Thermal Gradient — Schlieren Imaging of Hot Air
122.20 £
A Schlieren optical imaging setup revealing the hot air convection above a candle flame — the invisible temperature gradient rendered visible as flowing dark and light refractive index variations in a sharp, high-contrast image.
Description
Schlieren photography makes invisible air density variations visible by detecting the refraction of light at boundaries between regions of different temperature — the hot air above a flame has a lower refractive index than ambient air, and the Schlieren optical system converts this refractive index gradient into a spatial intensity variation in the image. This setup uses a large parabolic mirror system to collimate a bright LED point source, with a razor blade at the focal point as the knife-edge cutoff, producing a monochromatic image that reveals the invisible convective plume above a candle flame with extraordinary clarity. The flowing column of hot air is rendered as a dark twisted ribbon against the lighter ambient background, its turbulent mixing with ambient air visible as complex folded structures at the plume boundary. Shot at 1/2000 second to freeze the fastest convective turbulence.
