Re: [Utah-astronomy] ATM session report and next planned date
Maybe too much trouble for one time use, but if you do a lot of "star" testing it might be worthwhile.
Wow, that's an impressive setup for an artificial star!
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@thebluezone.net Sent: Tuesday, October 18, 2011 3:37 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] ATM session report and next planned date
Here is link about using a LED to build an artificial star, it does not seem to require more than about 100 ft of distance.
http://observatory.mvastro.org/library/Star_Test/ArtStar.html
On 10/18/11, Hutchings, Mat (H USA) <mat.hutchings@siemens.com> wrote:
Aw, come on, you can brave the cold at night in the winter!
Yeah, to a point, but then again, I am designing a heated observatory, so that's gotta tell you something... ;)
Re: Ronchi testing
With much experience, you can tell a lot with the Ronchi test. I used to hang-out with a local optical manufacturer, and we'd look at mirrors through the Ronchi. I would point-out problems that he had to stare and stare at, and most of the time he'd say "yeah, maybe..." until we star-tested it. Then he'd admit that I detected it with the grid.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
---------------------------------------------------------------------------- This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice@siemens.com
Thank you
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
I checked my copy of Richard Suiter's book on Star testing and he has a chapter on the physics of the artificial star. Regardless of the type of source it needs to be moved a good distance away to avoid introducing an error. 20 times the focal length of the optic was once the standard but physics says that for faster and larger mirrors you could need more than 100 times the focal length. The danger here is that you will proclaim a perfectly good parabola to be flawed, or worse you could carefully figure a prolate spheriod thinking it was a good parabola. Your own private reenactment of the Hubble Space telescope fiasco. DT ________________________________ From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, October 18, 2011 3:48 PM Subject: Re: [Utah-astronomy] ATM session report and next planned date
Maybe too much trouble for one time use, but if you do a lot of "star" testing it might be worthwhile.
Wow, that's an impressive setup for an artificial star!
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@thebluezone.net Sent: Tuesday, October 18, 2011 3:37 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] ATM session report and next planned date
Here is link about using a LED to build an artificial star, it does not seem to require more than about 100 ft of distance.
http://observatory.mvastro.org/library/Star_Test/ArtStar.html
On 10/18/11, Hutchings, Mat (H USA) <mat.hutchings@siemens.com> wrote:
Aw, come on, you can brave the cold at night in the winter!
Yeah, to a point, but then again, I am designing a heated observatory, so that's gotta tell you something... ;)
Re: Ronchi testing
With much experience, you can tell a lot with the Ronchi test. I used to hang-out with a local optical manufacturer, and we'd look at mirrors through the Ronchi. I would point-out problems that he had to stare and stare at, and most of the time he'd say "yeah, maybe..." until we star-tested it. Then he'd admit that I detected it with the grid.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
---------------------------------------------------------------------------- This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice@siemens.com
Thank you
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
Any ATM worth his salt knows this, DT. On Oct 18, 2011 4:05 PM, "daniel turner" <outwest112@yahoo.com> wrote:
I checked my copy of Richard Suiter's book on Star testing and he has a chapter on the physics of the artificial star. Regardless of the type of source it needs to be moved a good distance away to avoid introducing an error. 20 times the focal length of the optic was once the standard but physics says that for faster and larger mirrors you could need more than 100 times the focal length.
The danger here is that you will proclaim a perfectly good parabola to be flawed, or worse you could carefully figure a prolate spheriod thinking it was a good parabola. Your own private reenactment of the Hubble Space telescope fiasco.
DT
________________________________ From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, October 18, 2011 3:48 PM Subject: Re: [Utah-astronomy] ATM session report and next planned date
Maybe too much trouble for one time use, but if you do a lot of "star" testing it might be worthwhile.
Wow, that's an impressive setup for an artificial star!
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@thebluezone.net Sent: Tuesday, October 18, 2011 3:37 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] ATM session report and next planned date
Here is link about using a LED to build an artificial star, it does not seem to require more than about 100 ft of distance.
http://observatory.mvastro.org/library/Star_Test/ArtStar.html
On 10/18/11, Hutchings, Mat (H USA) <mat.hutchings@siemens.com> wrote:
Aw, come on, you can brave the cold at night in the winter!
Yeah, to a point, but then again, I am designing a heated observatory, so that's gotta tell you something... ;)
Re: Ronchi testing
With much experience, you can tell a lot with the Ronchi test. I used to hang-out with a local optical manufacturer, and we'd look at mirrors through the Ronchi. I would point-out problems that he had to stare and stare at, and most of the time he'd say "yeah, maybe..." until we star-tested it. Then he'd admit that I detected it with the grid.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
----------------------------------------------------------------------------
This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice@siemens.com
Thank you
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
To be fair, Daniel makes a valid point. But not everyone makes a diffraction-limited mirror on their first attempt, unless they have help from someone with experience. Few people have a Zygo interferometer in their basement. Yet, for decades, a select group of dedicated amateurs has been able to make optics that are unsurpassed, using the most basic of optical techniques. John Dobson tests and figures thin mirrors using a bare light bulb! For the life of me, I can't do that. It's an intuition and skill that God has bestowed upon him, and few others. Alika Hering could make mirrors as good as a government lab. The 200 inch Palomar mirror was figured by a man with no formal education. What I'm saying is that dedication is all that's needed. It can take the place of a lab full of million-dollar testing equipment and an engineering degree. Raw talent and strength of character are powerful tools. On Oct 18, 2011 6:50 PM, "Chuck Hards" <chuck.hards@gmail.com> wrote:
Any ATM worth his salt knows this, DT. On Oct 18, 2011 4:05 PM, "daniel turner" <outwest112@yahoo.com> wrote:
I checked my copy of Richard Suiter's book on Star testing and he has a chapter on the physics of the artificial star. Regardless of the type of source it needs to be moved a good distance away to avoid introducing an error. 20 times the focal length of the optic was once the standard but physics says that for faster and larger mirrors you could need more than 100 times the focal length.
