The design of the world's first production worthy broadband ultra-violet and visible small spot spectroscopic ellipsometer is described. The instrument, called the Prometrix UV-1250SE, was developed by the Prometrix division of Tencor Instruments in cooperation with SOPRA S.A., a pioneer in the field of spectroscopic ellipsometry. It has the ability to measure both the thickness and refractive index of different layers on a wide variety of materials in multiple layer film stacks. In this paper the optical system will be reviewed and spot size data presented. We will further discuss some of the design considerations such as the angle of incidence and allowed spread of the collection beam. Data characterizing the precision and stability of the instrument is presented for a variety of films including SiO 2 on silicon, and Si 3N 4 on silicon, and a multiple layer stack of SiO 2/poly- Si/SiO 2 on silicon.