Student Education Repository (மாணவர்கள் கல்விக் களஞ்சியம்): Today (December 11, 1945) is the anniversary of French physicist Charles Fabry, who invented the Fabry

Friday, December 11, 2020

Today (December 11, 1945) is the anniversary of French physicist Charles Fabry, who invented the Fabry – Pérot interferometer.

Today (December 11, 1945) is the anniversary of French physicist Charles Fabry, who invented the Fabry – Pérot interferometer.

Maurice Paul Auguste Charles Fabry was born on June 11, 1867, in Marseille. Charles Fabri graduated from the Ecole Polytechnic in Paris. He received a doctorate from the University of Paris in 1892 for his work on intersecting margins, establishing him as a personality in the field of optics and chromatography. In 1904 he was appointed Professor of Physics at the University of Marseille, where he worked for 26 years. Found an explanation for the phenomenon of intersecting edges in optics. In 1899, he, along with his colleague Alfred Perro, invented the Fabry-Pero interferometer. He discovered the ozone layer in 1913 with Enrique Puvason.

In optics, the Fabry – Pérot interferometer or Etalon is an instrument used to measure the wavelength of light. The instrument is named after Charles Fabry and Alfred Pero. Glass can reflect and transmit light. A glass reflects 95% of the light, reflecting 95% of the falling light and transmitting five percent. The effect is slightly different if you put another glass next to it. Thus the system for placing two glasses is called Etalon. How much light is available on the other side if light passes through this Edelon system? Shouldn’t less than five percent of the light be available according to our understanding? For example, let's say the first glass is M1 and the second glass is M2. Assume that these two glasses are 95% reflective. Assume that the light from the left side passes through the Edelon system. Five percent of the light penetrates the first glass (M1) and reaches the second glass (M2). In this second glass (M2) the remaining light penetrates and passes through five percent. So a total of 0.25% (5% of 5%, 0.25%) of light should reach the right side. But what is surprising is that at a certain distance between these two mirrors the total light (100%) reaches the other side.

Fabry, Perot, and their wonderful interferometer (1897, 1899) | Skulls in the Stars

Let us assume that one watt of energy flows from the left side into this etalon system. In the picture, some light beams between these two mirrors are shown to illustrate their function. Each beam shown in it has a different phase. There is no phase relationship between these beams. This Edelon is a non-resonant system due to a lack of phase contact. The result is a small amount of light passing through the Edelon system. The distance between these two glasses must be half the wavelength of light if a Fabry-Pero Edelon resonance is to occur. If this is the case then no full-phase transformation of the light beam takes place. The result is that light beams travelling in the same direction are all at the same point. The same goes for the re-direction. The power between the two mirrors increases as a result of the reflection of the light beams (approximately 20 watts of energy oscillates between the system!). However, the energy that falls in Edelon is only a watt of something! How is this possible?

The first glass (M1) has a reflectivity of 95% so that 0.95 watts is reflected on the left side and one watt is transmitted on the right side (beyond M2) (in the resonance system) so that the total emitted energy is greater than the energy falling in the Edolon system. This is contrary to the Law of Conservation of Energy. 20 watts of power is required between these two glasses to transmit one watt of light to the right. This 20-watt energy falls on the second (M2) glass and passes one watt to the right. The remaining 19 watts are reflected in the second (M2) glass and reach the first glass (M1). But because the first glass (M1) is 95% reflective, the remaining 0.95 watts (5% = 0.95 watts out of 19) are transmitted and exited on the left side. But the phase of light transmitted by M1 is opposite to the light reflected by M1. Thus the left side balances these two lights. Thus there is no energy on the left side. But a watt of energy on the right-hand side passes through M2. A mirror that was a reflective spot turns into the shattered glass along with a second mirror. This nature (resonance) can be brought about by distinguishing the distance between these two mirrors. The same thing happens with the Fabry-Pero intervention.

In 1921, Fabry was appointed professor of general physics at Sorbonne. He also became the first director of the new optics company. In 1926 Ecole became a professor at the University of Polytechnic. In 1929, he received the highest award of the French Astronomical Society. From 1931 to 1933 he served as president of the academy. During his tenure, Fabry has written 197 scientific research papers, 14 books, and more than a hundred articles. In 1918 he was awarded the Report Medal of the Royal Society of London for his important scientific achievements. His work was recognized in the United States and he received the Henry Draper Medal (1919) from the American National Academy of Sciences and the Medal from the Franklin Academy (1919). In 1927 he was elected to the French Academy of Sciences. Charles Fabry, the inventor of the Fabry-Pero interceptor, died in Paris on December 11, 1945, at the age of 78.

Source By: Wikipedia

Information: Ramesh, Assistant Professor of Physics, Nehru Memorial College, Puthanampatti, Trichy.