In order to quantitatively characterize biological objects, for example individual cells, a stimulus is applied to a biological object (8) in a contactless fashion. A measurement and a further measurement are performed on the biological object (8) in order to ascertain a response of the biological object (8) to the stimulus, wherein the measurement and the further measurement comprise detecting Raman scattering on and/or in the biological object (8) and/or capturing data using digital holographic microinterferometry (DHMI). The biological object (8) is characterized according to a result of the measurement and is sorted if needed. The stimulus can be applied by means of a laser beam that creates optical tweezers or an optical trap, by means of ultrasonic waves or an electric or magnetic radio frequency field.