  We report on the design and construction of a high-energy photon polarimeter
for measuring the degree of polarization of a linearly-polarized photon beam.
The photon polarimeter uses the process of pair production on an atomic
electron (triplet production). The azimuthal distribution of scattered atomic
electrons following triplet production yields information regarding the degree
of linear polarization of the incident photon beam. The polarimeter, operated
in conjunction with a pair spectrometer, uses a silicon strip detector to
measure the recoil electron distribution resulting from triplet photoproduction
in a beryllium target foil. The analyzing power $\Sigma_A$ for the device using
a 75 $\rm{\mu m}$ beryllium converter foil is about 0.2, with a relative
systematic uncertainty in $\Sigma_A$ of 1.5%.
