results for the grease spot test

Bunsen -- not "bursen" -- the same who invented the Bunsen Burner.

Two light sources are compared by holding a slip of paper between them. A small oil or grease spot on the paper becomes nearly invisible from both sides when the intensity is equal. If a sliding card is mounted on a meter stick the distances can be measured. The intensity ratio is the square of the distance ratio. This only works with light of the same color. You should try this as it is easy to do and gives surprisingly good results.

Photometer is an equipment commonly used on a clinical laboratory. It has different kinds which can do certain jobs like testing blood samples. The examples of photometer used in a clinical laboratory are the flame photometer and Hemoglobin Photometer.

The flame photometer

unit of photometer