Biomedical Engineering Reference
In-Depth Information
Head
Eye piece
Beam splitter
Stand
Revolving nosepiece
Objective
Stage
Condenser
X-Y translation mechanism
Field lens
Collector lens
Base
1. 1
Optical components and imaging pathways in a simple compound
microscope.
image projected by the objective. This process will be described in more
detail later on in this chapter. Imaging in a compound microscope is shown
in Fig. 1.1 .
When you look into a microscope, you are not looking at the specimen,
you are looking at an image of the specimen. The image is projected in
space about 10 mm below the top of the eyepiece tube where the eyepiece
is inserted. The image that is observed is the representation of the spec-
imen comprised of various colors and/or variations in light intensity. The
image is a highly accurate representation of the specimen with every point
on the specimen corresponding to a point in the image. This ability to pro-
duce highly accurate magnifi ed images of the specimen under observation
is the main function of the modern light microscope. Image formation in the
light microscope will now be discussed in greater detail.
1.3
Light microscopy
The light or optical microscope utilizes a beam of light rays to form images
of objects through interference or diffraction of the light rays with the indi-
vidual features of the specimen. The optical microscope physically forms
images of the object under investigation by focusing the light rays using
multiple series of physical glass or quartz lenses and diaphragms within the
instrument. The light microscope, in its various confi gurations, is the most
widely used imaging instrument used in biomaterials research today.
