Recent work in ground‐to‐orbit laser propulsion has focused on detonation wave thrusters driven by pulsed infrared lasers. In this concept, a pulsed laser is used to vaporize a small amount of solid propellant; a second laser pulse then drives a detonation wave through this vapor, substantially raising its temperature. Thermal energy is converted to thrust by the expansion of this hot vapor. Several aspects of the physics of these thrusters have recently been explored theoretically and with the aid of numerical models. Many of the theoretical predictions can be tested in the laboratory. We report here some results from on‐going experiments probing the physics of detonation wave thrusters. Included are spatially and temporally resolved measurements of radiance and opacity of absorption waves. We also present data on target mass loss and momentum transfer, and discuss the importance of the measured quantities in the design of a useful thruster.