Need Cylinder Lens specs -

Does anyone know the specs for the cylinder lens used in the Badder or
Badura star spectroscope (visual spectroscope)? The venodrs wont give
me the specs so I can buy a repalcement lens at Edmund ... and they wont

sell just the lens assembly.

If Ihad the specs maybe I could find a duplicate at Edmund?

Thanks for any help -
Bob

ps* Im sure glad car dealers dont work the way Baader and Badura do!
Civilisation would collapse!!!

In article , Robt wrote:
Does anyone know the specs for the cylinder lens used in the Badder or
Badura star spectroscope (visual spectroscope)? The venodrs wont give
me the specs so I can buy a repalcement lens at Edmund ... and they wont
sell just the lens assembly.

Does the information you have tell you the material that the lens
is made of? If so, then you can get the geometry from a couple of simple
measurements (the inverse of measuring the hog-out on your home-built
Newt), and that should specify the lens you need.
If the material in the lens isn't specified, you'll need to measure
either the focal length or refractive index of the material to specify the
lens adequately.
It's possible (but without knowing the details of the system I
can't say) that the dispersion (variation of refractive index with
wavelength) of the material is important to the function of the
instrument.

What's the context? It sounds like you're trying to replace a part
that's broken in some way? Do you have enough of the lens to be able to
measure the curvature of the cylindrical surface? What else could have
been damaged, distorted or misaligned during the misadventure that you're
trying to repair? That's the sort of questions I'd be asking if I worked
for the manufacturer and I had a client asking for non-standard spare
parts. The instruments that we build at work (not optical, but that's
irrelevant) get leased, not sold, and if the client needs the machines
fixed, it's us who designed and built it who faultfind and repair it. Then
we fill out the invoice for the repair, and after screams of pain the
clients pay up and hit the idiot who broke the machine in the first place.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

Robt wrote:

Does anyone know the specs for the cylinder lens used in the Badder or
Badura star spectroscope (visual spectroscope)? The venodrs wont give
me the specs so I can buy a repalcement lens at Edmund ... and they wont

sell just the lens assembly.

If Ihad the specs maybe I could find a duplicate at Edmund?

Thanks for any help -
Bob

ps* Im sure glad car dealers dont work the way Baader and Badura do!
Civilisation would collapse!!!

A device that measures lens curvature is very handy if you have a
piece of the original lens.

E.G.:
http://cgi.ebay.com/ws/eBayISAPI.dll...0324171& rd=1
--
John Popelish

Aidan Karley wrote:

In article , Robt wrote:
Does anyone know the specs for the cylinder lens used in the Badder or
Badura star spectroscope (visual spectroscope)? The venodrs wont give
me the specs so I can buy a repalcement lens at Edmund ... and they wont
sell just the lens assembly.

Does the information you have tell you the material that the lens
is made of? If so, then you can get the geometry from a couple of simple
measurements (the inverse of measuring the hog-out on your home-built
Newt), and that should specify the lens you need.
If the material in the lens isn't specified, you'll need to measure
either the focal length or refractive index of the material to specify the
lens adequately.

bk7.


It's possible (but without knowing the details of the system I
can't say) that the dispersion (variation of refractive index with
wavelength) of the material is important to the function of the
instrument.

What's the context?

as stated above - its one of these Star Spectroscopes. Specifically it is the
cylindrical lens that comes with the S t a r S p e c t r o s cope.

Thanks.
Bob

It sounds like you're trying to replace a part
that's broken in some way? Do you have enough of the lens to be able to
measure the curvature of the cylindrical surface? What else could have
been damaged, distorted or misaligned during the misadventure that you're
trying to repair? That's the sort of questions I'd be asking if I worked
for the manufacturer and I had a client asking for non-standard spare
parts. The instruments that we build at work (not optical, but that's
irrelevant) get leased, not sold, and if the client needs the machines
fixed, it's us who designed and built it who faultfind and repair it. Then
we fill out the invoice for the repair, and after screams of pain the
clients pay up and hit the idiot who broke the machine in the first place.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

In article , Robert wrote:
If the material in the lens isn't specified, you'll need to measure
either the focal length or refractive index of the material to specify the
lens adequately.

bk7.

Hmm, less than informative. Probably an internal code, either for their
stores records, or for their suppliers.

What's the context?

as stated above - its one of these Star Spectroscopes. Specifically it is the
cylindrical lens that comes with the S t a r S p e c t r o s cope.

