aperture mask *NOTE:When using these slides.it's important that the light illuminate only one aperture pattern at a time.You can use the Aperture Mask (OS-9139)for this purpose,as diffraction shown in Figure 20.Just place aperture the slide with the diffraction aperture on one side of a component holder and the Figure 20:Using the aperture mask on the other. Aperture Mask Diffraction Grating Type:Transmission,plastic replica diffraction grating Ruling:6000 lines per centimeter Viewing Screen with Metric Scale 40 mm scale on 45 x 45 mm white screen The radii for each zone,In units of millimeters. 1.590 1.509 1.422 1.331 1.232 Opaque Points and Fresnel Zone Plates 1.125 1.006 0.871 Opaque Points:Circular shape,with 0.711 diameters of 0.25,0.50,and 1.0 mm. 0.503 0.000 Tolerances:±0.05mm Fresnel Zone Plates:Figure 21 shows the Radii of the zones.The two zone plates on the Slide are complementary;the opaque Figure 21:Freznel Zone Radii zone of one is the transparent zone of the other.So the radii of the zones are the same for both plates. 019 Diffraction Grating Type: Transmission, plastic replica diffraction grating Ruling: 6000 lines per centimeter Viewing Screen with Metric Scale 40 mm scale on 45 x 45 mm white screen Opaque Points and Fresnel Zone Plates Opaque Points: Circular shape, with diameters of 0.25, 0.50, and 1.0 mm. Tolerances: ±0.05 mm Fresnel Zone Plates: Figure 21 shows the Radii of the zones. The two zone plates on the Slide are complementary; the opaque zone of one is the transparent zone of the other. So the radii of the zones are the same for both plates. ★NOTE: When using these slides, it's important that the light illuminate only one aperture pattern at a time. You can use the Aperture Mask (OS-9139) for this purpose, as shown in Figure 20. Just place the slide with the diffraction aperture on one side of a component holder and the aperture mask on the other