spectra physics 255 exciter and laser

[Joe]

We have one of these at the University I am attending, and it seems to have
stopped working. My professor was going to demonstrate the optical amplifier
concept in our lab, but the cavity doesn't seem to lase. It turns on for a
few flashes, then fades and turns off. It is vintage 1970's.

I think it's the laser, as it has the same symptoms as my old He-Ne had when
it died, but he thinks it could be the power supply. I obtained a schematic
of the power supply at Sam Goldwasser's page. I am not sure how to test the
supply though. I know it is very high voltage although I am not sure how
high. How does one test a high (on the order of KV I am sure) power supply ?

I am also posting this message to sci.electronics.basics, and alt.lasers

TIA,
Joe

 

[Pat B.]

We have one of these at the University I am attending, and it seems to have
stopped working. My professor was going to demonstrate the optical amplifier
concept in our lab, but the cavity doesn't seem to lase. It turns on for a
few flashes, then fades and turns off. It is vintage 1970's.

I think it's the laser, as it has the same symptoms as my old He-Ne had when
it died, but he thinks it could be the power supply. I obtained a schematic
of the power supply at Sam Goldwasser's page. I am not sure how to test the
supply though. I know it is very high voltage although I am not sure how
high. How does one test a high (on the order of KV I am sure) power supply ?

I am also posting this message to sci.electronics.basics, and alt.lasers

TIA,
Joe

Does the plasma tube light and stay on? Can you increase the current?
As usual, more information is needed.

 

[Sam Goldwasser]

Does the plasma tube light and stay on? Can you increase the current?
As usual, more information is needed.

He says it flashes a few times and turns off.

He also says it doesn't lase.

So, there may be more than one problem, or the gas may be contaminated
affecting both the operating voltage and the gain.

What color is the discharge when it is on?

Does it match one of these?:

http://www.repairfaq.org/sam/henedcol.gif

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[Joe]

He says it flashes a few times and turns off.

He also says it doesn't lase.

So, there may be more than one problem, or the gas may be contaminated
affecting both the operating voltage and the gain.

What color is the discharge when it is on?

Does it match one of these?:

http://www.repairfaq.org/sam/henedcol.gif

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above
is
ignored unless my full name AND either lasers or electronics is included
in the
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Hello Sam,

I would have to say the "moderate no output" would be the closest. The
professor opened it up to demonstrate optical amplification as part of our
laser optics course. He has used this for this purpose for a few years now.
He said that on the day we were supposed to see it, he heard a 'pop' and
then it stopped working. I found one of the professors in another lab today
who has a high voltage scope probe and he is going to check the output
voltage from the exciter. He is an electronics type and said it's probably a
cap in the power supply. It's vintage. We shall see.

Thanks for the reply Sam,

Joe

 

[Sam Goldwasser]

Hello Sam,

I would have to say the "moderate no output" would be the closest. The
professor opened it up to demonstrate optical amplification as part of our
laser optics course. He has used this for this purpose for a few years now.
He said that on the day we were supposed to see it, he heard a 'pop' and
then it stopped working. I found one of the professors in another lab today
who has a high voltage scope probe and he is going to check the output
voltage from the exciter. He is an electronics type and said it's probably a
cap in the power supply. It's vintage. We shall see.

Could be, though that would be unusual on a SP-255. The caps are high
quality and none are electrolytic.

What is the laser? An SP-124? These may go bad on the shelf since many, if
not all, are soft-sealed tubes.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
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[notbob]

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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Are any of these "vintage" he-ne lasers worth anything? I've got an
old circa 90s he-ne with pwr sply and everything. I'll have to dig it
out to see if it still works and the brand/model.

nb

 

[Pat B.]

Are any of these "vintage" he-ne lasers worth anything? I've got an
old circa 90s he-ne with pwr sply and everything. I'll have to dig it
out to see if it still works and the brand/model.

nb

THATS IT!!! NO MORE CRACK!!! I QUIT!!! I read problem with
Spectra-Physics 255 laser and my brain converted it to 265 laser.

 

[Sam Goldwasser]

Are any of these "vintage" he-ne lasers worth anything? I've got an
old circa 90s he-ne with pwr sply and everything. I'll have to dig it
out to see if it still works and the brand/model.

To me, vintage is 1960s, maybe 1970s for selected lasers.

You can check eBay or post here for what your late model laser is worth.

