The Kelvin probe force microscope (KFM) can measure both the surface potential and the topographic image simultaneously without contacting the sample surface. Furthermore, both conducting and non-conducting thin layers can be measured directly with a millivolt range potential resolution and a sub-micrometer lateral resolution. In this paper, we report two improvements on the KFM which entail a new method of controlling the tip-sample distance to obtain accurate surface potentials, and a new method for increasing the topographic lateral resolution. With these improvements, we can obtain a potential resolution that is less than 1 mV and a lateral resolution of about 10 nm. Also, we report some potential measurements on Langmuir-Blodgett thin films.