Abstract: A metal fluoride single crystal pulling apparatus that upward pulling initiation through termination, in the state of shallow melt capable of highly effective inhibition of scatterer formation, can perform stable growth of single crystal and can suppress any mixing of air bubbles and occurrence of crystal break during crystal growth, etc; and a process for producing a metal fluoride single crystal therewith. As a crucible for accommodating a melt of raw metal fluoride, use is made of a double structured crucible composed of an outer crucible and an inner crucible. In the upward pulling of single crystal, the accommodation depth of inner crucible relative to the outer crucible is increased in accordance with any decrease of melt accommodated in the inner crucible according to the growth of single crystal, so that the melt accommodated in the outer crucible is fed into the inner crucible to thereby maintain the amount of melt accommodated in the inner crucible within a given range.

Abstract: A metal fluoride single crystal pulling apparatus that upward pulling initiation through termination, in the state of shallow melt capable of highly effective inhibition of scatterer formation, can perform stable growth of single crystal and can suppress any mixing of air bubbles and occurrence of crystal break during crystal growth, etc; and a process for producing a metal fluoride single crystal therewith. As a crucible for accommodating a melt of raw metal fluoride, use is made of a double structured crucible composed of an outer crucible and an inner crucible. In the upward pulling of single crystal, the accommodation depth of inner crucible relative to the outer crucible is increased in accordance with any decrease of melt accommodated in the inner crucible according to the growth of single crystal, so that the melt accommodated in the outer crucible is fed into the inner crucible to thereby maintain the amount of melt accommodated in the inner crucible within a given range.

Abstract: A last lens for immersion lithography exposure equipment, composed of a crystal represented by formula BaLiF3. The crystal is preferably a single crystal represented by formula BaLiF3. The immersion lithography exposure equipment preferably comprises a light source which emits light with a wavelength of not more than 200 nm. More specifically, the immersion lithography exposure equipment preferably comprises an ArF excimer laser oscillator or an F2 excimer laser oscillator. In the last lens for the immersion lithography exposure equipment, at the wavelength of light used in a light source, preferably at a wavelength of not more than 200 nm, a high refractive index, a high transmission, and low SBR can be realized, and the resolution of the exposure equipment can easily be improved.