My friend was the co-founder of Omnichrome. The company was based out of southern California. The lasers were good for about 5,000 hours of use. He told me that there was good profits in servicing laser tubes as the cadmium eventually gets depleted. They didn't want them to last too long. Also, Omnichrome made a shorter wavelength version of this laser for UV curing epoxy for the first stereolithography machines.
Yeah, I actually own one of these that is dual wavelength. these were not cheap lasers. there’s a reason that they were only around for a period of time. Once solid state came out, they were very quickly replaced-one of the first gas lasers to go. These things were always temperamental. Also a minor correction-the cadmium remelt was not to remove cadmium from places where it shouldn’t be. it was to remove dendrites that would form on the cathode end of the laser where it re-condensed. I actually have one of the very last ones that was produced and was never completed. The glasswork is a work of art in itself.
The helium reservoir on the ones I’ve seen has a membrane that has increasing helium permeability as it’s temperature is increased. The heat sink band stops the heat conduction along the glass, so that the helium leakage is near zero. Incidentally, if a laser has been sitting too long, the helium pressure may be too high to achieve lasting until the tube has been run for possibly as much as 100-200 hours. And for the benefit of anyone who hasn’t already read a service manual on a helium cadmium laser, the discharge current is typically 100mA or more DC, with significant amounts of capacitance in the power supply. Accidents are likely somewhere between extremely painful and potentially deadly, from muscle contractions or heart stoppage. If you’re really lucky, you’ll only realize your heart stopped when it starts beating again and you just used up one of your nine lives. Or maybe that’s just what happens when voltage jumps without a direct contact with a HV lead.
Fascinating! I've never worked with optics but recently got to see some operating optical clocks. Have you ever thought of doing a teardown and demo of an atomic clock? Watching the PLL lock in a rubidium module might be interesting.
There isn't much to see, unfortunately - the transmission difference on the Rb cell at resonance is very small, which is why you have to modulate it and use a lock-in amplifier to detect it.
This might have been the first time I've heard emission line spectra described as "tones". But I get it! I have a H-𝛼 emission line filter in the filter wheel of my CCD camera I use for astrophotography. It produces some very nice images of emission nebula. Turns out there's a lot of hot hydrogen in the Universe!
Definitely like the variety of vids! As usual you show way more of the workings of these pieces of equipment than other channels, that makes it always interesting to watch.
I got into lasers on a hobby level with some HeNe tubes and not much later with an Argon Ion head and homemade power supply. But those transparent "glass" tube laser are always much nicer to watch ;)
Helium/Cadmium? Never heard before - thanks! Once upon a time I got a HeNe laser for measuring the angle of a worn out steel blade used in making soft tissue in a paper machine. The blade was about 1 mm in thickness and the edge was worn an polished maybe 0.1 to 0.3 mm size. The laser had 1.5 mm beam, so some of the beam passed on eatch side of the blade, when aligned. At that orientation the worn surface reflected light at an angle, which I calculated by arctan function from the dot on a graph paper. The reason for my angle measurements was that also the machine slightly barrel shaped cylinder wore out unevenly and the blade wear angle variation along the nearly 5 meter length of the blade gave a map of the cylinder wear. Some time later my boss got new glasses, which he found some way wrong. He suspected a mistake in the pupil distance and asked if I could somehow measure it from the lenses. He knew what his pupil distance had been "for ever". I found that both 18:41 the glass surfaces produced a reflection and they matched, and also reflected back to the laser aperture only when at the desired pupil spots. Marking them with ink, it was easy to to measure the distance and confirm his suspicion. He went back to the optician, who was surprised that the distance had been correctly measured without an optician's tool. A "feather to my hat". Some time later I was involved with a test whether the paper dryness could be measured in line with an experimental Water Vapor laser. Despite a good theory, the desired 5 meter distance quickly turned beyond reach. Our test setup was only about 1 meter and already was too challenging. At the time there were commercial infrared based paper web moisture measuring devices, but they required complex mechanisms on two sides of the paper web, source and receiver traveling in a synchronized way. Consequently, they were deemed too cumbersome in use, and also too expensive. That is why the idea of a water vapor laser was tried.
I have loved lasers since we got to experiment with a very low power HeNe laser when I was in 8th grade (a VERY long time ago). That looks like a very capable spectrometer. I have always been fascinated by how 19th century scientists doing some fairly crude spectroscopy produced results that led us to understand so much about the structure of the atom and, on a different branch of the scientific tree, to the beginnings of quantum mechanics. I encourage you to explore more fundamental science topics!
