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How to Make a Rheinberg Filter

A microscope uses a light source, which beams up from underneath a sample on a clear slide, to illuminate the sample for the analyst. Commonly the microscope simply shows the analyst the object, such as a microscopic parasite, under study in regular light. The parasite is visible, but due to the clear background and the transparency of the sample, the analyst may find it hard to see some of the detail. A Rheinberg filter goes between the sample and the light source, and confers color to the background and a contrasting color to the sample, which can bring out extra detail.

Things You'll Need

Measuring tape
Blue gelatin filter
Green gelatin filter
Adjustable circle cutter
Sticky tape
Scissors

Instructions

- 1
  Buy one blue gelatin filter and one green gelatin filter from a supply company that sells scientific equipment, such as a firm that specializes in microscopes.
- 2
  Measure the diameter of the filter holder in the microscope using measuring tape. This will hold the final filter product.
- 3
  Cut out a circle of the green gelatin filter to the same diameter as the filter holder. Use a circle cutter, which is available at craft stores.
- 4
  Cut and remove a circular hole inside the green gelatin filter. The diameter of the hole should be half the diameter of the original circle.
- 5
  Prepare a cut-out of the blue gelatin filter using the circle cutter set to the same diameter as the inner hole in the green filter.
- 6
  Place the blue circle inside the green circle. Attach these with strips of transparent sticky tape and, using a scissors, cut off all of the excess tape to leave a round filter.
- 7
  Slide the homemade Rheinberg filter into the filter holder of the microscope, and set the microscope to darkfield illumination. Add a sample slide. The filter should illuminate the sample with green light, on a background that has a blue color.

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