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Infrared sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency,
scalability, maturity, and cost. As a result, cryocooler selection has become application dependent, oftentimes
requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next
generation passive infrared (IR) sensors, the Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and
Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy
this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage
and 2-stage cold-head architectures with an inventive set of warm-end mechanisms into a single mechanical module,
allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common
axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling
cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of
the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction),
mass (30% reduction), thermodynamic efficiency (<20% improvement) and exported vibration performance (≤25
mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that
proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration
translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations,
eliminating the need for convoluted, expensive, massive, long lead damping hardware.
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