SOP of Microscope

SOP of Microscope

Objective of this SOP

To lay down the procedure for Operation, Cleaning and Maintenance of Microscope

Scope of this Microscope SOP 

This SOP is applicable for Operation, Cleaning and Maintenance of Microscope in Microbiology Laboratory of (Pharmaceutical Company Name).

Responsibility of this SOP

Chemist or above of Microbiology Laboratory.

Head – Microbiology Section.

Accountability of this SOP

Head – Quality Control.



Ensure that the microscope and its surrounding area is clean.

Plug the microscope power cord in to electrical out let.

Turn on the microscope by rotating the illumination control knob on the bottom left side of the instrument.

Set the intensity of light to the lowest setting using illumination control knob.

Fully open the aperture diaphragm of the condenser by rotating the ring to the extreme right.

Using the sub stage condenser-focusing knob, raise the condenser to the top of its excursion. Critical illumination only: If the condenser travel is excessive, limit the travel with the thumbscrew under the sub stage until the top lens of it is just below the stage surface (0.35mm)

Place the specimen slide on the stage.

Rotate the nosepiece to move the objective (40 X for dry mount and 10 X for wet mount   or 100 X oil immersion) into working position.

Raise the stage by rotating the coarse adjustment knob to its positive stop. Using the fine adjustment knob, bring the specimen into sharp focus.

Adjust the eye tubes for inter pupillary distance and eye difference. The left eyepiece tube is focusable to compensate for refractive differences of the eyes.

To correctly set the eye tubes, focus on the specimen through the right eyepiece tube only. Use the fine adjustment knob while covering the left eyepiece or closing the left eye.

Next, focus the specimen through the left eyepiece by turning the eye tube. Cover the right eyepiece while doing this and be sure to focus with the left eye tube only, without using the focusing knob.

Remove an eyepiece and view the back aperture of the objective. Close the condenser aperture diaphragm and then, to obtain the full resolving power of the microscope, reopen until the diaphragm leaves just disappear from view. Replace the eyepiece. The aperture diaphragm can be adjusted to enhance contrast and/or increase the depth of focus.

When changing to higher power objectives, the positions of the aperture diaphragm must be reset. As magnification increases, the aperture diaphragm must be opened as required.

Cleaning and Maintenance:

Whenever lack of contrast, cloudiness or poor definition is encountered, Clean the lower magnification objectives and optical surfaces with a lint free cloth or lens tissue moistened (not wet) with methanol or commercially available glass cleaner.

Clean the front lens with a toothpick covered with a cotton tip wetted with methanol.

Avoid excessive use of solvent for cleaning.

Cover the microscope always with dust cover, whenever the microscope is not in use.

Wipe the bottom of Oil immersion lens of a fast absorbing tissue paper before and after using the Lens.

Use Xylene to clean the lens surfaces.

Record the cleaning details of Microscope as per the annexure in SOP No.

Prompt 1: Rewrite the text using different words and sentence structures.

It is your responsibility to properly care for and use microscopes. Since microscopes are costly, it is important to follow the regulations and procedures outlined below.

The microscopes are stored in special cabinets and users must move them to their laboratory benches. The correct and only acceptable method is to firmly grip the microscope arm with your right hand and the base with your left hand. Lift the instrument from the cabinet shelf and carry it close to your body, gently placing it on the laboratory bench. This will prevent any collisions with furniture or colleagues and protect the instrument from damage.

Once the microscope is on the laboratory bench, adhere to the following guidelines:

1. Remove any unnecessary items such as books, papers, purses, and hats from the laboratory bench.

2. Unwind the microscope’s electric wire and plug it into an electrical outlet.

3. Clean all lens systems thoroughly. Even the tiniest speck of dust, oil, lint, or eyelash can reduce the microscope’s efficiency. The ocular, scanning, low-power, and high-power lenses can be cleaned by wiping them multiple times with appropriate lens tissue.

Never use paper towels or cloth on the lens surface. If the oil-immersion lens is sticky or tacky, use a piece of lens paper moistened with methanol to clean it. If the lens is extremely dirty, xylol can be used for cleaning, but this procedure should only be performed by the instructor and only if necessary. Excessive use of xylol may loosen the lens.

To ensure accurate and efficient use of the microscope while focusing, it is important to follow the following routine procedures:

1. Securely place the microscope slide containing the specimen within the stage clips on the fixed stage. Adjust the slide to center the specimen directly over the opening in the stage, aligning it with the light source.

2. Position either the scanning lens or the low power lens. While observing from the side to prevent any contact with the specimen, use the coarse focus knob to move the stage as close as possible to the lens without touching it. Always maintain a side view to avoid damaging the specimen.

3. Now, while looking through the ocular lens, carefully turn the coarse focus knob to gradually move the stage away from the lens until the specimen appears slightly focused. Then, utilize the fine focus knob to bring the specimen into clear and sharp focus.

4. If this is the first specimen of the day, it is necessary to Kohler your microscope at this point, while it is in focus. However, if your microscope has already been Kohlered, there is no need to repeat the process.

5. Regularly adjust the light source to achieve optimal illumination for each new slide and whenever there is a change in magnification. This can be done by adjusting the light source transformer setting and/or the iris diaphragm.

6. It is important to note that our microscopes are parfocal, meaning that when one lens is in focus, other lenses will also have the same focal length and can be rotated into position without major adjustments. However, in practice, a slight half-turn of the fine-adjustment knob in either direction is often required to achieve precise focus.

7. After achieving a clear focus on the specimen using a low-powered lens, it is important to prepare for visualizing the specimen under oil immersion. To do this, place a drop of oil directly over the area of interest on the slide. Then, rotate the nosepiece until the oil-immersion objective is securely in place. Be cautious not to let the high-power objective touch the oil droplet. As the objective is slowly rotated into position, observe the slide from the side. This ensures that the objective is properly immersed in the oil. Finally, readjust the fine-adjustment knob to bring the image into sharp focus.

8. When examining microbial organisms under a microscope, it is necessary to observe multiple areas of the preparation. This can be achieved by scanning the slide without applying additional immersion oil. To accomplish this, make continuous and precise adjustments by slowly rotating the fine adjustment knob back and forth. No other adjustments or techniques are required for this process.

After finishing the laboratory exercise, please ensure that the microscope is returned to its cabinet in its original state. We recommend following these steps:

1. Use dry, clean lens paper to clean all lenses. If necessary, you may use a small amount of methanol to assist in the cleaning process. Xylol should be used exclusively to remove oil from the stage.

2. Position the low-power objective and bring the stage and objectives close together.

3. Center the mechanical stage.

4. Carefully coil the electric wire around the body tube and the stage.

5. Transport the microscope to its designated position in the cabinet using the method previously explained.

General Safety in Microbiology

About Pharmaceutical Guidanace

Ms. Abha Maurya is the Author and founder of pharmaceutical guidance, he is a pharmaceutical Professional from India having more than 18 years of rich experience in pharmaceutical field. During his career, he work in quality assurance department with multinational company’s i.e Zydus Cadila Ltd, Unichem Laboratories Ltd, Indoco remedies Ltd, Panacea Biotec Ltd, Nectar life Science Ltd. During his experience, he face may regulatory Audit i.e. USFDA, MHRA, ANVISA, MCC, TGA, EU –GMP, WHO –Geneva, ISO 9001-2008 and many ROW Regularities Audit i.e.Uganda,Kenya, Tanzania, Zimbabwe. He is currently leading a regulatory pharmaceutical company as a head Quality. You can join him by Email, Facebook, Google+, Twitter and YouTube

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