mike Harrison wrote: > On Tue, 20 Dec 2005 04:14:05 -0500, you wrote: > > >Does anyone know where I can get some very simple to use red laser diode > >module units? Essentially I want a off the shelf laser pointer that I > >can power with 5v. (or some other easy to produce voltage) > > Have a look at > http://www.roithner-laser.com/ Thanks! That's a great link, looks like I've got a lot of possibilities to choose from. It's interesting that the barrel sizes seem to be somewhat standardized too, in light of this I'll probably make my mechanical mount for the pointer to have an insert so that any barrel size can be mounted by swapping inserts. > There are plenty of manufacturers of OEM laser modules at pretty much every price & performance > point. > > If you want good beam shape you are probably looking at something a bit better engineered than a > laser pointer, but may be significantly more expensive. > If you want really good beam quality, don't rule out a surplus helium-neon tube - these are > available pretty cheaply It would be nice to look at that's for sure... But no, anything good enough to be used as a laser pointer will be fine. As I explained to another poster the laser dot is not moving quickly or used to "draw", just to indicate. {Quote hidden}> >I've already tried the two modules from http://www.us-lasers.com/ > >(ordered through digikey, 38-1010-ND and 38-1003-ND) They are almost > >exactly what I need except for two annoying issues. First of all they > >require very precisely regulated voltage to them, I spoke to one of > >their engineers and he said that their input voltage must be exactly > >3.0V +- about 0.1 of a volt, doable, but a pain. Secondly the quality of > >the laser dot is rather poor, it's an unfocused oval rather than a tight > >round point. > > What's so hard about a 3V regulator..? 0.1V is trivially easy with a regulator chip. Oh it's pretty easy, heck, I've been running the us-laser pointer for awhile now while developing the PIC control hardware and software using a standard lm314. (or whatever the # is)I'm just thinking long term it'd make things easier, especially if the laser module has to be changed. I won't be around to do it! Looks like what I'll do in any case is supply power to the laser module with a adjustable regulator to make it easy to adapt to the requierments of whatever laser module gets used in the future. Just change a trim pot setting. I assume trim pots aren't known to drift... :) -- .....peteKILLspam.....petertodd.ca http://www.petertodd.ca

I suppose there's a reason you're not simply using the hour hand from a strong clock module? http://www.klockit.com/products/dept-157__sku-AAAAG.html The nice thing is that these are coil actuated, so if the timing isn't right, rip out the circuit, and pulse the coil yourself. Put it on the hour hand. The second hand is moved 1/60 rev each pulse, the minute hand goes 1/3600 rev per pulse, and hour hand 1/216,000 rev per pulse. The advantage above a micro-stepping stepper motor is that you don't need current between pulses, and in fact you could run the whole assembly off a AA cell for the year. Not to mention much higher resolution and accuracy than the microstepping stepper. Not that it matters much since you're running the laser continuously... Perhaps there are other constraints that this doesn't meet, but the high-torque clock in the link above may be worth considering. If it doesn't have a spot for a second hand, it is likely that the gears still provide 1/216,000 rev per pulse to the hour hand so the circuit is the same for all the clock modules. Sounds like a fun project. Good luck! -Adam On 12/20/05, Peter Todd <EraseMEpetespam_OUTTakeThisOuTpetertodd.ca> wrote: {Quote hidden}> On Tue, Dec 20, 2005 at 11:21:10PM +1300, Jinx wrote: > > I wonder though if 5mW is going to be enough. (I notice Digikey > > describe the 38-1010-ND as "4.8MW" but I'm guessing that > > should be mW !!!). 20mW might be more like it if the display > > starts getting big and the dot has to move around a lot > > It's going to be stationary actually. See, what I'm doing is mounting > the laser to the shaft of a stepper motor. Then I *very* slowly pan it > across a wall. Each 12 hour period the laser dot will make one trip from > one side of the wall to the other. The whole assembly is mounted into > the ceiling of a room and some control lines and power is run behind the > wall to a control panel somewhere. The only tricky part is microstepping > the motor for a sufficiently high resolution, I have a 400 step/rev > motor I'm using with 64x microstepping. Actual realised resolution seems > to be maybe 1600steps/rev. >

