How can you tell if a filament is not properly centered?

1. Select any specimen and click on filament alignment. The slide bar controls correspond to set screws on your microscope. Follow the directions to align the filament. Next, click on condenser alignment and optimize the condense height and openings. Answer the following questions:
a. How can you tell if a filament is not properly centered?
b. How do you adjust the intensity of the light from the filament?
c. Why cant you just turn the filament voltage up to the maximum setting?
d. What effect does moving the condense height have?
2. Use the standard scale, 40X magnification, and the arrowroot starch sample for this exercise. First, practice calibrating the reticle marks. Read through the laboratory procedure for an overview on how this is done. A red reticle scale works well and is easily aligned below the micrometer scale, which is in black. You will use a reticle scale in lab so spend as much time as needed to get comfortable with this procedure. Once you are comfortable, measure the size of the arrowroot starch under different magnification. Answer the following questions:
a. Which magnifications were best for measuring the starch grains and why?
b. Show an example calculation from one of your measurements of the long axis of one of the
starch grains.
3. At what angle does the fibre have to be in order to achieve maximum contrast, or the maximum contrast angle?

4. Describe and give the correct order of the components of the optical path. Briefly explain the purpose of each component.

5. Describe what is an interference colour?

6. When would you expect the background to be black when using a PLM? Explain why.

7. What other forensic samples can be analyzed using a PLM?