The Multi-Object Optical and Near-infrared Spectrograph (MOONS) is a new fiber-fed spectrograph for the VLT. MOONS will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of VLT and will be equipped with two dual-arm spectrographs covering the wavelength range 0.645 um-1.8 um. Each double-arm spectrograph will produce spectra for 500 targets simultaneously. To ensure the accurate positioning of the 1000 fibers over the 880 mm diameter focal plane, a metrology system has been designed to provide position measurements within ~20 um. 
The metrology system is based on the analysis of images taken by a circular array of 12 cameras located close to the VLT’s derotator ring around the Nasmyth focus. Thermal effects on the cameras are minimized by an in-house design for camera housing and stability is ensured by an integrated heat up procedure using the camera's pixel clock. A flexible pipeline based on VLT standards is used to process the images. Initial measurements with a single camera test system have shown that a ~15 micron accuracy can be achieved over a 30cm x 40cm field of view. The talk presents the final hardware and software design. The metrology system is currently in production.