EEVblog® Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: coppercone2 on March 31, 2024, 06:50:12 am
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If you want to experiment with lasers like with crystals and stuff, what is the generic equipment that you need for a setup?
I have one of those aluminum optics plates. say working in the 1mW range
I know you need a emitter, that is like a power supply. But what other common general purpose things do you need that can give you the most bang for your buck and last a long time?
Mirrors? prisms? gratings? lens?
Is there generic optical test equipment/hardware, or do you pretty much need all specific things for particular experiments? Generic optics lab 1000$ lab setup ?
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This may give you some inspration.
https://www.edmundoptics.co.uk/p/optical-component-kit/12345/ (https://www.edmundoptics.co.uk/p/optical-component-kit/12345/)
https://lambdasys.com/products/category/5 (https://lambdasys.com/products/category/5)
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I was hoping for more like a guide. Like maybe the stuff they use to develop colored lasers.
I don't know how to think about it. Mirrors seem like cable. We know for electronics your good if you like stick to say, BNC, and you are good for a ton of stuff, and then you can go up to N for high power or 3.5mm for stuff that is almost out of financial reach for private individuals. Of course there are the weirdos with their TNC affinity etc.
I guess what I am asking is like what is the BNC-like equipment standard for optics. Does anything have such a wide range?
Like say so you don't by accident end up with something as atrocious as a F-connector equivalent or as god damn incompatible and oddball as a GR874 (even though I wish it was more adopted because it kicks ass). Or make a mistake starting to collect TNC stuff when you know that BNC is just way more available and common.
And what is the optical equivalent of badass APC-7 connectors? (not cheap skate and not annoyingly small. Honestly other connectors can suck it compared to APC-7. If I was rich I would hire someone to modify literary every coaxial thing i have to APC-7 unless it requires a higher frequency, even if its audio generator. I would get the cheap ass router wifi antenna modified for APC-7 >:().
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I guess what I am asking is like what is the BNC-like equipment standard for optics. Does anything have such a wide range?
There is no common standard. Metric or Imperial? Tube/Cage/Post layout?
See if you can find much in common between typical suppliers:
https://www.edmundoptics.co.uk (https://www.edmundoptics.co.uk)
https://www.thorlabs.com (https://www.thorlabs.com)
https://www.newport.com (https://www.newport.com)
https://www.optosigma.com (https://www.optosigma.com)
https://www.holmarc.com (https://www.holmarc.com)
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I mean RF has no common standard either but you will do alot better with test equipment and BNC then say TNC.
Are you sure there is nothing to avoid?
Even metric vs imperial parts? avoiding particular manufacturers that are geared towards 'cost sensitive' industries that have enough man power and volume to bother endlessly fiddling around?
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triangular optical rail, 1m
brackets, suppports for laser diodes, lenses
beam spreader and collimator lenses for desired wavelegnth.
Eye protect goggles rated for laser wavelegnth and power
first surface mirrors
photodetector and power meter
Just a start.
Use vib isolated concrete pier for holography
Jon
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oh I see if I have a beamsplitter I want the optics plate and if I have a series circuit the rail is better?
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Coppercone2: Bravo for the interest! I have Been fascinated by optics, lasers, light, lamps since 1950s.
1/ Most complex optical setups use BOTH a magnetic/perforated table AND triangular rails as needed for Z axis adjustment of focal length etc.
2/ Both benches and rails need appropriate stands with X, Y or XY motion and lens, laser etc clamps.
Vernier and precision micrometer motion are available.
3/ Entire bench is vibration isolated, preferably on a concrete pier for stability. Especially important for interferometer and hologram setups, a fraction of a wave movement or vibration will caus bad results.
Very often several rails are placed on an optical bench.
4/ Linear setups with only one axis can use just a triangular rail.
Most rails are a std CX section, but various brands may have incompatible stands, etc.
Get all benches, rails, stands from one brand.
Attached a few typical setups, eg in labs, univ, R&D.
Beware the high cost of a good setup, even on epay.
USEAPPROVED EYE PROTECTION even with 1 mW lasers!
See Edmond and Newport and Roland Optics catalogs.
Read the text on Laser Safety to save your eyesight.
See the National Labs like LANL LBL LLNL, NIF etc for great optical setups.
Bon chance,
Jon
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If you want to experiment with lasers like with crystals and stuff, what is the generic equipment that you need for a setup?
I was hoping for more like a guide. Like maybe the stuff they use to develop colored lasers.
There's no single guide for "how to make lasers", which it sounds like you're after, because there is a huge variety of ways to build a laser. Color is determined predominantly by the gain medium, which can be a solid, liquid, gas, or plasma, and will generally only lase usefully at one or two wavelengths. It needs to be "pumped" to a high energy state, which can be accomplished optically, electrically, or chemically. It needs to be placed in an optical resonator ("cavity") to establish standing optical waves, which can be as simple as a pair of flat mirrors or as complex as you like, with multiple mirrors, filters, active and/or nonlinear optical elements, etc. The exact structure will be determined by the requirements of the gain medium and the intended application. Precise alignment of all of those components is critical to get the laser to work at all, let alone work well/efficiently. The intracavity optical power is vastly higher than the power of the output beam, so problems there can easily destroy components if you're not very careful or push the power too high.
