Coherent light waves are waves that have a constant phase difference and maintain a fixed relationship to one another. This means that the peaks and troughs of the waves are aligned and they have a consistent wavelength and frequency.
When two coherent light waves meet, they can either constructively or destructively interfere with each other. Constructive interference occurs when the peaks of the waves align, resulting in a larger amplitude. Destructive interference occurs when the peaks of one wave align with the troughs of the other wave, resulting in a cancellation of the waves.
Interference occurs when two or more waves interact with each other, while diffraction refers to the bending of waves around obstacles or through small openings. Diffraction can also occur when waves pass through a medium with varying density, causing them to change direction.
In the double-slit experiment, a coherent light source is shone through two parallel slits, creating two separate wave sources. These waves then interfere with each other, creating a pattern of bright and dark bands on a screen behind the slits. This pattern is caused by the constructive and destructive interference of the waves. Additionally, the edges of the slits cause the light to diffract, creating a diffraction pattern within the interference pattern.
Interference and diffraction of coherent light waves have many practical applications, including in technologies such as holography, fiber optics, and optical tweezers. They are also used in the study of crystal structures, as well as in medical imaging techniques such as X-ray diffraction. In daily life, diffraction can be seen in the colorful patterns on CDs and DVDs, while interference is used in the creation of anti-reflective coatings for eyeglasses and camera lenses.