World Interferometry Day Celebration: Technology that Made History!

World Interferometry Day Celebration: Technology that Made History!

World Interferometry Day will be celebrated on April 7, 2025. This day honors a technology introduced 140 years ago by Albert A. Michelson with his famous experiment. The event celebrates the revolution in measurement technology, with applications that are important in both precision engineering and gravity research. The preparation for this important event is carried out through a variety of events taking place at the Technical University of Ilmenau take place, supported.

The event includes lectures, live experiments in which participants can actively participate, as well as laboratory tours and an exhibition of holograms. Another highlight will be the laser show, which will start at 9:30 p.m. and will be enriched by the laser harp. Your physical well-being is also taken care of, as food and drinks are provided by the bc student café. Entry to all activities is free.

The Michelson interferometer

The Michelson interferometer, invented by Albert A. Michelson (1852–1931), is a fundamental instrument in optics. It produces interference fringes by splitting a light beam into two parts and bringing them together again using different optical paths. A basic understanding of how it works is important: The interferometer uses a half-silver mirror surface to split the light, with one part being reflected and the other part being transmitted. The reflected beam hits a moving mirror, while the transmitted beam is reflected by a stationary mirror and returns.

Both light rays are coherent and interfere because they originally come from the same point. A compensator plate ensures that both beams pass through the same thickness of glass. The difference in optical paths is described by the equation \(2d_1 – 2d_2\). Constructive interference occurs when the path difference is an integer multiple of the wavelength \(m\lambda_0\), resulting in bright fringes. The movement of a mirror by \(M_1\) by half a light wavelength value (\(\Delta d = \lambda_0/2\)) can cause a movement of the adjacent fringes.

The importance of the interferometer

The Michelson interferometer is not just a teaching tool; it also has significant implications for the definition of the standard meter, which was previously established by shifting a miror corresponding to 1,650,763.73 wavelengths of krypton-86 light. In addition, the light refraction index of a gas can be measured by observing the displaced fringes in a glass chamber. When a gas was introduced into an initially empty chamber, 122 fringes were observed passing a reference line.

By calculating the differences between the number of wavelengths in vacuum and in gas, a differentiated view of the refractive index results. Interferometric measurements require precise techniques because the refractive indices of gases are close to vacuum and sensitive measurements are often necessary. These technologies are not only important for science, but also make Interferometry Day a celebratory occasion.

Further information about the events marking World Interferometry Day 2025 is available on the Ilmenau University of Technology website. The event provides both an opportunity to learn and celebrate an essential technology in modern physics. Visitors are warmly invited to experience the fascinating world of interferometry up close.