They are worth something.

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[Pat B.]

To me, vintage is 1960s, maybe 1970s for selected lasers.

You can check eBay or post here for what your late model laser is worth.

They are worth something.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
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o me, vintage is 1960s, maybe 1970s for selected lasers.

You can check eBay or post here for what your late model laser is
worth.

They are worth something.


You are right there I think I pay about a penny per pound, and sell
them for about 2 cents per pound.

 

[Lostgallifreyan]

You are right there I think I pay about a penny per pound, and sell
them for about 2 cents per pound.

Are you hinting at some quasi magical ability to buy UK lasers and sell
them in the US against the current exchange rates? I'm just making this up
as I go along, but it would be kind of cool if you had, and did.

 

[Joe]

Could be, though that would be unusual on a SP-255. The caps are high
quality and none are electrolytic.

What is the laser? An SP-124? These may go bad on the shelf since many,
if
not all, are soft-sealed tubes.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above
is
ignored unless my full name AND either lasers or electronics is included
in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Hello Sam,

You were correct. They checked out the power supply today, apparently the
electronics prof went to my prof after I talked to him yesterday and they
tested the supply. It checked out, so my prof told me when I went to class.
He said something about contamination in the cavity, or byproducts forming
causing it to malfunction. I don't know what model the laser is. They did
this before I arrived for class, so I was a little miffed that I didn't get
to watch. Anyway, I don't know if he is going to get a new laser or not. He
said you can't buy them like that any more. He's been into lasers since the
early 70's. I didn't ask him what he meant about the laser diodes because he
started his lecture right away, so I just paid attention and wrote. But I
think you are right, he is an old time laser guy, and he is having trouble
dealing with how inexpensive the laser pointers and laser diode products are
nowadays. He has mentioned it a few times to the class.

What is meant by a soft sealed tube?

Joe

 

[Sam Goldwasser]

Hello Sam,

You were correct. They checked out the power supply today, apparently the
electronics prof went to my prof after I talked to him yesterday and they
tested the supply. It checked out, so my prof told me when I went to class.
He said something about contamination in the cavity, or byproducts forming
causing it to malfunction. I don't know what model the laser is. They did
this before I arrived for class, so I was a little miffed that I didn't get
to watch. Anyway, I don't know if he is going to get a new laser or not. He
said you can't buy them like that any more. He's been into lasers since the
early 70's. I didn't ask him what he meant about the laser diodes because he
started his lecture right away, so I just paid attention and wrote. But I
think you are right, he is an old time laser guy, and he is having trouble
dealing with how inexpensive the laser pointers and laser diode products are
nowadays. He has mentioned it a few times to the class.

What is meant by a soft sealed tube?

A soft-sealed tube has the mirror basically glued on with Epoxy (well,
perhaps TorrSeal or something more exotic than hardware store Epoxy) but
it still leaks and outgases. So, over time, these tubes die on the shelf.
That time can be anywhere from a year or so to forever, but mostly a few
years.

A hard-sealed tube has all joints made either with glass-metal seals or
with glass "frit", sort of like solder for glass. When properly made,
neither of these leaks on any time scale that matters. Most modern lasers
use hard-sealed tubes.

If he wants the laser evaluated, have him contact me.

Sometimes, if the tube can be convinced to stay lit, it will come back at
least partially after a few hours.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
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[Ron Capik]

To me, vintage is 1960s, maybe 1970s for selected lasers.
< ..snip... >

Ah, vintage lasers. I once had the open cavity HeNe laser
from Bill Rogrod's famous laser modes photo,
[W.W. Rigrod, Appl. Phys. Lett. 2 1963 51] the one that's
reproduced in many laser texts. I lost track of it in one of
my lab moves and it went in to storage. Actually there were
two of them side by side, one at 6328 and the other at
1.15 (or 1.5) microns depending on mirrors used.
There may be some photos of it in the NYC laser and
holography museum.

Those were the days. <G>


Later...

Ron Capik
--

 

[C what I mean]

THATS IT!!! NO MORE CRACK!!! I QUIT!!! I read problem with
Spectra-Physics 255 laser and my brain converted it to 265 laser.

too many times you have said look into my eyes.. They were just too blood
shot!

 

[Pat B.]

too many times you have said look into my eyes.. They were just too blood
shot!

yeah, I've had a pretty luff rife