Achromatic lensAn achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus on the same plane. Wavelengths in between these two then have better focus error than could be obtained with a simple lens. The most common type of achromat is the achromatic doublet, which is composed of two individual lenses made from glasses with different amounts of dispersion.
Ripple tankIn physics, a ripple tank is a shallow glass tank of water used to demonstrate the basic properties of waves. It is a specialized form of a wave tank. The ripple tank is usually illuminated from above, so that the light shines through the water. Some small ripple tanks fit onto the top of an overhead projector, i.e. they are illuminated from below. The ripples on the water show up as shadows on the screen underneath the tank. All the basic properties of waves, including reflection, refraction, interference and diffraction, can be demonstrated.
Telephoto lensA telephoto lens, in photography and cinematography, is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus lens in a much shorter overall design. The angle of view and other effects of long-focus lenses are the same for telephoto lenses of the same specified focal length.
VitelloVitello (Witelon; Witelo; 1230 – 1280/1314) was a friar, theologian, natural philosopher and an important figure in the history of philosophy in Poland. Vitello's name varies with some sources. In earlier publications he was quoted as Erazmus Ciolek Witelo, Erazm Ciołek, Vitellio and Vitulon. Today, he is usually referred to by his Latin name Vitello Thuringopolonis, often shortened to Vitello. Vitello's exact birth-name and birthplace are uncertain. He was most likely born around 1230 in Silesia, in the vicinity of Legnica.
