Testing apparatus operable to collect optical performance data of optoelectronic devices at different temperatures includes thermal-adjustment devices in thermal and mechanical contact with the optoelectronic devices via optoelectronic device stages. The thermal-adjustment devices can direct thermal energy to the optoelectronic devices under test without heating test targets in close proximity. Consequently, in some instances, spurious results can be avoided and rapid measurement of the optoelectronic devices different temperatures can be achieved.