Design of an all-reflective unobscured optical-power zoom objective

Abstract

A novel design for an all-reflective unobscured optical-power zoom (OPZ) objective with a zoom factor of 3 is presented. In contrast to OPZ objectives based on liquid lenses, all-reflective objectives use only reflective elements and are therefore free of chromatic aberrations. Thus, they can be used for a wide spectral range or in combination with image sensors that differ in their spectral characteristics. To avoid a decrease in image contrast encountered in on-axis designs with central obscuration, an unobscured off-axis or "Schiefspiegler" approach is adopted. The effective focal length of the objective is changed by two deformable mirrors, each with one actuator only. The simulated final design shows adequate image quality over the whole zooming range. Before starting the complex and cost-intensive development of deformable mirrors with the size, curvature, and dynamic range needed, the optical design should be evaluated first with respect to the practical achievable optical performance. Therefore, optomechanical setups with ultraprecision-manufactured solid mirrors were realized for three different focal lengths.

Actuation for carbon fiber reinforced polymer active optical mirrors

“…The weight budget may be further reduced since CFRP mirrors weigh significantly less than glass mirrors [17]. These attributes make active optical zoom ideal for military, security, and space-based applications where weight and power are of utmost importance.…”

CFRP variable curvature mirror being capable of generating a large variation of saggitus: prototype design and experimental demonstration

“…Taking space-borne camera as another example, the movement of large aperture component may probably give rise to vibrations that could break the momentum balance of satellite platform. Therefore, how to eliminate moving elements while realizing variation of focal length has been paid much attention in recent years and many related research have been carried out [1][2][3][4][5][6]. With no doubt, the key to implement non-moving-element optical zooming lies in the use of VCM.…”

Polymorphic optical zoom with MEMS DMs

“…Such aberrations have been characterized and found to be substantial for a number of specific active focusing configurations [10,17,18] . Recently, two systems with aberrationcompensated optics were reported for active focusing [17] and active zoom [19] . One, developed at National Taiwan University, described a prototype autofocus module for consumer cameras that featured a MEMS DM and a rigid aspheric mirror that was intended to compensate expected off-axis aberrations.…”