Crossed Dispersion Prism Sensors can detect and identify distant flash events such as muzzle flash based on the Spectral Temporal Signature. The sensor also locates the event more precisely than is possible with conventional imaging techniques. CDP sensors are well-suited to remote platforms where size, weight and power are at a premium. The on-board CDP post-processor reduces the measured spectral-temporal signature to an event declaration and a brief report of the event type, its charge and location.
  
     
   
 
Visible image sequence of a muzzle flash characterized by a CDP instrument.
 
     
   
 
The CDP sensor with a 12" scale. The sensor statically monitors
for flash events and reports on event type, charge and location.
 
  The key element in the CDP sensor is a crossed dispersion prism, which disperses short wavelengths perpendicular to long wavelengths forming two orthogonal arms. The arms are aligned away from the row and column axis to avoid sampling errors which degrade the location estimate. Location accuracies of 1/20th pixel have been demonstrated.  
     
   
 
A broadband point source is imaged as a chevron
by the Crossed Dispersion Prism sensor. Short wavelengths are dispersed orthogonally to long.
 
     
   
 
The signature of a muzzle flash event as recorded by a CDP instrument. The extracted spectral-temporal signature is shown here.
 
     
 
Each frame of data simultaneously records the entire event spectrum. It follows that the frame rate of the Focal Plane Array sets the temporal sampling rate of complete spectra. The spectral sampling for existing CDP instruments is on the order of 0.01um in the mid-wave infrared.

Classification and identification of the event from the CDP signature is performed using the SSSC Spectral Temporal processing and signature library.