Development of Optoelectronic Sensors and Transceivers for Spacecraft Applications

The main goal of this chapter is to show several optoelectronic systems to be applied in two different interest areas of spacecraft technologies: mechanical testing and optical communications. In the first part of this chapter, we present a simple, cost-effective and robust microcontrolled optoelectronic system that is able to measure with a reasonable accuracy a wide range of projectile velocities for impact testing of aeronautic and aerospace structures. In the second part of this chapter, we review different approaches to optimize the performance of free-space optical communications (FSOC) systems such as architecture of transceivers, pointing and tracking subsystems, wavelength tunability, diffraction limit, photodetectors’ performance, among others. A great effort was made in the last decades to design advanced shielding to protect aircraft and spacecraft structures and to evaluate the damage on structures impacted by projectiles and meteoroids. Although numerical simulation has been increasingly adopted to analyze these problems, experimental testing is still a need to validate numerical codes and to obtain reliable information. The importance of taking measurements during an impact event is evident from the vast amount of work performed in this area. Among the variables that should be measured during the impact test, an accurate determination of the velocity of the projectile is obviously of great importance, since its square is related to the kinetic energy applied to the specimen. Many different measurement techniques have been used; however, the purpose of the next section is not an exhaustive review of the literature but to provide an overview of some typical measurement methods. Optical communication is a major issue in both guided and unguided modes of transmission. In optical fiber systems, losses can approach less tan 0.15 dB/km and and multi-Gbps data streams can be transmitted over tens of thousands of kilometers without electronic regeneration. In free-space systems, optical communication again has advantages. Smaller diameter transmitter and receiver apertures are needed to establish high date-rate communication links and, unlike the congested microwave bands, there is plenty of available spectrum. In addition, the narrow beam divergence of an optical system can be used to provide additional security by lowering the probability of detecting and intercepting the transmission. The advent of technologies such as the erbium-doped fiber amplifier (EDFA) which made the implementation of nearquantum limited receiver performance achievable and the