A measurement device is configured to send a first light beam to a target which returns a reflected portion. The device includes a switch configured to receive a first signal, and to send the second portion out of the switch measure port if the first signal is in the first state or out of the switch reference port if the first signal is in the second state. The device also includes a first electrical circuit configured to provide the first signal, to convert the third portion into a first reference value, to convert the fifth portion into a first measure value if the first signal is in the first state, and to convert the seventh portion into a second reference value if the first signal is in the second state; and a processor configured to determine a first distance from the device to the target.