The article presents state of work in technology of free-space optical communications (Free Space Optics − FSO). Both commercially available optical data links and their further development are described. The main elements and operation limiting factors of FSO systems have been identified. Additionally, analyses of FSO/RF hybrid systems application are included. The main aspects of LasBITer project related to such hybrid technology for security and defence applications are presented.
The paper presents verification of a peak detection method cooperating with infrared radiation detector module applications. The work has been divided into parts including SPICE simulations and presentation of results obtained with the constructed prototype. The design of the peak detector dedicated to applications with very short pulses requires a different approach than that for standard solutions. It is mainly caused due to the ratio of pulse width and time period. In the described application this ratio is less than 10%. The paper shows testing of an analogue circuit which is capable to be inserted in these applications.
The paper presents a new construction of an optical pulse amplitude monitoring unit (PAMU) used in a transceiver of Free Space Optics. It consists of a buffer, constant fraction discriminator (CFD), delay line, and a sample and hold (S&H) circuit. In the design FSO system, the PAMU provides to monitor transmitted and received optical pulses with duration of few ns. Using this device, there is no need to apply complicated and expensive digitizing systems. The unique aspect of its construction is to control S&H circuit using the CFD. The lab model of this unit allows to perform tests to define some virtues of constant fraction and leading-edge discriminators. The results were implemented in optical signal monitoring of FSO system. The unit was prepared to cooperate with two different detection modules. Using this setup, it was possible, e.g. to determine operation characteristics of FSO transmitter, identify interruption of transmission, and control light power to provide high safety of work.