When　a　parallel　light　beam　illuminates　a　curved　air-liquid　interface,　a　group　of　self-interference　fringes　appears　in　the　reflection　field　in　the　region　near　the　critical　point.　A　model　describing　the　interface　height　and　slope　dependences　on　the　fringe　phase　supports　this　observation.　The　fringe　phase　function　is　determined　by　the　fringe　image.　The　height,　slope,　and　curvature　of　the　interface　curved　by　a　glass　slide　and　thin　rod　are　measured.　The　resolution,　for　the　curvature　measuring,　is　up　to　0.05　mu　m(-1).　A　comparison　of　the　experimental　results　of　the　interface　height　by　using　the　exponential　theory　verifies　this　approach＇s　reliability.　A　small　RMS　error　shows　that　the　results　are　in　good　agreement.