Figure 1 shows a high-resolution surface profile of a micro-patterned silicon diffraction grating, measured using an atomic force microscope. The vertical axis shows the surface displacement (height variation) of the micro-grooves, while the horizontal axis shows the distance along the grating.
Use the data in Figure 1 to calculate the wavelength of the surface wave pattern on the silicon grating. Give your answer in micrometres (μm\mu\text{m}μm).