Website that gives the schematics?
From what I know (theoretically) about spectroscopes, this would be one
of the cylindrical lenses for collimating the light from a slit, passing it
through a prism, then concentrating it again onto the imager (photo film or
CCD). That should be something that's a sealed unit. "No user serviceable parts
inside", as the labels say (the labels cost a few £ per roll of a thousand - we
use them ourselves on the GCs).
So, what are you wanting to change about this sealed unit? Or what have
you broken? If you've broken something that you can see, what have you broken,
bent or misaligned that you can't see? Do you have a second, pristine
spectrometer that you can take measurements from (you do have micrometers,
surface gauges etc and a machine shop?) to repair your damaged one.
If you're trying to adapt the Badura Spectroscope to do something
outside it's design envelope, then could it be that you're actually infringing
on the territory of a higher-specification ( = higher price) part of their
range. In one case, I'd expect the manufacturers to be interested in your
project, if it's explained properly; in the latter case, I fully understand why
the manufacturers would be unhappy about you trying to do this.

I did some web searching and found this page
http://amateurastronomy.org/EH/EHjun94.html
which tells me a little about the equipment you're using. Perhaps. You're
wanting an alternative cylindrical lens to obtain higher (or lower) dispersion
from your spectroscope assembly. "To obtain greater dispersion you can either
use a shorter focus eyepiece OR place the grating farther away from the
eyepiece! Too short a focal length eyepiece is not desirable since the
cylindrical lens needs to be positioned above the last lens and some eye relief
is desirable." Seems pretty plain to me! Alternatively, you could probably
jury-rig another cylindrical lens into a tubular holder and slip it *over* the
existing lens; align the axes and you're laughing, except for the issue of eye
relief mentioned above.
http://observers.org/tac.mailing.lis...July/0092.html is informative
too.

Frankly, I can't see what reason you'd have for needing to know the
characteristics of the cylindrical lens. There's plenty of range for
adjustments on a "suck it and see" basis. Because there's no provision I can
see for marking (e.g.) the eyepiece-lens distance, then any qualitative work
will need to be done in series with standards, so that in an observing run you
have internal references from which the dispersion of this particular assembly
can be calculated (minor variations in assembly may well alter the dispersion
noticeable). That's the difference between amateur level work and professional
level work.

Got to go - friends to visit in hospital.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

Aidan Karley wrote:
In article , Robert wrote:

If the material in the lens isn't specified, you'll need to measure
either the focal length or refractive index of the material to specify the
lens adequately.

bk7.


Hmm, less than informative. Probably an internal code, either for their
stores records, or for their suppliers.


BK7 is the common standard glass used around the world. When someone
thinks of a piece of glass they are probably thinking about BK7 glass.
It's the glass used for windows, basic optics, etc. At least that is
what they taught in my graduate optics class.


What's the context?

as stated above - its one of these Star Spectroscopes. Specifically it is the
cylindrical lens that comes with the S t a r S p e c t r o s cope.


Website that gives the schematics?
From what I know (theoretically) about spectroscopes, this would be one
of the cylindrical lenses for collimating the light from a slit, passing it
through a prism, then concentrating it again onto the imager (photo film or
CCD). That should be something that's a sealed unit. "No user serviceable parts
inside", as the labels say (the labels cost a few £ per roll of a thousand - we
use them ourselves on the GCs).
So, what are you wanting to change about this sealed unit? Or what have
you broken? If you've broken something that you can see, what have you broken,
bent or misaligned that you can't see? Do you have a second, pristine
spectrometer that you can take measurements from (you do have micrometers,
surface gauges etc and a machine shop?) to repair your damaged one.
If you're trying to adapt the Badura Spectroscope to do something
outside it's design envelope, then could it be that you're actually infringing
on the territory of a higher-specification ( = higher price) part of their
range. In one case, I'd expect the manufacturers to be interested in your
project, if it's explained properly; in the latter case, I fully understand why
the manufacturers would be unhappy about you trying to do this.

I did some web searching and found this page
http://amateurastronomy.org/EH/EHjun94.html
which tells me a little about the equipment you're using. Perhaps. You're
wanting an alternative cylindrical lens to obtain higher (or lower) dispersion
from your spectroscope assembly. "To obtain greater dispersion you can either
use a shorter focus eyepiece OR place the grating farther away from the
eyepiece! Too short a focal length eyepiece is not desirable since the
cylindrical lens needs to be positioned above the last lens and some eye relief
is desirable." Seems pretty plain to me! Alternatively, you could probably
jury-rig another cylindrical lens into a tubular holder and slip it *over* the
existing lens; align the axes and you're laughing, except for the issue of eye
relief mentioned above.
http://observers.org/tac.mailing.lis...July/0092.html is informative
too.

