It　is　found　that　the　photoelectric　technology　is　suitable　for　the　accurate　measurement　of　the　frost　height.　The　objectives　of　this　paper　are　to　experimentally　investigate　the　correspondence　between　the　output　signal　of　the　photoelectric　sensor　and　the　frost　height,　and　then　develop　a　generalized　correlation　to　predict　the　frost　height　directly　and　accurately.　The　experiments　are　conducted　in　a　wide　range　of　operating　conditions　for　air　temperature　17.7　degrees　C-27.2　degrees　C,　relative　humidity　21.6%　RH　to　64.9%　RH,　air　velocity　0.5　m/s　to　4.5　m/s　and　cold　surface　temperature　-10.5　degrees　C　to　-6.5　degrees　C.　Based　on　21　groups　of　experiments　with　total　600　data,　a　linear　correlation　with　a　relative　deviation　of　+/-　10%　is　setup.　Further　validation　of　this　correlation　is　conducted　by　comparing　the　predicted　results　with　4　additional　experiments,　and　approximately　95%　of　the　predicted　frost　heights　are　consistent　with　the　measured　data　within　a　relative　deviation　of　+/-　10%.　These　results　indicate　that　the　photoelectric　technology　can　predict　the　frost　height　directly.　The　application　of　the　proposed　correlation　to　provide　defrost　control　strategy　is　also　discussed　in　this　paper.　(C)　2010　Elsevier　Ltd　and　IIR.　All　rights　reserved.