The image produced by the eyepiece is a magnified virtual image.

In a sense, it acts as a magnifying glass that magnifies the intermediate image produced by the objective. The eyepiece is positioned so that the first image is within its focal length, so that it can further magnify the image. This first image serves as the object for the second lens, or eyepiece. The object is just beyond the focal length of the objective lens, producing a real, inverted image that is larger than the object. To see how the microscope in (Figure) forms an image, consider its two lenses in succession. The eyepiece forms final image that is further magnified. This first image is inside the focal length of the eyepiece and serves as the object for the eyepiece. The objective forms the first image, which is larger than the object. Also, the final enlarged image is produced sufficiently far from the observer to be easily viewed, since the eye cannot focus on objects or images that are too close (i.e., closer than the near point of the eye).Ī compound microscope is composed of two lenses: an objective and an eyepiece. The purpose of a microscope is to create magnified images of small objects, and both lenses contribute to the final magnification. The eyepiece, also referred to as the ocular, is a convex lens of longer focal length. The objective lens is a convex lens of short focal length (i.e., high power) with typical magnification from to. The simplest compound microscope is constructed from two convex lenses ( (Figure)). Microscopes were first developed in the early 1600s by eyeglass makers in The Netherlands and Denmark.

In this section, we examine microscopes that enlarge the details that we cannot see with the naked eye. To get higher magnification, we can combine the simple magnifying glass with one or more additional lenses. A magnification greater than is difficult without distorting the image. We have seen that a simple convex lens can create a magnified image, but it is hard to get large magnification with such a lens. The desire to see beyond what is possible with the naked eye led to the use of optical instruments. Although the eye is marvelous in its ability to see objects large and small, it obviously is limited in the smallest details it can detect.

Original sun spotter design