IR Filter on Artificial Tears
An IR filter (750–900 nm), placed in the center of a micrograph of artificial tear crystals with the field diaphragm fully open, reveals multiple wavelengths—from infrared in the center of the crystals to violet on the outer circumference.
—Baruc Zago Mazzocco, Instituto Nacional de Astrofísica Óptica y Electrónica, San Andrés Cholula, Mexico