With many of these laser pointers, the metal case of the laser module itself is connected to the positive supply. I used a bunch of Alpec units in a project last year & had to run them with a -3 Volt supply because the mounts they were to be put into were at PSU ground. These cheap laser units will often die if the supply is shorted out. I'm not sure why this is, it may be transients on the supply when the short is taken off? They do seem to be quite sensitive to the supply voltage. The diode itself is powered from a current regulated by feed back fron a photo diode inside the laser. With cheap units like these, designed to be run from batteries, you can be sure that the current regulator circuit is not over engineered. Joe > {Original Message removed}

part 0 44 bytes his is a multi-part message in MIME format. part 1 1041 bytes content-type:text/plain; charset=us-ascii; format=flowed (decoded 7bit) Peter Todd wrote: {Quote hidden}>On Tue, Dec 20, 2005 at 10:08:22PM +1300, Jinx wrote: > > >>>Does anyone know where I can get some very simple to use red >>>laser diode module units ? >>> >>> >>Why not just hack a laser pointer ? Dirt cheap >> >> > >Oh I would, but this is an art project that I've beeen comissioned to >make. So I have a budget of about $100US for the laser module but also I >have to think about the long-term maintanance of the project. >Unfortunately that means that potentially unreliable things like hacking >a laser pointer are out. It's gotta be off the shelf and documented, so >that in 10 years when the laser craps out it'll be easy to replace with >another one. > > > So what would be wrong with buying 10 of the $1 laser pointers, hacking all of them to fit the project and keeping them on hand as long as you are around to repair it or include them as spares in the deal. part 2 391 bytes content-type:text/x-vcard; charset=utf-8; (decoded 7bit) begin:vcard fn:Robert I. Nelson n:Nelson;Robert I. org:RIN Designs adr:;;P.O. BOX 373;RIPON;WI;54971;USA email;internet:rindesignsspam_OUTcharter.net tel;work:1-(920)-229-7152 tel;home:1-(920)-748-7443 note;quoted-printable:Custom design and building of small electro mechanical devices.=0D=0A= AUTOCAD work ver2002 x-mozilla-html:FALSE version:2.1 end:vcard part 3 35 bytes content-type:text/plain; charset="us-ascii" (decoded 7bit)

On Tue, Dec 20, 2005 at 09:45:50AM -0500, M. Adam Davis wrote: > I suppose there's a reason you're not simply using the hour hand from > a strong clock module? > > www.klockit.com/products/dept-157__sku-AAAAG.html > > The nice thing is that these are coil actuated, so if the timing isn't > right, rip out the circuit, and pulse the coil yourself. Put it on > the hour hand. The second hand is moved 1/60 rev each pulse, the > minute hand goes 1/3600 rev per pulse, and hour hand 1/216,000 rev per > pulse. > > The advantage above a micro-stepping stepper motor is that you don't > need current between pulses, and in fact you could run the whole > assembly off a AA cell for the year. Not to mention much higher > resolution and accuracy than the microstepping stepper. Not that it > matters much since you're running the laser continuously... Yeah, this will be wired to mains current. Though I do plan to add a supercap to power the PIC only for short power outages. I've done that once before for another clock powered off of a doorbell circuit and it's been tolerating about 10 power outages a day from people ringing the doorbell for months now with no problem. I just made it possible to have it detect when it's running off of the capacitor by isolating the PIC's Vcc from the rest of the circuit with a diode, then added a connection to the normal power to an IO line, the second the PIC detects that IO line go low it drastically reduces it's oscillator speed to go into low-power mode. As for why you'd power a clock from a doorbell circuit? Well, it's an old house, and I wasn't allowed to touch anything more than a small segment of the drywall, so no running power lines anywhere. Easiest just to tap off of the doorbell as I was installing the device by the front door! Website here if anyone's interested: http://petertodd.ca/art/meter_clock.php > Perhaps there are other constraints that this doesn't meet, but the > high-torque clock in the link above may be worth considering. If it > doesn't have a spot for a second hand, it is likely that the gears > still provide 1/216,000 rev per pulse to the hour hand so the circuit > is the same for all the clock modules. Hmm... That's actually a really interesting idea. One problem I see is that I need some method of reversing the mechanism when at the end of the 12 hour period, the laser needs to track back to the starting position. Still that could work rather well for some other clock designs I have... I've got metalworking equipment sure, but building gear trains takes lots of work! -- @spam@peteKILLspampetertodd.ca http://www.petertodd.ca

