Adaptavní optické systémy se vyznačují schopností měnit své optické vlastnosti na požádání a v reálném čase. V tomto příspěvku jsou diskutovány základní prvky adaptivních optických systémů využívaných v astronomii ke kompenzaci vlivu atmosféry na zobrazení velkých pozemských teleskopů., Adaptive optical systems are those whose optical responses can be adjusted on demand, in real time. Here we discuss the basics of adaptive optical systems utilised in astronomy for compensation of aberrations due to atmospheric turbulence, which seriously impairs the performance of uncorrected large ground-based telescopes., Jaroslav Řeháček, Bohumil Stoklasa., and Obsahuje seznam literatury
One of the basic questions in the Kleinian group theory is to understand both algebraic and geometric limiting behavior of sequences of discrete subgroups. In this paper we consider the geometric convergence in the setting of the isometric group of the real or complex hyperbolic space. It is known that if $\Gamma $ is a non-elementary finitely generated group and $\rho _{i}\colon \Gamma \rightarrow {\rm SO}(n,1)$ a sequence of discrete and faithful representations, then the geometric limit of $\rho _{i}(\Gamma )$ is a discrete subgroup of ${\rm SO}(n,1)$. We generalize this result by showing that for a sequence of discrete and non-elementary subgroups $\{G_{j}\}$ of ${\rm SO}(n,1)$ or ${\rm PU}(n,1)$, if $\{G_{j}\}$ has uniformly bounded torsion, then its geometric limit is either elementary, or discrete and non-elementary.