Curated optical setups

Worked optical setups, from interferometers and telescopes to microscopes, pulse compressors and nonlinear sources. Each comes with the background physics, a plain statement of what the model does and does not compute, and a live canvas to click through and open in the editor. The list of examples expands over time.

Lens Physics

Why a real lens has no focal point One collimated bundle through an ideal lens and through a real N-BK7 singlet of the same focal length — a point against a 30 mm smear. Singlet vs achromat — axial colour Two f = 40 mm prescriptions under the same 400–750 nm beam: one glass spreads the spectrum along the axis, two glasses fold it back. Spherical aberration: spherical lens, aspheric lens and ideal thin lens Three 1-inch lenses of the same 25 mm focal length under one 20 mm monochromatic bundle: a perfect point, a 7.5 mm smear, and a point again.

Reflective Imaging Systems

Gregorian telescope A parabola and an ellipse, each placed at the one pair of points it images perfectly, and a traced spot seven ten-millionths of a millimetre… Ritchey–Chrétien telescope Two hyperboloids that are measurably worse on the optical axis than a classical Cassegrain, and better everywhere else — the trade behind Hu… Inside an IR Cassegrain objective Follow the light through an open primary, onto a convex secondary, and back to a concave primary that focuses around it.

Beam Routing

Wavelength combining and separation Three lasers put on one axis by two dichroic mirrors, then taken apart again by the same two coatings: colour used as a routing label. Polarization send–return separation A polarizing beamsplitter and a quarter-wave plate send light out and take the reflection off at a different port, without the 75% loss of a…

Interferometers

Michelson interferometer One beamsplitter, two mirror arms, one recombined output — the interferometer behind the Michelson–Morley experiment and, scaled up four kil… Mach–Zehnder interferometer Two beamsplitters, two fully separate arms, two output ports — shown three ways: a mechanical delay, a driven phase modulator, and a phase o… I/Q optical modulator Two push-pull Mach–Zehnder modulators nested inside a third, 90° apart: one sets the real part of the optical field, the other the imaginary… Pulsed Mach–Zehnder Two arms, complementary spectra, and a path-dependent average power. Supercontinuum Mach–Zehnder Two arms, complementary spectra, and a path-dependent average power.

Nonlinear Optics

Optical parametric oscillator A synchronously pumped singly resonant OPO in a bow-tie ring: green pump photons split into an 800 nm signal and a 1588 nm idler. Synchronously pumped picosecond OPO A frequency-doubled 1032 nm picosecond laser pumps a cavity whose round trip lasts one pump period, giving an 800 nm signal. Near infrared supercontinuum in YAG Femtosecond pulses in a bulk crystal broaden into a continuum; the red side of a 1035 nm pump in YAG is a ready near-infrared band.

Microscopy Implementations

Multimodal multiphoton microscope One femtosecond beam, two contrast mechanisms: second-harmonic generation for non-centrosymmetric structure and two-photon fluorescence for … Coherent Raman microscope Two synchronised picosecond beams beating at a molecular vibration, read out three ways: stimulated Raman loss, forward CARS, and epi-CARS. Epi-fluorescence microscope One objective both illuminates the sample and collects its fluorescence; a dichroic mirror and two filters keep the excitation out of the ca…

Ultrashort Pulses

Ultrashort pulse chirping The same 150 fs pulse measured three ways — bare, chirped by 100 mm of dense flint, and recompressed — each on its own autocorrelator. Finding time zero — sum frequency of two beams Two colours in one crystal: the second harmonics are always there, and the line between them appears only when the pulses coincide. Hollow-core pulse compressor A gas-filled capillary broadens the spectrum of an intense pulse; a negative-GDD compressor then makes it shorter — and an autocorrelator sh…