INSTRUMENT 08 / OPTICS TABLE
Image formation
and refraction.
A geometric-optics workbench. Construct principal rays, change the material or focal length, and connect every visible bend to one compact law.
RAY CONSTRUCTION / CONVEX LENSYELLOW · TEAL · RED
YELLOW MARK = FOCAL POINTIDEAL PARAXIAL MODEL
Where does a lens put the image?
REPRESENTATIVE EQUATION1/f = 1/dₒ + 1/dᵢ
Move the object through one and two focal lengths. The image flips, enlarges, and eventually becomes virtual. Each colored line is a construction ray, so every change of direction follows a stated rule.
Where the outgoing rays meet, a real image forms. If they only appear to meet when traced backward, the image is virtual. This is an ideal geometric model. Real optics also have thickness, diffraction, dispersion, and edge aberrations.