Inexpensive Telescope Design Revealed

Having decided I am unlikely to be able to start a business importing
telescopes from China, and get rich thereby, I have decided to release
to the public a design I have come up with for an inexpensive telescope.

It is on the page

http://www.quadibloc.com/science/opt02.htm

and the design, as given, is a Field-Maksutov telescope with an f/13.9
focal ratio. The secondary mirror and the meniscus corrector of the
Field type are held in position by a full-aperture meniscus corrector,
but this corrector is curved in the opposite direction from that of a
Maksutov telescope.

I also provide a reference to a camera lens design by W. Mandler which
uses only one glass type and involves adding a reversed meniscus
corrector to a Maksutov-Cassegrain construction as well as what seems to
be a coma corrector. (The patent gives two examples, one of which is a
Gregory-Maksutov.)

John Savard
http://home.ecn.ab.ca/~jsavard/index.html
http://www.quadibloc.com/index.html
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Interesting idea and nice web site. Peter Ceravolo offered an
all-spherical Gregorian design along the same lines:

http://www.ceravolo.com/design/cat_greg.htm

John Savard wrote:
Having decided I am unlikely to be able to start a business importing
telescopes from China, and get rich thereby, I have decided to release
to the public a design I have come up with for an inexpensive telescope.

It is on the page

http://www.quadibloc.com/science/opt02.htm

and the design, as given, is a Field-Maksutov telescope with an f/13.9
focal ratio. The secondary mirror and the meniscus corrector of the
Field type are held in position by a full-aperture meniscus corrector,
but this corrector is curved in the opposite direction from that of a
Maksutov telescope.

I also provide a reference to a camera lens design by W. Mandler which
uses only one glass type and involves adding a reversed meniscus
corrector to a Maksutov-Cassegrain construction as well as what seems to
be a coma corrector. (The patent gives two examples, one of which is a
Gregory-Maksutov.)

John Savard
http://home.ecn.ab.ca/~jsavard/index.html
http://www.quadibloc.com/index.html
_________________________________________
Usenet Zone Free Binaries Usenet Server
More than 140,000 groups
Unlimited download
http://www.usenetzone.com to open account

John Savard wrote:
Having decided I am unlikely to be able to start a business importing
telescopes from China, and get rich thereby, I have decided to release
to the public a design I have come up with for an inexpensive telescope.

It is on the page

http://www.quadibloc.com/science/opt02.htm

and the design, as given, is a Field-Maksutov telescope with an f/13.9
focal ratio. The secondary mirror and the meniscus corrector of the
Field type are held in position by a full-aperture meniscus corrector,
but this corrector is curved in the opposite direction from that of a
Maksutov telescope.

I also provide a reference to a camera lens design by W. Mandler which
uses only one glass type and involves adding a reversed meniscus
corrector to a Maksutov-Cassegrain construction as well as what seems to
be a coma corrector. (The patent gives two examples, one of which is a
Gregory-Maksutov.)

John Savard
http://home.ecn.ab.ca/~jsavard/index.html
http://www.quadibloc.com/index.html
_________________________________________
Usenet Zone Free Binaries Usenet Server
More than 140,000 groups
Unlimited download
http://www.usenetzone.com to open account

Who cares, I have 4 telescopes! (o:
Just another cheap telescope!
JS

http://www.quadibloc.com/science/opt02.htm

How are you going to accurately figure those curves on a
corrector that is only 5mm thick?

Clear Skies

Chuck Taylor
Do you observe the moon? If so, try
http://groups.yahoo.com/group/lunar-observing/

If you enjoy optics, try
http://groups.yahoo.com/group/ATM_Optics_Software/
*********************************************

[quote=John Savard].... I have decided to release to the public a design I have come up with for an inexpensive telescope.

http://www.quadibloc.com/science/opt02.htm

and the design, as given, is a Field-Maksutov telescope with an f/13.9
focal ratio. The secondary mirror and the meniscus corrector of the
Field type are held in position by a full-aperture meniscus corrector,
but this corrector is curved in the opposite direction from that of a
Maksutov telescope.

