Question: Which tool gauges the properties of big structures?
About the article "Astrophysics", section "Theoretical astrophysics".

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Angle-resolved low-coherence interferometry (a/LCI) is an emerging biomedical imaging technology which uses the properties of scattered light to measure the average size of cell structures, including cell nuclei.
The technology shows promise as a clinical tool for "in situ" detection of dysplatic, or precancerous tissue. 
Piston-type gauges counterbalance the pressure of a fluid with a spring (for example tire-pressure gauges of comparatively low accuracy) or a solid weight, in which case it is known as a deadweight tester and may be used for calibration of other gauges. 
The yearbook contains many maps of railway systems, which since about 1990 have been redrawn in a consistent style.
The yearbook also contains many diagrams of structure gauges and loading gauges for some but not all countries. 
In philatelic terminology, perforation gauge has two meanings:  as a term for classification.
The "perforation gauge" of a stamp specifies the number of perforation holes that appear in a two-centimeter span along its edge.
The finest gauge ever used is 18 on stamps of the Malay States in the early 1950s, and the coarsest is 2, seen on the 1891 stamps of Bhopal.
Modern stamp perforations tend to range from 11 to 14.
Many stamps are produced with "compound perforations" "i. e.", the vertical and horizontal perforations will be of different gauges.
Many U. S. stamps have been perforated 10½ x 11.  as the name for a philatelic tool used to measure perforations.
The typical "perforation gauge" is a metal or plastic tile on which perforations of gauges ranging from 7 and 7½ to 16 and 16½ are pictured (the pictures sometimes appear at the edges of the tile).
The philatelist places each of these depictions beside a stamp until one is found that exactly matches the stamp’s perforations.
Such a gauge is an indispensable tool for identifying stamps that present identical images but have been issued with perforations of several different sizes.
An extreme example is the U. S. Washington-Franklin Issues, some of which are found with perforations of gauges 8½, 10, 11, 12, and 12½.  
Aneroid gauges are based on a metallic pressure sensing element that flexes elastically under the effect of a pressure difference across the element.
"Aneroid" means "without fluid," and the term originally distinguished these gauges from the hydrostatic gauges described above.
However, aneroid gauges can be used to measure the pressure of a liquid as well as a gas, and they are not the only type of gauge that can operate without fluid.
For this reason, they are often called mechanical gauges in modern language.
Aneroid gauges are not dependent on the type of gas being measured, unlike thermal and ionization gauges, and are less likely to contaminate the system than hydrostatic gauges.
The pressure sensing element may be a Bourdon tube, a diaphragm, a capsule, or a set of bellows, which will change shape in response to the pressure of the region in question.
The deflection of the pressure sensing element may be read by a linkage connected to a needle, or it may be read by a secondary transducer.
The most common secondary transducers in modern vacuum gauges measure a change in capacitance due to the mechanical deflection.
Gauges that rely on a change in capacitance are often referred to as capacitance manometers.