Optical instrument and optical element providing expanded exit pupil

摘要

The invention provides an optical instrument including means ( 1, 2 ) to produce an optical image to be viewed by an observer including a diffractive element ( 7 ) located at an intermediate focal or image plane ( 4 ) of the optical instrument and comprising a pattern of a plurality of areas effective to cause diffraction interference in light passing through the optical instrument and thereby produce an expanded exit pupil ( 6 ) comprising a combination of a multiplicity of exit pupils displaced relative to one another transverse to an optical axis ( 3 ) of said instrument.