Durchleuchten — to illuminate through, to x-ray something.
Auf Herz und Nieren prüfen — to examine heart and kidneys, from the biblical phrase, meaning to test exhaustively.
Unter die Lupe nehmen — to take under the magnifying glass.
Abklopfen — to knock against, the way you test a wall for cavities behind it.
Four ordinary German expressions for examination, and every one of them is physical.