The Goggles of Revealing are classified as Lost Knowledge. They are worn on the head equipment slot. The Goggle of Revealing provide two armour points of protection (one full chest-plate icon), but they also do not get damaged if the player takes a hit from a hostile mob. Just like the Thaumometer, they display an Aura bar and a Taint bar at the lower right. When you hover over a Thaumcraft-related item like a Vis storage Tank or a conduit, it will show the present levels of Vis and Taint as absolute values as well as the percentage of the full capacity. It also shows the Vis/Taint pressure, which is measured in "TCB" (Thaums per cubic block).
In addition to that, in the lower left of the screen, the Goggles of Revealing also show the absolute values of Vis and Taint that are currently present in the atmosphere of the chunk the wearer is in. The percentage at the right of those levels indicates whether the Aura (Vis) or the Taint is currently charged, and at what percentage the charge is.
The effects of an active charge are not yet known, but they presumably correlate with an increase of either Vis or Taint, and it also has an effect on the propagation of a local Taint infection. Presence of Taint producing mechanisms seem to raise the charge level of the Taint while presence of Vis producing mechanisms likewise seem to raise the charge level of the Vis.
Before the Goggles of Revealing can be crafted, they must be researched in the Quaesitum. Since they are classified as Lost Knowledge, the theory for them can theoretically be obtained with regular Thaumcraft artifacts or with most items from vanilla Minecraft (like Cobblestone, Books, or Pumpkins, for example). Books tend to be the quickest method, barring artifacts.