Saint Petersburg Astronomy Club - Mirror Lab


We are looking for a new home
As soon as we have the new location set we will post the location and hours here.

Our Founder

Paul McNabb founded the mirror lab in 1997 in order to create the best amateur telecopes possible. Inch for inch our mirrors surpass store bought or commercial grade scopes.

04/12/2012 more


  • Ralph Craig - Lab Instructor
  • Allen Maroney - Lab Instructor
  • Ron Jones - The Figurer
  • Mike Davis - Casts Mirrors
  • Dimitri - Support


  • James Lerch - Robo Foucault
  • Matt Terry
  • Charlie Mullen
  • Bruce Kazcmarik
  • Keevy McAlavy

In Memorium

  • Irv Nadelhaft
  • Lenny Remetta

04/12/2012 more


Where the 19th Century Art of Mirror Making Meets the 21st Century

The Saint Petersburg Mirror Lab is a small band of dedicated mirror grinders and telescope makers living in the Tampa Bay area of Florida. We offer a mirror making class for interested persons. We strive to create the best mirrors our home brew technology can muster. This includes robotic foucault testing and laser interferometry.

  Bath Interferometer
Paul McNabb built a Bath Interferometer and lab members have begun experimenting with a mirror that
was finished using the Foucault tester. The test uses a laser, beam splitter and a couple of
lenses to create fringes from the mirror's shape. An image of these fringes is processed by a
program appropriately called 'Fringe' that creates a 2D color topography of the mirror showing high
and low areas relative to the perfect parabola for that mirror's diameter and f-ratio.

  The 8" f3 Mirror is coming along
This is a lab staff project and we are taking turns working on whet will become a 8" f3 mirror. Ron
(left) is hogging it out at about the 152 thousandths depth with a goal of 166K. Right is a close
up of Ralph working on it with the used 80 grit becoming mud around the tool. We finished the day
right on the depth and we will be moving to 120 grit next week.

  Paul's drum shell
Paul is using a drum shell for the mirror box. Here he is preparing to cut the shell shorter. The
shell is on a sled over Ralph's table saw. The square plywood is used to prevent the shell from
moving sideways on the sled. The shell was rotated while the saw ws running. This was a three man
operation. The amazing thing was that it worked and made a beautiful cut.

  Deep Core Samples
The optical lab gang often enjoys science that diverges a bit from telescope making. Lately Geology
and fossil hunting have been popular. Here are some deep core samples from Manatee County.

  Mike's 12.5" Cast Aluminum Mirror Cell
After casting the 12.5" honeycomb mirror with pin holes for a mirror cell Mike cast an aluminum cell
using the lost foam method. The floatation cell uses felt pads and heat shrink tubing to protect
the mirror from direct contact with the aluminum.

  Jorge's 10" mirror cell
This is a Ralph designed mirror cell made out of 3/4" Baltic Birch.

  Jorge's 10" red tube gets its first coat of paint
Jorge's tube gets its first coat of read paint. That will not be missed on the observing field
during the day.

  Paul finished his 14 inch f/4.4 mirror.
Paul finished his 14 inch f/4.4 mirror. It's 1/6th wave with a 0.9 Strehl and it's extremely well
polished. The Pyrex blank for this mirror started out as a thick 12.5 inch that was melted in
Mike's kiln and made into a relatively thin 14 inch. Congratulations Paul!

  Twelve inch 11th wave Zerodur
After some serious experimenting that started with a thin 16 inch and continued with this 12 inch
Zerodur mirror allowed us to figure out how to use a swirl (circular) stroke that would beautifully
parabolize a mirror. More to come on this.

  Brad finished an awesome 10 inch mirror
Brad finished his 10 inch mirror also during the 7-29 8 hour figurathon. We were on a roll with the
better than 1/6th wave mirrors and another stunning polish. Next stop is Spectrum Coatings.

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