Light Microscope
The optical microscope typically referred to as a light microscope is a kind of microscope that uses visible light and a system of lenses to magnify images of tiny objects. Optical microscopes are the oldest design of a microscope.
The light microscope is an instrument utilized by researchers in several fields to magnify specimens to as much as a thousand times their original size. In its simplest form, it is composed of a clear lens that amplifies the sample and light to brighten it.
Nevertheless, most light microscopic lenses are far more intricate and fine-tuned lenses with firmly managed dimensions all within the body of the microscope itself and in elements such as the objectives and eyepieces.
History of Light Microscope
Light microscopes date a minimum of 1595 when Zacharias Jansen (1580– 1638) of Holland invented a compound light microscopic lens, one that utilized two lenses, with the second lens, even more, magnifying the image produced by the first.
Antony van Leeuwenhoek (1632– 1723) created a simple (one-lens) microscope around 1670 that magnified as much as 200x and accomplished two times the resolution of the best compound microscopic lens of his day.
Englishman Robert Hooke (1635– 1703) even more refined the compound microscope, adding such functions as a stage to hold the specimen, an illuminator, and coarse and fine focus controls.
The most considerable improvements in the microscopic lens were made by Carl Zeiss (1816– 1888) and Ernst Abbe (1840– 1905). They added the substage condenser and developed exceptional lenses that significantly reduced chromatic and spherical aberration while allowing significantly enhanced resolution and greater zoom.
Construction of Light Microscope
The primary components of a light microscope are eyepiece, lens tube, objective revolver, stage, table, condenser, focus, coarse focus, luminous-field diaphragm, light source, base.
Ocular/ Eyepiece
It is a construction of a minimum of several lenses. The function of the eyepiece in a microscope is to convert the real- enlarged-intermediate-image from the objective into an enlarged-virtual-image.
Objective revolver
Objective revolvers are used in microscopes with multiple objective lenses, that have various zoom elements.
Objective lens
An objective (lens) is that part of an optical system, which is directed to the object. Its function is to gather the light rays, that are reflected from the observed object. The objective produces a real-optical image.
Microscope phase/ cross table
On the stage, one can position the specimen plate with the cover glass on it. By moving the plate, one can choose the part of the things, which one wants to look at.
Condenser
The condenser gathers the rays from the light, so they are protected equally on the specimen. Thus, every part of the object is brightened on the same brightness level.
Light
The early microscopes utilized concave mirrors to refract light on the objects. Later on, they utilized light bulbs. Most microscopes run with LED light. The light source´s functions to brighten the specimen uniformly.
Types of Light Microscope
Compound Microscope
The simplest optical microscope is the magnifying glass and is excellent to about 10 times magnification. The compound microscopic lens has two systems of lenses for higher resolution.
- The ocular or eyepiece that looks into.
- The objective lens or the lens near to object
A modern compound microscope under ideal conditions can magnify an object from 1000X to 2000X the specimen’s original size.
Advantages of Compound Microscope:
- Easy to use and low-cost.
Disadvantages of CompoundMicroscope
- As magnifying power increases, the field of view diminishes.
- As magnifying power increases, the depth of focus decreases.
Stereo Microscope
The stereo microscope or stereoscope or dissecting microscope is an optical microscope alternative created for low magnification observation of a sample. The instrument uses 2 separate optical courses with 2 objectives and eyepieces to provide somewhat different view angles to the left and right eye.
Advantages of Stereo Microscope
A stereo microscope is often used to study the surface areas of the solid specimens or to perform close work such as dissection microscopy, surgical treatment, and evaluation.
Used commonly under low magnification has two eyepieces that give the three-dimensional image.
Downsides:
Only magnifies up to 125X.
Types of modern Light Microscope
Phase Contrast Microscope
This is a type of optical microscope whereby small light variances referred to as phase shifts occur during light penetration into the unstained specimen.
These stage shifts are converted into the image when the light passes through the opaque specimen, the phase shifts brighten the specimen forming a lit up (bright) image in the background.
Dark-Field Light Microscope
This is a customized type of bright field light microscope that has a number of resemblances to the Phase-Contrast microscope. To make a dark field microscope, place a darkfield stop beneath and a condenser lens which produces a hollow cone beam that enters the objective just, from the specimen.
The Fluorescent Microscope
On adding dye molecules, the specimen emits light. The light energy that is released by the excited particle has a long wavelength compared to its radiating light.
The color particle is typically a fluorochrome, that fluoresces when exposed to the light of a particular specific wavelength. The image formed is a fluorochrome-labeled image from the emitted light.
On the basis of Structure
Inverted microscope
- Observe the specimen from below.
- Specimen observes on slides.
Upright microscope
- Observe the specimen from above.
- Specimen observe cells soaked with culture in a dish.
MCQs for Light Microscope
- What is the primary function of the eyepiece in a light microscope?
- A) To gather light rays from the specimen
- B) To convert the real-enlarged-intermediate-image from the objective into an enlarged-virtual-image
- C) To focus the light onto the specimen
- D) To magnify the specimen’s original size
- Answer: B
- Who refined the compound microscope by adding features such as a stage to hold the specimen, an illuminator, and focus controls?
- A) Antony van Leeuwenhoek
- B) Zacharias Jansen
- C) Robert Hooke
- D) Carl Zeiss and Ernst Abbe
- Answer: C
- Which of the following components of a light microscope gathers the rays from the light to evenly illuminate the specimen?
- A) Ocular/Eyepiece
- B) Objective lens
- C) Microscope phase/cross table
- D) Condenser
- Answer: D
- Which type of microscope is often used for surface examination of solid specimens or for close work such as dissection microscopy?
