Using the flashing beam from IMC, set two iris diaphrams in a non-accrate height (without laser levels) in front of STM1 and IFI (Fig. 1). These are for saving the optical path information somehow. By the way, to do so, some fancy dog clamps were on the way, and wrongly (or tentatively) used (there was a washer under each dog clamp, and this treatment is commonly adopted in this chamber. So bad; Figs. 2 and 3), so I cleared them and newly fixed. Such kinds of modifications would be required one by one.