Patent ID: 7889997

Claim:
A portable terminal for performing visible light communication with other devices through free space, comprising: a beam splitter for dividing an optical signal input through the free space into first and second optical signals; an optical detector for generating an electrical signal after photoelectrically converting the first optical signal and outputting the electrical signal; a reflector for retro-reflecting the second optical signal, the reflector having a reflection surface on which at least one concave groove is formed; a modulator for twice modulating the second optical signal including modulating the second optical signal from the beam splitter and modulating the reflected second optical signal; a demodulator configured to demodulate a first data signal from the electrical signal input from the optical detector and outputting the demodulated signal; a controller configured to receive the first data signal from the demodulator and output a second data signal to be transmitted to other devices; and a driver configured to modulate the second data signal input from the controller into an electrical signal suitable for operation of the modulator and outputting the modulated electrical signal to the modulator.