Lenticular lenses are fundamental components in light field displays, which are usually optimized based on aberration correction. This letter proposes a forward-model-based non-imaging optimization method for designing lenticular lenses addressing the inherent limitations of the conventional imaging-based optimization method by accounting for the emission characteristics and physical size of the subpixels. We develop a forward modeling framework enabling direct control of viewpoint width and propose a subpixel-level evaluation algorithm for binocular crosstalk. Results demonstrate our method achieves a 78.75% crosstalk reduction at the maximum viewing angle, establishing an effective technical solution for target viewpoint distributions with the directional backlight unit.