Blue　laser　with　high　power　and　high　beam　quality　has　many　applications　such　as　in　laser　display,　underwater　communication　and　imaging,　and　non-ferrous　metal　processing.　Optically　pumped　external-cavity　surface-emitting　laser　combines　the　advantages　of　both　surface-emitting　semiconductor　lasers　and　solid-state　disk　lasers,　and　can　produce　high　output　power　and　good　beam　quality　simultaneously.　Its　high　intracavity　circulating　power　is　more　conducive　to　intracavity　frequency　doubling,　achieving　high-power　and　high　beam　quality　blue　light　through　fundamental　laser　in　the　near-infrared　waveband.　This　paper　reports　an　efficient　intracavity　frequency　doubled　490　nm　high　power　blue　light　by　using　a　980　nm　fundamental　laser　in　an　external-cavity　surface-emitting　laser.　The　V-type　resonant　cavity　is　formed　by　the　high　reflectivity　distributed　Bragg　reflector　(DBR)　at　the　bottom　of　gain　chip,　a　folded　flat　concave　mirror　(high　reflectivity　coated　for　980　nm　and　anti-reflectivity　coated　for　490　nm),　and　a　flat　concave　end　mirror　(high　reflectivity　coated　for　980　nm　and　490　nm).　By　inserting　a　nonlinear　crystal　LBO　into　the　cavity　at　the　beam　waist　formed　by　the　folded　mirror　and　end　mirror,　and　employing　a　birefringent　filter　(BRF)　to　polarize　the　fundamental　laser　and　narrow　the　linewidth　of　the　laser,　a　high　power　and　high　beam　quality　blue　laser　with　high　conversion　efficiency　is　obtained.　The　effects　of　different　factors　including　the　length　of　nonlinear　crystal,　the　linewidth　of　fundamental　laser,　and　the　compensation　of　walk　off　angle　on　the　output　power　of　the　blue　laser　are　studied　experimentally.　The　length　of　the　nonlinear　crystal　is　optimized　based　on　the　size　of　the　fundamental　laser　beam　waist　at　the　position　of　the　crystal　in　the　resonant　cavity.　Under　the　type-I　phase　matching　condition　of　LBO,　over　6　W　output　power　at　491　nm　wavelength　is　obtained　when　the　crystal　length　is　5　mm　and　the　BRF　thickness　is　1　mm.　The　beam　quality　M2　factor　in　the　x　direction　and　the　y　direction　are　both　1.08,　and　the　conversion　efficiency　of　frequency　doubling　is　63%.　The　experimental　results　also　show　that　symmetrically　placed　nonlinear　crystals　can　compensate　for　the　walk-off　angle　during　frequency　doubling　to　a　certain　extent,　thereby　clearly　improving　the　conversion　efficiency　of　the　frequency　doubled　blue　laser.　©　2024　Chinese　Physical　Society.