  Defocused speckle photography has long been used to measure rotations of
rough surfaces. This paper explains how, by adding a suitably perforated mask,
some measurement properties, such as range or lateral resolution, may be
changed at wish. Particularly, the maximum measurable tilt can be significantly
raised, although at the expense of poorer lateral resolution. Advantages over
previously described techniques include independent tuning of speckle size and
optical system aperture and more extended adaptability to different measuring
needs. The benefits and disadvantages of the new and old techniques are
thoroughly compared.
