Abstract—An optical system called the Fourier scope is an improved alternative to the conoscopic microscope for instant measurement of LCD viewing‐angle patterns. The Fourier scope includes a hand‐held detecting head for measuring on‐line flat‐panel LCDs, and allows non‐critical measurement distances ranging from millimeters to centimeters, a viewing‐angle range of ±70°, the use of true color patterns describing color fidelity or dispersion effects, and approximately linear viewing‐