- A) Compound Microscope
- B) Stereo Microscope
- C) Phase Contrast Microscope
- D) Fluorescent Microscope
- Answer: B
- What is the major advantage of a stereo microscope?
- A) High magnification up to 2000X
- B) Provides a three-dimensional image
- C) Ideal for observing phase shifts in unstained specimens
- D) Uses dye molecules to emit light from the specimen
- Answer: B
- What is the primary function of a phase contrast microscope?
- A) To observe the specimen from below
- B) To provide a three-dimensional image
- C) To detect small light variations during light penetration into the specimen
- D) To observe cells soaked with culture in a dish
- Answer: C
- Which type of microscope utilizes dye molecules to emit light from the specimen?
- A) Compound Microscope
- B) Stereo Microscope
- C) Phase Contrast Microscope
- D) Fluorescent Microscope
- Answer: D
- In which type of light microscope does the observer view the specimen from above?
- A) Inverted microscope
- B) Upright microscope
- Answer: B
- Which type of light microscope observes the specimen from below?
- A) Inverted microscope
- B) Upright microscope
- Answer: A
- What was the major advancement made by Carl Zeiss and Ernst Abbe in the development of microscopes?
- A) Invention of the compound microscope
- B) Addition of an illuminator to the microscope
- C) Introduction of a stage to hold the specimen
- D) Development of lenses that reduced chromatic and spherical aberration
- Answer: D
- How many lenses does the ocular/eyepiece typically contain?
- A) One lens
- B) Two lenses
- C) Three lenses
- D) Four lenses
- Answer: A
- What is the maximum magnification of a stereo microscope?
- A) Up to 2000X
- B) Up to 1000X
- C) Up to 500X
- D) Up to 125X
- Answer: D
- Which type of light microscope utilizes two separate optical paths with two objectives and eyepieces?
- A) Compound Microscope
- B) Stereo Microscope
- C) Phase Contrast Microscope
- D) Fluorescent Microscope
- Answer: B
- What does the objective lens of a microscope direct towards?
- A) The light source
- B) The specimen
- C) The eyepiece
- D) The stage
- Answer: B
- Which type of microscope is often used for observing phase shifts in unstained specimens?
- A) Compound Microscope
- B) Stereo Microscope
- C) Phase Contrast Microscope
- D) Fluorescent Microscope
- Answer: C
- What is the function of a condenser in a light microscope?
- A) To convert the real-enlarged-intermediate-image from the objective into an enlarged-virtual-image
- B) To focus the light onto the specimen
- C) To gather the rays from the light and evenly illuminate the specimen
- D) To magnify the specimen’s original size
- Answer: C
- Which type of light microscope is known for its high magnification and resolution?
- A) Compound Microscope
- B) Stereo Microscope
- C) Phase Contrast Microscope
- D) Fluorescent Microscope
- Answer: A
- What is the function of the ocular/eyepiece in a light microscope?
- A) To gather light rays from the specimen
- B) To convert the real-enlarged-intermediate-image from the objective into an enlarged-virtual-image
- C) To focus the light onto the specimen
- D) To magnify the specimen’s original size
- Answer: B
- Which of the following is NOT a component of a light microscope?
- A) Objective revolver
- B) Microscope phase/cross table
- C) Specimen plate
- D) Luminous-field diaphragm
- Answer: C
- What was the major contribution of Antony van Leeuwenhoek to microscopy?
- A) Invention of the compound microscope
- B) Addition of an illuminator to the microscope
- C) Creation of a simple microscope with high magnification
- D) Development of lenses that reduced chromatic and spherical aberration
- Answer: C
- Which type of light microscope observes cells soaked with culture in a dish?
- A) Inverted microscope
- B) Upright microscope
- Answer: B
- Which of the following is NOT a disadvantage of compound microscopes?
- A) As magnifying power increases, the field of view diminishes.
- B) As magnifying power increases, the depth of focus decreases.
- C) It is difficult to use and costly.
- D) It has a limited depth of field.
- Answer: C
- What was the primary purpose of Zacharias Jansen’s compound microscope?
- A) To observe cells soaked with culture in a dish
- B) To create a simple microscope with high magnification
- C) To gather light rays from the specimen
- D) To convert the real-enlarged-intermediate-image from the objective into an enlarged-virtual-image
- Answer: D
Summary
Introduction to Light Microscope: The light microscope, also known as the optical microscope, has a rich history dating back to the late 16th century when Zacharias Jansen invented the compound light microscope. Over time, notable figures like Antony van Leeuwenhoek and Robert Hooke made significant contributions, refining the design and functionality of microscopes. Carl Zeiss and Ernst Abbe made groundbreaking improvements, introducing features such as the substage condenser and superior lenses that enhanced resolution and zoom capabilities.
Construction of Light Microscope: The construction of a light microscope involves various components like the eyepiece, objective revolver, objective lens, microscope phase/cross table, condenser, and light source. Each component plays a crucial role in magnifying specimens and ensuring optimal illumination for observation.
Types of Light Microscope: Light microscopes come in different types, including compound microscopes, stereo microscopes, phase contrast microscopes, dark-field light microscopes, and fluorescent microscopes. These microscopes offer unique advantages and are suited for different applications, ranging from surface examination of solid specimens to observing phase shifts in unstained specimens.
Categorization Based on Structure: Additionally, light microscopes can be categorized based on their structure, with inverted microscopes observing specimens from below and upright microscopes observing specimens from above.
Conclusion: Overall, light microscopes have revolutionized scientific research by enabling scientists to observe and analyze tiny objects with unprecedented clarity and detail. Their evolution over the centuries has led to significant advancements in various fields of science and technology.