Question

a) Describe the difference between the three main photodetector types, specifically what they respond to and the process in which light is converted to a response signal. Give at least one example for each type of photodetector.

b) Give an example for a setup you may want to use for each listed circumstance and provide your reasoning for each.

1. You want to make a one time measurement and obtain a two-dimensional spectrum. Your sample is very sensitive to light, forcing you to use a very weak light source.

2. You want a device that can output a two-dimensional spectrum that can simultaneously measure and integrate samples at the same time. In addition, discuss the property of this device that allows it to perform this action.

3. You want a device that is very sensitive in the near-IR region.

4. You want a compact device that can be used for photon counting in a very wide range of wavelengths. It’s more important that the machine can handle larger quantities of radiation.

5. You want to measure the fluorescence of a material that is very weakly emissive in the UV region. You want fast and accurate measurements of the fluorescence of the material.

6. You want a machine that can detect a large variety of wavelengths. The machine must easily be able to switch between each type of wavelength.

7. You want a device that can measure many lines of the spectrum simultaneously. You want the lines to be discrete so that you may see how a material responds to specific wavelengths.

8. You want a device that will absorb in the IR region. There are three different devices that were discussed during class that can accomplish this. Pick your favorite one!

Answer 1

a).types of photodetectors and their application are discussed bellow