Augustin fresnel biography samples

Augustine-Jean Fresnel was a French physicist and engineer who made valuable contribution in the field of wave optics. Henry Cavendish was a theoretical chemist and physicist, renowned for discovery of hydrogen and calculation of the mass of earth. To know more about his childhood, profile, timeline and career read on. Nikola Tesla was a Serbian-American inventor, best known for his development of alternating current electrical systems.

Augustin-Jean Fresnel was a French physicist best remembered for his invention of compound lenses that transform the radiance of lighthouses and help save many ships from crashing into the rocks at sea. He developed formulas to elucidate refraction, double refraction, reflection and polarized light and also proved that light was a collection of transverse waves.

He embarked on a career as an engineer and began his research in optics. He researched on the diffraction of light and proposed the aether drag hypothesis in addition to many other discoveries and deductions. Building on the work of English physicist Thomas Young, he helped to establish the wave theory of light. Fresnel remained undeterred by this lack of appreciation and at all times remained focused on his research and work.

Browse through this biography to learn in details about his life, career, works and timeline. In fact the overlap between Arago's work and Biot's was minimal, Arago's being only qualitative and wider in scope attempting to include polarization by reflection. But the dispute triggered a notorious falling-out between the two men. Later that year, Biot tried to explain the observations as an oscillation of the alignment of the "affected" corpuscles at a frequency proportional to that of Newton's "fits", due to forces depending on the alignment.

This theory became known as mobile polarization. To reconcile his results with a sinusoidal oscillation, Biot had to suppose that the corpuscles emerged with one of two permitted orientations, namely the extremes of the oscillation, with probabilities depending on the phase of the oscillation. But in , Biot reported that the case of quartz was simpler: the observable phenomenon now called optical rotation or optical activity or sometimes rotary polarization was a gradual rotation of the polarization direction with distance, and could be explained by a corresponding rotation not oscillation of the corpuscles.

Early in , reviewing Biot's work on chromatic polarization, Young noted that the periodicity of the color as a function of the plate thickness—including the factor by which the period exceeded that for a reflective thin plate, and even the effect of obliquity of the plate but not the role of polarization —could be explained by the wave theory in terms of the different propagation times of the ordinary and extraordinary waves through the plate.

In summary, in the spring of , as Fresnel tried in vain to guess what polarization was, the corpuscularists thought that they knew, while the wave-theorists if we may use the plural literally had no idea. Both theories claimed to explain rectilinear propagation, but the wave explanation was overwhelmingly regarded as unconvincing. The corpuscular theory could not rigorously link double refraction to surface forces; the wave theory could not yet link it to polarization.

The corpuscular theory was weak on thin plates and silent on gratings; [ Note 2 ] the wave theory was strong on both, but under-appreciated. Concerning diffraction, the corpuscular theory did not yield quantitative predictions, while the wave theory had begun to do so by considering diffraction as a manifestation of interference, but had only considered two rays at a time.

Only the corpuscular theory gave even a vague insight into Brewster's angle, Malus's law, or optical rotation. Concerning chromatic polarization, the wave theory explained the periodicity far better than the corpuscular theory, but had nothing to say about the role of polarization; and its explanation of the periodicity was largely ignored.

Such were the circumstances in which Arago first heard of Fresnel's interest in optics. Fresnel's letters from later in reveal his interest in the wave theory, including his awareness that it explained the constancy of the speed of light and was at least compatible with stellar aberration. In mid , on his way home to Mathieu to serve his suspension, Fresnel met Arago in Paris and spoke of the wave theory and stellar aberration.

I do not know of any book that contains all the experiments that physicists are doing on the diffraction of light. M'sieur Fresnel will only be able to get to know this part of the optics by reading the work by Grimaldi , the one by Newton, the English treatise by Jordan, [ 92 ] and the memoirs of Brougham and Young, which are part of the collection of the Philosophical Transactions.

