TELESCOPE / BEAM EXPANDER MODULES 

Optical telescope configurations provide the ability to magnify the apparent angular size of objects. The optical telescope is also known as beam expander “reducer” is ubiquitous in optical setups and is useful heavily used in optics in various applications spanning from microscopy to beam shaping to Fourier optics.

The ratio and the distance between the focal lengths of those lenses or curved mirrors determine the angular magnification of the input beam. Common configurations include the Newtonian telescope configuration, Galileo telescope configuration, curved mirror based on axis configurations, and off-axis parabolic mirror based telescopes.

In this education webpage, the reader will experience the various parameters that control the accurate functionality of the telescope as well as the various telescope configurations. We will start with the simple Newtonian telescope, which combined with two curved convex lenses, with focus distances of f1and  f2, which are associated with the first and second lenses that the light hits.


We will start with the simple Newtonian telescope, which combined with two curved convex lenses. In order to reach the right magnification M=f2/f1, the lenses should be separated by a distance of L=f2+f1. Any deviation from this distance, will result in deviation from the accuracy of the output collimation.

Picture 1

In the following real-live simulation, the user can experience the sensitivity of those parameters. The user can change various lenses as well as can change the distance of the second lens from the first lens:

 

 

Next, we will explore the Galilean telescope configuration that is combined with one convex lens and the second concave lens. The advantage of the Galilean telescope is that 

Picture 2

In the following real-live simulation, the user can experience the sensitivity of those parameters. The user can change various lenses as well as can change the distance of the second lens from the first lens: