Measurement system and measurement method

A measuring method executed by a measuring system comprising a first laser device for outputting pump light which is a pulse laser in response to a first signal inputted thereto, a second laser device for outputting probe light which is a pulse laser in response to a second signal inputted thereto, an auxiliary optical system for guiding the pump light and the probe light to a sample, a cantilever having probe tip disposed in proximity to the sample, and lock-in amplifier, the measuring method comprising:

• inputting the first signal and the second signal to the first laser device and the second laser device, respectively;
• repeatedly inputting the first signal and the second signal by switching a variable delay value, which is a difference between a timing at which the first signal is input to the first laser device and a timing at which the second signal is input to the second laser, to a plurality of values;
• and
• outputting a reference signal to the lock-in amplifier when switching the variable delay value;
• and
• applying a periodically varying voltage to the cantilever and outputting a change amount signal which is a voltage or a current corresponding to a change in a resonance frequency of the cantilever;
• measuring, by the lock-in amplifier, the change-amount signal by phase-sensitive detection using reference signal.