15. Consider an absorption experimental set-up shown in the figure below in which a laser is used as a light source. The light enters through a small hole in one mirror and after making 19 passes (18 reflections) it exits through another hole and hits a photodetector as indicated. The reflectance of each mirror surface is determined by the index of refraction of the air flowing through the cell and the index of refraction of the mirror surface. a) If the index of refraction of the air being sampled is 1.03 and the index of refraction of the mirrors is 100, calculate the reflectance of both mirrors. (You can treat this as if it's at normal (perpendicular) incidence, like the equation in your info sheet). b) Given the reflectance calculated in part a, if the laser beam enters the cell with a power of 5 mW, what will be the power of the exiting beam if there is no absorption or scattering of the light from the air inside the cell? c) Consider a situation in which the optical cell is temperature controlled at 35 C, but the sampled air starts at between 3 C and 13 C and warms up as it flows through the cell (there was no bend in the inlet like we saw in the slide from Monday!). This change in temperature of the gas leads to a change in the density of the gas, which in turns affects the index of refraction of the air. How could this affect the measurement? What experimental procedure be implemented to address this problem? (in addition to inserting a U-bend in the