If you just want to get a feel for how optics work generally, then any cheap laser pointer (or ~collimated LED source), scavenged lenses, and mirrors will do. There are plenty of university lectures with practical demonstrations online you could watch for inspiration. Surplus Shed (https://www.surplusshed.com/) is a decent place to get cheap lenses to experiment with, and for basic experiments you can cobble together lens mounts out of anything, although I bet there are existing designs for 3D printable mounts as well. If you want to go beyond that, you'll need to narrow your focus quite a bit, and start investing in better optomechanical components to put things together. That's when the optical breadboard or cage systems become really valuable. These can be found on eBay or similar once you have an idea of what you're looking for.
Alternatively, if you have a lot of money to blow, Thorlabs (and I'm sure others) offer ready-made kits (https://www.thorlabs.com/navigation.cfm?guide_id=2310) designed for specific experiments, which you could easily modify/expand with additional components to do other things.
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lol at these prices I think this is how the guy jumping out of Excelsior felt like. small steps. If I was going to spend money at thorlabs it would probobly be on their THZ stuff. But I got some exotic colored pointers and its fascinating (i.e. yellow) that you can actually make this stuff with mixers etc, where it shows up on the wall and won't be used for drunken late night political rants bouncing off the moon or something like that.
glasses and reflective surfaces are a responcibility but so is turning off the mind scrambler that is the radio, which seemingly can make you blind towards honest ethical politics and common sense
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Saying optics is kind of like saying electronics, and then asking for a setup that will cover audio, analog, digital, RF communication, RADAR and anything else you might think of.
I would be hard pressed to say anything beyond the basic ideas that JonPaul has identified. Rails are ideal for one class of work, while benches are useful for multipath work. Vibration control is imperative for some things, not an issue for others.
For developing color lasers you want things like mirrors, Q switches, and protective gear. Are you thinking of gas lasers, which require handling facilities for those? Or going back to the origins and using crystals. In both of those types of lasers you will be need specific wavelength sources to pump your laser, so you need to do your design activity before you buy equipment.
There were several articles in the Scientific American amateur scientist column from the late sixties through the seventies that might give you some ideas.
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I don't know enough about it I just know I won't learn unless I have some stuff
What I need is some machine that uses both lasers and microwaves to do something
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So try to go at or beyond the bleeding edge of technology. Use your laser to put patterned heat into the surface of a crystal (inducing local thermal expansion). The basis of a dynamically tunable SAW filter.
In lieu of that do a lot of reading. I know, hands on provides a lot of knowledge that reading can never touch. But reading can get you half way there, and focus your investment in equipment. AFAIK this is an area where there is almost nothing in the way of kits to give you a pre-paved pathway.
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I'm including photo here, of a crystal mass, plus my cheap-ass 'toy' MICROSCOPE.
Somewhat of a scattershot, very unplanned accumulation, for my optics related education.
It isn't much; but the quartz crystal mass cost me $60 (US), at a nearby festival/county fair type event, (in beautiful Sonora, California). No particular 'direct' use or application currently, but this is the kind of items that I feel a priority, to obtain.
It can be a bit backwards, from maybe your efforts, but my aim was to force myself to set things up, and explore, maybe without a crystal clear agenda (** pun **).
The MICROSCOPE helps me in encountering various components, on tiny scales. For example, I've made myself a little better at discerning objects at 20 microns, and how that relates to other, small scale constructions. (Please see also, the Mark Rober videos, on micro sized nerf gun toy.)
The crystal, I barely know much about. The one I have, shown, seems to be a chaotic mass at base, with many individual growths poking up, (which likely have more interesting properties.
- - Rick B.
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got some Thorlabs glasses. I tried the cheap ones and it was like a bad joke.
I bet someone slapped some car skins on the cheapest possible lab glasses. they are downright hood. I thought I was gonna get robbed by children and subsequently beaten by the police.
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Go to Base Lab Tools , baselabtools.com
Order a half inch thick, double density inch baseplate, four or six inches wide, and as long as possible.
Go to Mcmaster.com , order 1/2" long and 3/4" long 1/4-20 Allen's ie set screws, as post studs. Order boxes of 50 pcs 3/4 and 5/4ths long 1/4-20 Allen screws with straight sided heads. Yes, in professional optics we refer to 1and 1/4 as five forths screws
Then go to Thorlabs and work with KM1 and half inch posts and post holders. You'll need 8/32 hardware in Allen as well. Thorlabs 5 packs and six packs of posts and post holders are awesome, as are their BA1s and RA90s.
Congrats, you are now compatable with 80% of the rest of the world and most of what is on EBAY as surplus lab optics from other vendors.
Skip the old triangular rails unless your teaching geometric optics.
Steve
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Is there like a laser power limiter device for setup?
I..e you can run the laser at low power if possible, then use alignment glasses to adjust everything, then try a higher power.
Do people consider current limiting safe enough with a special power supply, or is there some kind of optics element you can put in there that will fail if the electronics go haywire and mechanically disable the system?
Like, the laser equivalent of a fuse. Fuses really make things alot safer in general. Like a simple one that does not require control electronics to run, but relies on materials physics. or are laser researchers crazy like mechanical engineers and think active safety systems are good enough?
Well, I guess you can fuse the diode if you know its characteristic. But still interesting to know if there is a optical fuse
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One approach is to use neutral density filters. You can get sets that let you set total transmission to within a few dB. But pay attention to specs. Some are "neutral density" over a very limited spectral range, and all have limits on total incident power.
