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A spectral domain optical coherence tomography (OCT) system operates with a broadband light source with a center wavelength of 810nm. The OCT system operates with an imaging depth range of 4mm in water (refractive index n=1.33) and a depth resolution of 5 um in water. (a) The spectrometer operates in air (refractive index 1.0) but the object being imaged is immersed in water. Calculate the required spectral range of the spectrometer to achieve the target depth resolution of 5 um of the object in water. [6 marks] (b) Calculate the required spectral resolution of the spectrometer. [7 marks] (c) The OCT light is scattered by red blood cells which introduces a doppler frequency shift of 12kHz. Assume the red blood cells are moving at 45 degrees relative to the incident beam direction and the refractive index of blood plasma is 1.368. Calculate the speed of the red blood cells as measured by the OCT system. [8 marks] (d) State the main advantages of spectral domain OCT over time domain OCT imaging systems. [4 marks]