Lateral shearing interferometer based on two Ronchi phase gratings in series

Shearing interferometers are very popular and have a growing range of applications, especially in the field of optical testing. We describe a new kind of a lateral shearing interferometer. The lateral shear is produced by two Ronchi phase gratings in series. The phase can be shifted by a lateral movement of one grating relative to the other, and the amount of shear can easily be adjusted by variation of the distance of the gratings. The simplicity of the device is an important advantage, especially in the near IR.