In this work, we present the equations and the method to evaluate the aspheric surface of a condenser lens using the null-screen test. As is well known, a condenser lens has two surfaces, one of them is flat or spherical and the other one is a conic surface with aspheric deformation constants. We propose a variant of evolutionary algorithms to retrieval the conic constant, radius of curvature and the aspheric deformation coefficients of the aspheric surface. For the validation of the proposed method, we analyzed the LAG017 condenser lens fabricated by Melles Griot. The results show that the conic constant coefficients, the radius of curvature and the aspheric deformation coefficients can be retrieved with good accuracy (>98%).