You can install power monitors and hook them up to shutoffs, usually with a beam splitter that deflects a portion of the beam into the sensor, passing the majority on. This requires careful thought because any device in the path is an opportunity to send energy places you didn't intend, and also because reliability failures in the sensing/shutdown path can remove the protection while the sense of security remains. A fuse fails open making the failure obvious.
There are also materials which saturate at a given power level, limiting maximum power transmission. Thinking about the eyeglasses which darken in sunlight gives the idea, and also hints at some of the cautions a limitations.
The approach I have seen most often is to use two completely different sources. An intrinsically low power one for alignment, and then install the higher power source. That may still have to be aligned but at least you know the rest of the optics are right. As always requires thought if there are dispersive elements in your setup.
As a last suggestion, search for YouTube videos on alignment of the CNC laser cutter systems. You will see examples of people doing some pretty wild stuff, but also some demonstrating proper concern, making measurements with all safety barriers in place, the opening the system and making an adjustment and then closing it up again before the next measurement. It is slow, tedious, and avoids burns and blinding.
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Beginners with Lasers start with 5-15 mW of visible light for a reason.
Until you understand what coherent light does, you have no business playing with high power Co2, Diode, DPSS, or Fiber lasers. YOU WILL end up with retinal or corneal degradation.
Optical Limiters, NO... While RF and Laser is closely related in terms of wave theory, Circulators for lasers are not circulators as you know them, the military considers optical limiters the unobtainable Holy Grail, and stray laser light arrives from places you would not expect to be a hazard in RF. Accurate optical power meters are incredibly expensive and extremely difficult to calibrate. We control the source for power where possible. Variable density filters (What you would think of as a Attenuator Pad) do exist, but are incredibly expensive. For very, very low powers, crossed polarizers are used as a "Dimmer", but those start to die around 1oo mW, unless you have really, really, expensive polarization techniques. Glass or Reflective ND filters are the same as attenuator pads, but can have severe reflections.
The Laser version of VSWR is Fresnel Reflection, and can be very angle and polarization dependent, ie Index of Refraction, Total Internal Refraction, Law of Malus, Brewster's Angle, Variable reflection with Angle.. Reflection can vary when you pass through changes in materials, Air to Glass, then Glass to Air for example gets you a pair of reflections unless the Glass has an AR coating. Coatings on optics can be thought of as a good RF match, or a VERY BAD RF match, and can be frequency dependent. The mathematical propagation matrices for RF and Optics are very similar.
This is a reliable vendor for beginner lasers I have used for years in academic and school situations. Order the matching heatsink.
https://www.z-bolt.com/Single-Module-Purchase_c_29.html (https://www.z-bolt.com/Single-Module-Purchase_c_29.html)
I'm sending you to Z-Bolt because they have low power systems and actually measure the output for being in the compliance range before shipping. (Thats a GOOD thing)
Get a Z-Bolt class IIIA (4.95 mW) green DPSS with known CDRH compliance and learn. Buy the Heatsink, pump diode to laser conversion efficiency is temperature dependent, DPSS are not stable unless properly thermally conditioned. Why, you may ask? Not only are they a great learning tool, when you move to high power you will need low power alignment lasers for safety.
This is the old route. Buy a HENE, they have the ultimate in beam quality, are easily mathematically modeled, and dont die from DC power spikes like Diode Lasers. Visible CLASS IIIA HENEs under 4.95 mW can be considered very safe, HENEs that are CLASS IIA are for all practical purposes intrinsically safe, due to Blink Reflex, with the caveat that the beam can still startle you or temporarely impare your vision.
These guys are great:
https://www.mi-lasers.com/ (https://www.mi-lasers.com/) Buy a bare tube and have lots of fun learning, and the HV does STING if your not careful. Get a Tem00 mode tube if you can.
DO NOT START OUT AT HIGH POWER. Until you can recite the Safety Classes from memory, ie Class I, Class IIA, CLASS IIIA, CLASS IIIB, Class IV, and know what different wavelengths do to tissue, as well as having the knowledge of how to contain laser light, JUST DON'T buy high power. I've started a small flame on a wall at 70 feet, while testing wall material, with far less power then you might think.
. EBAY lasers from China often ship at powers far beyond or below their stated rating, you can order a 5 mW and get a 50-150 mW. Reason being the Chinese trying to get around import US Regs for high power devices because they lust after the cash from laser experimenters. More then one beginner has went to the hospital to find out retinal and other eye tissue often does not heal when damaged. Blindness is very, very permanent. Cheap Ebay / Amazon Lasers often have IR leakage of higher power then the visible light.
When you know the Class your working on you can select your Eye Protection and determine the correct wavelength and optical density to purchase.
The tone in your writing suggests you can't wait to F around with Laser Optics. Take some time and do it right. Spurious and Indirect Reflections (Specular reflections) are a big problem in laser safety.
Look at Sam's Laser FAQ, I'm a co-author on some of the older gas laser portions.
Then once your used to low power, PM me and I'll link you to good, inexpensive, trustworthy vendors for hobbyists.
Avoid shining beams around in the sky without a Laser Show Variance. That can catch you a Federal felony in the US if you illuminate an aircraft by accident. Have a safe beam-stop at all times.
Good source of visible and Near IR lenses:
https://www.surplusshed.com/search_lenses.php (https://www.surplusshed.com/search_lenses.php)
THIS IS A CLASSIC: :
https://www.mi-lasers.com/wp-content/uploads/101waysTOuseAlaser.pdf (https://www.mi-lasers.com/wp-content/uploads/101waysTOuseAlaser.pdf)
Was from Metrologic Corp, when they still made HENEs.
