Human eye
Focuses light through an adjustable pupil onto a modeled retina, for exploring how focal length and pupil size change the detected spot.
Open in the canvas →In the real world
The eye forms an image on the retina using the refractive power of the cornea and crystalline lens. The iris controls the pupil opening, while accommodation changes the lens shape to bring different object distances into focus.
In OpticalSetup
The pupil clips incoming rays, an equivalent thin lens bends the accepted light, and a retinal detector records the resulting signal. Adjust Eye diameter, Pupil diameter, and Lens focal length to compare the illuminated spot. A linked detector screen makes the retinal reading visible beside the eye.
In the example, a parallel beam enters the pupil. Change the focal length to move the best focus relative to the retinal plane, or narrow the pupil to admit less of the beam.
This is a geometric teaching model, not an anatomical eye prescription. It does not predict visual acuity, diffraction, accommodation dynamics, retinal physiology, or laser exposure limits.