Microscope Basics and Beyond PDF

M I C RO S CO P Basics E: and Beyond  MICROsCOPE Amicroscope is an instrument designed to make fine details visible. The microscope must accomplish three tasks: produce a magnified image of the specimen (magnification), separate the details in the image (resolution), and render...

M I C RO S CO P Basics E: and Beyond  MICROsCOPE Amicroscope is an instrument designed to make fine details visible. The microscope must accomplish three tasks: produce a magnified image of the specimen (magnification), separate the details in the image (resolution), and render the details visible to the eye, camera, or other imaging device (contrast).  HISTORY OF MICROSCOPE In ancient Greek, ‘mikro’ means ‘of minute size’ and ‘skopion’ refers to ‘means of viewing’. Although the term ‘microscope’ only began gaining popularity in 1625, the journey towards their invention began centuries in advance, in the bellies of the Roman, Greek and Chinese civilizations.  EVOLUTION OF MICROSCOPY OPTICS: THE BEGINNING The history of microscopy cannot be told without beginning with the field of optics. Glass pieces or lenses made from ground glass have been excavated from many ancient civilizations. The most popular discovery was the Nimrud lens dating back to the Assyrian civilization (modern-day Iraq), 710 BC.  EVOLUTION OF MICROSCOPY OPTICS: THE BEGINNING The phenomenon of glass-magnification was known to both the Greeks and Romans. However, the year of this discovery remains unknown. Euclid (300 BC) was the first philosopher to record this effect. In his magnum treatise ‘Optica’, Euclid writes that the text seen through a glass ball filled with water appeared larger.  EVOLUTION OF MICROSCOPY OPTICS: THE BEGINNING Seneca (4 BC – AD 65), a Greek philosopher expanded on this theory, observing that the degree or scale of magnification depended on the angle between the eye and the glass.  EVOLUTION OF MICROSCOPY OPTICS: THE BEGINNING There is also evidence to suggest that Chinese civilizations understood and used magnification over 4000 years ago. The Chow-Foo dynasty developed instruments we now call ‘water microscopes’ which consisted of a long tube filled with varying levels of water depending on the magnification required. These simple but effective instruments were capable of achieving a magnification over 150-fold.  EVOLUTION OF MICROSCOPY OPTICS: THE BEGINNING In the western world, inventors began experimenting with lenses only in the 13th century. In 1284 AD, Salvino d’Aramento Degli Amati (Italy) is thought to have invented the first wearable spectacle. By the 14th century, these eye glasses came to be widely used across Europe. 300 years later, the Renaissance had arrived, aiding scientists from all over Europe to communicate freely. Thus, ushering in the invention of microscopes.  EVOLUTION OF MICROSCOPY THE EARLY MICROSCOPES Galileo Galilei (1564 AD – 1642 AD) is widely credited with inventing the telescope capable of magnifying objects at a distance. He then quickly discovered that rearranging the lenses in the telescope with a shorter distance between them helped magnify little things, thereby building the first compound microscope he called ‘Occhiolino’. The device achieved magnification several fold higher than widely used magnifying glasses.  EVOLUTION OF MICROSCOPY THE EARLY MICROSCOPES Zaccharias Janssen and Hans Lipperhey also claimed to have independently built a compound microscope using a combination of tubes and two lenses; the objective lens located over the specimen and an eye piece to view the image. Although it is unclear who first came up with the design for a microscope, the term was widely being used across Europe by 1625 AD  EVOLUTION OF MICROSCOPY THE EARLY MICROSCOPES Anton Van Leeuwenhoek built the first simple microscope, using a very small but strong lens Interestingly, it took 150 years to build compound microscopes that could replicate the magnification of Leeuwenhoek’s simple home-made microscopes! In 1674, he used his device to observe bacteria in a drop of water, earning himself the title ‘Father ofiMicroscopes’.  EVOLUTION OF MICROSCOPY THE EARLY MICROSCOPES An English physicist, Robert Hooke, Leeuwenhoek’s contemporary was also using microscopes to investigate biological organisms. He used a simple microscope illuminated with candle light to discover cells and their characteristic honeycomb structure. In 1665 the term ‘cells’ was coined and published in his seminary work titled ‘Micrographia’ known for its vivid illustrations of skin and hair. Interestingly it would take over 200 years for scientists to agree cells were the basic units of life.  