Are those cadmium deposits on the working laser inside of the tube meant to be there or was that due to improper shutdown sequence? and how do you know if hasn't negatively affected the mirror on the front of the laser tube?
I remember working with helium cadmium lasers back in the 1970s at Intec corporation. We used them to test certain types of photographic film without exposing the film.
I think the connectors are MIL-DTL-5015. On the back of the case, the left most connector looks like insert 22-20, the middle one is 24-5, and the last one is 24-22. Maybe. Is the keying rotated? You can get MIL-DTL-5015 connectors on Mouser, though for whatever reason the pictures of circular connectors are always wrong.
great -- very interesting video again, never saw a he cd laser in action. I use laser in my profession usually semiconductor, also for spectrum analysis, I have a helium neon laser for experiments and reference -- @the signal path : which spectrometer have you used ? - I myself have a thorlab spectrometer CCS200 (200nm-1000nm) your seem to have a larger range !
Thanks for another good and informative video! Those Omron hour counters lose their count when the internal battery dies, so they're not always accurate.
Incredibly cool laser and a great explenation. Could you maybe do a breakdown of the power supply? It would be interesting to see how all the current regulation and the controls work.
It would be nice if you could disassemble the broken unit. I'm very interested how the helium storage and release mechanism is looking / working. First time seeing something like that for a nobel gas.
@@Gameboygenius You normally work at a place where there is a lot of high tech companies around you or in the same building where all the companies throw their things at one place where you have access to, and that was (is?) the case with Dave. I don't know where he in the video is (forgot your name) but its no doubt not in the middle of nowhere but high tech companies in the close vicinity or building is my guess where he has access to any dumpster room.
These lasers are extremely tricky to operate. Each laser head has to married with the power supply. To retune a head to a new power supply you have to run it to heat up properly and then adjust the the cadmium and helium heater to get the correct pressure and gas mix. The filaments burning out are usually due to a current regulation fault in the power supply. ❤
It threw me off at first seeing the laser spot through the goggles with a rated attenuation of 10^9 at the wavelength being emitted. I'd guess the light seen is not the emitted ~400nm light but instead longer wavelengths generated by fluorescence of the paper.
I have a question, when you examine the incoherent light in the chamber with the spectrometer what you see are the spectra lines of helium or you see also spectra lines of cadmium?
@@Thesignalpath If it is exposed, glassblowing is not that specialized. Though it is a very manual process, and the cadmium is nasty. Plus cleaning/ovenizing and refilling, probably best done befor ethe cadmium is everywhere like it is now.
Near the start of this video you say that “if you only were to use helium and make a helium laser, you would get wavelengths at 632 nm or so which depends on the helium atomic structure.” I think that the 632 nm wavelength is associated with a helium-neon laser. The light from a He-Ne laser is from some of the neon atoms that radiate at 632 nm. The light is from neon not helium.
@@Thesignalpath Laser gain media have special properties. Even more so if one wants some modicum of efficiency. One needs an easy pumping transition, then a quick relaxation to an excited relatively stable level that is not much lower. Stable, so only stimulated emission occurs and no spontaneous. Then, after that stimulated emission, the energy level should drop again quickly and spontaneously. Otherwise, the atom that just "cooled down" would absorb laser light again to get excited. So no, one cannot just use any transmission line in a laser. (Note that these transitions/levels are also achieved through gas mixtures, AFAIR. The levels do not need to be in a single atom.)
Very neat! We have a coherent source of light lasing at a specific wavelength. What is this light source used for exactly in it’s time period? I’ve heard of lasers dubbed as a solution looking for a problem…what applications does this particular unit used for?
@@NiHaoMike64 Yes, but from what I understand the multiple lines of a HeCd laser are advantageous for exciting fluorescence in different biological molecules.
Not a fan of HeCd lasers... which were developed over 50 years ago. You can see by looking at it: they're very expensive. Supposedly Melles Griot still produces them (or at least sells them)... and some old photolith processes need them. I think newer, more robust, and affordable technologies have almost completely replaced them.
I've watched like 1 minute of the video and I'm guessing it's a helium laser that fires up and heats the cadmium enough to get that part of the process started... probably not...but am I close even?
![[DRAGON BALL LEGENDS REVEALS ＆ STUFF] LEGENDS FESTIVAL 2024 Special Edition Part 1](http://i.ytimg.com/vi/mV5bGIswTtQ/mqdefault.jpg)
Another step on the long road to Signal Path lithography. We know what the chip logo will be.
