Topography Laser Tools

Topography refers to the study of geographical attributes, as well as of the attributes themselves, such as the slope and elevation of a terrain. The first laser, known as a ruby laser, was invented in 1960, and since that time scientists have developed laser topography tools to determine the topography of the Moon and planets, including the Earth, as well as the cornea of the eye.

Mapping the Planets

• In 1998 and 1999 NASA introduced the Mars Orbiter Laser Altimeter (MOLA) to measure the topography of Mars. MOLA is a laser-enhanced topography tool that was sent into orbit aboard the NASA craft Mars Global Surveyer. Information obtained from the study greatly increased understanding of the planet and included 27 million measurements of Mars's topography. From the data obtained in the study, NASA constructed a grid that charted the entire planet. NASA has also used laser topography to chart the Moon. In 2010 NASA created a detailed map of the Moon using the Lunar Orbiter Laser Altimeter (LOLA). Information provided by this endeavor indicated that ancient asteroid and comet impacts on the Moon's surface are much more prevalent than previously thought.

Mapping the Earth

• The topographical laser tool used to survey the Earth is known as Light Detection and Ranging (LiDAR). This tool enables scientists to measure geological features of the Earth's surface at a scale of less than a meter, which enhances previous documentation of the dynamic structure of the Earth. As Global Positioning Systems (GPS) become more prevalent in society, laser topography tools will aid in their accuracy. LiDAR uses invisible laser pulses instead of previously used radio waves to measure the distance between a laser and the surface of the Earth. The position and direction of LiDAR enable geologists to produce a "point cloud," an accurate picture of the topography LiDAR is scanning. These images are used to create a three-dimensional topographical representation of an area.

Mapping the Cornea

• Laser topography is not used as a regular eye test but rather is applied to diagnose problems with a patient's cornea. A laser topographic tool maps the surface of the cornea, the clear membrane that covers the front of the eye. The shape of the cornea determines the focusing power of the eye, and a cornea that is flat or unevenly curved can impair the vision of an eye that would otherwise have healthy vision. The test is most often performed when assessing a patient's eye prior to refractive eye surgery to determine the amount of corneal tissue to remove. The corneal topography created with the laser tool helps create an image of the cornea that can reveal any problems. The laser topographic tool is also used in the diagnosis of keratoconus and degenerative corneal thinning and can be used to diagnose scars or deformities on a cornea or when astigmatism remains after corneal transplant. The procedure is painless and works without touching the eye.