Mechanical Engineering ETDs

Publication Date

Summer 7-24-2024

Abstract

Concentrating solar mirrors need to have correct geometry to accurately focus sunlight onto a receiver. SOFAST is a tool created at Sandia National Laboratories which measures a mirror’s surface normal at a dense sampling of points, enabling evaluation of a given mirror’s expected performance. SOFAST supports general mirrors, including concentrating solar heliostats, troughs, and dishes. The examples presented in this report predominantly focus on heliostats.

There are generally four major components of a SOFAST system – the mirror, camera, projector, and screen. For SOFAST to properly measure a mirror, the following geometric constraints must be satisfied:

1. The reflection of the screen seen by the camera (the “mirror reflection”) is contained within screen’s boundary.

2. The mirror is within camera’s field of view (FOV).

3. The projector’s field of projection (FOP) spans the required screen area. Note the FOP may spill off the edges of screen.

4. The mirror reflection, FOP, and FOV optical paths must not be occluded.

Finding a design that satisfies all requirements can be challenging, due to coupling between optical components and complex environments with other equipment present. The CAD layout tool aids in this problem. It allows the user to manipulate the four main components to determine a proper layout, with the mirror reflection updating automatically according to Snell’s law. The tool also updates the camera FOV and projector FOP, enabling inspection of optical functionality. This enables the designer to find a design that satisfies the above constraints. Objects in the environment can also be added into the layout tool to check for collisions and further cement the final design before physical implementation. This also aids whether a SOFAST test is physically possible in the desired space. Several varying physical layouts have been created that confirm the model’s solutions. This overview will cover the foundation of the SOFAST CAD Layout Tool and best practices to utilize the tool to the best of its ability.

Keywords

SOFAST, Deflectometry, CAD, CAD Layout Tool, SOFAST 2.0, Metrology

Degree Name

Mechanical Engineering

Level of Degree

Masters

Department Name

Mechanical Engineering

First Committee Member (Chair)

Dr. Peter Vorobieff

Second Committee Member

Dr. Randy Brost

Third Committee Member

Dr. Georgios Koutsakis

Document Type

Thesis

Language

English

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