مرشحات الاستقطاب المانعة للأنعكاس .. كتاب التصوير الملون

- Radiology. When the rays leave their source they spread in all directions, in the form of waves that oscillate perpendicular to the direction in which the rays travel (Fig. - b) Other waves also oscillate in another direction, so the top is located to the right, while the bottom is directed to the left (Fig.

Case D These oscillations continue to proceed as before until they meet a shiny reflective surface. It has been shown from the study of light reflections that the reflected rays do not fluctuate except in one plane only, and then it is said that the light has been polarized on one plane Plane Polarized, as this name is called. Polarization ». Here the naming of the filter originated as the Polarizing Filter, or the polarizing filter. It is possible to liken the polarized ray in one plane only as a result of reflection with a rope fixed on one side, and moved by the hand on the other side (Fig. 18-D).

Polarizing Filters

It is obvious that the rope can be moved in waves in all directions according to the movement of the hand (Fig. 18-(e), however, if the rope passes through an opening, its movement will be determined according to the shape of this opening. If the opening is transverse, then the waves only move in a plane. Transverse (Fig. 18-f), and if the opening is longitudinal, it can move up and down (Fig. 18-g), and its movement continues even if it has to pass through another longitudinal opening (Fig. 18-g), but if the first opening is longitudinal and the second transversely (Fig. 18-h), it is certain that his movement will stop after he exits the second hole

For example - it is not allowed, and taking into account the previous analogy, we say that the polarization filter represents a barrier with many (virtual) parallel slots, as it is not allowed to pass through it except for light waves that oscillate in the same direction as its slots (Fig. 18-i). If the filter is in a position that makes its slots (default) is longitudinal, it is not allowed to permeate it except for waves that run in a longitudinal plane, and those that run in other planes are transverse to it (Fig. 18-i

And since the rotation of this filter around its center changes the direction of its slots from the longitudinal position to the transverse position, it is easy to control the passage of light waves (caused by reflection and which oscillate in one plane) by simply rotating the filter around its center, because its rotation is like a barrier with slots. Cross-sectional in the path of light waves whose level of positive movement differs from the direction of the filter holes that we assumed.

Thus, this filter sometimes takes the place of the aperture transverse barrier (it prevents the penetration of the reflected light polarized in a vertical plane) and at other times takes the place of the second longitudinal barrier (shown in Figure 18-g), and its performance of this or that function depends on the degree of its rotation around its center.

The theory of polarizing filters depends on what research has shown that some materials do not allow their crystals to pass light waves through them unless they are oscillating in a certain plane. Accordingly, if light rays pass through these crystals, and the rays are oscillating at the same level that these crystals allow, they will pass through them. Polarization of light, and therefore the properties of these materials were used in the manufacture of chips that are suitable as polarizing chips, and they are characterized by the ability to reduce reflections on glossy or polished and non-metallic surfaces if they are

Therefore, the light intensity, the angle of reflection, is not less than 35 and not more than 70. It is suitable for photographing the glass facades of commercial stores (Fig. 19), photographing shiny oil paintings, photographing furniture and the shiny floor, photographing what is underwater to show the herbs or fish in it, or photographing round, concave or convex Chinese utensils..etc. We see from the previous explanation that polarizing filters do not change the spectral properties of the rays, and therefore they are considered valid for color imaging, and are similar in this respect to neutral filters that reduce the Neutral Density filter without affecting its spectral properties (and we will talk about it later). When polarizing filters are used, the sky usually appears clear when photographing black and white, and its blue color is more saturated in color photography, and this is due to the fact that the filter prevents the passage of rays that are reflected by dust and airborne particles. Perhaps this is a correction of the misconception prevalent among some photographers, which attributes the appearance of the sky standing still in black and white photography, and its intensity in blue in color photos, to that this is a result of the polarizing filter absorbing some of the colors of the blue sky, and this is wrong.

Some such filters have been prepared from heat-resistant glass to be placed in front of the light source, and these filters also play an important role in microscopic imaging conditions, whether in color or black and white. It is difficult to estimate the filter factor accurately when using a polarizing filter, as it depends on the ratio of the rays that the filter does not allow to pass to the rays falling on it, and this factor depends in itself on the extent of the filter’s deviation and rotation around its center