Scientists use a number of instruments to expand their vision of things unseen, either because they're too small for the eye to see or too far away. Some instruments help scientists see inside other objects, including your body. Some tools magnify objects, while others penetrate tissue, water or inorganic material to show what lies below the surface.
Microscopes use light or electrons to magnify small objects such as microorganisms. A standard laboratory microscope, often called a compound microscope because it has two lenses to magnify an object, uses light for magnification. The objective lens, which is nearest the object being magnified, and the optical lens, the one nearest your eye, work together. A compound microscope can magnify objects up to 2,000 times. Electron microscopes, on the other hand, can magnify up to 500,000 times but cannot magnify living objects, because objects must be viewed in a vacuum. Scientists use two types of electron microscopes, transmission electron microscopes and scanning electron microscopes, with transmission electron microscopes the more common of the two.
Scientists use telescopes to look at far-away stars, planets and galaxies. Telescopes, which magnify objects far away, also use light to magnify objects. But telescopes need to gather large amounts of light; for this a telescope needs a large objective lens. The light-gathering ability of a telescope is more important than its magnification power. When using a telescope, you change the power of the optical lens, the lens nearest your eye, rather than the objective lens. With a microscope, you adjust the objective lens rather than the optical lens.
While you may think of X-rays primarily as a way to examine bones inside your body, X-ray has uses outside the orthopedic clinic. Scientists use X-rays not only for medical purposes but also to visualize solid structures buried under the earth. X-rays are used at the airport to scan luggage and people for potentially harmful solid objects. X-rays send electrons through objects until they hit a solid object. The electrons collide with atoms in the target object, creating energy visible as X-rays. Computerized tomography or CT scans combine X-ray images to make 3-D images of organs or structures that can help detect tumors and other soft tissue and organ abnormalities.
Scientists use ultrasound machines to outline soft tissues within your body by bouncing sound waves off tissue. A computer forms an image based on the sound waves. One of the most common uses of ultrasound is pregnancy; 70 percent of women in the United States have at least one fetal ultrasound, according to Dr. Stephen Carr of Brown University. Underwater sonar, which stands for Sound Navigation and Ranging, is used by fishermen to detect fish as well to locate boats and structures under the water.
Magnetic Resonance Imaging
Better known as MRI, magnetic resonance imaging uses magnets and radio waves to create detailed slices of organs and tissues that are then put together to create an image. These machines can detect tumors and abnormalities in soft tissue and organs.