<Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2010) (Learn how and when to remove this template message) </Td> </Tr> <P> A collimator is a device that narrows a beam of particles or waves . To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spatial cross section of the beam to become smaller (beam limiting device). </P> <P> An English physicist Henry Kater was the inventor of the floating collimator, which rendered a great service to practical astronomy . He reported about his invention in January 1825 . In his report, Kater mentioned previous work in this area by Carl Friedrich Gauss and Friedrich Bessel . </P> <P> In optics, a collimator may consist of a curved mirror or lens with some type of light source and / or an image at its focus . This can be used to replicate a target focused at infinity with little or no parallax . </P>

Who designed a pinhole gamma ray called the collimeter