John Savard

Thanks John - interesting webpage. Could you identify this design more precisely for me as I seem lost in the many options;-).

Regarding forming aspheric corrector plates I thought the plane plate was vacuum deformed against a metal former and ground/figured flat to form the required profile when the vacuum was released??

Of possible interest, my experiments published in S&T http://home.freeuk.com/m.gavin/flux.htm
with partial vacuum induced membrane mirrors formed an approximate oblate spheroid figure and not a spherical or paraboloidal figure as commonly assumed. You refer on your page to a vacuum induced plate glass as spherical - admittedly glass is [on the short time scale] rigid.

regards
Nytecam
www.astroman.fsnet.co.uk

Chuck Taylor wrote:
How are you going to accurately figure those curves on a
corrector that is only 5mm thick?

If that's a difficulty, I suppose I will try a different design...

John Savard

nytecam wrote:
Thanks John - interesting webpage. Could you identify this design more
precisely for me as I seem lost in the many options;-).

It's the only one for which a detailed prescription is given, quite a
ways down the page.

Regarding forming aspheric corrector plates I thought the plane plate
was vacuum deformed against a metal former and ground/figured flat to
form the required profile when the vacuum was released??

I've seen that claimed, however it doesn't quite seem to make sense.
Thus, I think that it instead is ground *spherical* to form the
required profile. Which I've also seen written somewhere.

You refer on your page to a vacuum induced plate
glass as spherical - admittedly glass is [on the short time scale]
rigid.

If the vacuum made the glass spherical - instead of a more 'pointy'
shape - then vacuum forming would, of course, be irrelevant to the
manufacture of Schmidt correctors.

John Savard

How are you going to accurately figure those curves on a
corrector that is only 5mm thick?


If that's a difficulty, I suppose I will try a different design...

Accurate figuring would be extremely difficult even for a very
experienced optician (if not impossible). It would have to be
done by hand to have any chance of succeeding.

Clear Skies

Chuck Taylor
Do you observe the moon? If so, try
http://groups.yahoo.com/group/lunar-observing/

If you enjoy optics, try
http://groups.yahoo.com/group/ATM_Optics_Software/
*********************************************

wrote:

I've seen that claimed, however it doesn't quite seem to make sense.
Thus, I think that it instead is ground *spherical* to form the
required profile. Which I've also seen written somewhere.

You refer on your page to a vacuum induced plate
glass as spherical - admittedly glass is [on the short time scale]
rigid.

If the vacuum made the glass spherical - instead of a more 'pointy'
shape - then vacuum forming would, of course, be irrelevant to the
manufacture of Schmidt correctors.

Have you ever made a Schmidt plate, Maksutov corrector or for that
matter ANY
optics yourself ?
From your webpage it seems that you haven't, but let's clear that.

BTW your sense of "inexpensive" seems rather humorous. Full size ultra
thin menisk, another (thick) one, two mirrors ... Lots of work, lots of
expensive coatings, for what seems rather like abysmal correction.

Bratislav

wrote:
wrote:


I've seen that claimed, however it doesn't quite seem to make sense.
Thus, I think that it instead is ground *spherical* to form the
required profile. Which I've also seen written somewhere.


You refer on your page to a vacuum induced plate
glass as spherical - admittedly glass is [on the short time scale]
rigid.

If the vacuum made the glass spherical - instead of a more 'pointy'
shape - then vacuum forming would, of course, be irrelevant to the
manufacture of Schmidt correctors.


Have you ever made a Schmidt plate, Maksutov corrector or for that
matter ANY
optics yourself ?
From your webpage it seems that you haven't, but let's clear that.

BTW your sense of "inexpensive" seems rather humorous. Full size ultra
thin menisk, another (thick) one, two mirrors ... Lots of work, lots of
expensive coatings, for what seems rather like abysmal correction.

Yep. Six surfaces plus coatings. Makes a 4 surface Super Schupmann seem
almost trivial by comparison G

--
Jeff (STM)