Fresnel would not have ready access to these works outside Paris, and could not read English. Later in July, after Napoleon's final defeat, Fresnel was reinstated with the advantage of having backed the winning side. He requested a two-month leave of absence, which was readily granted because roadworks were in abeyance. On 23 September he wrote to Arago, beginning "I think I have found the explanation and the law of colored fringes which one notices in the shadows of bodies illuminated by a luminous point.

In a memoir sent to the institute on 15 October , Fresnel mapped the external and internal fringes in the shadow of a wire. To explain the diffraction pattern, Fresnel constructed the internal fringes by considering the intersections of circular wavefronts emitted from the two edges of the obstruction, and the external fringes by considering the intersections between direct waves and waves reflected off the nearer edge.

For the external fringes, to obtain tolerable agreement with observation, he had to suppose that the reflected wave was inverted ; and he noted that the predicted paths of the fringes were hyperbolic. In the part of the memoir that most clearly surpassed Young, Fresnel explained the ordinary laws of reflection and refraction in terms of interference, noting that if two parallel rays were reflected or refracted at other than the prescribed angle, they would no longer have the same phase in a common perpendicular plane, and every vibration would be cancelled by a nearby vibration.

He noted that his explanation was valid provided that the surface irregularities were much smaller than the wavelength. On 10 November, Fresnel sent a supplementary note dealing with Newton's rings and with gratings, [ ] including, for the first time, transmission gratings—although in that case the interfering rays were still assumed to be "inflected", and the experimental verification was inadequate because it used only two threads.

As Fresnel was not a member of the institute, the fate of his memoir depended heavily on the report of a single member. The reporter for Fresnel's memoir turned out to be Arago with Poinsot as the other reviewer. I have been instructed by the Institute to examine your memoir on the diffraction of light; I have studied it carefully, and found many interesting experiments, some of which had already been done by Dr.

Thomas Young, who in general regards this phenomenon in a manner rather analogous to the one you have adopted. But what neither he nor anyone had seen before you is that the external colored bands do not travel in a straight line as one moves away from the opaque body. The results you have achieved in this regard seem to me very important; perhaps they can serve to prove the truth of the undulatory system, so often and so feebly combated by physicists who have not bothered to understand it.

Fresnel was troubled, wanting to know more precisely where he had collided with Young. Thus Arago erred in his belief that the curved paths of the fringes were fundamentally incompatible with the corpuscular theory. Arago's letter went on to request more data on the external fringes. He arrived in March , and his leave was subsequently extended through the middle of the year.

Meanwhile, in an experiment reported on 26 February , Arago verified Fresnel's prediction that the internal fringes were shifted if the rays on one side of the obstacle passed through a thin glass lamina. Fresnel correctly attributed this phenomenon to the lower wave velocity in the glass. But the new link was not rigorous, and Pouillet himself would become a distinguished early adopter of the wave theory.

On 24 May , Fresnel wrote to Young in French , acknowledging how little of his own memoir was new. To explain this, he divided the incident wavefront at the obstacle into what we now call Fresnel zones , such that the secondary waves from each zone were spread over half a cycle when they arrived at the observation point. The zones on one side of the obstacle largely canceled out in pairs, except the first zone, which was represented by an "efficacious ray".

This approach worked for the internal fringes, but the superposition of the efficacious ray and the direct ray did not work for the external fringes. The contribution from the "efficacious ray" was thought to be only partly canceled, for reasons involving the dynamics of the medium: where the wavefront was continuous, symmetry forbade oblique vibrations; but near the obstacle that truncated the wavefront, the asymmetry allowed some sideways vibration towards the geometric shadow.

This argument showed that Fresnel had not yet fully accepted Huygens's principle, which would have permitted oblique radiation from all portions of the front. A conventional double-slit experiment required a preliminary single slit to ensure that the light falling on the double slit was coherent synchronized. In Fresnel's version, the preliminary single slit was retained, and the double slit was replaced by the double mirror—which bore no physical resemblance to the double slit and yet performed the same function.

