goniometer


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goniometer

[‚gō·nē′äm·əd·ər]
(electromagnetism)
An instrument for determining the direction of maximum response to a received radio signal, or selecting the direction of maximum radiation of a transmitted radio signal; consists of two fixed perpendicular coils, each attached to one of a pair of loop antennas which are also perpendicular, and a rotatable coil which bears the same space relationship to the coils as the direction of the signal to the antennas.
(engineering)
An instrument used to measure the angles between crystal faces.
An instrument which uses x-ray diffraction to measure the angular positions of the axes of a crystal.
Any instrument for measuring angles.

Goniometer

 

(1) In physics, an instrument for measuring the angles between the planes of crystals, and also for measuring the angles of various prisms. Crystals can be distinctively characterized by the angles between their facets. Before the discovery of X-ray structural analysis, the method of measuring crystals with a goniometer was the main means of diagnosing crystalline substances. It was later superseded to a considerable degree by X-ray structural analysis.

Goniometers may be of the contact or reflecting types. The simplest contact goniometer consists of a protractor attached

Figure 1. Single-disk reflecting goniometer: (a) overall view; (b) diagram. C is the collimator, T is the viewing tube, L is the limb, ν is the vernier, and N1 and N2 are normals corresponding to facets a and b. to a ruler; it permits measurement of angles with an accuracy of 0.25°-0.5°. A more precise reflecting goniometer is shown in Figure I.

A crystal attached to a rotating axis is illuminated by a collimated beam of light, and the rays reflected from its facets are observed in sequence by looking into a viewing tube T (a single-circle goniometer). The angles of rotation of the crystal are read from a scale. In more advanced two-circle goniometers (developed by Fedorov, Gol’dshmidt, and Chapskii), the crystal or the viewing tube can be rotated about two axes. The precision of measurement is to within l’ to 10’-20’.

REFERENCES

Flint, E. E. Prakticheskoe rukovodstvo po geometricheskoi kristallografii, 3rd ed. Moscow, 1956.
Flint. E. E. Nachala kristallografii, 2nd ed. Moscow, 1961.

M. P. SHASKOL’SKAIA

(2) In anthropology, a goniometer is an instrument for measuring angles of curvature of the spine, the facial angle, the angle of the nose, and so on. A contact goniometer consists of a graduated metal plate in the form of an arc; its ends are joined by a transverse plate with a rotating pointer with a plumb bob attached to its center. The goniometer is attached to dividers (for example, of the sliding type), and the size of the angle being measured is determined by the distance of deflection of the pointer from the vertical.

goniometer

i. A direction-finding device commonly used in radio location and radio navigation. It has a fixed antenna, and the direction response is varied electrically. Using a method called phase comparison, it senses the angle between a fixed reference point and the direction from which a radio signal is being received. See automatic direction finder.
ii. A motor-driven instrument used with four stationary aerials to a deliver rotating signal field for VOR (very high frequency omnidirectional radio-range).
References in periodicals archive ?
The traverse is brought about by laying a convenient weight in a pan connected by a cord with the goniometer table, and passing over a pulley.
For example, a goniometer can be aligned at a 90[degrees] angle with the hip while the subject sits on the floor with the back against the wall.
This study was undertaken to determine the effects of UST with exercises versus LLLT with exercises in the treatment of SAIS for reducing pain with the help of VAS and increasing ROM with the help Universal goniometer.
In the first section of this research, the accuracy and reliability of the angle reproduction measured by pedal goniometer were evaluated.
Hip external rotation, TPT, and TAT were measured in the clinical setting by goniometer.
The diversity of goniometer models is comparable to that of microscopes and theodolites.
In Cadavers, LSA was measured by Goniometer (Fig 2) and the readings were recorded.
Secondarily we wanted to determine if the intra-examiner reliability of this new device was of a similar magnitude to that of a standard goniometer.
In the first phase different registered cricket clubs in Mandi Bahauddin District were visited and the players were interviewed and assessed for hamstring tightness; measurement of Active Knee Extension Angle AKEA with goniometer was used as an indicator of hamstring flexibility range.
Inherent tolerance in the XRD goniometer production and assembly is inevitable, therefore fictitious shear and normal stresses are always present.
A goniometer pairs a light detector with a motorized system for rotating a source around its center point in two axes, allowing light output to be measured as a function of angle (the spatial power distribution).
The evaluations on the flexion and extension range of motion of the lumbar spine were made using a simple goniometer after instructing the volunteer regarding positioning and the correct way of doing the test.