Newbie Q: Helium Neon?

[sysadmn]

With <5mW laser diodes under a dollar, is there any point in paying $50 for a HeNe in the <10mW range? As I see it, the only benefit is that you get to play with a different technology, and it looks Buck Rogerish. The drawbacks are high kV, lack of portability, and unknown tube life and quality.

These things were all the rage back when I was in High School (not long after dirt was invented), but it seems that for the experimenter, solid state is the way to go.

In particular, reasonable Melles Griot HeNe seem to be available on eBay for ~$50 from private sellers. (Salvage and industrial suppliers want $150-200!). Some sellers claim HeNe looks better or brighter. Even though I know people would not say things that are not true just to sell you something , I'm skeptical. How much apparent difference is there from a well-collimated <5mW at 632.8 nm versus a good quality laser diode at 650-680?

- Edit: Formatting & Apologies if this is off-topic. There are some pretty knowledgeable people posting here!

 

[jkaiser3000]

A He-Ne for just 50$ seems strange, probably only the tube, with no power supply, or probably a laser with lots of time on it. In either case, these lasers are interesting to play with, if you feel inclined to. They do seem brighter than similarly powered diodes, as 632nm is brighter to our eyes than 650nm. I have a ~1mw He-Ne that looks as bright as a 660nm, 5mw laser. The beam looks different as well, as it does have a true TEMoo, gaussian profile (very pretty :naughty. Also, generally speaking, the divergence is similar between the gas lasers and solid state ones. However, shorter tubes (less power) tend to have a slightly higher divergence that longer ones.

However, there are drawbacks to this technology, as you stated. Not portable, low power (for cheaper models), high voltage, gas filled, and delicate tubes, etc.

If you like lasers, and like to play with the beam, then you'll appreciate the He-Ne. If you just want to mess with solid state lasers, then the gas lasers will probably not be fun for you. In the end, it's up to you to decide

 

[The_LED_Museum]

HeNe lasers were the cat's meow when I was in school - though unless you're doing holography, diode lasers might be the better option for you.

The reasons why HeNe lasers are less convenient were already explained (not portable (except for some very low power units), generally lower output power levels (less expensive models anyway), high voltage (ouch!!!), fragile glass tubes, etc.).

 

[SenKat]

BUT - EVERY Laser Enthusiast MUST have at least one of them for their collection !

 

[The_LED_Museum]

I have several of these little rascals; in addition to the 60-some-odd other lasers (mostly directly-injected diode and DPSS) lasers in my arsenal. :thumbsup:

 

[SenKat]

VERY sweet - i only have one (637nm)- I picked it up for $40.00 with a power supply from Fleabay Looks really nice and bright though !

I love it though - so "elegant" I guess is a great way to put it - my Dad was stunned - he was telling me about the costs of them YEARS ago....some are still up there, but no-where near what they used to be ! Good for us collectors !

 

[The_LED_Museum]

When I was 12 or 13, I got a Metrologic ML-800 HeNe laser.
It had all of 0.5mW output power (it was labelled as "BRH Class II"), but I had fun shining it at a mirror loosely taped to a speaker cone and playing Pink Floyd "The Wall", and making it "portable" by powering it with some D cells and a motorised inverter.

 

[kf4zht]

I have a 5mw red MG laser I picked up at a hamfest for $20, with a power supply that requires 12v, and a right angle adapter on the front.

It is cool, and projects a very good looking beam/dot, I mostly use it to sit on the shelf in the shop and make people wonder what I do in there... I did make a cord to run it off the cigarette lighter in my car

 

[ted_park]

There are certain advantages to hene lasers.
1) They are much less prone to mode hopping problems - the coherence length isn't as great as for properly set up diode lasers, but once they are settled, you can pretty much count on the wavelength not hopping.
2) beam is pretty much gaussian, not some weird elliptical shape.

3) wavelength is quite visible - 635nm diodes tend to hop a lot, and the more reliable 650nm diodes aren't as visible, and the plates I use tend not to be as sensitive to that wavelength.

--Ted

 

[The_LED_Museum]

There's a Metrologic Neon Laser on Ebay, but it has now gone over what I can afford...so if anybody else wants a crack at it, be my guest.

 

[sysadmn]

Decisions, Decisions... Sounds like it's worth $50 - $100 to find out. As The_LED_Museum guy pointed out, this was THE thing for lasers for a long time. The HeNe we used in high school physics was about the cheapest available, and sold for about the equivalent of $1000 today. I do recall the dot looking prettier than even nice red laser pointers, but thought that was Good Old Days syndrome kicking in.

My hobby budget has to recover from an upcoming trip to Mendelsohn's and Dayton (Hamvention). I'll watch eBay to learn the market til then.

 

[The_LED_Museum]

I just purchased a Metrologic Neon Laser off Ebay, thanks to a timely payment on my advertising banners. :thumbsup:
It isn't the one I listed on my Tuesday morning post, but is another, said to be functional.

 

[ks_physicist]

HeNe beams have a better profile than most diode lasers simply because of the geometry of the lasing material. Circular cross section, TEM00, gets a nice beam profile.

 

[PhotonWrangler]

There's always the sense of adventure and danger from getting shocked by the HV supply. I've done that too many times. Oww!

My experience has been that the HeNes do look a little bit brighter and more tightly collimated than their equivalent-wavelength laser diodes, although I haven't performed any scientific measurements to validate this.

HeNe units seem to be better suited for producing a smooth, round, gaussian spot vs a LD, and I believe this is because of the shape of the LD cavity and it's elliptical radiation pattern. This is clearly visible when looking at an un-lensed LD projecting onto a white sheet of paper. Getting that elliptical pattern to form into a perfectly round beam is not a perfect process and I believe that this explains the difference in beam uniformity as compared to a HeNe.

Having said all that, I'm personally done with HeNe units. They're too large and fragile and there's that nagging HV power supply requirement.

 

[The_LED_Museum]

I've gotten zapped off HeNe laser power supplies my fair share of times; most recently in 2004 with this little baby HeNe that a fan of my website sent me on Christmas Eve 2003.

 

[badhorsey]

I've got a couple; a red ex-military HeNe that's a steel tube about a metre long, and the star of my collection:

A GREEN HeNe from a Quasar set with PSU. I love that thing.

 

[The_LED_Museum]

My green HeNe was rated to output 260µW (0.26mW) when new, but now only outputs probably 10µW and starts sputtering after several seconds.
So it's reaching the end of its life, awwwww, the poor thing. :shakehead:

 

[rmzalbar]

Somewhat related -

There used to be a laser arena game called Q-Zar that was popular when I was in high school. The laser rifles fired thin red or green beams through fog during play. These were surely He-Ne lasers, there were no green DPSS that long ago.

Q-Zar is pretty much gone now, and recently I saw a bunch of surplus Q-Zar equipment going on ebay for nearly nothing. Something to keep an eye out for.

 

[The_LED_Museum]

That Metrologic HeNe laser I purchased from Ebaby arrived today, and wouldn't you know, the silly thing actually WORKS!!! :thumbsup:

 

[The_LED_Museum]

I recently put my evaluation of it up; go to my thread in the Reviews forum and look for the post timestamped 02-26-07 05:31 PM.