This result which had been announced by Arago in the March issue of the Annales made it hard to believe that the two-slit pattern had anything to do with corpuscles being deflected as they passed near the edges of the slits. But was the " Year Without a Summer ": crops failed; hungry farming families lined the streets of Rennes; the central government organized "charity workhouses" for the needy; and in October, Fresnel was sent back to Ille-et-Vilaine to supervise charity workers in addition to his regular road crew.

The mission to defend the revenues of the state, to obtain for them the best employment possible, appeared to his eyes in the light of a question of honour.

Augustin fresnel biography samples

The functionary, whatever might be his rank, who submitted to him an ambiguous account, became at once the object of his profound contempt. Fresnel's letters from December reveal his consequent anxiety. In the fall of , Fresnel, supported by de Prony, obtained a leave of absence from the new head of the Corp des Ponts, Louis Becquey , and returned to Paris.

On 15 January , in a different context revisited below , Fresnel showed that the addition of sinusoidal functions of the same frequency but different phases is analogous to the addition of forces with different directions. The explanation was algebraic rather than geometric. Knowledge of this method was assumed in a preliminary note on diffraction, [ ] dated 19 April and deposited on 20 April, in which Fresnel outlined the elementary theory of diffraction as found in modern textbooks.

He restated Huygens's principle in combination with the superposition principle , saying that the vibration at each point on a wavefront is the sum of the vibrations that would be sent to it at that moment by all the elements of the wavefront in any of its previous positions, all elements acting separately see Huygens—Fresnel principle.

For a wavefront partly obstructed in a previous position, the summation was to be carried out over the unobstructed portion. In directions other than the normal to the primary wavefront, the secondary waves were weakened due to obliquity, but weakened much more by destructive interference, so that the effect of obliquity alone could be ignored.

The same note included a table of the integrals, for an upper limit ranging from 0 to 5. For completeness, he repeated his solution to "the problem of interference", whereby sinusoidal functions are added like vectors. He acknowledged the directionality of the secondary sources and the variation in their distances from the observation point, chiefly to explain why these things make negligible difference in the context, provided of course that the secondary sources do not radiate in the retrograde direction.

Then, applying his theory of interference to the secondary waves, he expressed the intensity of light diffracted by a single straight edge half-plane in terms of integrals which involved the dimensions of the problem, but which could be converted to the normalized forms above. With reference to the integrals, he explained the calculation of the maxima and minima of the intensity external fringes , and noted that the calculated intensity falls very rapidly as one moves into the geometric shadow.

For the experimental testing of his calculations, Fresnel used red light with a wavelength of nm, which he deduced from the diffraction pattern in the simple case in which light incident on a single slit was focused by a cylindrical lens. For a variety of distances from the source to the obstacle and from the obstacle to the field point, he compared the calculated and observed positions of the fringes for diffraction by a half-plane, a slit, and a narrow strip—concentrating on the minima, which were visually sharper than the maxima.

For the slit and the strip, he could not use the previously computed table of maxima and minima; for each combination of dimensions, the intensity had to be expressed in terms of sums or differences of Fresnel integrals and calculated from the table of integrals, and the extrema had to be calculated anew. Near the end of the memoir, Fresnel summed up the difference between Huygens's use of secondary waves and his own: whereas Huygens says there is light only where the secondary waves exactly agree, Fresnel says there is complete darkness only where the secondary waves exactly cancel out.

The judging committee comprised Laplace, Biot, and Poisson all corpuscularists , Gay-Lussac uncommitted , and Arago, who eventually wrote the committee's report. In the words of John Worrall , "The competition facing Fresnel could hardly have been less stiff. The committee deliberated into the new year. This seems to have been intended as a reductio ad absurdum.

Arago, undeterred, assembled an experiment with an obstacle 2 mm in diameter—and there, in the center of the shadow, was Poisson's spot. Arago's verification of Poisson's counter-intuitive prediction passed into folklore as if it had decided the prize. First, although the professionalization of science in France had established common standards, it was one thing to acknowledge a piece of research as meeting those standards, and another thing to regard it as conclusive.

