The Badal principle is based on the observation that if the eye is placed at the focal point of a positive lens, the

virtual image of an object located between the lens and anterior focal point will always subtend the same visual

angle. Badal optics are disclosed in which aperture array at an optical system under test is interrogated for the

deflection of light between a detector array conjugate with the aperture array of the optical system under test being

examined.The excursion is measured in a plane normal to the axis of the Badal optics instead of observing towards

and away from image focus along the axis of the Badal system.