Existing technical conditions make it difficult for a single surgeon t
o simultaneously observe the endoscope and the observation field of th
e operating microscope. Video endoscopy is not adapted, because it res
pects neither the constraints of microsurgery (the surgeon has to stop
observing the binoculars of the microscope to watch the video screen)
nor the micromanipulations necessary for the specialties using micro
endoscopy. A new device is described that closely joins endoscope and
microscope. This coupling device allows the surgeon to permanently con
trol and alternate the images according to his choice. The surgeon is
able to observe in the binoculars the images transmitted by the endosc
ope and/or the operating microscope. This device respects the requirem
ents of the microscope, and, thanks to its optical capabilities, the e
ndoscopic image is improved. The professions requiring double observat
ion will improve their ability in diagnosis and therapy.