Frankly, I can't see what reason you'd have for needing to know the
characteristics of the cylindrical lens. There's plenty of range for
adjustments on a "suck it and see" basis. Because there's no provision I can
see for marking (e.g.) the eyepiece-lens distance, then any qualitative work
will need to be done in series with standards, so that in an observing run you
have internal references from which the dispersion of this particular assembly
can be calculated (minor variations in assembly may well alter the dispersion
noticeable). That's the difference between amateur level work and professional
level work.

Got to go - friends to visit in hospital.


- Tom

In article , Thomas Stephens wrote:
BK7 is the common standard glass used around the world. When someone
thinks of a piece of glass they are probably thinking about BK7 glass.
It's the glass used for windows, basic optics, etc. At least that is
what they taught in my graduate optics class.

Can you give a link to it's dispersion
(seconds-of-arc/per/angstrom? and refractive index?

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

Aidan Karley wrote:

In article , Robert wrote:
If the material in the lens isn't specified, you'll need to measure
either the focal length or refractive index of the material to specify the
lens adequately.

bk7.

Hmm, less than informative. Probably an internal code, either for their
stores records, or for their suppliers.

What's the context?

as stated above - its one of these Star Spectroscopes. Specifically it is the
cylindrical lens that comes with the S t a r S p e c t r o s cope.

Website that gives the schematics?
From what I know (theoretically) about spectroscopes, this would be one
of the cylindrical lenses for collimating the light from a slit, passing it
through a prism, then concentrating it again onto the imager (photo film or
CCD). That should be something that's a sealed unit. "No user serviceable parts
inside", as the labels say (the labels cost a few £ per roll of a thousand - we
use them ourselves on the GCs).
So, what are you wanting to change about this sealed unit? Or what have
you broken? If you've broken something that you can see, what have you broken,
bent or misaligned that you can't see? Do you have a second, pristine
spectrometer that you can take measurements from (you do have micrometers,
surface gauges etc and a machine shop?) to repair your damaged one.
If you're trying to adapt the Badura Spectroscope to do something
outside it's design envelope, then could it be that you're actually infringing
on the territory of a higher-specification ( = higher price) part of their
range. In one case, I'd expect the manufacturers to be interested in your
project, if it's explained properly; in the latter case, I fully understand why
the manufacturers would be unhappy about you trying to do this.

This is quite simple. I am looking for thespecs of the cyl lens used by both
Badura and Baader - nothing synister here!

Thanks for all your help.

Bob









I did some web searching and found this page
http://amateurastronomy.org/EH/EHjun94.html
which tells me a little about the equipment you're using. Perhaps. You're
wanting an alternative cylindrical lens to obtain higher (or lower) dispersion
from your spectroscope assembly. "To obtain greater dispersion you can either
use a shorter focus eyepiece OR place the grating farther away from the
eyepiece! Too short a focal length eyepiece is not desirable since the
cylindrical lens needs to be positioned above the last lens and some eye relief
is desirable." Seems pretty plain to me! Alternatively, you could probably
jury-rig another cylindrical lens into a tubular holder and slip it *over* the
existing lens; align the axes and you're laughing, except for the issue of eye
relief mentioned above.
http://observers.org/tac.mailing.lis...July/0092.html is informative
too.

Frankly, I can't see what reason you'd have for needing to know the
characteristics of the cylindrical lens. There's plenty of range for
adjustments on a "suck it and see" basis. Because there's no provision I can
see for marking (e.g.) the eyepiece-lens distance, then any qualitative work
will need to be done in series with standards, so that in an observing run you
have internal references from which the dispersion of this particular assembly
can be calculated (minor variations in assembly may well alter the dispersion
noticeable). That's the difference between amateur level work and professional
level work.

Got to go - friends to visit in hospital.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

No those are among the specs Im asking if anyone has. Most critical is
back focal length. Its very simple but evidently a national secret!



Aidan Karley wrote:

In article , Thomas Stephens wrote:
BK7 is the common standard glass used around the world. When someone
thinks of a piece of glass they are probably thinking about BK7 glass.
It's the glass used for windows, basic optics, etc. At least that is
what they taught in my graduate optics class.

Can you give a link to it's dispersion
(seconds-of-arc/per/angstrom? and refractive index?

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

Aidan Karley wrote:
In article , Thomas Stephens wrote:

BK7 is the common standard glass used around the world. When someone
thinks of a piece of glass they are probably thinking about BK7 glass.
It's the glass used for windows, basic optics, etc. At least that is
what they taught in my graduate optics class.


Can you give a link to it's dispersion
(seconds-of-arc/per/angstrom? and refractive index?


Try this one
http://www.mellesgriot.com/products/optics/mp_3_1.htm

- Tom