Pooch, definitely
Bug Report: FLUKE 233 magical multimeter is clipping through objects again.
I thought it was a recording from a 2. camera that he overlaid... until he touched in the the second scene...
My friend was the co-founder of Omnichrome. The company was based out of southern California. The lasers were good for about 5,000 hours of use. He told me that there was good profits in servicing laser tubes as the cadmium eventually gets depleted. They didn't want them to last too long. Also, Omnichrome made a shorter wavelength version of this laser for UV curing epoxy for the first stereolithography machines.
Nice!
Yeah, I actually own one of these that is dual wavelength. these were not cheap lasers. there’s a reason that they were only around for a period of time. Once solid state came out, they were very quickly replaced-one of the first gas lasers to go. These things were always temperamental. Also a minor correction-the cadmium remelt was not to remove cadmium from places where it shouldn’t be. it was to remove dendrites that would form on the cathode end of the laser where it re-condensed. I actually have one of the very last ones that was produced and was never completed. The glasswork is a work of art in itself.
@@r100curtaincall, good info! Thanks for the u0pdate, Jay
14:16 The sudden horror of a decapitated multimeter head never fails to appall!
Thanks for still doing these vids they are often far too advanced for me but your delivery makes me understand a little more each time. Keep it up!
The helium reservoir on the ones I’ve seen has a membrane that has increasing helium permeability as it’s temperature is increased. The heat sink band stops the heat conduction along the glass, so that the helium leakage is near zero.
Incidentally, if a laser has been sitting too long, the helium pressure may be too high to achieve lasting until the tube has been run for possibly as much as 100-200 hours.
And for the benefit of anyone who hasn’t already read a service manual on a helium cadmium laser, the discharge current is typically 100mA or more DC, with significant amounts of capacitance in the power supply. Accidents are likely somewhere between extremely painful and potentially deadly, from muscle contractions or heart stoppage. If you’re really lucky, you’ll only realize your heart stopped when it starts beating again and you just used up one of your nine lives. Or maybe that’s just what happens when voltage jumps without a direct contact with a HV lead.
Fascinating! I've never worked with optics but recently got to see some operating optical clocks. Have you ever thought of doing a teardown and demo of an atomic clock? Watching the PLL lock in a rubidium module might be interesting.
i'm pretty sure he did a bunch of videos about rubidium timing modules 5-6 years ago!
There isn't much to see, unfortunately - the transmission difference on the Rb cell at resonance is very small, which is why you have to modulate it and use a lock-in amplifier to detect it.
This might have been the first time I've heard emission line spectra described as "tones". But I get it! I have a H-𝛼 emission line filter in the filter wheel of my CCD camera I use for astrophotography. It produces some very nice images of emission nebula. Turns out there's a lot of hot hydrogen in the Universe!
Beautiful! I have seen a couple of these pop up en eBay, but minus the power supply. So nice to see one up and running!
Great addition to the channel. From microwave to nanowave!
DC to Daylight
Very cool indeed. It reminds me my studies and specifically the lab time we spent building a HeNe laser "from scratch".
Definitely like the variety of vids! As usual you show way more of the workings of these pieces of equipment than other channels, that makes it always interesting to watch.
I got into lasers on a hobby level with some HeNe tubes and not much later with an Argon Ion head and homemade power supply. But those transparent "glass" tube laser are always much nicer to watch ;)
Helium/Cadmium? Never heard before - thanks! Once upon a time I got a HeNe laser for measuring the angle of a worn out steel blade used in making soft tissue in a paper machine. The blade was about 1 mm in thickness and the edge was worn an polished maybe 0.1 to 0.3 mm size.
The laser had 1.5 mm beam, so some of the beam passed on eatch side of the blade, when aligned. At that orientation the worn surface reflected light at an angle, which I calculated by arctan function from the dot on a graph paper. The reason for my angle measurements was that also the machine slightly barrel shaped cylinder wore out unevenly and the blade wear angle variation along the nearly 5 meter length of the blade gave a map of the cylinder wear.
Some time later my boss got new glasses, which he found some way wrong. He suspected a mistake in the pupil distance and asked if I could somehow measure it from the lenses. He knew what his pupil distance had been "for ever". I found that both 18:41 the glass surfaces produced a reflection and they matched, and also reflected back to the laser aperture only when at the desired pupil spots. Marking them with ink, it was easy to to measure the distance and confirm his suspicion. He went back to the optician, who was surprised that the distance had been correctly measured without an optician's tool. A "feather to my hat".
