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Sun Tracking Stablility Through Imaging

Tyson Seto-Mook

Institute for Astronomy

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Overview

Coelostat back ground General Project Overview Research and Design

Cascade Camera 1k Centroid Equation Centroid routine design

Problems encountered Limitations Project status Future goals

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Coelostat

An optical system which is designed to track and reflect a portion of the sky continuously so that the image doesn’t appear to rotate as the earth spins.

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General Project Overview

Problem Coelostat sun tracking

Drifts Jitters

Solution Take images of reflected beam Calculate centroid of the image Give centroid coordinates

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Photometrics Cascade Cameras

Cascade 1K Low light sensitive 1004x1002 high

resolution

Cascade 128+ Low Light sensitive 128x128 high speed

Availability Programmable control

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Centroid Equation

also known as the center of mass equation

,

0,0

1

3

4 5

65

1

3

3

2

1

1

0 0

0

0

0

0

0

0 0 0 0

0

0

Y = 2X = 3

1 2 3 4

5

1

5

4

2

3

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A B C D

Centroid Routine Design

Object oriented programming Keep routine

independent of program C++ Copy 1d array into a 2d

array for easier programming

Visual Studio 2008 Simple GUI provided Coelostat driver

A B C D

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Problems Encountered Initial Program Design

Overflow when calculating centroid Image intensity values range from 0 to 65535

Possibility of slow calculation Copying 1d array into a 2d array

Modified Program Design Divided by factor of 1000

Prevented overflow Threshold Value of 80% of maximum intensity

Allowed only important data to be read Read Original 1d array

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Limitations Works for high contrast images

Detects flat images at low contrast Image saturation

Placed neutral density filters in front of beam to ensure non-saturated images

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Current status

Base of project completed Working Routine created GUI provided

GUI Single image output Streaming images output

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Possible Future goals

Combine simple GUI with centroid program Have visual and

numerical outputs

Combine Centroid with Coelostat driver

Optimize functions Make more efficient

Create new functions Rate of change function

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Acknowledgements

The Akamai Internship Program is funded by the Center for Adaptive Optics through its National Science Foundation Science and Technology Center grant (#AST-987683) and by grants to the Akamai Workforce Initiative from the National Science Foundation and Air

Force Office of Science Research (both administered by NSF, #AST-0710699) and from the University of Hawaii

Akamai Internship Program

Institute for Atronomy Mentors Jeff Kuhn JD Armstrong John Messersmith Joe Ritter

Scott Seagroves Lynne Raschke Lisa Hunter Lani Lebron