Everything in there can be done with 5 mW of DPSS green. The last three bonus items are from the April fools edition, ignore them. Type Two DPSS Green has inherent polarization, making it even more fun.
One little warning. Laser diodes require very carefully designed current sources to drive them. Most bench power supplies will "Spike" the diode in a few hundreds of nanoseconds. Many beginners buy raw diodes and kill them on attempts 1,2,3,4, 5, 6, etc... Laser Diodes have a very steep learning curve unless you use a very good current source with known startup and shutdown conditions... There is a specially developed product called a Lasorb for a reason, to deal with static charges / voltage surges when using diodes. If you look at the patent, its a lot more then just a TVS. TVS are inherently slower in most surge cases then the LD junction.
https://pangolin.com/collections/lasorb (https://pangolin.com/collections/lasorb)
Very few devices respond to current faster then a LD...
Steve
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Hmm interesting but that sounds like a deficency because after all you can have all the experiance in the world and electronics is still better with a fuse. IMO people refusing to add a fuse to their circuit because '40 years experiance' are not that bright. Honestly probobly something will happen with CDROM read only laser and home made mirrors or whatever to see if I even like it Seems like a good invention that is missing
all I found were fiber optic fuse things, but that is not gonna work with a diode
probobly need a power meter first to verify power though.... if your really that careful you should not trust the supplier of your diode! Incase they mail you the 50 megawatt version by accident with the wrong label . Corporate can always go wrong... probobly not but I basically seen every single company screw up something
, regardless of reputation.
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THIS IS A CLASSIC: :https://www.mi-lasers.com/wp-content/uploads/101waysTOuseAlaser.pdf (https://www.mi-lasers.com/wp-content/uploads/101waysTOuseAlaser.pdf)
#18, always a crowd pleaser
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Well there are ultrafast silicon / semiconductor fuses, and we do use them in Galvanometer Scanner systems, but none of them are very transparent.
One thing about optical fibers, they have a self destructive mode at high power that is not intuitive, the melting glass fiber turns into a plasma ball that runs AWAY from the laser source end
Trying to find a video, but I've seen it twice in person on overdriven long coils of fiber. There is another mode where the destruction comes back to you from the far end, which is more or less Newtonian. . Non Linear Optics can take decades to wrap your mind around.
Ah, it took about ten minutes to find, but here you go, THE FIBER FUSE: https://www.youtube.com/watch?v=qDxcGHWK3vU (https://www.youtube.com/watch?v=qDxcGHWK3vU)
I've seen it in jacketed fiber where it should not have occurred, and might have set the entertainment venue carpet on fiber, this demo video was deliberate.
That purple color means the laser was probably IR, with very short pulses. Right before the the fiber goes critical, you see that purple glow on the fiber shelf in the left of the video, that is that insidious uncontrolled stray light matter I was talking about. That cloud of purple is probably the specular reflection / scattering dispersion from I'm guessing, 500 kW or more peak power and I know its 25-50 Watts of Average Power. The white glow is the glass core of the fiber molten at well over 1400'C. The visitors are somewhat safe from optical scattering due to a layer of Kapton like diffused polymer in the fiber jacket.
A bit better video:
https://www.youtube.com/watch?v=NZkaTU-G4_o (https://www.youtube.com/watch?v=NZkaTU-G4_o)
PS, Never look at a laser with a telescope or microscope. That's called "Optically Aided Viewing", and only fools do that outside of incredibly controlled conditions. We do, in some cases, have to consider the eye a 7 mm collection aperture for safety calculations, but a person with glasses on in the room can change that to a 50 mm aperture, which drastically lowers the permitted scattered power allowed after the safety calculations. Usually good CCD or CMOS cameras lose pixels at a far lower threshold then the eye when hit, as many ravers holding their expensive cameras above the three meter safety line can attest. Laser Beams in public above Class IIA or 3A in industrial / retail / surveying / medical alignment (US) without an audience scanning variance are supposed to be three meters above the highest accessible point and two meters horizontal from the reach of any audience member.
Steve
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Hmm interesting but that sounds like a deficency because after all you can have all the experiance in the world and electronics is still better with a fuse. IMO people refusing to add a fuse to their circuit because '40 years experiance' are not that bright. Honestly probobly something will happen with CDROM read only laser and home made mirrors or whatever to see if I even like it Seems like a good invention that is missing
all I found were fiber optic fuse things, but that is not gonna work with a diode
probobly need a power meter first to verify power though.... if your really that careful you should not trust the supplier of your diode! Incase they mail you the 50 megawatt version by accident with the wrong label . Corporate can always go wrong... probobly not but I basically seen every single company screw up something
, regardless of reputation.
What I really was saying, and LaserSteve said better is not that fuses are not a good idea, but that the equivalent of an electrical fuse doesn't exist. You are right, an invention would be welcome, but it hasn't happened yet, and not for want of trying.
The other thing that LaserSteve said fairly bluntly, but may not be obvious yet to you, is that the danger from lasers is fundamentally different. Bad electrical equipment can hurt you, but only in specific cases that are uncommon in the hobby world can life changing damage happen before you can vacate the emergency. A table saw is visibly dangerous, and when one of the bad things happens you usually know instantly that it happened, you stop and get treatment. With a HP laser you can lose much of your vision without even realizing that anything is going on. And you can start a fire on the other side of the room, or other side of the yard without being aware that it happened until it is too late to stop. It is more analogous to your concern with fiberglass particles that don't seem bad until you can't breath 30 years later.
