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WHAT on Earth IS This?

Started by Thomas Dey, 02/23/2018 09:49PM
Posted 02/23/2018 09:49PM Opening Post
Well, here it is. I figured Telescope Making is the closest category. I'm thinking fringes is what it looks like... But not so sure. I'll research it and report back, hoping some guesses come in in the meantime... Tom

Attached Image:

Thomas Dey's attachment for post 61309

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 02/24/2018 08:16AM #1
Hint #1: The fringes were intended to be quadratic frequency with radius, ref phase zero at the center dot. Tom

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 02/24/2018 09:19AM | Edited 02/24/2018 09:21AM #2
Hint #2: If the radial fringe density goes as 1/r, what is the shape of the surface?

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 02/24/2018 10:11AM #3
Thomas Dey said:

Well, here it is. I figured Telescope Making is the closest category. I'm thinking fringes is what it looks like... But not so sure. I'll research it and report back, hoping some guesses come in in the meantime... Tom

Looks like wood to me smile

20" MidnighTelescopes f/5
8" f/16 Muffoletto Achro
Meade 6" AR6 f/8.0 Achro
Celestron C11
Parallax PI250 10" F/5 Newt
Vixen FL102S,NA140SS,R200SS
80mm Stellarvue Nighthawk with WO APOupgrade lens, 90mm f/16.67 Parallax Achro
LXD75/LX200, Mini-tower, GP-DX, CG5 ASGT, LXD650, GM-8, G11, GM-100, GM-150EX, GM-200 and a Gemini G40
4" portable AP convertable 44" or 70" pier
Stellarvue M7 Alt-Az, TSL7 Pier/Tripod
12.5" f/5 MidnighTelescopes DOB Swayze optics
Statham GA
Posted 02/24/2018 04:45PM #4
It's a primitive pizza stone.
Posted 02/24/2018 06:20PM #5
Are these the results from creative beavers bored to insanity during the winter months? :S :S :S

Scopejunkie



40 year old restored C14 with recirculating cooling

w/Skywatcher DOB GOTO Conversion (CPC14)
Posted 02/25/2018 02:20AM #6
I'm guessing a mirror cover three feet diameter.

This is the reason I don't have a dob now. Mine would have been ready two months ago. My mirrors been sitting in a box all winter.
Posted 02/25/2018 09:10PM #7
More pictures; the 36 surrogate is coming great! This shows it all assembled, cept for the 1/4-inch round plate glass "bathroom" mirror faceplate, which is being made now. I have just come in from disassembling it and sanding all the parts for stain and seal next. Notice that there are four stems inside to ballast with barbell weights to achieve 130 lb and CG same place as the real mirror. I will make a crate this week and send the entire thing out to support building of the scope. Tom

Attached Image:

Thomas Dey's attachment for post 152233

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 02/25/2018 09:14PM #8
Nother picture. BTW this is a corner of my home shop, upstairs in the barn, nice 20x30 ft area where I make stuff. Tom

Attached Image:

Thomas Dey's attachment for post 152234

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 02/25/2018 09:25PM | Edited 02/26/2018 02:45AM #9
And another, showing the convex back, made to match the 270-inch convex radius of the Fullum Technofusion 36. After I finished the fine sanding tonight... it's absolutely smooth. Will seat identically in the 27-point back-whiffle / 16-point side-whiffle. Not shown: There will be a 1/20th wave 4-inch plano mirror at the center, so one can also do a ~mock alignment~ of the scope using this surrogate. That will give a good feel for the finesse and stability of alignment (aka "collimation"), and how alignment holds with change in elevation angle. All that, without even needing to the REAL PM in there... Ummmm... this is my aerospace experience prior to semi-retirement. We Always have various surrogates for Big Mirrors, mostly mechanical equivalents, populated with optical references. Tom

Attached Image:

Thomas Dey's attachment for post 152235

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos