About how many layers of exposed silver will result if the 633-nm red light from a helium-neon laser is used to make a volume hologram as in Figure 14.23, and the emulsion is 15 um thick? (Assume that the wavelength is the same in the emulsion as in the air.) (b) Repeat part (a) making the more realistic assumption that the index of refraction of the emulsion is about 1.3. Film Hologram Reconstruction beam Reference Object beam beam Reconstructed beam Standing (a) (b) waves FIGURE 14.23