The compound microscope is one of many two forms of modern microscopes (the other being the stereo microscope). It is named compound as it uses several major optical parts.
In the older times, the compound microscope could be monocular or binocular. A monocular compound is one wherein you only have to use one of one's eyes to check through the eyepiece. You can get more information about compound microscopes at https://www.microscopeinternational.com/product/olympus-cx23-binocular-microscope/.
A binocular compound, on another hand, permits the usage of both of one's eyes. Today, you never visit a monocular microscope anymore.
A trinocular microscope is merely a spin-off of the binocular, wherein a next vertical viewing port is available.
Since no ordinary individual has three eyes, the next part isn't intended for your third eye.
Rather, it can be utilized by a second viewer – your instructor, perhaps -to view the same specimen that you want to examine.
As mentioned earlier, the compound microscope is powerful because of the usage of two optical parts. Let's examine what each part means, and what it is employed for:
a. The objective lenses – The objective lenses are those who are closest to the specimen. They're mainly used to gather light from the specimen.
b. The eyepiece. This is the part where you add your eyes on to truly have a clear view of the specimen being examined.