Answer the following questions about a Blu-ray laser:
(a) The laser on a Blu-ray player has a wavelength of $405 \mathrm{nm}$. In what region of the electromagnetic spectrum is this radiation? What is its frequency?
(b) A Blu-ray laser has a power of 5 milliwatts (1 watt $=1 \mathrm{J} \mathrm{s}^{-1}$ ). How many photons of light are produced by the laser in 1 hour?
(c) The ideal resolution of a player using a laser (such as a Blu-ray player), which determines how close together data can be stored on a compact disk, is determined using the following formula: Resolution $=0.60(\lambda \text { (NA), where } \lambda$ is the wavelength of the laser and NA is the numerical aperture. Numerical aperture is a measure of the size of the spot of light on the disk; the larger the NA, the smaller the spot. In a typical Blu-ray system, NA = 0.95. If the 405-nm laser is used in a Blu-ray player, what is the closest that information can be stored on a Blu-ray disk?
(d) The data density of a Blu-ray disk using a 405-nm laser is 1.5 $\times 10^{7}$ bits $\mathrm{mm}^{-2}$. Disks have an outside diameter
of $120 \mathrm{mm}$ and a hole of $15-\mathrm{mm}$ diameter. How many data bits can be contained on the disk? If a Blu-ray disk can hold 9,400,000 pages of text, how many data bits are needed for a typed page? (Hint: Determine the area of the disk that is available to hold data. The area inside a circle is given by $\mathrm{A}=\pi r^{2},$ where the radius $r$ is one-half of the diameter.)