HEAT TREATMENT APPARATUS FOR CERAMIC MATERIALS FOR OPTICAL USE, HEAT TREATMENT METHOD FOR CERAMIC MATERIALS FOR OPTICAL USE, HEAT TREATMENT METHOD FOR SYNTHETIC QUARTZ GLASS, METHOD FOR PRODUCING OPTICAL SYSTEM, AND METHOD FOR MANUFACTURING EXPOSURE APPARATUS

摘要

An optical ceramic material heat treatment apparatus, comprising: a furnace body that is capable to contain an optical ceramic material to be heat treated in the inside thereof; a temperature drop control heater that generates heat during dropping a temperature of the optical ceramic material; a refrigerant intake unit that introduces a refrigerant into the inside of the furnace body to flow the refrigerant therein; and a control unit that controls the temperature drop rate, wherein the temperature drop control heater is arranged in the inside of the furnace body and/or in the refrigerant intake unit, the control unit controls at least one of an amount of heat generation of the temperature drop control heater, and a flow rate of the refrigerant in the inside of the furnace body to control a temperature drop rate at the optical ceramic material or in the vicinity thereof to be kept in a predetermined profile.