X-Ray Crystallography: Ewald Sphere Construction

This simulator renders the Ewald sphere construction that underlies every X-ray diffraction experiment: a real 3D reciprocal lattice of a simple cubic crystal sits beside a sphere of radius k = 2π/λ, and rotating the crystal sweeps reciprocal lattice points through the sphere's surface exactly when the Bragg condition is satisfied. Adjust the X-ray wavelength and the crystal's lattice constant to watch the sphere and lattice spacing change, spin the crystal manually or auto-rotate to reproduce the flashing reflections of the rotating-crystal method, and read live counts of active reflections plus the scattering angle 2θ of the nearest one.