Array of diffractive microlenses used as coupling elements for integrated optical interferometer chips

The feasibility and the functionality of a monolithic double-interferometer displacement sensor with wavelength stabilization of the semiconductor laser diode source have been previously demonstrated by Voirin et al. A precision better than 10^-6 has been achieved over a measurement range of 200 mm. The interferometer configuration has been implemented on an integrated optics circuit whose six waveguides need to be lensed for the input and output coupling of the measurement beams. The present authors concentrate on the array of diffractive microlenses used as coupling elements for the integrated optics circuit. The design fabrication and characterization of the coupling optics as well as the results of measurements performed with the optical head are reported