On Tue, Dec 20, 2005 at 09:08:06AM -0600, R. I. Nelson wrote: > >Oh I would, but this is an art project that I've beeen comissioned to > >make. So I have a budget of about $100US for the laser module but also I > >have to think about the long-term maintanance of the project. > >Unfortunately that means that potentially unreliable things like hacking > >a laser pointer are out. It's gotta be off the shelf and documented, so > >that in 10 years when the laser craps out it'll be easy to replace with > >another one. > > > > > > > So what would be wrong with buying 10 of the $1 laser pointers, hacking > all of them to fit the project and keeping them on hand as long as you > are around to repair it or include them as spares in the deal. I was considering that. But then someone needs to keep track of those laser pointers, and unfortunately they'll probably get lost. As it is I'm going to do my best to keep the unit "self-documenting", so for instance every important connection is labeled as to what it is and what voltages it expects. I'll give the client a copy of the schematics and source code also. Finally I'm burning an offering to the FLASH gods to try to make sure my PIC chips flash memory doesn't die in 20 years. :) -- KILLspampeteKILLspampetertodd.ca http://www.petertodd.ca

On Tue, Dec 20, 2005 at 03:02:21PM -0000, Joe McCauley wrote: > With many of these laser pointers, the metal case of the laser module itself > is connected to the positive supply. I used a bunch of Alpec units in a > project last year & had to run them with a -3 Volt supply because the mounts > they were to be put into were at PSU ground. !!! Thanks for the heads up! Looks like the case will be plastic then. I'm lucky I can easilly isolate it electrically. > These cheap laser units will often die if the supply is shorted out. I'm not > sure why this is, it may be transients on the supply when the short is taken > off? They do seem to be quite sensitive to the supply voltage. The diode > itself is powered from a current regulated by feed back fron a photo diode > inside the laser. With cheap units like these, designed to be run from > batteries, you can be sure that the current regulator circuit is not over > engineered. Definetely. I've read through Sam's Laser FAQ on the subject, aparently most of the cheap laser pointer's except the battery to do most of the current regulation. The laser diodes are then engineered to tolerate a fairly wide range of currents/voltages compared to standard diodes. Very, very cheap indeed. -- RemoveMEpeteTakeThisOuTpetertodd.ca http://www.petertodd.ca

On 12/20/05, Peter Todd <spamBeGonepetespamBeGonepetertodd.ca> wrote: > I was considering that. But then someone needs to keep track of those > laser pointers, and unfortunately they'll probably get lost. As it is > I'm going to do my best to keep the unit "self-documenting", so for > instance every important connection is labeled as to what it is and what > voltages it expects. I'll give the client a copy of the schematics and > source code also. Finally I'm burning an offering to the FLASH gods to > try to make sure my PIC chips flash memory doesn't die in 20 years. :) Any reason not to just stick the extra laser pointers in the unit's case? Bill -- Psst... Hey, you... Buddy... Want a kitten? straycatblues.petfinder.org

