astronomy

Oswald Leroy

Oswald Leroy is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Oswald Leroy rather than just read about it. In short: Oswald Jozef Leroy (16 May 1936 – 7 September 2022) was a Belgian mathematician known for his contributions to theoretical acousto-optics. Leroy's biggest achievement was a theoretical study of the interaction of light with two adjacent ultrasonic beams under different conditions in terms of beam shape, frequency content and intensity.

Key takeaways

Oswald Leroy belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Oswald Leroy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Oswald Leroy from memory before moving on to harder problems.

Reference excerpt

Oswald Jozef Leroy (16 May 1936 – 7 September 2022) was a Belgian mathematician known for his contributions to theoretical acousto-optics. Leroy's biggest achievement was a theoretical study of the interaction of light with two adjacent ultrasonic beams under different conditions in terms of beam shape, frequency content and intensity. Understanding of this phenomenon was very important in the 1970s when new acousto-optic devices were developed (mainly due to novel developments in laser technology) that utilized adjacent ultrasonic beams. Such devices were being used in optical modulators, optical scanners, information processing , optical filtering and frequency-spectrum analysis. Before his contribution only the interaction of light with one ultrasonic beam was understood. Since then, acousto-optic devices have been used in telecommunication and military applications. Leroy died at Ostend, Belgium in 2022.

Career

Leroy received his PhD from Ghent University in the group of Robert A. Mertens for his thesis entitled Diffraction of light by ultrasound. He worked as an assistant professor at Ghent University from 1966 to 1972 and has been a tenured professor at the Catholic University of Leuven since 1972. New developments in laser physics formed the ground for collaborations between the team of Leroy and different other laboratories. He was a guest professor at the Paris Diderot University and Université de Bordeaux, the University of Tennessee and the Tokyo Institute of Technology. Furthermore, he has collaborated with the University of Gdansk, Georgetown University, and the University of Houston. He retired in 2001 and received the title of emeritus professor.

Awards

In 1991 Leroy was awarded an honorary doctorate from the University of Gdansk, for his contributions to theoretical acousto-optics and to celebrate a collaboration with the team of Antoni Sliwinski at the Institute of Physics of the University of Gdansk. In 2001 he has received the ‘Médaille étrangère’ of the French Acoustical Society.

Selected articles

Leroy O., "Diffraction of light by two adjacent parallel ultrasonic-waves", journal of the acoustical society of America 51(1), 148, 1972 Leroy O., "Theory of diffraction of light by ultrasonic-waves consisting of a fundamental tone and its first n − 1 harmonics", ultrasonics 10(4), 182, 1972 Leroy O., "Diffraction of light by 2 adjacent parallel ultrasonic beams", acustica 29(5), 303–310, 1973 Leroy O., "General symmetry properties of diffraction pattern in diffraction of light by parallel adjacent ultrasonic beams", Journal of sound and vibration 26(3), 389–393, 1973 Leroy O., "Diffraction of light by 2 parallel adjacent ultrasonic-waves, having same wavelengths", journal of sound and vibration 32(2), 241–249, 1974 Leroy, O., "TI light-diffraction caused by adjacent ultrasonics", IEEE transactions on sonics and ultrasonics su22(3), 233, 1975 Poleunis F., Leroy O., "Diffraction of light by 2 adjacent parallel ultrasonic-waves, one being a fundamental tone and other its 2nd harmonic", Journal of sound and vibration, 58(4), 509–515, 1978 Leroy O., Mertens R., "Diffraction of light by adjacent parallel ultrasonic-waves with arbitrary frequencies (noa-method)", acustica 26(2), 96, 1972 W. Hereman, R. Mertens, F. Verheest, O. Leroy, J.M. Claeys, E. Blomme, "Interaction of light and ultrasound : Acoustoopics", Physicalia Magazine 6(4), 213–245, 1984.

Books Physical Acoustics – Fundamentals and Applications, M.A. Breazeale O. Leroy (Eds.), Plenum US, 1991 Advances in Acousto-Optics : 5th International Meeting of the European Acousto-Optical Club, Oswald Leroy (Edt.), Institute of Physics, 2001.

References

Illustrations

Worked examples

Example 1 — a first encounter with Oswald Leroy

Start with the simplest possible case. Write down what Oswald Leroy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Oswald Leroy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Oswald Leroy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Oswald Leroy

In research: Oswald Leroy appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Oswald Leroy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Oswald Leroy is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1935 births, 2022 deaths, Academic staff of Ghent University, so understanding it makes those chapters shorter.
In everyday life: Look for Oswald Leroy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Oswald Leroy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oswald Leroy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Oswald Leroy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oswald Leroy in simple terms?

Why does Oswald Leroy matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Oswald Leroy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Oswald Leroy.