I am not, and don't really think LaserSteve is trying to scare you away from this hobby area. But each of us in our own way is telling you to be very careful, thoughtful and deliberate about what you do.
Another thought that popped up. Early in my career I worked with a fairly prominent optical designer. It was late in his career and he loved the arrival of HeNe lasers for use in aligning some of his fairly exotic creations. And developed the habit of staring down the optical axis of his systems as he adjusted things. A habit which is absolutely terrible with higher power units. Even when you start with low power establish the habits that will save you as you move up the power chain.
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Forgive my bluntness. However in more then one case I have received late night phone calls from Laser Hobbyists and Emergency Room Doctors both. I used to have the phone number of a US Military Medical Laser Safety Facility handy for the once or twice a year phone calls. That way I could route the victim to a professional. The best you can hope for is to reduce damage from bleeding and swelling, calm the victim from doing further damage by rubbing the eye, provide some specialized protein building blocks, and increase healing speed with a few Direct INJECTION options.. :o That facility is now closed, I do not know where they relocated after BRAC.
I know a fellow who is now a national leader in Laser Safety Engineering and Education. He has a what he refers to, as a Quarter (US Coin) sized spot in his vision, from looking down the bore of a Large Frame Ion Laser, when the Igniter timer had an intermittent capacitor. Looking down the bore for diagnostics is the most common error. Light leaking around the safety glasses is another, and entering a room with an active system is probably number three, followed by hey bypass the interlocks, so old HU can figure out why the mirror slipped out of the mirror mount, and running in at four, is "Here, Hold My Beer and Watch This" also known as "Burning Stuff". Specular reflection is evil, and probably trumps ALL of the above. Just say NO to hemostats holding lens cleaning tissue in LIVE Lasers.
I know or have met others ranging from Lab Researchers, Hobbyists, Medical Doctors, Military Personnel, and Laser Entertainment personnel who have eye damage ranging from barely detectable to eye totally removed.
I have a friend whom was in a hurry to get an Entertainment System running at an amusement park. He received a 600 volt 40 Amp arc to his palm when a 35 Kv or more arc lamp ignitor started an over two inch long CW Plasma Arc to his palm, in AIR. When all was said and done, and after others got his heart restarted, he looked up to seeing through a charred hole in his palm, to the sky. He opened a case, turned a key, ignored an alarm, held down start for 20 seconds, removed a insulated safety shield, and bypassed at least two safety switches to do that. I said he was a good friend, but I never said he was the sharpest tool in the shed when hurried. . After Six months and many, many surgeries later, his hand became somewhat functional again. Moral of the story, don't "spark test" the lamp power supply. M. If you read this, I miss talking to you.
I knew another technician who rested his head on the side of the case and touched the Flashlamp capacitor terminal, he's shockingly, as expected, not himself anymore. I'm told it drastically changed his personality after he recovered. He certainly was a different person the next time I met him.
I have a tiny burn in one eye from an idiot removing a Lockout-Tagout tag and turning a key, from ~20 mW of blue light. The micro-computer booted and He opened a shutter, and moved an actuator I was calibrating due to an undefined logic startup state. Of course he was over 1000 feet away in a control booth. Mine is in the edge of the peripheral, very tiny, and I assure you it is not fun watching your eye recalibrate itself, and a brain neural network will try to correct your vision over time. The migraines were immense. The panic, more so. I'm cleared to drive, and over time, decades, I can no longer find the spot.
Don't go looking for spots, you have a few natural ones that can be found with training and once in while by accident, but you can cause severe eye strain trying. An Amsler Grid test card will help you for main field of view problems, but peripheral requires a surgeon with some pretty good gear. Another problem is the damage is often so small your eye surgeon can't find it. Simply develop the shop discipline, procedures, the enclosures, the optical safety glasses, and have others check your work, in such a way you never can make a mistake. Do not leave easily activated lasers laying around. The key switch must not be removable in the "ON" position, and for most American made lasers, the key cut code is a Cherry (or others) A126.
Most laser damage incidents start at the peripheral vision. You wont know you have an injury till the truck hits you, when crossing the sidewalk.
If you'd like, I can find you the paragraph of a researcher describing watching his eye fill with blood in real time..
Lasers can safely be used in the home and the classroom. But you must know what your doing, and never stop learning. Stats on Laser Show incidents show that most non-audience scanning shows are incredibly safe. Audience Scanning is allowed in many nations, but the prep work required to do it safely is immense.
This just might be a pet peeve of mine, but the YouTube video of a home experimenter running a 60 Watt Green Q-Switched Surplus Medical Laser without a beam stop and beam containment a few meters from a baby in a high-chair sticks in my mind as how depraved a human can become. Diode laser technology has proliferated faster then regulation and enforcement can keep up.
Know your NODH, Nominal Ocular Hazard Distance... One of my personal favorite devices has an NOHD of seven miles or 11.7 Kilometers. Yes, MILES.
Enjoy experimenting with very low powered CW* visible lasers, and learn from them. :-+
* Note, Pulsed lasers with Q-Switching, Mode Locking, Flashlamp Pumping, Pulse Driven Plasma, Cavity Dumping, or Kerr Lensing need serious respect in use. Your eye does not have a blink response to Ultraviolet and Infrared Light.
