Patent ID: 8102522

Claim:
A defect inspection apparatus emits light to a test object, detects reflected or scattered light from the test object and detects a defect in the test object, comprising: a temperature-controlled part accommodating section for accommodating a plurality of parts that need temperature control, which is out of the plurality of parts in the defect inspection apparatus; a first temperature measuring instrument measures a temperature in the temperature-controlled part accommodating section; a temperature control unit controls the temperature of the interior of the temperature-controlled part accommodating section at a fixed level by controlling air temperature so that a deviation from a predetermined temperature range is eliminated; a first heat radiating unit for accommodating parts that do not need temperature control, which is out of the plurality of parts in the defect inspection apparatus; a second heat radiating unit performs heat exchange outside the defect inspection apparatus; a second temperature measuring instrument for measuring the temperature of the first heat radiating unit; and a third temperature measuring instrument for measuring the temperature of the second heat radiating unit, wherein the temperature control unit determines whether either the first heat radiating unit or the second heat radiating unit is used for heat exchange according to temperature measurement results obtained by the second temperature measuring instrument and the third temperature measuring instrument, and controls the temperature of the interior of the temperature-controlled part accommodating section at a prescribed temperature.