The CTI-Cryogenics Cryocooler is a closed–cycle liquid helium cooled cryostat. The cold head is mounted on a slide rail for convenient positioning in front of the spectral QE measurement kit for low temperature QE or white light I-V measurements down to 5K. The cold finger accepts 24-pin DIP ceramic packages and other custom mounted samples. A custom Labview interface operates with a Lakeshore 331/332 temperature controller and Keithley 2400/2420 source meter for automated I-V vs. temperature sweep.