A method for performing microrheological measurements in a viscoelastic medium by employing at least two optical traps acting on a single particle located in said medium, comprising the steps of: - choosing the particle to be stiffer than the medium; - placing the particle within the medium; - generating a single laser beam from a single laser source; - dividing the single laser beam into a first laser beam and a second laser beam; - producing a first optical trap acting on the particle by focusing the first laser beam therein; - producing a second optical trap acting on the particle by focusing the second laser beam therein; - positioning the first and second optical traps at the optical center of the particle; - displacing the second optical trap out of the optical center of the particle on a timedependent motion, while the first optical trap is held fixed; - using back-focal-plane interferometry (BFPI) with a photodetector in order to acquire a first temporal series for the voltage signal V1(t) representative of the force exerted by the first optical trap on the particle; - using BFPI with the photodetector to acquire a second temporal series for the voltage signal V2(t) representative of the force exerted by the second optical trap on the particle; - computing the force exerted by the first and second optical traps on the particle as the temporal series F(t) = a·(V1(t)+V2(t)), where a is a proportionality constant depending on the shape of the particle, on the optical properties of the particle and on the optical properties of the medium; - computing the displacement xp(t) of the particle as the temporal series xp(t) = - a·V1(t)/k, where k is the trap stiffness of the first optical trap; and - deriving at least one microrheological magnitude of the medium from the corresponding values of the two temporal series F(t) and xp(t). - choosing the particle to be stiffer than the medium; - placing the particle within the medium; - generating a single laser beam from a single laser source; - dividing the single laser beam into a first laser beam and a second laser beam; - producing a first optical trap acting on the particle by focusing the first laser beam therein; - producing a second optical trap acting on the particle by focusing the second laser beam therein; - positioning the first and second optical traps at the optical center of the particle; - displacing the second optical trap out of the optical center of the particle on a timedependent motion, while the first optical trap is held fixed; - using back-focal-plane interferometry (BFPI) with a photodetector in order to acquire a first temporal series for the voltage signal V1(t) representative of the force exerted by the first optical trap on the particle; - using BFPI with the photodetector to acquire a second temporal series for the voltage signal V2(t) representative of the force exerted by the second optical trap on the particle; - computing the force exerted by the first and second optical traps on the particle as the temporal series F(t) = a·(V1(t)+V2(t)), where a is a proportionality constant depending on the shape of the particle, on the optical properties of the particle and on the optical properties of the medium; - computing the displacement xp(t) of the particle as the temporal series xp(t) = - a·V1(t)/k, where k is the trap stiffness of the first optical trap; and - deriving at least one microrheological magnitude of the medium from the corresponding values of the two temporal series F(t) and xp(t).