為何「兩光源的程差小」是干涉條紋的產生條件之一？

2012-02-15 10:25 pm

One of the conditions for the interference of light to occur is:
The path difference of the light for the two sources must be small and comparable to the wavelength of the light source.

What does that mean?

回答 (1)

天同

2012-02-17 5:04 am

✔ 最佳答案

For constructive interference to occur, you would expect
path difference = m入
where m is an interger, and 入 is the wavelength of light

In general circumstances, m is a small number (m = 1, 2, 3...etc). The path difference is thus only a small multiple of the wavelength.

For large value of m, though constructive interference could still occur in theory, it may so happen that the path difference is longer than the "coherence length" of the light used, which practically would not produce good interference.
.

👍 0 👎 0