�� = 1 expresses the most ideal condition, which is the biggest contrast.�� = 0 expresses the worst condition, which means no luminance difference between two adjoining points.The spatial frequency, cross axle, means number of the cycles in each millimeter (mm), where each black-and-white pair is called a cycle in Figure 3. A line on the top of this graph, which is a black line with small circles through it, represents the ideal curve.Figure 3.Spatial frequency of a reflecting type Cassegrain telescope.For a good telescope design the MTF curve comes close to this line. The purple line with the crosses through it shows the on-axis values. The goal is to get this line as high and close to the ideal curve as possible. The violet and the green lines with the triangles and squares through them show the off-axis values.

Ideally, these lines should be as good as the on-axis line, and they should be balanced with each other so they are close together [20].The modulation value which over 0.8 respects to 20 cycles/mm means discrimination or contrast of this design is high and excellent [21]. Hence, we often use MTF to analyze the ability as the resolving power or the sharpness of the telescope. This also makes sure that our designed telescope can obtain clear Sun image outlines.During design process, we tried to use a plane mirror to replace the right prism and also relocated the right angle prism to a location between the convex mirror and the concave one. For the first case, all
Radar systems are key components in military and civilian schemes.

Different applications have emerged since World War II related to this kind of sensor. A Radio Aid to Detection And Ranging (radar [1]) is an electromagnetic sensor used for the detection and location of energy scattering objects. These systems not only have the ability to detect targets and show their position, but also to generate images and carry out certain electronic attack tasks, among many other applications. The basic principle of radar sensors is based on the time needed by the emitted electromagnetic wave to reach a target and back.This principle is depicted in Figure 1, and can be divided into the following phases [1,2]:The radar emits an electromagnetic energy which travels through space.If the transmitted energy hits a target, it will be scattered in all directions.

Part of the scattered energy travels back to the radar and it will be sensed by the receiving antenna.In the receiver, energy is amplified and with the aid of signal processing techniques the presence of a target may be determined. Not only the existence of Cilengitide targets can a radar detect but also other parameters such as its range, its radial velocity, or even the shape and size of the target if the radar has enough resolution to resolve closely spaced points within a target.Figure 1.