A laser optical fiber storage device for temporarily storing a free end of an elongated flexible laser optical fiber. This invention also relates to a method of making azithromycin from desmethyl-azithromycin by dissolving desmethyl-azithromycin in acetone, adding activated carbon, adding formaldehyde, adding formic acid; refluxing the desmethyl-azithromycin acetone solution, adding sodium hydroxide to induce precipitation of azithromycin, and isolating azithromycin. Further, the n signal output circuits each include the following: a transistor whose gate potential varies in accordance with the amount of light entering the photoelectric conversion element; a first switching element which holds the gate potential of the transistor; and a second switching element which controls a signal output from the transistor.