Optical microscope

Optical microscope

The optical microscope, often referred to as the light microscope, is a type of microscope that uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast.

History

The invention of the optical microscope is often attributed to Hans Janssen and his son Zacharias Janssen, Dutch eyeglass makers, in the late 16th century. The details of their invention are unclear, but it is believed they discovered the principle of the compound microscope, which uses a series of lenses to magnify objects. The first recorded use of a microscope was by Galileo Galilei in 1610, who made improvements to the compound microscope design.

Principles of Operation

The optical microscope functions by passing visible light transmitted through or reflected from the sample through a single or multiple lenses to produce a magnified image. The total magnification is determined by the product of the ocular (eyepiece) and objective lenses. Modern microscopes are often equipped with a condenser lens system that focuses the light onto the sample to increase the illumination quality and the resolution.

Types of Optical Microscopes

Simple Microscopes

A simple microscope uses a single lens or a group of lenses acting together to magnify an object. The most common example is the magnifying glass.

Compound Microscopes

Compound microscopes use multiple lenses to achieve higher magnification. The objective lens provides the primary magnification, which is then increased by the ocular lens.

Stereoscopic Microscopes

Also known as stereo microscopes, these are designed for low magnification observation of a sample, using light reflected from the surface of an object rather than transmitted through it.

Digital Microscopes

Digital microscopes are a variation of optical microscopes that use a digital camera to generate an image displayed on a monitor, bypassing the need for eyepieces.

Applications

Optical microscopes are used in a wide range of applications from medical research to education and industry. In the field of biology, they are essential tools for observing cells and tissues, while in materials science, they are used to examine the structure of materials.

Limitations

The primary limitation of optical microscopes is their resolution. Due to the wave nature of light, optical microscopes have a resolution limit of about 200 nanometers, meaning they cannot distinguish objects closer together than this distance.

See Also

• Electron microscope
• Scanning probe microscopy
• Microscopy