{"mode":"built-in image_gen","asset":"/img/ray-transfer-matrix/00-cover.png","purpose":"Conceptual editorial cover; not a quantitative ray trace.","prompt":"Use case: scientific-educational. Asset type: wide editorial cover illustration for a Chinese university-level optics article about ray transfer matrices. Create an elegant refined 3D scientific editorial illustration on a warm ivory background: a single transparent glass biconvex lens seen in side perspective, a few fine teal parallel ray lines arriving from the left, bending toward a common focal point to the right and diverging gently beyond it. Minimal optical-bench atmosphere, no crowded mechanical mounts, soft glass caustics, restrained navy and teal with one amber accent. Large clean negative space around the optics. The focal ray paths should be visually coherent and straight between interactions. No words, no letters, no equations, no numeric labels, no logos, no watermark. Landscape aspect ratio approximately 16:9. This is a conceptual cover, not a measurement plot or a literal construction drawing.","scientific_figures":"Figures 1–5 are computed with figures-and-checks.py, not generated with image_gen."}