Significant progress has been made recently in solar parabolic trough technology development and deployment. Part of this success is due to the changing world energy scenario and the recognition that viable renewable energy technologies can play a role in supplying world energy needs. Part is also due to ongoing collaborative efforts by industry and the Department of Energy’s (DOE) Concentrating Solar Power Program (CSP) to enhance the state of the technology in terms of both cost and performance. Currently, there are two trough concentrator projects which the DOE CSP program is supporting. One company, Solargenix, is developing a design to be used in a 64MW plant outside of Boulder City, Nevada. This design is based on the original LUZ LS-2 trough concentrators employed at the Solar Electric Generating Systems (SEGS) plants in Southern California. Another company, Industrial Solar Technology (IST), is working on a scale-up of their design used historically for process heat applications. Very different from the LS-2 approach, this design is still in the research and development stages. One way in which the DOE CSP parabolic trough program assists industry is by providing optical testing and qualification of their concentrator designs. This paper describes the Video Scanning Hartmann Optical Test System (VSHOT) used to optically test both of these designs. The paper also presents the results of tests performed in the past year and what impact the testing has had on the developmental direction of each design.