A cantilever assembly (1) comprises a cantilever (10) having a cantilever tip (11). The cantilever is mounted to a rigid support (12,120,121) and is provided on its back side with an area (110) of a high reflectance material having a boundary (111) sloping towards the support (12). The extensions (c, Δc) of the area (110) and of the boundary (111) towards the support fulfil the condition c/Δc≧1 wherein c denotes the extension of the area (110) of the high reflectance material in the direction towards the support (12), and Δc denotes the extension of the sloped boundary (111) of the area (110) of the high reflectance material in the direction towards the support (12).