LESSON 2

• Magnification


  refers to how much larger the image appears compared to the specimen. It is the ratio of the size of an object in the image produced by the microscope to its actual size. It is typically expressed in a dimensionless ratio, such as 1000x.
• While increasing magnification enlarges the image of the specimen, it does not necessarily improve resolution. In fact, excessive magnification without sufficient resolution can lead to blurry or pixelated images.
• Resolution


  The ability of the microscope to distinguish between two closely spaced objects as separate entities. It determines the level of detail or clarity that can be observed in an image and is typically expressed in micrometers (um) and nanometers (nm)
• Light Microscope

  or optical microscope, is a microscope that uses visible light and a system of lenses to magnify images. 
• Compound Light Microscope


  • microscope with more than one lens and its own light source. In this type of microscope, there are ocular lenses/eyepiece and objective lenses in a rotating nosepiece. Although sometimes found as monocular (w/ one ocular lens), the compound binocular microscope is more commonly used today.
  • typically has a magnification power of up to 1000x.
• Dissecting Light Microscope


  ,

  • used to view three-dimensional objects and larger specimens such as insects, plants, and geologic samples.
  • They are designed for low to moderate magnification levels (with a maximum magnification of 100x)
  • This type of microscope might be used to study external features on an object or to examine structures not easily mounted onto flat slides.
• Brightfield Microscope


  • microscope where the specimen appears darker against a bright background.
  • It is well-suited for observing stained samples or specimens that naturally absorb or scatter light.
  • This type of microscope is not well suited for unstained specimens due to low contrast.
• Darkfield Microscope


  • microscope where the specimen appears brighter against a dark background. The dark background is achieved by using a special condenser that allows only oblique or scattered light to illuminate the specimen.
  • It is well-suited for observing transparent or translucent specimens
• Phase-Contrast Microscope


  A microscope that enhances the contrast of transparent and semi-transparent specimens without the need for staining. It achieves this by exploiting the differences in the phase of light passing through different parts of the specimen.
• Differential Interference Contrast Microscope

  • An advanced optical microscope that uses employs Nomarski prisms, which are special optical components that split the polarized light into 2 orthogonal beams. These beams pass through different regions of the specimen and then recombine, producing interference patterns.
  • It provides excellent contrast and three-dimensional appearance of transparent specimens.
• Fluorescent Microscope


  A microscope that uses light source ,such as mercury or xenon arc lamp, to provide excitation light and an excitation filter to select the desired excitation wavelength. This ensures that only the appropriate wavelength of light reaches the specimen to excite the fluorophore.
• fluorophore


  refers to any molecule or compound, such as dyes and proteins, that is used to label specific structures or molecules within a specimen.
• Fluorescent Microscope


  This microscope allows for the detection of specific molecules or structures within a sample with high specificity and is well-suited for live cell imaging experiments, allowing the tracking of cellular behaviors and responses in real time.
• Scanning Acoustic Microscope (SAM)


  •A microscope that uses sound waves to create high-resolution images.

  •Characterization of cellular properties is achieved by utilizing the differences in the measure of resistance (acoustic impedance) encountered by sound waves as they pass through cellular structures.
• Electron Microscope


  A microscope that uses a beam of accelerated electrons. Unlike light microscopes, this type of microscope have much shorter wavelengths, enabling them to achieve much higher magnification and resolution.
• Transmission Electron Microscopy (TEM)


  • Provides a two-dimensional images of thin sections of specimens by electrons passing through the specimen.
  • Samples for TEM requires extensive preparation such as thin sectioning (typically less than 100 nm thick) and staining with heavy metals.
  • It offers higher resolution than SEM.
• Scanning Electron Microscopy (SEM)


  • Provides a three-dimensional surface images of specimens by scanning the surface of the specimen.
  • Requires less preparation compared to TEM. Samples can be typically coated with a conductive layer, such as gold or carbon, to prevent charging effects during imaging.
  • Resolution is generally lower than TEM.
• Scanning-Probe Microscopy


  used to create images of nanoscale surfaces and structures or manipulate atoms to move them in specific patterns.
• Scanning-Tunneling Microscope (STM)


  • Operates by measuring the tunneling current that flows between a sharp probe tip and conductive sample surface when they are brought into close proximity.
  • It achieves a higher resolution compared to AFM but primarily provides topographic imaging of surfaces.
• Atomic Force Microscope (AFM)


  • Operates by scanning a sharp probe tip across the surface of a sample while measuring the interactions between the tip and the surface.
  • It provides a slightly lower resolution compared to STM but offers multiple imaging models including topographic imaging and phase imaging.