EEVblog 1412 - Argon Ion Laser TEARDOWN - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: August 05, 2021, 02:05:26 pm
content: Dave tears down the 10W Coherent 300C Argon Ion laser. All 42kg, 1.2m and 24kW worth!

author: alxpo
author_rank: Contributor
timestamp: August 05, 2021, 07:46:16 pm
content: The cylindrical side appendage could be a gas reservoir to replenish the argon lost through entrapment in the walls of the discharge tube by sputtering (not a photodiode).

author: djacobow
author_rank: Super Contributor
timestamp: August 05, 2021, 08:58:59 pm
content: 80C196KB! Nice to see it in a product. '196 was the first chip series I ever worked on. First job out of college at Intel in Chandler, AZ.

author: EEVblog
author_rank: Unknown
timestamp: August 06, 2021, 08:02:13 am
content: Quote from: alxpo on August 05, 2021, 07:46:16 pmYes, someone in the youtube comments said the same thing. Seems plausible.The power output sensor is on the front as I showed. Shot that bit afterwards, forgot to correct.

author: EEVblog
author_rank: Unknown
timestamp: August 06, 2021, 08:02:44 am
content: Quote from: djacobow on August 05, 2021, 08:58:59 pmQuite common in industrial stuff.

author: CJay
author_rank: Super Contributor
timestamp: August 06, 2021, 10:18:54 am
content: Quote from: EEVblog on August 06, 2021, 08:02:44 amAlso in Automotive, I *think* the Ford EEC ECUs used a variant of it.

author: Kareem
author_rank: Newbie
timestamp: August 07, 2021, 12:27:33 am
content: The "lens" you held at 25:35 may not be the output mirror. Hear me out.What you described in the video is a basic Fabry-Perot resonance cavity. These things are insanely sensitive to the distance between the mirrors, which leads me to believe that the 1% transmissive mirror is fixed within the black casing.Now, I have three hypotheses as to what the thing you were holding is:1- Wavelength filter (basically a band-pass filter for optical signals).2- Waveplate (a piece of glass that have different refractive indices along its x-axis and y-axis). These, with a combination of other optical components, are sometimes used as optical isolators that prevent unwanted back reflections.3- The actual acousto-optic modulator, which means that the two perpendicular barrels are piezo-electric transducers.Of course I could be wrong in all fronts, but I think if hypothesis 3 is correct, you could do a few fun optical experiments.Love the channel, been a long term viewer.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 07, 2021, 06:37:11 am
content: The 99.x% refelctive mirror may not look like a mirror as it only should mainly reflect the blue light. Other light should come out of the cavity or at least attenuated more. The mirror is more like an interference filter made from multiple layer on the glass. So it is wavelength filter and mirror in 1 piece. In some sense like Fabry-Perrot resonator, but only very short ( 1 wavelength ).For a fixed wavelegth there is no need for a fancy acousto-optic modulator.The facy looking metal bellow is likely just for dust protection and also to catch the beam in case something goes wrong. Just plastics may melt from the laser power.

author: Kareem
author_rank: Newbie
timestamp: August 07, 2021, 06:50:53 am
content: Quote from: Kleinstein on August 07, 2021, 06:37:11 amI thought I heard Dave mention that this model has an acousto-optic modulator. I could be mistaken.Quote from: Kleinstein on August 07, 2021, 06:37:11 amLike a Bragg-Grating? I think you're right. Fabry-Perot lasers typically have poor spectral purity as far as I know.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 07, 2021, 08:50:52 am
content: A Bragg-Grating seems to be right name for the refelctor. The wavelength selective mirror is only for the corase range, Ar lasers have multiple wavelengths (AFAIR yellow and green besides the main blue line). There are still mutiple longitudinal modes, but for just illumination this is OK. It would be somerthing different for things like Raman scattering and the like. This may want extra measures.

author: djacobow
author_rank: Super Contributor
timestamp: August 18, 2021, 01:22:05 am
content: Quote from: CJay on August 06, 2021, 10:18:54 amGood to know. At the time, this would have been early 90's, I seem to remember our main market was Western Digital hard drives.

author: james_s
author_rank: Super Contributor
timestamp: August 18, 2021, 05:25:59 am
content: Quote from: alxpo on August 05, 2021, 07:46:16 pmIIRC that's exactly what it is.Sam Goldwasser would know for sure, I don't think he's on this forum but his laser FAQ is easy to find. I'm pretty sure we have at least one member here with experience rebuilding ion lasers. Those were the holy grail of laser enthusiasts for many years, prior to high power diode lasers appearing about 10 years ago, 1W+ of visible laser light meant in most cases a large frame ion laser.I still have a small aircooled argon ion laser that I fire up now and then.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 18, 2021, 02:10:52 pm
content: replenishing the argon and helium gas is usually not that important. The more problematic part with the gas is keeping contraminations low. So the extra part is likely more like a getter to catch any oxigen or water that for some reason diffused out of some walls or holes. The tube should be seal good enough to avoid loosing much of the wanted gas, but it only take a relatively small amount of the wrong gases to cause problems.

author: james_s
author_rank: Super Contributor
timestamp: August 19, 2021, 01:51:42 am
content: In case anyone has not seen it, this was for many years the definitive source of hobbyist information on ion lasers.https://www.repairfaq.org/sam/laserarg.htm#argtswAnd lasers in general.https://www.repairfaq.org/sam/laserfaq.htm#faqtoc