Dear Abbas Rahdar, I don't know if your oil gives flourescence itself. Mostly, we add fluorescent dyes that, depending upon its solubility, will be incorporated in continuous oil phase or dispersed aqueous phase. If you are using lipophilic dyes, the continuous phase will give fluorescence with dull or non-fluorescent aqueous droplet dispersed in it. This test is used to identify type of emulsion being o/e or w/o.