BINOSPEC METROLOGY

BINOSPEC METROLOGY

Alex Gary

Astronomical spectrograph for the MMT Observatory on Mount Hopkins in Arizona

2007- project design completed by Harvard University

Used extensively by the University of Arizonaand other institutions

Binospec

Binospec is an imaging spectrograph with dual 8'x15' fields of view

dual slitmasks which can hold up to 150 slitlets for multiobject spectroscopy.

Superior sky subtraction with these slitlets will allow Binospec to reach 3-4 magnitudes deeper than Hectospec

Binospec uses the fiber spectroscopy configuration of the corrector, which has built-in atmospheric dispersion compensation.

Binospec

In order to allow the design to work with so many slitlets a callibration screen was necessary in order to assure proper viewing.

This is the specific part of the assembly that I was involved in.

Calibration Screen

As the project came to fruition a precise method of measuring and checking key points and joints in the connecting structures was essential

Between manufacturing and assembly, metrology is required to troubleshoot any problems that may come up during assembly before assembly begins

As parts come in for assembly they were measured and compared to nominal coordinates to determine any problems or complications

The Metrology Stage

The Metrology process involved a FARO Arm and CAM 2 Measure 10 Software.

The entire process of metrology involved a 3-Stage Process.

The Three Stages to the Metrology involved Set Up, Measurement, and Analysis.

Metrology Technique

Set up involves both physical and virtual set up.

The piece to be measured had to strategically mounted to get all of the required measurements

A solid works model was uploaded to the CAM 2 Software and the desired planes and circles had to be selected before measurement could begin

Set Up

Cover 5

•FARO Arm •Solid Works Model (Before Set Up)

•Model in CAM 2 Software (Post Set Up)

Set Up (Physical and Virtual)

After Set Up is complete measurements can be taken with the FARO Arm. It is a rather simple process but involves attention to detail and care to make sure no simple mistakes are made.

Measurement

Analysis involves comparing the actual and nominal measurements, determining sources of error in either manufacturing or the measurement stage, and deciding on actions to be take on any error found.

Actions taken during the analysis stage can range from returning to the measurement stage, making slight modifications ourselves, or returning the entire part to the manufacturer.

Analysis

CAM 2 Software allows does some of the analysis on its own. This is a sample of the analysis for the handling cart interface. This crucial part had to be precisely manufactured so every plane and circle was analyzed with scrutiny (and passed)

Analysis Sample

After a week and a half of Metrology we found no crucial problem so we began assembly. The entire frame assembly was simple with only one minor modification needed.

Beyond this the internal structure of the Calibrator Screen and Derotator Assembly had to be completed.

Recently other metrology and engineering decisions had to be made to make assembly run smoother

Overall Summer Metrology Results

Directions vs Reality

BINOSPEC TEAM