Arago even encouraged that interpretation, presumably in order to minimize resistance to Fresnel's ideas. An emission theory of light was one that regarded the propagation of light as the transport of some kind of matter. While the corpuscular theory was obviously an emission theory, the converse did not follow: in principle, one could be an emissionist without being a corpuscularist.

This was convenient because, beyond the ordinary laws of reflection and refraction, emissionists never managed to make testable quantitative predictions from a theory of forces acting on corpuscles of light. But they did make quantitative predictions from the premises that rays were countable objects, which were conserved in their interactions with matter except absorbent media , and which had particular orientations with respect to their directions of propagation.

This approach, which Jed Buchwald has called selectionism , was pioneered by Malus and diligently pursued by Biot. In July or August , Fresnel discovered that when a birefringent crystal produced two images of a single slit, he could not obtain the usual two-slit interference pattern, even if he compensated for the different propagation times.

A more general experiment, suggested by Arago, found that if the two beams of a double-slit device were separately polarized, the interference pattern appeared and disappeared as the polarization of one beam was rotated, giving full interference for parallel polarizations, but no interference for perpendicular polarizations see Fresnel—Arago laws.

In a memoir drafted on 30 August and revised on 6 October, Fresnel reported an experiment in which he placed two matching thin laminae in a double-slit apparatus—one over each slit, with their optic axes perpendicular—and obtained two interference patterns offset in opposite directions, with perpendicular polarizations. This, in combination with the previous findings, meant that each lamina split the incident light into perpendicularly polarized components with different velocities—just like a normal thick birefringent crystal, and contrary to Biot's "mobile polarization" hypothesis.

Accordingly, in the same memoir, Fresnel offered his first attempt at a wave theory of chromatic polarization. When polarized light passed through a crystal lamina, it was split into ordinary and extraordinary waves with intensities described by Malus's law , and these were perpendicularly polarized and therefore did not interfere, so that no colors were produced yet.

But if they then passed through an analyzer second polarizer , their polarizations were brought into alignment with intensities again modified according to Malus's law , and they would interfere. But in fact, as Arago and Biot had found, they are of complementary colors. This inversion was a weakness in the theory relative to Biot's, as Fresnel acknowledged, [ ] although the rule specified which of the two images had the inverted wave.

Although modern readers easily interpret these factors in terms of perpendicular components of a transverse oscillation, Fresnel did not yet explain them that way. Hence he still needed the phase-inversion rule. Fresnel applied the same principles to the standard case of chromatic polarization, in which one birefringent lamina was sliced parallel to its axis and placed between a polarizer and an analyzer.

If the analyzer took the form of a thick calcite crystal with its axis in the plane of polarization, Fresnel predicted that the intensities of the ordinary and extraordinary images of the lamina were respectively proportional to. These equations were included in an undated note that Fresnel gave to Biot, [ ] to which Biot added a few lines of his own.

If we substitute. If Biot's substitutions were accurate, they would imply that his experimental results were more fully explained by Fresnel's theory than by his own. Arago delayed reporting on Fresnel's works on chromatic polarization until June , when he used them in a broad attack on Biot's theory. In his written response, Biot protested that Arago's attack went beyond the proper scope of a report on the nominated works of Fresnel.

That claim drew a written reply from Fresnel, [ ] who disputed whether the colors changed as abruptly as Biot claimed, [ ] and whether the human eye could judge color with sufficient objectivity for the purpose. On the latter question, Fresnel pointed out that different observers may give different names to the same color. Furthermore, he said, a single observer can only compare colors side by side; and even if they are judged to be the same, the identity is of sensation, not necessarily of composition.

Arago and Fresnel were seen to have won the debate. Moreover, by this time Fresnel had a new, simpler explanation of his equations on chromatic polarization. But Fresnel could not develop either of these ideas into a comprehensive theory. But that would raise a new difficulty: as natural light seemed to be un polarized and its waves were therefore presumed to be longitudinal, one would need to explain how the longitudinal component of vibration disappeared on polarization, and why it did not reappear when polarized light was reflected or refracted obliquely by a glass plate.

