The paper presents operation rules of wireless optical link FSO (<i>Free Space Optics</i>) as well as implementation limits in real conditions. The limits are mainly connected with atmospheric factors. The article takes under consideration the choosing criterions of optical emission sources and ability of implementing them. The speed transfer results of proposed optical link, working in a wavelength range 800 ÷ 900 [nm], are presented. There is mentioned an implementation possibility of such solutions in dedicated systems that takes under consideration limits of attenuation in the atmosphere and others (e.g. correct orientations of optical modules between them). There are presented two diversity methods: <i>spatial diversity</i> and <i>wavelength diversity</i>, which a main goal is to improve the stability of optical link. There is discussed an issue of hybrid solution FSO/RF that significantly increases the probability of delivering data in real weather conditions.