Primary Mirror Repairs

On Wednesday April 27th, we received our repaired lightweighted primary mirror blank from ITT Geospatial Systems who generously donated time and money to the repair of the part. We received the part in September with cracks around the outer part of the mirror as shown below:

ITT sandblasted out the cracks such that the mirror now looks as follows in the areas where the cracks existed:

With the cracks removed the mirror is now less susceptible to damage in the grinding and polishing process as well as to damage due to random loads in everyday use. With the repairs completed the mirror is now moving to Optimax who generously agreed to grind and polish both our primary and secondary mirrors to the best fit sphere (the primary and secondary mirror are both hyperbolas, so before directly polishing to the hyperbolic shape, we usually polish to the best fit sphere). After Optimax finishes the work on the part, it will then pass to QED who graciously agreed to aspherize (figure to the hyperbolic shape) both our primary and secondary mirrors. Finally, at the conclusion of that process, Accucoat has agreed to donate their services to put a reflective coating on our mirrors.

Primary Mirror Mount Design

The team has completed a preliminary design for the primary mirror mount.  The design utilizes a floating 9 point mount composed of three brackets with "V" grooves underneath.   The brackets interface with the existing holes on the open back of the light-weighted primary and exactly constrain the primary mirror.  The PM mount will have 3 differential screws allowing for tip / tilt and piston adjustments.

The optical tube assembly with the PM mount attached to the hexagonal PM casing.

An isometric view of the top of the PM mount.  The three cylinders protruding from the sides are meant to interface with three V grooves on the bottom of the hexagonal casing. This kinematic constraint allows for repeatable mounting and demounting of the primary mirror. 

The PM mount as viewed from underneath.

-Joni

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Mechanical Design Update

The overall mechanical design has been updated to match vendor parts as they keep coming in. Below is a rendering of the most up to date CAD model.

Procurement/Construction

Currently we are procuring parts in anticipation of mechanical design completion in the next few weeks. We appreciate all the support of our sponsors, faculty, friends, and family and cannot wait to unveil our completed scope.

-Alex

Primary Mirror Blank

The 16" blank for the primary mirror was received from AGI in November 2010 with a radius of -3008 mm.
Currently the primary blank is in the our lab awaiting further optical fabrication.

Jig Assembly

The  team completed assembly of a jig structure intended to help with the construction of the OTA [Optical Tube Assembly]. The jig is complete with XYZ control, and will be the primary tool used in assembly the OTA carbon fiber truss.