Independently, on 12 January , Young wrote to Arago in English noting that a transverse vibration would constitute a polarization, and that if two longitudinal waves crossed at a significant angle, they could not cancel without leaving a residual transverse vibration. Thus Fresnel, by his own testimony, may not have been the first person to suspect that light waves could have a transverse component , or that polarized waves were exclusively transverse.

And it was Young, not Fresnel, who first published the idea that polarization depends on the orientation of a transverse vibration. But these incomplete theories had not reconciled the nature of polarization with the apparent existence of unpolarized light; that achievement was to be Fresnel's alone. In a note that Buchwald dates in the summer of , Fresnel entertained the idea that unpolarized waves could have vibrations of the same energy and obliquity, with their orientations distributed uniformly about the wave-normal, and that the degree of polarization was the degree of non -uniformity in the distribution.

Two pages later he noted, apparently for the first time in writing, that his phase-inversion rule and the non-interference of orthogonally-polarized beams would be easily explained if the vibrations of fully polarized waves were "perpendicular to the normal to the wave"—that is, purely transverse. But if he could account for lack of polarization by averaging out the transverse component, he did not also need to assume a longitudinal component.

It was enough to suppose that light waves are purely transverse, hence always polarized in the sense of having a particular transverse orientation, and that the "unpolarized" state of natural or "direct" light is due to rapid and random variations in that orientation, in which case two coherent portions of "unpolarized" light will still interfere because their orientations will be synchronized.

But he first published the idea in a paper on " Calcul des teintes… " "calculation of the tints…" , serialized in Arago's Annales for May, June, and July It has only been for a few months that in meditating more attentively on this subject, I have realized that it was very probable that the oscillatory movements of light waves were executed solely along the plane of these waves, for direct light as well as for polarized light.

According to this new view, he wrote, "the act of polarization consists not in creating these transverse movements, but in decomposing them into two fixed perpendicular directions and in separating the two components". While selectionists could insist on interpreting Fresnel's diffraction integrals in terms of discrete, countable rays, they could not do the same with his theory of polarization.

For a selectionist, the state of polarization of a beam concerned the distribution of orientations over the population of rays, and that distribution was presumed to be static. For Fresnel, the state of polarization of a beam concerned the variation of a displacement over time. That displacement might be constrained but was not static, and rays were geometric constructions, not countable objects.

The conceptual gap between the wave theory and selectionism had become unbridgeable. The other difficulty posed by pure transverse waves, of course, was the apparent implication that the aether was an elastic solid , except that, unlike other elastic solids, it was incapable of transmitting longitudinal waves. In the second installment of "Calcul des teintes" June , Fresnel supposed, by analogy with sound waves, that the density of the aether in a refractive medium was inversely proportional to the square of the wave velocity, and therefore directly proportional to the square of the refractive index.

For reflection and refraction at the surface between two isotropic media of different indices, Fresnel decomposed the transverse vibrations into two perpendicular components, now known as the s and p components, which are parallel to the surface and the plane of incidence, respectively; in other words, the s and p components are respectively square and parallel to the plane of incidence.

The predicted reflectivity was non-zero at all angles. The third installment July was a short "postscript" in which Fresnel announced that he had found, by a "mechanical solution", a formula for the reflectivity of the p component, which predicted that the reflectivity was zero at the Brewster angle. So polarization by reflection had been accounted for—but with the proviso that the direction of vibration in Fresnel's model was perpendicular to the plane of polarization as defined by Malus.

On the ensuing controversy, see Plane of polarization. The technology of the time did not allow the s and p reflectivities to be measured accurately enough to test Fresnel's formulae at arbitrary angles of incidence. But the formulae could be rewritten in terms of what we now call the reflection coefficient : the signed ratio of the reflected amplitude to the incident amplitude.

Fresnel had measured it for a range of angles of incidence, for glass and water, and the agreement between the calculated and measured angles was better than 1. The reflection coefficients for the s and p polarizations are most succinctly expressed as. This success inspired James MacCullagh and Augustin-Louis Cauchy , beginning in , to analyze reflection from metals by using the Fresnel equations with a complex refractive index.

