Week 5 Discussion
Do some research on the internet on smart optical sensors or on optical sensors for smart or mobile applications. Pick one smart optical sensor or one smart or mobile application of optical sensors, and explain how it works. Make sure your choice is different than other students. Provide at least a one to two paragraph description.
Week 5 Assignment
Work the problems below. To receive any credit, you must show all work. You may submit your work in a word processing document or in a pdf file. Graphic files are not acceptable submissions. Your file submission document should be entitled Week5AYourGID (replace YourGID with your specific GID).
1. A source of green light has a frequency of 6.2 x 1014 Hz. What is the wavelength in nanometers (nm) and in ?
2. A flashlight beam has an exit power of 100mW, an exit diameter of 3.8cm, and a divergence of 1.1. Calculate the intensity in mW/cm2 at 55m and the size of the beam at that distance.
3. Suppose a 680-nm beam with a power of 0.2 mW and a 4.5-cm diameter strikes a detector with a 0.2-cm diameter. How many photons strike the detector per second?
4. A photomultiplier has a current gain of 3 x 106. A weak light beam produces 55 electrons/s at the photocathode. What anode-to-ground resistance must be used to get a 2.8 V voltage from the light pulse? The charge of an electron is 1.6 x 10-19 coulomb.
Week 5 Lab
1. Using Multisim, design a system using the photoconductive cell shown in the figure below to measure and display light intensity. Make the design such that 20 to 100mW/cm2produces an output of 0.2 to 1.0V. What is the readout error when the intensity is 60mW/cm2? Show all calculations and Multisim results.
2. For the turbidity system show in Figure 2 below, two matched photoconductive cells are used in R vs. IL as given in Figure 3 below. Design a signal-conditioning system that outputs the deviation of the flowing system turbidity in volts and triggers an alarm if the intensity is reduced by 10% from the nominal of 15mW/cm2.