Off-chip time-delayed integration area array Fraunhofer line discriminator

Abstract

Abstract An apparatus for determining the fluorescence of materials in a scene which includes optical means to collect radiation from the scene. Means are provided to divide the collected radiation into first and second beam paths. The first beam path traverses a first filter centered on a Fraunhofer line and having a passband which extends into the solar continuum on either side of the Fraunhofer line. The second beam path traverses the first filter and a second filter, also centered on the Fraunhofer line, with a passband on the order of half the bandwidth, at half-depth, of the Fraunhofer line. Means are provided to image the first and second beams onto first and second detector arrays, respectively. The image on the first detector array is registered with the image on the second detector array. Co-adding means are provided whereby successive detector pixels at successive time intervals corresponding to a single point on the ground are added and averaged. The time interval is a function of a constant clock rate and a V/H signal. A single detector is provided to detect the intensity of direct solar radiation outside the Fraunhofer line. A processor compares the value of intensity from the co-added point on the ground from the first and second detector arrays and the single detector to determine fluorescence at each point on the ground in the scene being viewed. In another form, where an optical laser illuminator is employed, the first beam path traverses a first filter which only allows the laser radiation to pass. The second beam path has a passband which passes the emission spectrum of a material excited by the laser radiation.

Inventors

• 👤 Sherman K. Poultney
• 👤 Hans G. Sippach
• 👤 Joseph H. Oberheuser

Bibliographic Details