Some serious LIGHT reading links:
https://ehs.stanford.edu/manual/laser-safety-manual (https://ehs.stanford.edu/manual/laser-safety-manual)
https://researchsafety.uchicago.edu/programs/laser-safety/ (https://researchsafety.uchicago.edu/programs/laser-safety/)
https://www.ehs.harvard.edu/sites/default/files/laser_safety_manual.pdf (https://www.ehs.harvard.edu/sites/default/files/laser_safety_manual.pdf)
https://www.laserpointersafety.com/ (https://www.laserpointersafety.com/)
Texts on the hardware:
https://www.amazon.com/Laser-Fundamentals-William-T-Silfvast/dp/0521556171 (https://www.amazon.com/Laser-Fundamentals-William-T-Silfvast/dp/0521556171) (Get second edition as shown )
http://www-personal.umich.edu/~andrewcb/DSO/Books/Solid-State%20Lasers%20-%20A%20Graduate%20Text%20-%20%20W.Koechner,%20M.Bass.pdf (http://www-personal.umich.edu/~andrewcb/DSO/Books/Solid-State%20Lasers%20-%20A%20Graduate%20Text%20-%20%20W.Koechner,%20M.Bass.pdf)
https://www.holographyforum.org/data/pdf/aa-Collection_a_k/aa-Laser/Solid-State_Laser_Engineering.pdf (https://www.holographyforum.org/data/pdf/aa-Collection_a_k/aa-Laser/Solid-State_Laser_Engineering.pdf)
https://www.idex-hs.com/resources/resources-detail/cvi-melles-griot-technical-guide (https://www.idex-hs.com/resources/resources-detail/cvi-melles-griot-technical-guide)
https://maritime.org/doc/pdf/opticalman-navedtra-10215.pdf (https://maritime.org/doc/pdf/opticalman-navedtra-10215.pdf)
And Yes Mr. Cone, I do love your zeal for learning. Consider graduate school...
Kind Regards,
Laser "Over 30 years in lasing" Steve
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Coppercone, For your request on nerve wracking observed post burn vision details, check your PMs. Not publishing that one... No eye surgeon has ever found the burn spot, too small. Even when I guided their instrument aiming beam in.
Only way I can explain the exceptional energy density is that the system optics imaged the Gaussian Beam's "Waist" onto my retina. That and that 488 nm blue-cyan is the peak color for Hemoglobin adsorption in the blood. The two meter long optical cavity makes a very, very tight beam. The Photodiode PM section of that ancient system is single point calibrated at 21-22 Watts All Lines Argon, using a Thermopile, , so 20 mW was approximate reading on the low range switch of PM section. It would be anything but accurate, and in current mode, small surges of higher power could happen due to power supply system noise. In 1989 my late teenage eye lenses were exceptional. Argon Lasers have exceptional gain at 488 nm, and in multiline systems, 488 nm usually comes up first as current increases.
The built in PM is for tuning the cavity mirrors and constant light mode regulation, its a solar cell of sorts on a AR coated beam splitter sampler, with a combination of opaque ceramic disks and thin film absorbers in front of the cell to shape it's response vs intensity. We never expected more then +/- 10% accuracy on anything silicon cell back then. Moving my head and the blink reflex certainly reduced the damage, guessing exposure was 100 milliseconds.
Very, very, high quality beam mode, tiny beam size, and very low divergence when idling. Not so at full power. Not too likely to happen at Idle without the relay optics in the beam.
At that power level, its an unlikely case, but hey, inadvertent case of the relay optics for the blanking Galvo being at the right place upstream.
Other tech was a College student with some liberal arts major, system operator, not engineer. LOTO tag probably didn't mean much to him, he was the senior operator/ arrogant / bossy.
To give you the idea of the quality and size of the cavity, I've attached a still shot taken from the web.
One other difficult to learn lesson. NEVER TRUST YOUR EYES FOR LASER SAFETY. Human eyes have an incredible dynamic range, and really, really, are useless at GUESSING laser power outside a range of a say half a milliwatt to around sixty milliwatts if you work with the visible wavelength regularly. They are much, much better at GUESSING wavelengths under some circumstances. With practice, when working on tunable lasers daily, I am usually within +/- 5 nm on low power monochromic light within the range 450 nm to 580 nm. Some of us can see out to 750 nm or longer, which appears deep red. However your eye is so inefficient in the deep red that Watts of 750 nm can look deceptively dim, appearing almost harmless. The actual long limit is apparently genetic. BTDTGTS.
The only true way to measure laser power is with a calibrated laser power meter. You can get close with certain widgets if you have serious skills and a data sheet, but the ONLY true way is with a traceable calibrated PM sensor. Homemade LPMs usually use a Silicon PD, or Backwards TEC with an absorber as thermopile. (Voltnuts, Metrologists, with all due respect, we can have "THAT" LPM calibration argument later. )
Steve
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what if you had two lasers that are connected in parallel with a photocolor sensitive thin film (like glasses for sunlight) in the circuit that is sensitive to one of the lasers. then if the power level increased both lasers would get brighter and the mirror would get disabled? And the only way to run it would be to close one of the lasers off with like a lens cover
but it does assume a laser remains functional
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Also how are those safety glasses made?
Is it safe to buff out small scratches or do they have thin films on them? The cheapo ones I have look like its a car wrap type deal (saran wrap type coating over normal acrylic glasses), which makes them unsuitable for scratch removal.
