In order to optically vary the effect focal length of optical zoom system , adds two or more active optics which could
supply variable the focal length, and create an imaging system with variable optical magnification that has no
macroscopic moving parts. Based on this design concept, and connected with off-axis three-mirror reflective optical
system design, we have presented preliminary modeling showing that active optical elements can be used as to create a
zoom system that the effective focal length from 1000 mm to 3000 mm in ZEMAX, the FOV(Field of view) is 16°×2°
-6.87°×0.86°, and the F/# is 5-15, the whole system is composed of 3 reflective mirrors(DM, Deformable Mirrors). In
order to zoom system, the F/# and three reflective mirror's radius, were variable. The MTF more than 0.45 at the spatial
frequency of 42lp/mm and approaches the diffraction limit, the maximum RMS spot diameter less than detector's size.
The results show that the imaging quality can satisfy the requirement of the system.