There is presented an up-conversion infrared microscope (110) arranged for imaging an associated object (130), wherein the up-conversion infrared microscope (110) comprises a non-linear crystal (120) arranged for up-conversion of infrared electromagnetic radiation, and wherein an objective optical component (100) has an entrance pupil with a first diameter D1, and an optical component system which is arranged for forming an external image (136) of the back-focal plane (132) of the objective optical component (100), which has a diameter (given by the diameter of a circle enclosing all optical paths at the plane of the 10 external image) which is denominated D2 and wherein D1 is larger than a second diameter D2.