A NOVEL MEASUREMENT SYSTEM FOR DENSE FOAM USING A SINGLE-TIP OPTICAL FIBER PROBE NIHEI A.(*), MIZUSHIMA Y.(**), SAITO T.(***) (*) Graduate School of Engineering, Shizuoka University, Japan, (**) Graduate School of Science and Technology, Shizuoka University, Japan, (***) Research Institute of Green Science and Technology, Shizuoka University, Japan