Laser-backscattering instruments, such as the focused beam reflectance measurement or threefold dynamical optical reflectance measurement, are promising tools to aid crystallization process development, allowing an in situ, real-time, and nondestructive measurement of particle size distributions. Besides the instrument principles, in detail geometrical and optical models are discussed which deconvolute the recorded chord length distribution. Emphasis is thereby laid on the influence of the suspension density on instrument recordings. The application of laser-backscattering devices for determination of kinetic constants is discussed and future directions and perspectives are given.