We report on novel investigations on non-linear optical 2-docosylamino-5-nitropyridine (DCANP) Langmuir-Blodgett (LB) films by means of polarization, second harmonic and scanning force microscopy (SFM). Direct optical measurements at the air/water interface showed the molecules to reorient when depositing a LB film onto a solid substrate by the Langmuir-Blodgett method. Horizontal dipping (Langmuir-Schäfer method), however, resulted in the same surface structure being transferred onto substrates as was found for the LB film floating on a water subphase. Furthermore, the LB film was improved in film quality by adding 10-20% of arachidic acid (AA) to the pure DCANP phase. As shown by SFM, this results in a smooth surface structure free of defects while no significant changes in the optical properties of the mixed LB film were found. Such LB films therefore show improved structural and optical properties for optical wave guide applications. Additionally, a novel force microscope was set up which is able to image the conformation of the chromophores of a LB monolayer floating at the air/water interface. Never so far has this interface been inspected on such a small scale in direct space. Combined operation of both this new force microscope and the optical methods offers the possibility for the simultaneous inspection of both the structural and optical properties of the floating Langmuir films down to the molecular scale.