| 摘要 |
A jacket is provided to surround coils in a stationary member of a linear motor. An inlet of the jacket is directed toward the optical path of a laser beam from a laser interferometer, and a temperature-controlled fluid is circulated through the jacket. Temperature sensors are provided at the outlet and inlet, respectively, of a temperature controller. The temperature of the fluid supplied to the stationary member is controlled so as to become equal to the temperature around the optical path of the laser beam on the basis of the values of temperature measured by the temperature sensors, thereby suppressing fluctuations of air in the optical path of the laser beam. An exhaust groove is provided in a guide bar transport member so as to surround a bearing surface around a gas outlet, and partition walls flush with the bearing surface are provided outside the exhaust groove. The discharge opening of the exhaust groove is provided on the leeward of an environmental air stream, and a temperature sensor is provided at the discharge opening. The temperature of compressed air supplied to the gas outlet is controlled such that the temperature measured by the temperature sensor becomes equal to the temperature of the environmental air stream.
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