>> Perhaps there are other constraints that this doesn't meet, but the >> high-torque clock in the link above may be worth considering. If it >> doesn't have a spot for a second hand, it is likely that the gears >> still provide 1/216,000 rev per pulse to the hour hand so the circuit >> is the same for all the clock modules. > >Hmm... That's actually a really interesting idea. One problem I see is >that I need some method of reversing the mechanism when at the end of >the 12 hour period, the laser needs to track back to the starting >position. How about a 2-sided Mirror on the clock mechanism reflecting the beam from a stationary laser, so it gives a 180 deg sweep for each 12 hour period (clock mech driven at half speed to give 1 rotation every 24 hrs)

On Tue, Dec 20, 2005 at 11:03:04AM -0500, William Couture wrote: > > I was considering that. But then someone needs to keep track of those > > laser pointers, and unfortunately they'll probably get lost. As it is > > I'm going to do my best to keep the unit "self-documenting", so for > > instance every important connection is labeled as to what it is and what > > voltages it expects. I'll give the client a copy of the schematics and > > source code also. Finally I'm burning an offering to the FLASH gods to > > try to make sure my PIC chips flash memory doesn't die in 20 years. :) > > Any reason not to just stick the extra laser pointers in the unit's case? The case has got to fit inside a ceiling with 2 inches of usable depth. :( I also need to keep the length and width to a minimum by order of the client. That said... I could probably get away with sticking them in a ziplock bag and hiding them next to the case! Maybe I'll do that for at least the documentation for the work, schematics and sourcecode. PIC chips probably won't be available in 20 years, but that'll at least tell peopel what the pieces behavior was. In the art world it's considered ok to replace the "brains" of an electronic work so long as it's not visible to the viewer, so make the behavior the same. -- TakeThisOuTpeteEraseMEspam_OUTpetertodd.ca http://www.petertodd.ca

> Secondly the quality of > the laser dot is rather poor, it's an unfocused oval rather than a tight > round point. > > Something like one of those modules but that can accept less tightly > regulation power and has a good quality dot would be perfect. Anyone > here dealt with this sort of thing before? Hi Peter, There seem to be a lot of replies, I hope this message doesn't get lost in all the noise. I have lots of experience with lasers. The output from a laser diode is an oval. It is usually about 4:1 although some newer and more expensive diodes are 2:1. The usual way to make it round is to clip the beam. There is a company that makes laser diodes with circular correcting optics inside although you pay dearly for it: http://www.blueskyresearch.com/index.htm The diodes are called CircuLaser. If you want the best beam quality, start with one of these. They also sell laser modules but I have no experience with those. Any red laser module decently constructed should have a very long lifetime - green is where the reliability would be more of an issue. Cheerful regards, Bob

No need to reverse it - just fast step it back around to the beginning. -Adam On 12/20/05, Peter Todd <RemoveMEpeteTakeThisOuTpetertodd.ca> wrote: {Quote hidden}> On Tue, Dec 20, 2005 at 09:45:50AM -0500, M. Adam Davis wrote: > > www.klockit.com/products/dept-157__sku-AAAAG.html > > Perhaps there are other constraints that this doesn't meet, but the > > high-torque clock in the link above may be worth considering. If it > > doesn't have a spot for a second hand, it is likely that the gears > > still provide 1/216,000 rev per pulse to the hour hand so the circuit > > is the same for all the clock modules. > > Hmm... That's actually a really interesting idea. One problem I see is > that I need some method of reversing the mechanism when at the end of > the 12 hour period, the laser needs to track back to the starting > position. Still that could work rather well for some other clock designs > I have... I've got metalworking equipment sure, but building gear trains > takes lots of work! >

>> It's going to be stationary actually. See, what I'm doing is mounting >> the laser to the shaft of a stepper motor. Then I *very* slowly pan it >> across a wall. Each 12 hour period the laser dot will make one trip from >> one side of the wall to the other. The whole assembly is mounted into >> the ceiling of a room and some control lines and power is run behind the >> wall to a control panel somewhere. The only tricky part is microstepping >> the motor for a sufficiently high resolution, I have a 400 step/rev >> motor I'm using with 64x microstepping. Actual realised resolution seems >> to be maybe 1600steps/rev. How accurate does it have to be (as in f.s. and repeating) ? Gluing a small mirror on the bent needle of an analog meter should help you here. A 50uA f.s. scale meter would likely need only half that current on average. 25uA is very nice for battery power. The meter can be driven by a single PWM channel. It could work with about 18mAh for a month. Two AA cells contain a hundred times more energy than that. Peter

