Benchtop and Portable Microscopes

Benchtop and Portable Microscopes

Microscopes magnify objects too small to see with the naked eye. While there are several types of microscopes, our focus at TEquipment is on optical microscopes and fiber optic scopes. Fiber optic scopes are discussed in our Fiber Optic equipment section. Optical microscopes are the oldest and most common. They contain one or more lenses to enlarge the target sample. While microscopes have been around for hundreds of years, it is modern day sample lighting techniques that have helped generate the better quality seen today.

How to Choose a Microscope and Common Optical Microscope Terminology

Consider the Microscope Type

• Single Lens Microscopes use only one magnification lens. Illuminated Magnifiers fall into this category.
• Compound Microscopes use multiple lenses and a separate set to focus the light into the eye. Specimens are Illuminated from underneath. Compound microscopes are considered high power.
• Stereo Microscopes or Dissecting Microscopes, as the name implies, gives the viewer an erect (upright and un-reversed) stereoscopic 3D effect image. Typically using light reflected by the image instead of through it. Stereo microscopes are considered Low Power microscopes. The two main optical systems used are CMO (common main objective or two separate optical paths (Objectives). Stereo microscopes are considered Low Power microscopes.
• High Power vs. Low Power refers to the magnification capability of the microscope. High Power microscopes are suited for tiny subjects  illuminated from underneath such as bacteria where Low Power microscopes are used for larger objects such as a small part.

Consider the Microscope Ocular and Objective Lenses

• Monocular and Binocular microscopes refer to one or two eyepieces, or oculars. Eyepieces compensate for residual chromatic aberrations inherent in the magnification lenses. Monocular eyepieces are on the lower end of cost, so more typically found for students, but increasingly some binocular eyepieces are available at only a marginal additional cost.  Binocular microscopes are not to be confused with stereo microscopes. Binocular microscopes are not to be confused with stereo microscopes. The Binocular eyepieces see the same image and provide greater viewing comfort.
• Trinocular microscopes refer to three oculars and have the ability to add a camera or video option.
• The Objective Lens of a microscope is the one closest to the sample. It is a cylinder containing one or more lenses. Often a microscope will have more than one Objective Lens with different focal lengths (i.e. magnification) that can be rotated for use. There are two main  types of objectives:
  • Achromatic. Color Correct
  • Plan Achromatic. Color corrected and Flat Field
• Multi-Head Microscopes are equipped with multiple heads for more persons observing at the same time. Multi-Head Microscopes are mainly used in medical teaching and biological teaching or for more experts at the same time.

Consider the Microscope Lighting of the Sample

• Tungsten is common on very low end microscopes using standard incandescent light bulbs. These light bulbs emit more heat that may affect specimens and the light itself is yellowish.
• Fluorescent and LED lighting produces a white light with less heat. Color rendition can vary compared to sunlight. LED lighting provides longer life just the same as for room lighting.
• Halogen is the most expensive and preferred for best color rendition when high heat is not a problem.
• Polarized Light Microscope involves illuminating the sample with polarized light. Polarized light can improve contrast with certain samples such as rocks and minerals. Polarizing has other applications. Polarized sunglasses, for example, reduce glare. Using polarized light, the origin, content and chemical makeup of many different organic and inorganic materials may possibly be discovered.

Consider Microscope Options and Accessories

• Microscope Stands are available in a great variety and worth considering as an accessory with purchase.
  • Boom Stands
  • Articulating Arms
  • Post Stand
  • Track Stand
• Photography and Video options are available for trinocular microscopes. Traditional factors in personal camera and video camera selection apply such as:
  • Number of megapixels
  • Field of view
  • Zoom vs close-up