The danger here is that you will proclaim a perfectly good parabola to be flawed, or worse you could carefully figure a prolate spheriod thinking it was a good parabola. Your own private reenactment of the Hubble Space telescope fiasco.
DT
________________________________ From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, October 18, 2011 3:48 PM Subject: Re: [Utah-astronomy] ATM session report and next planned date
Maybe too much trouble for one time use, but if you do a lot of "star" testing it might be worthwhile.
Wow, that's an impressive setup for an artificial star!
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@thebluezone.net Sent: Tuesday, October 18, 2011 3:37 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] ATM session report and next planned date
Here is link about using a LED to build an artificial star, it does not seem to require more than about 100 ft of distance.
http://observatory.mvastro.org/library/Star_Test/ArtStar.html
On 10/18/11, Hutchings, Mat (H USA) <mat.hutchings@siemens.com> wrote:
Aw, come on, you can brave the cold at night in the winter!
Yeah, to a point, but then again, I am designing a heated observatory, so that's gotta tell you something... ;)
Re: Ronchi testing
With much experience, you can tell a lot with the Ronchi test. I used to hang-out with a local optical manufacturer, and we'd look at mirrors through the Ronchi. I would point-out problems that he had to stare and stare at, and most of the time he'd say "yeah, maybe..." until we star-tested it. Then he'd admit that I detected it with the grid.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
----------------------------------------------------------------------------
This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice@siemens.com
Thank you
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
"The danger here is that you will proclaim a perfectly good parabola to be
flawed, or worse you could carefully figure a prolate spheriod thinking it was a good parabola. Your own private reenactment of the Hubble Space telescope fiasco."
Well, I guess when the mirror is used for real this would become apparent. Mirror Grinding is more of an art than science and John Dobson would not grind a fast mirror. To be fair, Daniel makes a valid point. But not everyone makes a
diffraction-limited mirror on their first attempt, unless they have help from someone with experience. Few people have a Zygo interferometer in their basement. Yet, for decades, a select group of dedicated amateurs has been able to make optics that are unsurpassed, using the most basic of optical techniques. John Dobson tests and figures thin mirrors using a bare light bulb! For the life of me, I can't do that. It's an intuition and skill that God has bestowed upon him, and few others. Alika Hering could make mirrors as good as a government lab. The 200 inch Palomar mirror was figured by a man with no formal education. What I'm saying is that dedication is all that's needed. It can take the place of a lab full of million-dollar testing equipment and an engineering degree. Raw talent and strength of character are powerful tools. On Oct 18, 2011 6:50 PM, "Chuck Hards" <chuck.hards@gmail.com> wrote:
Any ATM worth his salt knows this, DT. On Oct 18, 2011 4:05 PM, "daniel turner" <outwest112@yahoo.com> wrote:
I checked my copy of Richard Suiter's book on Star testing and he has a chapter on the physics of the artificial star. Regardless of the type of source it needs to be moved a good distance away to avoid introducing an error. 20 times the focal length of the optic was once the standard but physics says that for faster and larger mirrors you could need more than 100 times the focal length.
The danger here is that you will proclaim a perfectly good parabola to be flawed, or worse you could carefully figure a prolate spheriod thinking it was a good parabola. Your own private reenactment of the Hubble Space telescope fiasco.
DT
________________________________ From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, October 18, 2011 3:48 PM Subject: Re: [Utah-astronomy] ATM session report and next planned date
Maybe too much trouble for one time use, but if you do a lot of "star" testing it might be worthwhile.
Wow, that's an impressive setup for an artificial star!
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@thebluezone.net Sent: Tuesday, October 18, 2011 3:37 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] ATM session report and next planned
date
Here is link about using a LED to build an artificial star, it does
not
seem to require more than about 100 ft of distance.
http://observatory.mvastro.org/library/Star_Test/ArtStar.html
On 10/18/11, Hutchings, Mat (H USA) <mat.hutchings@siemens.com> wrote:
Aw, come on, you can brave the cold at night in the winter!
Yeah, to a point, but then again, I am designing a heated observatory, so that's gotta tell you something... ;)
Re: Ronchi testing
With much experience, you can tell a lot with the Ronchi test. I used to hang-out with a local optical manufacturer, and we'd look at mirrors through the Ronchi. I would point-out problems that he had to stare and stare at, and most of the time he'd say "yeah, maybe..." until we star-tested it. Then he'd admit that I detected it with the grid.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
----------------------------------------------------------------------------
This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice@siemens.com
Thank you
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
participants (3)
-
Chuck Hards -
daniel turner -
erikhansen＠thebluezone.net