Available on both high and low power microscopes, tri heads have two eyepiece lenses (one for each eye) and a third port at the top for a camera.  Some microscopes give you the option of sending all the light to the tri port, or perhaps half and half, or maybe 70/30%.  On some stereo tri heads with dual power,  the tri port transmits the image thro [..]

A microscope that has a binocular head for viewing and an additional eyepiece for a camera mount.