When does a convex lens form a real versus virtual image?

A convex (converging) lens forms a real image when the object distance d_o is greater than the focal length f. The image is real, inverted, and appears on the opposite side of the lens from the object. When d_o < f, the lens cannot converge the rays quickly enough and the image is virtual, erect, and magnified � appearing on the same side as the object. When d_o = f the image is at infinity. The thin-lens equation 1/f = 1/d_o + 1/d_i describes all three cases: positive d_i means real image, negative means virtual.

How does a compound microscope produce high magnification?

A compound microscope uses two converging lenses in series. The objective lens (very short focal length, typically 2�20 mm) is placed just beyond its focal length from the specimen, forming a highly magnified real intermediate image inside the microscope tube. The eyepiece lens (10�25 mm focal length) then acts as a magnifying glass for the eye, further magnifying this intermediate image. Total magnification M � m_obj � M_eye, where m_obj = -d_i/d_o (typically -40 to -100�) and M_eye = 250/f_eye (typically 10�), giving total magnification of 400�1000�.

What causes chromatic aberration and how is it corrected?

Chromatic aberration arises because the refractive index of glass depends on wavelength (dispersion): n(?). Blue light bends more than red light, so a simple lens has a shorter focal length for blue than for red � different colours focus at different positions, producing colour fringes around images. The Abbe number V = (n_D-1)/(n_F-n_C) quantifies a glass's dispersion. Correction uses an achromatic doublet: a converging crown glass element (high V) cemented with a diverging flint glass element (low V). The doublet brings two wavelengths (typically red and blue) to the same focus while partially correcting the intermediate wavelengths. An apochromat corrects three wavelengths.

Home▸Optics & Light▸Optics Simulator – Lenses, Microscope, Telescope & Aberrations

🧪 Optics Simulator – Lenses, Microscope, Telescope & Aberrations

Interactive ray-diagram optics simulator. Six presets: Convex Lens, Concave Lens, Lens Combination, Microscope, Telescope, and Aberrations. Visualise real and virtual images, focal points, and chromatic aberration using the thin-lens equation 1/f=1/do+1/di. Focal length, object distance, and aperture sliders.

Optics & Light2DModerate60 FPS

⚙ Under the hood

This simulation models the behavior of light through various optical components like lenses. It allows users to experiment with microscope, telescope designs and explore the effects of aberrations on image formation.

Optics SimulatorLensesAberrations

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install