Eggplant.place

1y

<a href="/tags/otd/" rel="tag">#OTD</a> in 1818.French physicist Augustin Fresnel signs his preliminary "Note on the Theory of Diffraction" (deposited on the following day). The document ends with what we now call the Fresnel integrals.The Fresnel integrals have various applications in optics, such as in the calculation of the diffraction pattern produced by a single slit or a circular aperture, as well as in the study of the propagation of light through various optical systems. <a href="/tags/books/" rel="tag">#books</a> <a href="/tags/science/" rel="tag">#science</a> <a href="/tags/physics/" rel="tag">#physics</a> <a href="/tags/optics/" rel="tag">#optics</a>

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1y

<a href="/tags/otd/" rel="tag">#OTD</a> in 1822.French physicist Augustin-Jean Fresnel, in a "note" read to the Academy of Sciences, reports a direct refraction experiment verifying David Brewster's hypothesis that photoelasticity (as it is now known) is stress-induced birefringence.<a href="https://en.wikipedia.org/wiki/Birefringence" rel="nofollow" class="ellipsis" title="en.wikipedia.org/wiki/Birefringence">https://en.wikipedia.org/wiki/Birefringence</a><a href="/tags/science/" rel="tag">#science</a> <a href="/tags/physics/" rel="tag">#physics</a> <a href="/tags/optics/" rel="tag">#optics</a>

Annales de Chimie et de Physique, Ser. 2, vol. 17, pp. 102–111 (May 1821)

https://archive.org/details/s3id13207850/page/102/mode/2up

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1y

French physicist Léon Foucault was born <a href="/tags/otd/" rel="tag">#OTD</a> in 1819.He is best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of Earth's rotation. With Hippolyte Fizeau he carried out a series of investigations on the intensity of the light of the sun, as compared with that of carbon in the arc lamp, and of lime in the flame of the oxyhydrogen blowpipe. His is one of the 72 names inscribed on the Eiffel Tower.<a href="https://en.wikipedia.org/wiki/L%C3%A9on_Foucault" rel="nofollow" class="ellipsis" title="en.wikipedia.org/wiki/L%C3%A9on_Foucault">https://en.wikipedia.org/wiki/L%C3%A9on_Foucault</a><a href="/tags/physics/" rel="tag">#physics</a> <a href="/tags/optics/" rel="tag">#optics</a> <a href="/tags/mechanics/" rel="tag">#mechanics</a>

Portrait of Léon Foucault french physicist, astronomer(1819–1868).
Photograph by Bertall & Cie.

Foucault’s face is often characterized by a calm, serious expression, fitting for a scientist of his stature. His features, which include a high forehead and prominent nose, reflect the intellectual rigor and curiosity that drove his scientific work.

Foucault is depicted wearing formal attire, typically a dark coat and a high-collared shirt, as was customary for gentlemen and scholars in the 19th century.

Foucault is often portrayed with neatly styled hair, parted at the side, and a well-groomed beard or mustache.

Foucault is seated or standing in a formal pose with a book in his left hand.

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245d

Watching the World in a Dark Room The Early Modern Camera ObscuraBy Julie ParkCenturies before photography froze the world into neat frames, scientists, poets, and artists streamed transient images into dark interior spaces with the help of a camera obscura. <a href="https://publicdomainreview.org/essay/the-early-modern-camera-obscura/?utm_source=newsletter" rel="nofollow" class="ellipsis" title="publicdomainreview.org/essay/the-early-modern-camera-obscura/?utm_source=newsletter">https://publicdomainreview.org/essay/the-early-modern-camera-obscura/?utm_source=newsletter</a>Books about Photography at PG: <a href="https://www.gutenberg.org/ebooks/subject/117" rel="nofollow" class="ellipsis" title="www.gutenberg.org/ebooks/subject/117">https://www.gutenberg.org/ebooks/subject/117</a><a href="/tags/camera_obscura/" rel="tag">#camera_obscura</a> <a href="/tags/photography/" rel="tag">#photography</a> <a href="/tags/optics/" rel="tag">#optics</a>

Illustration of the camera obscura principle from James Ayscough's A short account of the eye and nature of vision (1755 fourth edition).

A camera obscura is the natural phenomenon in which the rays of light passing through a small hole into a dark space form an image where they strike a surface, resulting in an inverted (upside down) and reversed (left to right) projection of the view outside.

https://commons.wikimedia.org/wiki/File:1755_james_ayscough.jpg

Original image:
https://archive.org/details/b30373177/page/n33/mode/2up

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1d

By now, you have seen the Earth image by the <a href="/tags/artemis/" rel="tag">#Artemis</a> crew at least a hundred times. In this annotated version, several <a href="/tags/optics/" rel="tag">#optics</a> effects are highlighted. It also shows how fragile planet <a href="/tags/earth/" rel="tag">#Earth</a> is, with a super thin <a href="/tags/atmosphere/" rel="tag">#atmosphere</a> protecting us from the harsh vacuum of space. Let's protect it.

Earth is shown against a black background with stars and planet Venus. Aurora, moonglint, moonshine, airglow, the atmosphere, blue scattered light and city lights are indicated. Zodiacal light is visible as well.

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