Developing Optical Constants for Use in Space Exploration and Earth Science

Answering the Big Questions About Earth and Space

In the Department of Physics and Astronomy, students and professors are working in the field of optics to answer big questions about earth and space.

To learn about the physical properties of stars, for example, or the materials that make up the earth, scientists have begun working in the extreme ultraviolet range of the electromagnetic spectrum. Compared to ultraviolet light, extreme ultraviolet is even more difficult to detect, but has the ability to help scientists understand gases at the center of stars and at the earth’s core.

To study objects using extreme ultraviolet wavelengths, scientists use mirrors to manipulate light at tiny wavelengths. An optics scientist’s goal is to create the smoothest mirror possible in order to see the various spectra in their purest form. A perfectly smooth surface on a mirror is impossible, but scientists are learning new ways to minimize and account for the “roughness,” creating a more accurate picture. The mirrors can be mounted on a space probe to monitor the stars or on a satellite to monitor the earth.

The department is studying how new materials can minimize roughness on a mirror. A material called thorium dioxide is showing the most promise for the researchers. But even thorium dioxide can’t create a completely smooth surface. So Harrison has created a program that can account for the roughness on a mirror.

A professor had been looking for a broad mathematics library that also has an easy programming
language. He found the IMSL Numerical Library for Java (JMSL). They uses the JMSL Library on a Windows PC along with Eclipse, a Java development platform. The researchers took advantage of the Quick Start feature in the JMSL Library.

The Quick Start guide was very useful. It made learning the JMSL Library language very easy. Chart routines and math routines are also very easy to find.

Using the JMSL Library, researchers simulated a perfectly smooth mirror and an ordinary mirror coated with thorium dioxide. They used the chart class to easily create images of her random surfaces. Then modeled the radiation (EUV rays) reflecting off of the surface. For the models, researchers used the Random, Quadrature, Spline, and Fourier Transform math routines.

The researchers collected the reflection readings from 0 to 90 degrees across the surface of the mirror. At each degree, they would collect 1000 points. The application compares reflection from the smooth surface data to the rough surface data to get an effective reflection coefficient for the thorium dioxide. The program could apply to any kind of material, which would help scientists explore other materials for minimizing mirror roughness. 

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