Neil Baylis wrote: > You don't need to mount the laser on the shaft of the stepping motor. > All you need is a tiny mirror mounted on the end of the shaft at 45 > degrees. Point the laser into it, i.e. along the axis of the motor, > and it will scan the beam through 360 degrees if you want.<snip> IIRC, the mirror should be a front surface mirror (the reflecting surface is on the front of the glass), or you will get ghosting and distortion from the laser. Some medical laser imagers (to expose film from a digital source - eg Kodak DryView 8900) use a tilted 6 sided front surface mirror that spins to trace across the film while it drives through (like a raster scan). Laser alignment tools for doing suspended ceiling tile spin a mirror to put a red line around the room at the same height, and some of the inexpensive laser leveling tools seem to have fairly bright lasers in them.....

> It's gotta be off the shelf and documented, so that in 10 years when > the laser craps out it'll be easy to replace with another one. > "off the shelf and documented" is an entirely different problem than "the same part will still be available in 10 years." The latter is MUCH harder to find. This is a major PITA when trying to use OTS PCs or PC components for an embedded design with a long lifetime; THOSE parts tend to disappear in a year or two, never to be seen again, perhaps with any driver SW that existed disappeared as well. I don't think that red laser modules have enough 'real' applications that there's been any standardization of form factors or pin-outs or any of that; you'll just have to take your chances... BillW

On Tue, Dec 20, 2005 at 08:54:08AM -0800, Bob Blick wrote: > There seem to be a lot of replies, I hope this message doesn't get lost in > all the noise. > > I have lots of experience with lasers. The output from a laser diode is an > oval. It is usually about 4:1 although some newer and more expensive > diodes are 2:1. The usual way to make it round is to clip the beam. There > is a company that makes laser diodes with circular correcting optics > inside although you pay dearly for it: > http://www.blueskyresearch.com/index.htm > The diodes are called CircuLaser. If you want the best beam quality, start > with one of these. They also sell laser modules but I have no experience > with those. Ahh, that explains a lot! The nice circular point laser pointers I have are probably the "clipping" type, I've noticed they always place a round hole some distance away from the diode assembly... CircuLaser looks nice, though it's probably overkill. I'll suggest that if the client isn't happy! > Any red laser module decently constructed should have a very long lifetime > - green is where the reliability would be more of an issue. Well, very long yes, but most of the ones I see list a MTTF of 10,000 hours. Running constantly that's really only a little over a year. 10 years guaranteed running time would be much perferable. Superpermarket checkout scanners (bottom scan) use lasers if I'm not mistaken. I'd assume they have fairly long lifetimes, so what sort of laser do they use now? -- peteEraseME.....petertodd.ca http://www.petertodd.ca

On Tue, Dec 20, 2005 at 08:12:06AM -0800, Neil Baylis wrote: > You don't need to mount the laser on the shaft of the stepping motor. > All you need is a tiny mirror mounted on the end of the shaft at 45 > degrees. Point the laser into it, i.e. along the axis of the motor, > and it will scan the beam through 360 degrees if you want. This will > also work with a clock movement, even a very small one. The mirror > only needs to be big enough to intercept the laser. This lets you use > any laser. As someone else mentioned I'll need a front-silvered mirror for that. I thought of this option initially, and decided against it as the mirror would eventually get dusty. Cleaning is problimatic as it's high up on a ceiling and would requier special training. I wonder though... Is there such a thing as a "pseudo-half-silvered" mirror? Make one that applys the silver to a glass carrier and then applies a very thin protective film to the silver. While there still would be two reflections present they could be very close to each other, making the resulting beam be for all practical purposes a single beam. > Meredith instruments is a source of good quality modules. You can get > one with a built in collimating lens, and a good long lifetime. Good resource! Their 650nm 3.5mW is cheap too, only $20. At 3.5mW it's about the brightness I want, as described below... > Be careful with safety issues if the beam is moving slowly. Well I plan to use a very *low-powered* laser. One that is (relatively) eye-safe. Most laser pointers are such that if you look at one, even star at one, you are only temporarily blinded. That level of safety is exactly what I want. 3.5mW might just give that to me... :) -- EraseMEpetepetertodd.ca http://www.petertodd.ca

