A system and method for simultaneous imaging of both infrared and millimeter
wave
radiation. The novel optical system (10) includes a primary mirror (20),
a Mangin secondary mirror (30) positioned to receive energy reflected from
the primary mirror (20), and an immersion lens (40) for focusing
energy received from the Mangin mirror (30). In the illustrative embodiment,
the primary mirror (20) and Mangin mirror (30) are arranged in a
Cassegrain configuration. Central to this invention is the use of a negative power
refractive Mangin mirror (30) as the Cassegrain secondary mirror, so that
the field curvature of the secondary mirror (30) and immersion lens (40)
can be made to cancel. The immersion lens (40) effectively decreases the
wavelength of the millimeter wave radiation, allowing a smaller detector to collect
the same amount of radiation as would a larger detector in air. In the illustrative
embodiment, the system (10) further includes a detector array (52)
placed in intimate contact with the immersion lens (40).
