Spectra Physics 155 laser Problems

[carloto]

Hi i have a Spectra Physics 155 He Ne laser and i am totally new to Gas lasers and i have tested every think i can think of. All the components are good it is i believe it is a .5 mW laser and it dose glow as seen below. but there is no lase i have pictures and here they are.

 

[Bluefan]

If discharge is stable, it's not the electronics. The discharge looks very purple, that usually indicates a gas fill problem. Let it run for a few hours, see if it cleans up.

from sam's laserfaq:

 

[photonaholic]

Your tube looks like "moderate no output"

I was going to suggest that the tube is no good, that confirms it.

Sadly, re-gassing such a HeNe costs more than just getting another.

 

[Alshere]

As suggested let it run for a few hours. May take quite a few. As cameras and monitors can be deceptive on colors what do you see looking at the chart?
So you get nothing? Not even a glow at the end of the tube?

Good Luck as it is a nice little HeNe
Al

 

[carloto]

actually I think it might be an electrical problem. I had measured the voltage going in to the tube and it was a whopping 5kv and the manual said it needs to be something like 1.2kv so I think that may be a problem. also i was wondering how i can measure current because i cant afford the equipment if i burn my meter or oscilloscope

 

[daguin]

actually I think it might be an electrical problem. I had measured the voltage going in to the tube and it was a whopping 5kv and the manual said it needs to be something like 1.2kv so I think that may be a problem. also i was wondering how i can measure current because i cant afford the equipment if i burn my meter or oscilloscope

It appears that you have the original PSU still attached. I do not think that it is a power problem. If it has a good, steady plasma, the power source is probably good.

MANY (maybe most) of these old tubes have outgassed to a significant extent. They are interesting to play with, but if it is all original, it is probably a gas mixture problem.

Buying used gas lasers (especially old ones) is a gamble from the beginning. If they are listed as "untested" or the like, the odds are against you from the start

Peace,
dave

 

[carloto]

lol i got this one free from one of my dads buddies.

hmm well let me run it for a while and ill come back with results

 

[Alshere]

actually I think it might be an electrical problem. I had measured the voltage going in to the tube and it was a whopping 5kv and the manual said it needs to be something like 1.2kv so I think that may be a problem. also i was wondering how i can measure current because i cant afford the equipment if i burn my meter or oscilloscope

Just for general information here are some links on your tube and power supply.

Sam's Laser FAQ - HeNe Laser Power Supplies
Sam's Laser FAQ - Commercial Unstabilized HeNe Lasers
Sam's Laser FAQ - Complete HeNe Laser Power Supply Schematics

Let us know what letting it run does for the tube. As stated gas problems looks to be the most likley.

Al

 

[MarioMaster]

The getter on your tube looks awfully white (the film on the glass by the cathode) - hard to tell if it's the picture or if it's actually white or not.

A white getter indicates that it has absorbed significant amounts of impurities (supports the gas fill problem idea) if it is a good metallic silver then the getter is probably fine.

Ruined tube:

Healthy tube:

 

[carloto]

ill get a picture of it