Diffraction Gratings: Principal Maxima, Wavelength Dispersion, and Uses

All flashcards

What is a diffraction grating?

An optical element containing many precisely spaced parallel slits or lines. Light from the openings interferes to form sharp principal maxima.

What happens to the principal maxima when more slits are illuminated?

They become narrower and brighter, while secondary maxima become less pronounced.

State the grating equation and define its symbols.

$d\sin\theta=m\lambda$, where $d$ is adjacent-slit spacing, $\theta$ is the maximum's angle, $m$ is an integer diffraction order, and $\lambda$ is wavelength.

What is the zero-order maximum?

The central principal maximum corresponding to $m=0$, which lies in the incident direction for normal incidence.

How can a bird feather produce iridescent color?

Regular microscopic structures in the feather can act as a reflection grating. Interference among reflected waves produces structural colors that are not due solely to pigment.

Quiz questions

1. What is one benefit of the narrow principal maxima produced by a diffraction grating?Answer: They make nearby wavelengths appear in more distinct directions.
2. How does a transmission grating interact with light?Answer: It allows light to pass through its openings.
3. What does a grating do in a monochromator?Answer: It helps select a particular wavelength of light.
4. A grating has 10,000 lines per centimeter. What is the spacing between adjacent lines?Answer: $1.00\times10^{-6}\text{ m}$
5. A screen is perpendicular to the central direction, a distance $x$ from a grating. If a principal maximum is at angle $\theta$, what is its screen displacement $y$?Answer: $y=x\tan\theta$