As immersion lithography will be the lithography technique for sub-65nm generation device fabrication, benefits and drawbacks of the introduction of an immersion fluid between the imaging optics and the wafer have to be studied. In this context, it is of high interest to be able to understand the properties of hyper high NA imaging and to do so, to have access to a technique which can mimic an industrial immersion stepper by having the possibility to tune the polarization state and numerical aperture. Interferometric lithography has proven to be a useful method to study projection imaging at high numerical aperture (NA). It has been shown to help addressing several issues of immersion lithography such as polarization state impact on imaging, photoresists material screening as well as preliminary defectivity considerations due to the introduction of water and high index fluid studies [1, 2, 3]. In the frame of this work, a home-built interferometer with immersion lithography capabilities has been fully designed and mounted in our facilities. Specific designs have been made in order to reach NAs as high as 1.4. All issues preventing the printing of high-contrasted lines over a large area, such as laser beam uniformity and vibrations control have been addressed and 40-nm-half-pitch resist lines can be currently printed with water immersion lithography. As a result, the interferometer has been used to screen resist and topcoat candidates for immersion lithography before their introduction in a production environment. An overview of our results is presented, focusing on the topcoat/resist compatibility. Besides, in order to prepare hyper NA lithography, We have implemented a simulation model which can be used to predict the light distribution inside a photolithographic stack. This model enables us to predict the resist image created by the interference of two coherent beams in the photo-resist volume. Simulations of polarization effects at oblique angles will be presented as well as the evaluation of image contrast in both TE and TM polarization. The contrast in TM polarization is dropping with increasing NA. Finally, we validate those predictions by experiments on our interferometer.