This paper contains two optical designs that utilize the Alvarez-Humphrey surfaces to provide the miniature multi-modal microscope (4M device) with the additional capability of imaging different object depths onto the same image plane. The Alvarez-Humphrey surfaces are a pair of conjugate, rotationally asymmetrical, aspheric surfaces such that, the lateral movement of these surfaces across the optical axis, results in an element of variable optical power. The first design is a direct application of the Alvarez-Humphrey concept to the 4M device. However, due to the inadequate imaging performance and unavailability of space for the actuator due to proximity of the Alvarez Plates, a second design was created. The Separated Alvarez Plate Design is a unique design involving two conjugate pairs of Alvarez-Humphrey surfaces. The lateral movement of the central element changes the optical power. However, due to the symmetry of the system and the incorporation of the theoretical work done on induced aberration correction, this system has far superior performance. It also has adequate space for the actuator due to the separation of the elements.
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