Some time later I was involved with a test whether the paper dryness could be measured in line with an experimental Water Vapor laser. Despite a good theory, the desired 5 meter distance quickly turned beyond reach. Our test setup was only about 1 meter and already was too challenging. At the time there were commercial infrared based paper web moisture measuring devices, but they required complex mechanisms on two sides of the paper web, source and receiver traveling in a synchronized way. Consequently, they were deemed too cumbersome in use, and also too expensive. That is why the idea of a water vapor laser was tried.
Thank you, this is fascinating!
Love it! I've been reading a few books on laser physics so this came at a perfect time.
I would love to see more laser and optics videos!
Curious as to what the Optical Power output of the Laser is?
Gotta love seeing the spectral pairs.
I have loved lasers since we got to experiment with a very low power HeNe laser when I was in 8th grade (a VERY long time ago). That looks like a very capable spectrometer. I have always been fascinated by how 19th century scientists doing some fairly crude spectroscopy produced results that led us to understand so much about the structure of the atom and, on a different branch of the scientific tree, to the beginnings of quantum mechanics. I encourage you to explore more fundamental science topics!
It was very crude indeed, not much different from what Newton did with his prism.
Big burney lasers always get my attention, never seen this type before. Big Thumbs Up 👍👍
Are those cadmium deposits on the working laser inside of the tube meant to be there or was that due to improper shutdown sequence? and how do you know if hasn't negatively affected the mirror on the front of the laser tube?
I don’t think it affects anything as it is not on the mirrors.
I remember working with helium cadmium lasers back in the 1970s at Intec corporation. We used them to test certain types of photographic film without exposing the film.
Another incredible breath of knowledge with a side of nerdgasm 🍻
Very illuminating!
Would be nice to follow-up with a measurement of the narrowband laser spectrum and the coherence length of the laser..
What a beautiful machine, thank you
Nice!
Really enjoyed this one!
Very cool and unusual laser, thanks for sharing it with us!
Amazing!
I think the connectors are MIL-DTL-5015. On the back of the case, the left most connector looks like insert 22-20, the middle one is 24-5, and the last one is 24-22. Maybe. Is the keying rotated?
You can get MIL-DTL-5015 connectors on Mouser, though for whatever reason the pictures of circular connectors are always wrong.
great -- very interesting video again, never saw a he cd laser in action. I use laser in my profession usually semiconductor, also for spectrum analysis, I have a helium neon laser for experiments and reference -- @the signal path : which spectrometer have you used ? - I myself have a thorlab spectrometer CCS200 (200nm-1000nm) your seem to have a larger range !
Awesome work many thanks 🙏🏼
The three metal rods that form the structure are made of a highly specialized alloy with extremally low thermal expansion.
Thank you
Thanks for another good and informative video! Those Omron hour counters lose their count when the internal battery dies, so they're not always accurate.
Awesome topic !....cheers.
Thats a heck of a laser pointer to keep your cat entertained!!☺☺😎
Incredibly cool laser and a great explenation.
Could you maybe do a breakdown of the power supply? It would be interesting to see how all the current regulation and the controls work.
Great Video Thanks.
Had a rodenstock laser lens calibration machine back then from the scrapyard, luckily it tripped the breaker before anything worse happened.. ^^
Love this video, more lasers please!!!
Just brilliant.
It would be nice if you could disassemble the broken unit. I'm very interested how the helium storage and release mechanism is looking / working. First time seeing something like that for a nobel gas.
No please don't poison yourself with cadmium(!)
@@MarkTillotson I asked to disassemble the tube, not to eat it. :v
0:33 "dumpster find", yea your dumpster is not the same as mine.. for sure.
Dave's (EEVBlog's) dumpster room also has a bunch of good stuff all the time. How do they do it?
@@Gameboygenius You normally work at a place where there is a lot of high tech companies around you or in the same building where all the companies throw their things at one place where you have access to, and that was (is?) the case with Dave. I don't know where he in the video is (forgot your name) but its no doubt not in the middle of nowhere but high tech companies in the close vicinity or building is my guess where he has access to any dumpster room.
@@Gameboygenius Dave finds it (or is given it) first, and it's a "dumpster find." Some people believe 'reality T.V." too.
@@dtiydror, ya' know, he bought it off ebay
I might have missed it, but what's the rated input and output power of this unit?
It is rated for up to 60mW optical output power.
That is gorgeous all right. Was it out of something or is it some sort of lab optical source?
