Microscopy

Microscopy is the science of using microscopes to view and magnify objects or specimens that are too small to be seen by the naked eye. It enables the study of structures at the microscopic level, which are typically in the range of nanometers to millimeters. There are several types of microscopy techniques available, including optical microscopy, electron microscopy, scanning probe microscopy, and various advanced imaging methods.

Microscopy

In microscopy, we use an optical instrument known as a microscope to observe and magnify small objects through the lens, enabling the observer to examine the minute structures closely. The word “microscope” comes from the Latin “microscopium,” which is derived from the Greek words “mikros,” meaning “small,” and “skopein,” meaning “to look at.” While the microscope has many parts like an eyepiece, objective lens, aperture, nose piece, stage, and microscopic illuminator, the most important is its lenses. It is through the lenses that the image of the object can be magnified and viewed in detail. Two important parameters in microscopy are magnification and resolution. Magnification measures the total enlargement of the image of an object. The magnification factor varies between 5x-30x. Resolution is the ability of a microscope to differentiate the details of a sample. Microscopy comes in various types, each serving specific purposes. They find applications in research, metallurgy, educational institutions, crime investigation, etc. The different types of microscopy are:

• Optical microscopy
• Electron microscopy
• Scanning probe microscopy
• Ultraviolet microscopy
• Infrared microscopy
• Laser microscopy
• Photoacoustic microscopy

Optical Microscopy

Optical microscopy, also known as light microscopy, is a widely used technique that uses visible light and lenses to observe and magnify samples. A sample is illuminated with visible light, and the light interacts with the specimen to provide detailed information about its structure. The interaction of light with the sample can be modified using various techniques, resulting in different types of optical microscopes. These are as follows:

• Bright field microscopy
• Darkfield microscopy
• Phase-contrast microscopy
• Differential Interference Contrast (DIC) Microscopy

Application of Optical Microscopy

• It can be used to examine jewelry, stamps, coins, or any other item requiring magnification for detailed observation.
• It can aid in reading small or fine print in books, documents, labels, or maps.
• In microbiology, it is used to study microscopic algae, fungi, and biological specimens.
• A simple microscope is used in laboratories in educational institutions such as schools and colleges.

Electron Microscopy

Electron microscopy is a powerful technique that uses a beam of accelerated electrons instead of light to magnify and view samples. The image obtained is of high resolution and highly magnified as compared to an image obtained in optical microscopy. There are two main types of electron microscopes:

1. Transmission electron microscope (TEM): It provides high-resolution images and detailed information on the internal structure of the specimen.
2. Scanning electron microscope (SEM): SEM is used to obtain detailed information and a 3D image of the surface of a sample.

Application of Electron Microscopy

• Electron microscopy is used to analyze the structure, composition, and properties of materials at the atomic and molecular levels.
• Electron microscopy is used in the semiconductor industry for quality control and failure analysis of microelectronic devices.
• Electron microscopy plays a vital role in nanotechnology research and development.

Ultraviolet Microscopy

Ultraviolet (UV) microscopy is a specialized technique that uses ultraviolet light instead of visible light to illuminate and observe samples. UV microscopy takes advantage of the shorter wavelength and higher energy of the UV light to provide images with enhanced resolution and improved contrast compared to traditional visible light microscopy.

Application of Ultraviolet Microscopy

• UV microscopy is used in forensic science, especially in examining documents, fingerprints, and other types of evidence.
• UV microscopy finds application in environmental sciences, such as the study of atmospheric particles, aerosols, and pollution.
• UV microscopy is commonly used in fluorescence microscopy, where UV light is used to excite fluorescent molecules or dyes within a sample. This technique is widely used in biology, medicine, and materials science to study cellular structure and processes.

Scanning Probe Microscopy

Scanning probe microscopy forms the image of the surface using a probe tip that scans the sample. It allows for imaging and manipulation of surfaces at the nanoscale. Unlike optical microscopy, which uses light, or electron microscopy which uses electron beams, scanning probe microscopy uses a physical probe to interact with the surface of a sample. A probe tip is attached to a cantilever and used to scan the surface of a sample. The probe tip is sharp and precisely moves across the sample surface, scanning each atom. The tip is positioned close to the sample surface, causing the cantilever to undergo deflection in response to forces. This deflection distance is measured using a laser. After the scanning process is complete, The resulting measurements are used to generate an image on a computer.

Application of scanning probe microscopy

• Scanning probe microscopy is used to investigate the magnetic and electronic properties of materials.
• They are used in the semiconductor industry to analyze and characterize devices at the nano level.
• Information is transferred to the sample with the help of a scanning probe microscopy.

Infrared microscopy

Infrared microscopy is a technique that uses infrared light to study and analyze samples at the micro level. Unlike other optical microscopy that uses absorbent glass optics, infrared microscopy uses reflective optics to allow the microscope to cover the entire spectral range of infrared light. Infrared light has longer wavelengths than visible light providing detailed information about the chemical composition and molecular structure of materials.

Application of Infrared Microscopy

• Infrared microscopy is widely used for chemical analysis, like in the identification and characterization of organic compounds.
• Infrared microscopy finds applications in biomedical research, particularly in the analysis of biological tissues and cells.
• It has widespread applications in research, industry, and forensic sciences and provides valuable information about the structure, and composition of various materials and substances.

Laser Microscopy

Laser microscopy is a fast-growing field that uses laser light as the source of illumination for imaging and analyzing samples at a microscopic level. Laser microscopy offers several advantages over traditional microscopy techniques, including enhanced resolution, sensitivity, and specificity. The laser light interacts with the sample, and the resulting signals, such as fluorescence or scattering, are collected and analyzed to generate an image or obtain information about the sample’s properties.

Application of Laser Microscopy

• Laser microscopy finds application in art conservation and restoration.
• Laser microscopy is utilized in forensic science for the analysis of trace evidence and crime scene investigations.
• Laser microscopy is applied in environmental science to analyze and monitor pollutants, contaminants, and environmental samples.

​Photoacoustic Microscopy

Photoacoustic microscopy (PAM) combines the principles of ultrasound and laser-induced photoacoustic effect to observe the samples. It utilizes laser pulses to generate photoacoustic waves, which are then detected and used to reconstruct high-resolution images. When a sample absorbs laser light, it undergoes rapid thermal expansion, leading to the generation of acoustic waves. Ultrasound transducers or detectors capture the generated acoustic waves, which are then converted into electrical signals. The acquired signals are processed and used to reconstruct images based on the depth and intensity of the photoacoustic waves.

Application of Photoacoustic microscopy (PAM)

• Photoacoustic microscopy (PAM) can be used for early detection, diagnosis, and monitoring of cancer.
• PAM is used in biomedical engineering to assess the performance of engineered tissues, biomaterials, and implants.

FAQs on Microscopy

Q1: What are the different types of microscopy?

Answer:

Different types of microscopy are light (or optical) microscopy electron microscopy, X-ray microscopy, and acoustic microscopy.

Q2: Who is the father of microscopy?

Answer:

Antoni van Leeuwenhoek is the father of microscopy.

Q3: What are the two important concepts in microscopy?

Answer:

Two important concepts of microscopy are: magnification and resolution.

Q4: What is the role of microscopy?

Answer:

Microscopy is the technical field of using microscopes to view samples & objects that cannot be seen with the unaided eye (objects that are not within the resolution range of the normal eye).