A common-aperture, multispectral device uses a folded beamsplitter to
simultaneously image near infrared (NIR) and long wave infrared (LWIR)
spectral bands. The folded-path optical design makes the sensor extremely
compact and lightweight without compromising the F/# or field of view.
The design is split into two channels; a NIR channel and a LWIR channel.
A Zinc Sulfide environmental window provides the input to the device. The
input first is split into the two channels via a Germanium (Ge)
beam-splitter. For the NIR Channel, the input is focused directly onto a
faceplate through a series of optics. For the LWIR Channel, the input is
focused onto the Ge window via a folded design including a first Ge lens,
a fold mirror, and then a second Ge lens. From the faceplate of the NIR
channel and the Ge window of the LWIR channel, the input is then
processed by respective focal planes.