The optical microscope has been a standard tool in life science as well as material science for more than one and a half centuries now. The optical microscope widely use in the field of cell biology, microbiology, biotechnology, pharmacology, forensic and medical diagnosis especially when dealing with tissue fragments. It is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. In other words, Optical microscope is a technical device which is used for visualizing structures that re too small to see with the unaided eye.
The LED Of microscope features a long service life of 20,000 hours and offers low power consumption. The overall weight of an typical microscope is egg. The overall height of an optical microscope is 384. Mm and mom wide, compact enough to be stored in a typical classroom cabinet. There are 3 main parts of the microscope such as illuminating parts, magnifying parts and mechanical parts. The sub-parts in illuminating parts are electric lamp and iris diaphragm while the sub-parts of magnifying parts are eyepiece and objective lens.
The mechanical parts consist of most sub-parts among these three such as barrel, arm, stage, coarse focus knob, fine focus knob and base. Figure 1 Illuminating Parts: Electric Lamp Fully Assembled Optical Microscope. The illuminating parts such as electric lamp and iris diaphragm are used to provide light. The 20 watt electric lamp is the light source for the microscope. Usually optical microscope utilizes a built-in halogen bulb for bright illumination and to prevent eyestrain. It is located underneath the stage. It has maximum overall diameter of 1. 31 inches.
The brightness of the lamp can be adjusted with the dimmer. Iris Diaphragm Iris Diaphragm is a rotating disk under the stage. It is made up of usually a series of metal plates. An iris diaphragm is constructed of a number of interconnected “leaves” that, when adjusted with a simple clockwise and anti- clockwise rotation, open and close much like the pupil in your eye. It helps to regulate the amount of light that enters to the specimen observed. Opening the diaphragm lets more light in and closing the diaphragm let less light in. High power objectives need more light to view an object.
The overall diameter of an iris diaphragm is 1. 9 inches including the rotating disk. The beauty of such a device on a microscope is that it gives you almost an infinite number of settings. You are not limited to 5 or 6 holes like you would be with the disk diaphragm. (See figure 2 and figure 3 for an illustration of fully labeled optical microscope parts and Iris diaphragm. ) Figure 2 : The illustration of fully labeled optical microscope parts Figure 3 : The opening and closing of iris diaphragm Magnifying Parts: Eyepiece lens The eyepiece is also known as “ocular lens”.
It is the first point of magnification with the lox or 1 xx magnification. It is found on top of the barrel and function as to further magnify the image produced by the objective lenses. The diameter of the eyepiece lens 1. 4 inches. If you are using lox magnification microscope, the image you see will immediately 1 0 times larger than what you see with your naked eyes. Objective lens The objectives lens is the second point of magnification. They revolved around but is connected to the eyepiece lens. Usually you will find 3 or 4 objective lenses on a microscope.
They almost always consist of xx, lox, xx and 1 Ox powers. For easier recognition, the four different magnifying power objective lenses have their own standard color coding. For example there will be a red band on xx objective lens, yellow band for lox objective lens, blue band for xx objective lens and grey band for 1 Ox objective lens. As you go from lower to higher power of magnification, the objective lens is longer, with length range from mom for xx objective lens, mom for lox objective lens, mom for xx objective lens, and mom for xx objective lens. Mechanical Parts:
Barrel The barrel connects the eyepiece to the revolving objective lenses. Barrel also called as body tube. From the distance of eyepiece to the objective lenses, the length of barrel is about mom. Arm Arm is the part of an optical microscope that arches backwards. Arm is considered as the backbone of optical microscope. It functions as the mechanical support to hold the upper parts of the optical microscope above the stage. Stage Stage is the platform where the slide is placed for viewing. The size of the stage is about mom long and mom wide. On the stage, you will see metal clips.
The metal clips are called as slide clips. The slide clips are movable to cover up specimen in order to prevent it from moving when observing the image of an object. The stage is movable to left and right by using the stage control. Course focus knob This is the rough focus knob on the microscope. It is located on the right hand side and bottom part Of the arm. It functions as to adjust the distance between the stage and the objective lens . You use it to move the objective lenses toward or away from the specimen. The coarse movement stroke (stage height movement) is about mom.
Fine focus knob Fine focus knob is a smaller knob for delicate focusing bringing the object into the perfect focus. It is attached on top of the coarse focus knob. In other words, It is used to find the correct adjustment to focus on various part of the specimen to increase contrast and resolution. The fine focus graduation can be as small as up to 2. 5 pm- Generally one uses the coarse knob to get close then moves to the fine focus knob for fine tuning. Base The base is the bottom part of the microscope. It is use for supporting the whole optical microscope.
It also works with arm for carrying the microscope room one place to another. One’s hand should firmly grip the arm while the other support the base. This is to prevent the eyepiece lens from falling out. Conclusion In conclusion, Basic optical microscopes can be very simple, although there are many complex designs which aim to improve resolution and sample contrast. Optical microscopes are very versatile tools that can be used for magnifications from xx to xx. It is an useful research and observation tools. This allows us to see various type of cell of living organism that we are unable to see it using our naked eyes.