But like a thor labs one. is it a isotropic material or layered?
no one takes laser safety more seriously then a sardukar
(https://agscollectibles.com/cdn/shop/files/L014407_1.jpg?v=1682686931)
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and for visible light that you might encounter with most lasers unless its red which is boring anyway,
the thorlabs LG10 and LG12 are ok?
LG3 is cheaper but it does not block the infrared rays, which might be present if you are trying to make colors with mixers... so I think that one is out.
They really charge a god damn arm and a leg for the LG12 that have high IR cutoff.
ANd lets say one day you make a yellow laser or whatever thing like that. What should you use for that? A pink lens?
LG15 is the only one I can find. The transfer function looks kinda dodgy. There is no glasses with a brickwall response between say above 500?
I wanna know what to keep my eyes open for deals, assuming I don't want to use chinese shit I can tell that getting all this stuff together at a reasonable price range is going to take a while and be a side project.
ALso what is the best frame? B looks comfortable. B or C I guess, it reminds me of hypertherm plasma cutter goggles. I like those alot the standard frame makes me feel like budget university physics lab. The stock version looks like it might not get stolen by children but B and C are gonna disappear IMO. A looks like it will make you feel uncomfortable with heat. i know I need to make the right decision here because uncomfortable goggles are a good reason why people don't wear eye protection.
Well C look good but realistically I won't be doing laser adjustments under the floor of a C130 darpa plane so I don't think I need the strap. Any input on B?
I can see if your making things that convert color it might get pretty ridiculous with the safety requirements if different colors appear in different parts of the circuit lol
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What you mean with color lasers? That "does not make sense" since for wide spectrum you need fs laser - forget it you do not have money for Alexandrite crystal rod. For tunable lasers you can use Rhodamine 6G - it was used in past, but is highly toxic and you do not work with it; it is usually pumped with second harmonic of Nd:YAG.
If you do not care about transversal mode of the laser you can use laser diodes. If yes, than in visible spectrum is He:Ne (risk to buy old one - sealing of the mirrors usually fail after some time) or Ruby laser (history - it can produce only pulses, never seen one running, only historical laser rods). Most affordable is diode pumped Nd:YAG, in school we have had some setup with standalone rod and we have build an exterior resonance chamber, but such a system is in IR @1064nm.
Easiest and most affordable is to use DPSS Nd:YAG with second harmonic generation (green laser pointers works the same way), but be careful since as was mentioned there is usually no blocking filter for 1064nm nm of Nd:YAG and this light passes directly to the retina in full power. Gas discharge lamp pumped solid state lasers uses high voltage and high power together with active water cooling and have low efficiency - definitely not recommended for beginner. Gas lasers uses high voltage - He:Ne or CO2 are common, but CO2 is 10,6um which is far IR and needs special optics; before fiber lasers and high power laser diodes they were most common lasers for industrial use.
Regarding safety - price of glasses is high and they are certified only for certain wavelengths and power. They are made from solid glass, which blocks the required wavelength. Usually one for "green" are blocking also IR light from Nd:YAG since it is common issue that second generation does not work and you have all power in IR. Forget about interference filters - you can damage them with scratching - they can be used in system, but not as a safety measure.
Corrected the Nd:YAG wavelength - it should be 1064nm |O
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I will repeat. Think deeply. Your suggestion of using paired lasers with one monitored by something like the sun darkening glasses. Have you thought about how long those take to darken? When I was young those used to take minutes, fifty years later it is still many seconds.
Did you understand every sentence of what DavidKo wrote? If not you probably shouldn't be inventing new concepts in laser safety. Lots of homework to do first.
Laser safety goggles are not cheap. How much is your vision worth?
You do have to set your own standards. Maybe you can get by with enough layers of alternate protection. Multiple physical barriers. Multiple power lockouts. Safety glasses are just one layer of protection, not a magical thing that automatically makes your eyes safe.
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You do have to set your own standards. Maybe you can get by with enough layers of alternate protection. Multiple physical barriers. Multiple power lockouts. Safety glasses are just one layer of protection, not a magical thing that automatically makes your eyes safe.
And I completely forgot to mention that laser beam of Class > 2 can be dangerous even at diffuse reflection - for example looking at the beam on the wall, light reflected from previously ablated surface etc. Beam stoppers are not easy to create when we start to speak about high power. Every surface (nothing is black body) have Fresnel reflection - ordinary glass reflects cca 4% of light on each surface for perpendicular beam. Bigger the incident angle bigger the reflection.
@coppercone2 The Thorlabs glasses are good for laser pointers. Real safety glasses need to be enclosed like the one for brazing. No light should get inside. Something like this (https://www.laser2000.com/fr/fr/lunettes-pour-la-securite-laser/1564-laser-safety-goggle-180-532-1064-nm--glass-filter.html). Expected cost will be in thousands of EUR/USD because such a lasers should be working enclosed with lockouts as mentioned by CatalinaWOW. Opened laser systems are used only in scientific applications.
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Thorlabs glasses are common in most labs in the US. Especially in the comfort style and the "modern goggle style. Both of which are certified.
While full wrap-around is still available, it is rare these days. I've used Thorlabs glasses in some very high power labs, you just need to match the energy ratings to the need. Philips Laser Safety is an alternative.
Plastic lenses with testing and certification have made huge progress in the last ten years.
What is scary is some of the cheap E-Bay glasses, I've tested more then one model to find it rated OD6 yet have 90% transmission at the designated wavelength.
Steve
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I can put that on the class VIII nuclear chemical laser roadmap. Unlike the Czech republic, I am not building a death star.
