An interferometric measuring device for detecting the shape of rough surfaces includes a spatially coherent beam gun unit that emits a short time coherent and broad-band beam. Further, the present invention relates to high-density detergent particles using the particles for supporting a surfactant, and a process for preparing the same. Further, although the respective side irradiating lamp piece units are constituted by the lamp piece units of the parabolic pillar type having an angular outer shape as a whole, a large depth space for arranging the units is dispensed with.