A method of performing a measurement routine on a probe, the probe comprising a cantilever extending from a support. An interferometer is operated to reflect a sensing beam with the cantilever thereby generating a reflected sensing beam and combine the reflected sensing beam with a reference beam to generate an interferogram. The interferometer generates a first interference measurement value at a first measurement time by measuring the interferogram and a second interference measurement value at a second measurement time by measuring the interferogram, The cantilever deforms to form a different shape between the measurement times. A change in height of the probe between the measurement times is estimated in accordance with a difference between the first and second interference measurement values, and corrected in accordance with the difference in shape of the cantilever between the measurement times.