These lasers are extremely tricky to operate. Each laser head has to married with the power supply. To retune a head to a new power supply you have to run it to heat up properly and then adjust the the cadmium and helium heater to get the correct pressure and gas mix. The filaments burning out are usually due to a current regulation fault in the power supply. ❤
@TheSignalPath i completely agree, never take lasers lightly, darkly yes but not lightly. 😉
It threw me off at first seeing the laser spot through the goggles with a rated attenuation of 10^9 at the wavelength being emitted. I'd guess the light seen is not the emitted ~400nm light but instead longer wavelengths generated by fluorescence of the paper.
Im firing with my lazooor! Nice video!
Please use some polarizing lens to demonstrate Bell's theorem.
Do you have any thoughts on optical transconductance varistors and their applicability to microwave transmitters?
Really enjoy these photonics videos. 🤌
Hi. What spectrometer are you using?
Wowsers what dumpster are you looking through?
Could you make video on phase array radar too ?
I have a question, when you examine the incoherent light in the chamber with the spectrometer what you see are the spectra lines of helium or you see also spectra lines of cadmium?
I mostly saw the lines of He.
That was fun.
I see people repairing CRTs from vintage TVs. Maybe there is hope for the broken laser. Although cadmium isn't exactly friendly to play with.
With the filament broken, I am not sure if it can be repaired.
@@Thesignalpath If it is exposed, glassblowing is not that specialized. Though it is a very manual process, and the cadmium is nasty. Plus cleaning/ovenizing and refilling, probably best done befor ethe cadmium is everywhere like it is now.
Near the start of this video you say that “if you only were to use helium and make a helium laser, you would get wavelengths at 632 nm or so which depends on the helium atomic structure.” I think that the 632 nm wavelength is associated with a helium-neon laser. The light from a He-Ne laser is from some of the neon atoms that radiate at 632 nm. The light is from neon not helium.
Yes, He by itself is not a best gain medium and is often mixed with something else. What I meant to say was the common HeNe laser.
@@Thesignalpath Laser gain media have special properties. Even more so if one wants some modicum of efficiency.
One needs an easy pumping transition, then a quick relaxation to an excited relatively stable level that is not much lower. Stable, so only stimulated emission occurs and no spontaneous.
Then, after that stimulated emission, the energy level should drop again quickly and spontaneously. Otherwise, the atom that just "cooled down" would absorb laser light again to get excited.
So no, one cannot just use any transmission line in a laser. (Note that these transitions/levels are also achieved through gas mixtures, AFAIR. The levels do not need to be in a single atom.)
FIX MOAR TEST EQUIPMENT!!! J/k - this is really interesting.
Very neat! We have a coherent source of light lasing at a specific wavelength. What is this light source used for exactly in it’s time period? I’ve heard of lasers dubbed as a solution looking for a problem…what applications does this particular unit used for?
So what are these lasers used for ?
Is the helium or cadmium being consumed when the laser is operating?
No, the system is closed. There will be small losses over time. Nothing is perfectly contained.
What were these lasers used for?
Laser fluorescence, primarily in confocal microscopy, where they are still in use today.
@@douro20 Have they been replaced with 445nm diode lasers which nowadays are very common?
@@NiHaoMike64 Yes, but from what I understand the multiple lines of a HeCd laser are advantageous for exciting fluorescence in different biological molecules.
@@douro20 Ah, interesting, thanks!
@@douro20 At 16:16, there is only one line. Or did I misunderstand your sentence?
As Spock would say…..fascinating 🧐
Can the glass experience a catastrophic failure?
If it is met with a hammer, I suppose.
I had a friend of mine who got killed at home by stepping on a laser cable part of his home laser setup - he was in his 20ies.
he because the lasing medium
So what makes cd go its own place?
The cavity size of the laser.
@@Thesignalpath how , why not it deposit on glass !!
Where is the the rest body of the multimeter ? :D
it was a bad meter and had it's head chopped off!
The reason you can see the spot with the OD9 goggles is because of the fluorescence wavelengths.
I think so!
I would've thought that laser was much older than 1996.
Brilliant, thanks 👍
Not a fan of HeCd lasers... which were developed over 50 years ago. You can see by looking at it: they're very expensive. Supposedly Melles Griot still produces them (or at least sells them)... and some old photolith processes need them. I think newer, more robust, and affordable technologies have almost completely replaced them.
👍🙏❤
LED luminous coating produces visible light and semiconductor produce UV
I've watched like 1 minute of the video and I'm guessing it's a helium laser that fires up and heats the cadmium enough to get that part of the process started... probably not...but am I close even?