On Tue, Dec 20, 2005 at 10:38:07PM -0800, William Chops Westfield wrote: > > > It's gotta be off the shelf and documented, so that in 10 years when > > the laser craps out it'll be easy to replace with another one. > > > > > "off the shelf and documented" is an entirely different problem than > "the same part will still be available in 10 years." The latter is > MUCH harder to find. This is a major PITA when trying to use OTS > PCs or PC components for an embedded design with a long lifetime; > THOSE parts tend to disappear in a year or two, never to be seen > again, perhaps with any driver SW that existed disappeared as well. > > I don't think that red laser modules have enough 'real' applications > that there's been any standardization of form factors or pin-outs or > any of that; you'll just have to take your chances... Actualy I disagree on that. Practically every laser module I've seen has a number of things in common: Cylindrical case > 5mm in dia < 30 mm in dia. I can handle this by making the mount have a removable liner to adapt to the size of the pointer. If a new one needs to be made, chances are in 10 years 3d printing technology will make that job much easier than it is now! Minimum voltage required from 3V to 6V So I'll just put a easilly adjustable pot to change that as needed. Current is always less than 500mA and probably will be for any eye-safe laser! Pin-outs? You mean one wire is black and one is red? Seriously, they are all simple power devices. Some of the odder ones have adjustable brightness with a third lead, but I think non-adjustables will always be available. Nah, the laser doesn't worry me too much, other then the annoying issue of them probably burning out after 10,000 hours. In the very long term flash memory is going to die which means that we run into the fun issue of drive SW and dev kit availability as you so accurately mentioned. That's the real killer. The one that will force an expensive reimplementation of the elctronics is 30-50 years time. I'll probably be alive too to regret all the dumb choices I made when I get the warrenty call. :) -- RemoveMEpeteEraseMEEraseMEpetertodd.ca http://www.petertodd.ca

----- Original Message ----- From: "Peter Todd" <RemoveMEpetespam_OUTKILLspampetertodd.ca> To: "Microcontroller discussion list - Public." <RemoveMEpiclistTakeThisOuTspammit.edu> Sent: Friday, December 23, 2005 11:52 AM Subject: Re: [EE] Simple to use 650nm (red) laser diode modules? > > As someone else mentioned I'll need a front-silvered mirror for that. I > thought of this option initially, and decided against it as the mirror > would eventually get dusty. Cleaning is problimatic as it's high up on a > ceiling and would requier special training. In an application of a turning infrared temperature sensor I saw the dust has been caught with a high voltage electrode. Enrico

Russell, On Sat, 24 Dec 2005 00:47:28 +1300, Russell McMahon wrote: {Quote hidden}> >> As someone else mentioned I'll need a front-silvered mirror for > >> that. I > >> thought of this option initially, and decided against it as the > >> mirror > >> would eventually get dusty. Cleaning is problimatic as it's high up > >> on a > >> ceiling and would requier special training. > > > In an application of a turning infrared temperature sensor I saw the > > dust > > has been caught with a high voltage electrode. > > A negative ion generator may also be useful. Similar effect but > perhaps more aggressive as it actively attempts to cast ions adrift. As long as the mirror isn't seen as more positive than the ions, in which case it will be dusted-over pretty quickly! I had a negative ion generator in my bedroom, and anything plastic (mains plugs and sockets for example) within a few feet of it was covered in a fine dust within a week. Cheers, Howard Winter St.Albans, England