With these generalizations, the Fresnel equations can predict the appearance of a wide variety of objects under illumination—for example, in computer graphics see Physically based rendering. He then explained how optical rotation could be understood as a species of birefringence. Linearly-polarized light could be resolved into two circularly-polarized components rotating in opposite directions.

If these components propagated at slightly different speeds, the phase difference between them—and therefore the direction of their linearly-polarized resultant—would vary continuously with distance. These concepts called for a redefinition of the distinction between polarized and unpolarized light. At this stage he had carried out fairly similar investigations that Thomas Young had carried out between and in Cambridge, but Fresnel next moved forward to a new understanding by developing a theory based on a new mathematical formulation.

He put forward the idea that [ 1 ] The problem was to determine the resultant vibration produced by all the wavelets reaching any point behind the diffracter. The mathematical difficulties were formidable, and a solution was to require many months of effort. Fresnel published his first tentative results in July but asked that the readers of his article show patience while he worked out further consequences of the mathematics.

It was a great chance for Fresnel to put his revolutionary work before the world and he was very confident of his theory since his mathematical deductions from the one simple hypothesis led to results which he had verified experimentally giving a highly accurate agreement between theory and experimental evidence. He completed his mathematical work just before the time for submission and this allowed him to calculate the intensity of light at every point behind the diffracter using what were later called Fresnel's integrals.

It was a committee which was not well disposed to the wave theory of light, most believing in the corpuscular model. However Poisson was fascinated by the mathematical model which Fresnel proposed and succeeded in computing some of the integrals to find further consequences beyond those which Fresnel had deduced. Poisson wrote [ 3 ] :- Let parallel light impinge on an opaque disk, the surrounding being perfectly transparent.

The disk casts a shadow - of course - but the very centre of the shadow will be bright. Succinctly, there is no darkness anywhere along the central perpendicular behind an opaque disk except immediately behind the disk. This was a remarkable prediction, but Arago asked that Poisson 's predictions based on Fresnel's mathematical model be tested.

Indeed the bright spot was seen to be there exactly as Fresnel's theory predicted. The consequence has been submitted to the test of direct experiment, and observation has perfectly confirmed the calculation. Fresnel was awarded the Grand Prix and his work was a strong argument for a wave theory of light. However polarisation of light produced by reflection still provided a strong argument in favour of the corpuscular theory, since no explanation from a wave theory had ever been made.

Fresnel and Arago , now very confident that they could explain this effect with Fresnel's theory, undertook further work on polarisation and Fresnel discovered what was later called circularly polarised light. No hypothesis led to the experimental results obtained other than that light is a transverse wave and, in , Fresnel published a paper in which he claimed with certainty that light is a transverse wave.

Jean-Augustin Fresnel, physicist, was born in Broglie, near Bernay, in this part of the former province of Normandy which today forms the department of Eure, May 10, He died in Ville-d Avray, near Paris, June 27, He entered the Ecole polytechnique at the age of sixteen, and his older brother had preceded him by one year. His health was extremely feeble, and made him fear that he could not endure the fatigues of so rough a novitiate.

But this stupid body contained a vigorous soul. When he left this school, after having been a brilliant pupil and having received the public congratulations of the geometer Legendre, for the difficult solution of a problem of geometry, he entered the School of Bridges and Roads, that he left with the title and functions of an ordinary engineer, and was first sent to Vendee, then successively to the departments of Drome and Ille-et-Vilaine.

Fresnel devoted himself to the pure sciences only in His first memoir dates back to this time. It is an attempt to rectify the very imperfect explanation of the phenomenon of the annual aberration of the stars. From this moment, memories succeeded memories, discoveries discoveries, with a rapidity of which the history of science offers few examples.

On December 28th of this year, we see him writing from Nyons: "I do not know what is meant by the polarization of the light, Pray M. Merimee, my uncle, to send me the works in which I will be able to learn.