The OL Series 454 Integrating Sphere Calibration Standard is designed to produce a high intensity Lambertian distribution. It is useful as a highly uniform illumination source for contrast measurements, linearity tests, flat-fielding of devices for response uniformity, and device MTF with the optional filter holder and the desired target resolution. It consists of an optics head and a separate current source. The integrating spheres are available in diameters of 4, 6, 8, 12, and 18 inches with exit (radiating) ports of 1, 1½, 2, 3, and 6 inches, respectively.