EVOLUTION OF MICROSCOPY THE NINETEENTH CENTURY In 1830, Joseph Jackson Lister made massive strides in correcting a phenomenon called spherical aberration. Up until then the image viewed through a microscope would distort based on the angle between the lenses. However, Lister built a device by placing weak lenses at precise distances from each other which eliminated spherical aberration. This tremendously aided the naturalists of the day in observing distinct biological structures which up until then were just blurred distortions.  EVOLUTION OF MICROSCOPY THE NINETEENTH CENTURY A decade later, the microscope manufacturing company, ‘Ernst Leitz’ built microscopes that incorporated five lenses of different magnifications which could be adjusted based on requirement. They achieved this by fixing multiple lenses on a movable turret located at the end of the lens tube. Concurrently, a rival company ‘Zeiss Optical Works’ was also working toward advancing microscopy.  EVOLUTION OF MICROSCOPY THE NINETEENTH CENTURY In 1866, Ernst Abbe while working at Zeiss laid down the principles that guides computational optics development to this day. With the advancement of physics, microscope designs came to favor proved theories over trial and error methods. Using the newly discovered wave properties of light, Abbe built over 17 objectives, each with different magnifications. He also developed the first immersion objectives, in which both the sample and the lens is immersed in a liquid that has a higher refractive index than air.  EVOLUTION OF MICROSCOPY THE NINETEENTH CENTURY He developed the mathematical formula called the ‘Abbe Equation’ that helps calculate the maximum resolution of a microscope. But perhaps his best known contribution to microscopy is the invention of the Abbe Condenser, a device placed over the light source in the microscope that concentrates light into a single cone  EVOLUTION OF MICROSCOPY Mo d e r n Mi c r o s c o p y : 19 0 0 ’s – No w The Ultra Microscope Transmission Electron Microscope by Richard Zsigmondy (1903) by Max Knoll and Ernst Ruska (1930s)  EVOLUTION OF MICROSCOPY Mo d e r n Mi c r o s c o p y : 19 0 0 ’s – No w Phase Contrast Microscope Scanning Tunneling Microscope by Frits Zernike (1932) by Gerd Binning and Heinrich Rohrer (1981)  EVOLUTION OF MICROSCOPY Mo d e r n Mi c r o s c o p y : 19 0 0 ’s – No w X-ray Microscope Acoustic Microscope THE COMPOUND MICROSCOPE  THE COMPOUND MICROSCOPE STRUCTURAL OPTICAL PARTs PARTs  THE COMPOUND MICROSCOPE STRUCTURAL OPTICAL PARTs PARTs THE COMPOUND MICROsCOPE STRUCTURAL P A R T s Figure: Diagram of parts of a microscope There are three structural parts of the microscope i.e. head, base, and arm. THE COMPOUND MICRO S COPE: ITS P A R T S AND FUNCTIONDHead This is also known as the body. It carries the optical parts in the upper part of the microscope. THE COMPOUND MICROsCOPE: ITS P A R T s AND FUNCTIOND Base It acts as microscopes support. It also carries microscopic illuminators. THE COMPOUND M I CRO S CO PE: ITS P A R T S AND FUNCTIOND Arms This is the part connecting the base and to the head and the eyepiece tube to the base of the microscope. It gives support to the head of the microscope and it is also used when carrying the microscope. Some high-quality microscopes have an articulated arm with more than one joint allowing more movement of the microscopic head for better viewing. THE COMPOUND MICROsCOPE OPTICA L P A R T s The optical parts of the microscope are used to view, magnify, and produce an image from a specimen placed on a slide. THE COMPOUND MICROsCOPE: ITS P A R T s AND FUNCTIOND Ocular Lens or Eyepiece This is the part used to look through the microscope. Its found at the top of the microscope. Its standard magnification is 10x with an optional eyepiece having magnifications from 5Xto 30X. THE COMPOUND MICROsCOPE: ITS P A R T s AND FUNCTIOND Eyepiece Tube The eyepiece holder. It carries the eyepiece just above the objective lens. In some microscopes such as the binoculars, the eyepiece tube is flexible and can be rotated for maximum visualization, for variance in distance. For monocular microscopes, they are none flexible. THE COMPOUND M IC R O s C OPE : ITS P A R T s AND FUNCTIOND Objective Lenses These are the major lenses used for specimen visualization. They have a magnification power of 40x-100X. There are about 1- 4 objective lenses placed on one microscope, in that some are rare facing and others face forward. Each lens has its own magnification power. THE COMPOUND M I CRO s CO PE : ITS P A R T s AND FUNCTIOND Nose Piece It is also known as the revolving turret. It holds the objective