Automated Rendezvous and Docking of Spacecraft

In this section two types of optical sensors are considered: scanning laser range finders and camera sensors. Both require optical corner-cube reflectors as interfaces on the target. These two types of sensor principles were developed in the final two decades of the 20th century, precisely for the application in automated rendezvous and docking missions. With the advance of image recognition techniques and other new technologies, it can be expected that in future a larger variety of sensor principles will be both available and suitable for automated rendezvous.
Scanning laser range finder types of sensors (in some publications called 'telegoniometers') function according to the same basic physical principles (see section 7.1.2) as radar types of sensors, described in section 7.2. The difference in technology is due to the wavelength of the electro-magnetic signal. The wavelengths used for these types of optical sensors are in present applications in the near infrared range of the order of 1000 nm, depending on the available laser diode technology. The range can be determined either by measuring the time-of-flight (cf. Eq. (7.3) for pulse laser range finder) or by the shift of phase of the returning signal (cf. Eq. (7.5) for continuous wave laser range finder). The direction can be determined by scanning the laser beam and measuring the angle at which a return signal is received, either by guiding the transmitted and received laser signals via two mirrors or by placing the optical head of the...