We demonstrate optical imaging with a resolution of around 50 nm on an electroluminescent polymer by conducting atomic force microscopy. The results indicate that brighter light emission occurs from asperities on the polymer surface. By comparing surface morphologies of the polymer and the indium tin oxide substrate, it is found that similar asperities exist on both surfaces and the polymer becomes thinner on these locations. Therefore, stronger luminescence intensity from asperities is caused by higher electric field due to reduced polymer thickness. The present method can also be extended to obtain simultaneous optical and electrical transport properties.