lenses. It is movable hence it cal revolve the objective lenses depending on the magnification power of the lens. THE COMPOUND MICROsCOPE: ITS P A R T s AND FUNCTIOND Fine Adjustment Knob A slow but precise control used to fine focus the image when viewing at the higher magnifications. THE COMPOUND MICROsCOPE: ITS P A R T s AND FUNCTIOND Coarse Adjustment Knob A rapid control which allows for quick focusing by moving the objective lens or stage up and down. It is used for initial focusing. THE COMPOUND MICROsCOPE: ITS P A R T s AND Stage FUNCTIOND This is the section in which the specimen is placed for viewing. They have stage clips that hold the specimen slides in place. The most common stage is the mechanical stage, which allows the control of the slides by moving the slides using the mechanical knobs on the stage instead of moving them manually. THE COMPOUND M I CRO s CO PE: ITS P A R T s AND FUNCTIOND Stage Clips Stage clips hold the slides in place. If your microscope has a mechanical stage, you will be able to move the slide around by turning two knobs. One moves it left and right, the other moves it up and down. THE COMPOUND MI C R Os C OP E : ITS P A R T s AND FUNCTIOND Illuminator This is the microscopes light source, located at the base. It is used instead of a mirror. It captures light from an external source of a low voltage of about 100v. THE COMPOUND MI C R Os C OP E : ITS P A R T s AND FUNCTION Condenser These are lenses that are used to collect and focus light from the illuminator into the specimen. They are found under the stage next to the diaphragm of the microscope. They play a major role in ensuring clear sharp images are produced with a high magnification of 400X and above. The higher the magnification of the condenser, the more the image clarity. THE COMPOUND M I CRO s CO PE: ITS P A R T s AND FUNCTION Diaphragm It’s also known as the iris. Its found under the stage of the microscope and its primary role is to control the amount of light that reaches the specimen. It’s an adjustable apparatus, hence controlling the light intensity and the size of the beam of light that gets to the specimen.  PROCEDURE FOR FOCUSING THE MICROSCOPE 1.Turn on the lamp and set the intensity for comfortable viewing. 2.While looking through the eyepieces of the binocular observation tubes, grasp the binocular tubes with both hands and bring the tubes closer together (or further apart) to fuse the two circles of light into one circle. This sets the interpupillary distance for YOUR eyes. If the viewing tubes have a scale for this setting, memorize the position so that you can readily return to it the next time.  PROCEDURE FOR FOCUsING THE MICROsCOPE 3. Place a specimen slide on the stage. Using your RIGHT eye and your right eye Only, with the 10X objective on the nosepiece in the light path, slowly raise (or lower) the stage by use of the coarse adjustment knob (the larger of the two concentric focusing knobs). Bring the image into focus and then use the fine adjustment knob (the smaller of the two knobs) to perfect the focus.  PROCEDURE FOR FOCUsING THE MICROsCOPE 4. Now, using your LEFT eye and your left eye Only, WITHOUT touching the focusing knobs, rotate the knurled ring on the left eyepiece tube to bring the image into focus for your left eye. This procedure adjusts for differences in acuity between your left and right eyes.  PROCEDURE FORFOCUSING THE MICROSCOPE 5. If you wish to move to a higher power objective, it should take very little movement of the fine adjustment knob to bring the image into focus. This is a built-in design feature which is known as Parfocality. Similarly, a particle in the image which is centered in the field of view should remain in the center as objectives are changed; a feature known as Parcentricity.  IMPORTANCE OF MICROSCOPE There would be little to do in a microbiology laboratory without a microscope, because the objects of our attention (bacteria, fungi, and other single celled creatures) are otherwise too small to see. Microscopes are optical instruments that permit us to view the microbial world. THANK YOU  SOURCEs AND R E F E R E N C E S : Abramowitz, M. (2003). Microscope - Basic and Beyond. Olympus. Mokobi, F. (2022). Parts of a microscope with functions and labeled diagram. Microbe Notes. https://microbenotes.com/parts-of-a-microscope/ Madhayan, D. (n.d.). The First Microscope to Modern Microscopes: Evolution and History of Microscopes. Microscope Clarity. https://microscopeclarity.com/the-first-microscope-to-modern-microscopes-evolution- and-history-of-microscopes/?fbclid=IwAR266zYc6OogXhVXFPrWJter2mbOTmpWBtFd- YSJG1gDJPBWWbmqNDHhDR4