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a) A back vertex and b) side view of the crude prototype of the Keplerian design in-the-lens telescope illustrated in Fig. 4. The telescope was constructed from an ophthalmic lens blank cut to provide the erecting mirrors through total internal reflection. Off the shelf ocular and objective lenses provided the magnification and small right angle prisms served as the periscopic mirrors (M1 and M4 in Fig. 4a).
