There are lots of optical design books out there. IIRC, most follow the approach of Warren Smith's classic: "Modern Optical Engineering" in starting out from si

There are lots of optical design books out there. IIRC, most follow the approach of Warren Smith's classic: "Modern Optical Engineering" in starting out from simple paraxial ray tracing, where sin(x)≈x in radians, and advance from there. If you have some specific topics to learn, you might find them in separate texts, such as Reflective Optics, by Dietrich Korsch (technical) or others.