A new confocal microscope and a new device fabrication method in which linewidth control is achieved using the new confocal microscope are disclosed. This new confocal microscope has a configuration which achieves multiple passes, e.g., three, four, five, six, seven or more passes, of the incident light through the objective lens of the microscope. As a consequence, the new confocal microscope exhibits a smaller effective depth of focus and a smaller effective resolution than a conventional confocal microscope.

There is provided a polarization converter for producing a beam of linearly polarized light from a randomly polarized light. The randomly polarized light is separated into a first polarized light which is projected in a first predetermined direction and a second polarized light having a predetermined angular relationship with the first polarized light. The second polarized light is converted into a third polarized light a polarization of which is identical to that of the first polarized light. By providing a predetermined two-dimensional positional relationship between the first and third polarized lights, the beam of linearly polarized light is produced and advanced on the outside of the converter in a second predetermined direction.