An acquisition device, configured to be mounted on a first vehicle and comprising an acquisition circuit, configured to obtain identification information of the first vehicle; and an optical signal transmitting circuit, configured to generate and transmit a first optical signal corresponding to the identification information of the first vehicle, wherein the acquisition circuit is further configured to generate, and send to the optical signal transmitting circuit, a first identification electrical signal based on the identification information of the first vehicle; and the optical signal transmitting circuit is configured to generate the first optical signal based on the first identification electrical signal and comprises a third processing subcircuit, an optical transmitter and an optical signal receiving subcircuit, the third processing subcircuit is configured to modulate the first identification electrical signal to thereby generate, and to send to the optical transmitter, a modulated first identification electrical signal; the optical transmitter is configured to transmit the first optical signal based on the modulated first identification electrical signal; and the optical signal receiving subcircuit is configured to receive a second optical signal transmitted from, and corresponding to identification information of, a second vehicle immediately behind the first vehicle, and to convert the second optical signal into a third electrical signal, wherein the acquisition circuit is further configured to encrypt the first identification electrical signal to thereby generate an encrypted identification electrical signal, and to generate a second identification electrical signal based on the third electrical signal and the encrypted first identification electrical signal; the third processing subcircuit is further configured to modulate the second identification electrical signal to generate a modulated second identification electrical signal; and the optical transmitter is further configured to transmit an optical signal corresponding to the identification information of the first vehicle and the identification of the second vehicle based on the modulated second identification electrical signal. an acquisition circuit, configured to obtain identification information of the first vehicle; and an optical signal transmitting circuit, configured to generate and transmit a first optical signal corresponding to the identification information of the first vehicle, wherein the acquisition circuit is further configured to generate, and send to the optical signal transmitting circuit, a first identification electrical signal based on the identification information of the first vehicle; and the optical signal transmitting circuit is configured to generate the first optical signal based on the first identification electrical signal and comprises a third processing subcircuit, an optical transmitter and an optical signal receiving subcircuit, the third processing subcircuit is configured to modulate the first identification electrical signal to thereby generate, and to send to the optical transmitter, a modulated first identification electrical signal; the optical transmitter is configured to transmit the first optical signal based on the modulated first identification electrical signal; and the optical signal receiving subcircuit is configured to receive a second optical signal transmitted from, and corresponding to identification information of, a second vehicle immediately behind the first vehicle, and to convert the second optical signal into a third electrical signal, wherein the acquisition circuit is further configured to encrypt the first identification electrical signal to thereby generate an encrypted identification electrical signal, and to generate a second identification electrical signal based on the third electrical signal and the encrypted first identification electrical signal; the third processing subcircuit is further configured to modulate the second identification electrical signal to generate a modulated second identification electrical signal; and the optical transmitter is further configured to transmit an optical signal corresponding to the identification information of the first vehicle and the identification of the second vehicle based on the modulated second identification electrical signal.