1. A method for differential height measurement of an object using structured illumination sectioning microscopy, comprising: moving a surface of the object into a linear region of axial response curve of a microscope configured for structured illumination sectioning microscopy, wherein the intensity of an image is linearly correlated to a height variation of the object in the linear region of the axial response curve; obtaining an image of the surface of the object; and determining a profile of the surface of the object based on intensity variations in the obtained image without scanning the object along an optical axis of the microscope.