Abstract: This disclosure relates to a digital holographic microscope which is robust to an external environment. According to an aspect of the present embodiment, there is provided an optical system for a digital holographic microscope, the optical system including a beam splitter which reflects a light radiated from a light source toward an object, or passes a light reflected from and traveling from the object; an objective lens focusing the light reflected by the beam splitter on the object; a transflective mirror which is located on the surface of the objective lens and is determined to be transparent or reflective depending on a polarization direction of a light incident to the transflective mirror; and a wave plate which converts the light passing through the beam splitter into a circularly polarized light.

Abstract: Provided are a molten metal refining device and method. The molten metal refining method includes: preparing molten metal; dipping an impeller into the molten metal; supplying a liquid dephosphorization agent on top of the molten metal; and stirring the molten metal by rotating the impeller, wherein a solid dephosphorization agent in a powder state is supplied through the lower portion of the impeller in the stirring of the molten metal, thereby improving the stirring efficiency of the molten metal and efficiently controlling the phosphorus concentration in the molten metal.

Abstract: Provided are a molten metal refining device and method. The molten metal refining method includes: preparing molten metal; dipping an impeller into the molten metal; supplying a liquid dephosphorization agent on top of the molten metal; and stirring the molten metal by rotating the impeller, wherein a solid dephosphorization agent in a powder state is supplied through the lower portion of the impeller in the stirring of the molten metal, thereby improving the stirring efficiency of the molten metal and efficiently controlling the phosphorus concentration in the molten metal.