On Fri, Dec 23, 2005 at 01:37:59PM +0000, Howard Winter wrote: > > A negative ion generator may also be useful. Similar effect but > > perhaps more aggressive as it actively attempts to cast ions adrift. > > As long as the mirror isn't seen as more positive than the ions, in which case it will be dusted-over pretty > quickly! I had a negative ion generator in my bedroom, and anything plastic (mains plugs and sockets for > example) within a few feet of it was covered in a fine dust within a week. And while the mirror wouldn't be more positive, if I'm correct the laser sure will be as all these laser modules have a positive case... Some of that dust would probably get to obstruct the lens in the laser soon enough. -- EraseMEpetespamspamBeGonepetertodd.ca http://www.petertodd.ca

On Fri, 23 Dec 2005, Peter Todd wrote: {Quote hidden}> On Tue, Dec 20, 2005 at 08:12:06AM -0800, Neil Baylis wrote: >> You don't need to mount the laser on the shaft of the stepping motor. >> All you need is a tiny mirror mounted on the end of the shaft at 45 >> degrees. Point the laser into it, i.e. along the axis of the motor, >> and it will scan the beam through 360 degrees if you want. This will >> also work with a clock movement, even a very small one. The mirror >> only needs to be big enough to intercept the laser. This lets you use >> any laser. > > As someone else mentioned I'll need a front-silvered mirror for that. I > thought of this option initially, and decided against it as the mirror > would eventually get dusty. Cleaning is problimatic as it's high up on a > ceiling and would requier special training. You do not need a front silvered mirror. The double reflexion produced by the usual mirror is not a problem as it is weak (<10%) of the main beam and very close to it (at most sqrt(glass thickness) for angles of +/-45 degrees). You may also want to give up on the stepper and use an analog 50uA meter movement from an analog DVM. You can glue the mirror on that and drive it with PWM from a pic as I said. You may find that the stepper will not be able to stop on positions you like. For a reasonable sized room even a 0.5 degree per step stepper will cause your spot to stop far away from any reasonable-sized stops on a wall. The analog movement can be driven with say 16-bit pwm and will easily be settable for such situations. good luck, Peter

>I wonder though... Is there such a thing as a >"pseudo-half-silvered" mirror? Make one that applys >the silver to a glass carrier and then applies a very >thin protective film to the silver. While there still >would be two reflections present they could be very >close to each other, making the resulting beam be for >all practical purposes a single beam. The descan mirrors used in the space craft instruments I am dealing with are done this way. I do not know what the protective coating over the silver is, but there is certainly an extremely thin coating on top of the silver to protect from tarnishing while still earth bound. I suspect that if you went out and purchased a front silvered mirror, it would come with such a coating as a normal finish.

On Fri, Dec 23, 2005 at 06:41:12PM +0200, Peter wrote: > You do not need a front silvered mirror. The double reflexion produced > by the usual mirror is not a problem as it is weak (<10%) of the main > beam and very close to it (at most sqrt(glass thickness) for angles of > +/-45 degrees). I found an interesting possibility at http://www.theodoregray.com/PeriodicTableDisplay/Elements/045/index.s7.html Turns out dental mirrors are front silvered, don't tarnish, and are extremely hard due to their being coated with Rhodium rather than silver. I also know a surplus place where I can get dental mirrors a heck of a lot cheaper than even standard mirrors. Testing awaits! -- RemoveMEpeteKILLspampetertodd.ca http://www.petertodd.ca

Hello people, I'm glad to see this discussion about laser diodes/modules as I'm working in a little project that will use it (if it ever takes off). My question: What exactly the circuit on the PCB of a laser diode module does? It seens to be a simple current regulator. There are some *cheap* way of measuring 635nm and 532nm laser beam power? Best regards, Brusque --------------------------------------------------------------------- Edson Brusque C.I.Tronics Lighting Designers Ltda Research and Development Joinville - SC - Brazil http://www.ryan.com.br/netiqueta.htm http://www.citronics.com.br ---------------------------------------------------------------------