In this paper we present basic properties of polarisation birefringent interference filters used for construction of special spectral devices. A mathematical method of Šolc filter design is explained. and V práci jsou uvedeny základní vlastnosti dvojlomných polarizačně interferenčních filtrů, používaných k realizaci unikátních spektrálních přístrojů. Je naznačen způsob výpočtu takového filtru v Šolcově uspořádání.
Když se Kosťa Novoselov chystal v Manchesteru v roce 2003 sloupnout obyčejnou lepicí páskou několik vrstviček z krystalu grafitu, zřejmě ještě netušil, že startuje novou éru v nanotechnologickém výzkumu - éru dvojrozměrných (2D) neboli jednovrstvých materiálů; a že za to bude o deset let později spolu s prof. Andre Geimem přebírat Nobelovu cenu za fyziku. Podařilo se mu totiž nečekané - izolovat jedinou vrstvu tvořenou atomy uhlíku uspořádaných do vrcholů pravidelných šestiúhelníků, tedy grafen. and Otakar Frank, Ladislav Kavan, Martin Kalbáč.
This paper informs a reader about a construction of the all-spherical Cassegrain telescope with a lens corrector of Volosov. The front dublet of Volosov radically corrects optical aberrations of the system and makes possible to obtain high quality images across wide field of view to 2˚ in broad spectral region. In the past one optical set of such system was manufactured in the Development Optical Workshop AS CR, now the IPP AV CR, v.v.i. - Toptec Center in Turnov. Its diameter is 280 mm and focal length 2450 mm. and Článek informuje čtenáře o konstrukci dvojzrcadlového dalekohledu se sférickými zrcadly a s dvojčočkovým korektorem Volosova. Tento vstupní člen radikálně opravuje optické vady soustavy a umožňuje kvalitní zobrazení v zorném poli o průměru 2° v celém viditelném oboru spektra. V minulosti byla vyrobena jedna soustava tohoto přístroje ve Vývojové optické dílně AV ČR, dnes ÚFP AV ČR, v.v.i. - Centrum TOPTEC v Turnově. Jeho průměr je 280 mm a ohnisková vzdálenost 2450 mm.
Antonín Dvořák used to be seen as an excellent writer of melodies, but a poor builder. But, the analysis of the Dies irae – Tuba mirum – Dies irae (DI 1 – TM – DI 2) movements of his Requiem (1890) reveals, in an impressive way, the author’s abilities of construction. Both choral movements (DI 1 and DI 2) were based by Dvořák on mere two three verse sections of the text. In DI 1, therefore, he repeated them twice, and gave them a different tectonic function each time – the first time in an ascending, gradating part of both movements, the second time at the peak and descent. The two movements, however, are not identical. The instrumental setting of the second is denser, there are more short counterparts and instrumental insertions (including the double quotation of the theme of the first movement in the bass instruments), and, especially: DI 2 at its peak brings several layers of confrontation of the text and motivic material of both movements. The composer also joined the whole set of three movements rhythmically. Every movement (DI x TM) uses its own basic rhythmical model, which also plays a key role at the juncture at the peak of DI 2: both rhythmical models sound simultaneously (together with other layers) with different speeds and instrumentation. Dvořák the constructivist? Certainly not in the primary sense of the word, but surely a composer who, at the peak of his composing career, was capable of impressive achievements in the field of construction and combination.
Dvořák’s five symphonic poems, composed between 1896 and 1897, attempt to bridge the antagonism existing between pure and programmatic music. Trying to overcome their typical differences, Dvořák reconciled the characteristic features of poetry and folklore with grand classical forms, demonstrating in this way his ability to utilise Liszt’s model and transform it by creating a new concept of programmatic music founded on the use of the Czech folkloric heritage. Four of the five poems are based on ballads by K. J. Erben, taken from the poetry book, The Bouquet (Kytice), where Dvořák found the sense of wonder, where simplicity meets with moral strength. Dvořák underlines the narration and the folk tone, applying the new processes which are based on the unity of poetic and musical setting. He, who initiated truly national music, models his orchestral ideas on the rhythms and intonations of the poetic text, creating a musical expression which conforms to the Czech character of the poem, opening in this way the path for Janáček. The folkloric character and his treatment of music setting, based on the will to translate as closely as possible the Czech soul, make these works an elaborate synthesis of Dvořák’s aspirations of appeasement between learned music and folklore.
Studie Jana Kachlíka se zabývá dobovou recepcí kantáty Stabat Mater hudebního skladatele Antonína Dvořáka a také skladatelovou citací motivu z tohoto díla v komické opeře Šelma sedlák., Jan Kachlík., Rubrika: Studie, and Německé resumé na s. 341, anglický abstrakt na s. 331.