Let us consider two patterns made of parallel and equidistant lines, e.g., vertical lines. The step of the first pattern is p, the step of the second is p + δp, with 0 < δp < p.
If the lines of the patterns are superimposed at the left of the figure, the shift between the lines increase when going to the right. After a given number of lines, the patterns are opposed: the lines of the second pattern are between the lines of the first pattern. If we look from a far distance, we have the feeling of pale zones when the lines are superimposed (there is white between the lines), and of dark zones when the lines are "opposed".
The middle of the first dark zone is when the shift is equal to p/2. The nth line of the second pattern is shifted by n δp compared to the nth line of the first network. The middle of the first dark zone thus corresponds to
n\cdot \delta p=p/2
that is
n={\frac {p}{2\delta p}}.}
The distance d between the middle of a pale zone and a dark zone is
d=n\cdot p={\frac {p^{2}}{2\delta p}}}
the distance between the middle of two dark zones, which is also the distance between two pale zones, is
2d={\frac {p^{2}}{\delta p}}}
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Moire pattern ช่วยตีความช่วง calculate หน่อยครับ
If the lines of the patterns are superimposed at the left of the figure, the shift between the lines increase when going to the right. After a given number of lines, the patterns are opposed: the lines of the second pattern are between the lines of the first pattern. If we look from a far distance, we have the feeling of pale zones when the lines are superimposed (there is white between the lines), and of dark zones when the lines are "opposed".
The middle of the first dark zone is when the shift is equal to p/2. The nth line of the second pattern is shifted by n δp compared to the nth line of the first network. The middle of the first dark zone thus corresponds to
n\cdot \delta p=p/2
that is
n={\frac {p}{2\delta p}}.}
The distance d between the middle of a pale zone and a dark zone is
d=n\cdot p={\frac {p^{2}}{2\delta p}}}
the distance between the middle of two dark zones, which is also the distance between two pale zones, is
2d={\frac {p^{2}}{\delta p}}}
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