  We have studied the optical properties of gratings micro-fabricated into
semiconductor wafers, which can be used for simplifying cold-atom experiments.
The study entailed characterisation of diffraction efficiency as a function of
coating, periodicity, duty cycle and geometry using over 100 distinct gratings.
The critical parameters of experimental use, such as diffraction angle and
wavelength are also discussed, with an outlook to achieving optimal ultracold
experimental conditions.
