6 Types of Goniometers

Goniometer is derived from two Greek words, gonia meaning angle, and metron meaning measurement.

A goniometer is a measuring device, but what does it measure? As mentioned earlier, its etymology indicates that this device measures angles or gives an accurate support to an object to be moved at a particular angle. It is widely used in industries and various fields of science.

Gemma Frisius, a Dutch physician, mathematician, cartographer, philosopher, and instrument maker, first described goniometer around 1538. He derived the goniometer from the astrolabe―a device that measures the tilts, elevations or depressions of an object, which was used by astrologers, astronomers, and navigators.

Today, the goniometer of old has undergone many modifications and finds application in a variety of fields in different forms. Let's take a brief look at the different types of goniometers.

An audio goniometer is used in analog audio equipment, which displays the phase differences in the audio. It helps a sound technician to know if the audio is optimal or not, and also helps find errors.

An audio signal contains stereo and mono sound signals, and a goniometer is used to determine the stereo sound signal. It plots the audio channels on a 2D screen to give a clear phase difference between the two axes of the signal.

Communication goniometers identify and locate audio transmissions, and enable the receiver to intercept and hear the signals transmitted over a long distance. This has found application in civil and military operations to find directions with the help of signal transmissions.

During World War I and World War II, Bellini-Tosi Direction Finder was used to check for directions. It would use signals from two crossed antennas to re-create radio signals in small areas.

These goniometers are used to measure the angles between the crystal faces. The first crystallographic goniometer that was made in 1780, was only a pair of limbs connected by a joint, which when kept on the two faces of a crystal, gave an angle with 15' accuracy.

After this experiment, in the early 20th century, crystallograhy goniometers were used to find out the atomic structure of crystals. They were also used to identify several mineral and rock forms.

These goniometers are made either of plastic or metal. There are two main types of therapeutic goniometers―bubble goniometers and traditional goniometers. Bubble goniometers have a 360°rotating dial and fluid indicator for measuring angles.

Scientific goniometers measure the static contact angle, advancing and receding contact angles, and surface tension between two liquids, and are also used for physical and Earth sciences measurements. Another type is the gonioreflector which measures the ability of a surface to reflect light.

A positioning goniometer or goniometric stage is used to rotate an object in space at an exact angle about a fixed point above the mounting surface of the device or stage. It uses worm drive which can be rotated manually or by a motor.

▶ Checking of initial and subsequent range of motion to know the progress, or disability of the injured area is done by goniometers.

▶ It is used to measure the spatial distribution of light that is visible to humans at a specific angle.

▶ A laser reflecting goniometer is used to measure the accurate angle of all the knives and sharp cutting blades.