An infinite diffraction grating has rulings of 800 lines per mm. The monochromat
ID: 1508743 • Letter: A
Question
An infinite diffraction grating has rulings of 800 lines per mm. The monochromatic, 400 nm wavelength, light leaving the grating is incident on a convex focusing lens with focal length f = 5 cm placed a distance u = 9 cm from the grating as shown in the figure below. A magnified image of the grating is formed on a screen at a distance v from the lens. What is the separation between the diffraction fringes formed between the screen and lens? Follow up: What happens as the diameter of the lens is increased? (Explain) The LIGO gravitational interferometer (https://www.ligo.caltech.edu/page/ligos-ifo) and Hubble Space Telescope (http://hubblesite.org/the_telescope/nuts_and_bolis/optics/) are two simple yet powerful optical devices that allow us to learn about the cosmos. Briefly describe what design features make these devices so powerful. (In the case of LIGO how it can detect subtle change in space due to gravity waves and in the case of Hubble how it can image such distant objects.)Explanation / Answer
SOLUTION:
Problem 2:
Designing instruments like LIGO's interferometers, capable of measuring a distance on the order of 10-19 meters required inventing and refining innovative technology. Most of LIGO’s most impressive technology resides in its seismic isolation systems (which remove unwanted vibrations), vacuum systems (to make sure the laser light is kept pure), optics components (to preserve laser light and laser power), and computing infrastructure (to handle the mindboggling amount of data that LIGO collects). These systems are like LIGO's internal organs. If any one fails, the whole instrument suffers.
Ref: https://www.ligo.caltech.edu/page/ligo-technology