Projection objective and waveguide display device

A projection objective for projecting an image from a first plane to an in-coupling grating of a waveguide element on a second plane, the objective comprising in order from the second plane:

• a first optical element group having a positive effective focal length,
• a second optical element group placed between the first plane and the first optical element group and having a negative effective focal length, and
• a third optical element group placed between the first plane and the second optical element group and having a positive effective focal length,
• wherein said optical element groups have refractive surfaces such that in order from the second plane
• the first refractive surface of the second optical element group is concave towards the second plane, and
• the second refractive surface of the third optical element group is convex towards the first plane,
• the objective comprising an aperture stop, which is located at the second plane or between the second plane and the first optical element group, and
• wherein the objective is adapted to collect an image radius of Rimg from the first plane, wherein an edge field marginal ray height from the third optical element group (MrhG3) satisfies the condition of
• Rimg−BFL*0.44<MrhG3<Rimg+BFL*0.44,
• wherein BFL is the back focal length (BFL) between the third optical element group and the first plane, measured in air.