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At one time, in early history, there was a CLASS V classification.
Having had the privilege of working on some still manufactured "Eastern Block" very fast single pulse lasers, I can assure you, the Eastern Block not having a Death Star was not for the lack of trying. I won't mock them with comments ending in "Ski" as the old senior scientist I met was a wonderful teacher, knowing hands on skills as well as having the equal to two western PhDs in physics and quantum mechanics. It was highly educational to have thirty minutes with him on a manufacturing floor in his new job. Sadly from a modern point of view, and thankfully from a lets not make War point of view, they never quite had the ability to make some high speed widgets the Western Block did. That hampered implementation. They certainly knew what they needed, but weren't there yet. One of the work arounds for creating short pulses, was incredibly well developed, simple, now exported, and fun to use in lab situations. I have privilege of the visiting the plant for a past employer. It's now in a NATO block country.
Steve
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Maybe somewhere are still Nd:Glass rods (glass was easier to produce in big blocks compared to Nd:YAG monocrystals) which was intended to be used for death star configuration :D. They have moved them a lot without making the final laser, but in the mean time Czech Academy of Sciences get the chemical Asterix laser from Germany. We had been in Eastern block, who had one of the firsts Ruby lasers. It was incredible story how the professor smuggled one rod from US conference in his shirt breast pocket and the beginning of lasers in former Czechoslovakia. With diode pumped lasers everything had changed. The high power lasers are now easier to build and have significantly better efficiency compared to ~0.5% with discharge lamps pumped lasers and low voltage required - the biggest thing was how to deliver kV high current pulse with short ramp to the lamps. Transmission lines was used to deliver energy and switching was done by thyratrons and on some lectures were mentioned even krytrons. Second issue was how to cool such a systems due the inefficiency - Nd:Glass lasers had easily overheated and it seems that chemical lasers are the right way. In industry the fiber lasers are replacing the CO2 lasers.
Some people which had worked on LAGEOS project had holes in their retina. Never had heard what had happened in clear words (it happened at our station in Helwan, Egypt). It was somehow "classified" and people did not want to speak about it. Similar was the info regarding first person in Czechoslovakia which had received cataract treatment with Ruby laser in Soviet union (he knew personally the person doing that, laser community was small in that time) - it had hurt since it was only Q-switching.
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how is a HP current source power supply for laser diodes?
I don't mean a PSU used as Current source, I mean a "current source"
I think their mad well built. Its like a harrison supply got put through star fleet boot camp
I just need to hook up a oscilloscope on very fast time base to see what happens during power up on various loads right? maybe some power LED to simulate the laser transfer function etc
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For laser drivers is most important not to overshoot the current. The laser diodes do not like it.
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Well I got the Thorlabs UV glasses.
I can see more and they block way more then the China glasses. And the are 10x more comfortable.
I see if you wanna work with a laser correctly, you should get band specific goggles for the frequency you are working with.My suggestion is to take it slow, save money and buy the optimum safety equipment. Seeing more makes the work more enjoyable and pleasant also. As usual, trying to be frugal ends up making you feel like the victim of a joke.
same as butter knives, you don't wanna be using the plastic butter knife from macdonalds to make toast.
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Well I got the Thorlabs UV glasses.
I can see more and they block way more then the China glasses. And the are 10x more comfortable.
I see if you wanna work with a laser correctly, you should get band specific goggles for the frequency you are working with.My suggestion is to take it slow, save money and buy the optimum safety equipment. Seeing more makes the work more enjoyable and pleasant also. As usual, trying to be frugal ends up making you feel like the victim of a joke.
same as butter knives, you don't wanna be using the plastic butter knife from macdonalds to make toast.
Once more proving the universal truth. Labor can be substituted for capital, but sometimes the amount of labor is astonishing and/or unbearable. The right equipment makes any job easier and safer. The other thing that has been demonstrated here is that the limits on capital are always fuzzy.
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You might like looking at back issues of Laser Focus magazine. Lots of lab setups shown. When you see something that looks similar to what you think you need, it's usually not hard to figure out the specifics.
https://www.laserfocusworld.com/magazine (https://www.laserfocusworld.com/magazine)
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i guess its one reason to keep dragging your ass to work
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OK i got some collimator lens and a diode mount that sits diodes in a place where I can attach a little heat exchanger to them do temperature control for experiments (copper)
the prices are not people friendly (and fuck europe shipping!!!), but getting the emitter section and safety right, lets me allow for messing around with the subsequent optics, hopefully at a much lower cost. (adjust prisms, mirrors, screens, etc), hopefully maybe with some scavanged and DIY stuff. I have a bad feeling about the cheap chinese mounts and optics, as simple as it seems. at least the first stage will be quality and I can maybe identify or qualify subsequent parts if I have confidence about the first part
Building your own laser diode mount seems akin to building your own power supply chassis, which is a bit much for beginners. I hope the thermal contact surfaces will be good and that it mounts well and is more stable then something I can put together myself, that I will not need to fight with a tapered, oval or otherwise messed up bore for mounting diodes. That will probobly end with buying a special reamer and lapping tools lol :(
I can also do some testing on the electrical supply and hookup method with cheap diodes before I start getting optical system elements. I want to standardize the electrical hookup in my own way
also trade the steak for a baked potato to pay this expensive ass shit off. glad i did not throw away that old potato, its actually fine to eat. and I spent the entire week sharpening damaged ass kitchen knives so I don't buy that new set I was planing on