Ch 3 Microscope

Question 1

What are the commonly used types of microscopes in veterinary in-house laboratories?

Answer 1

Compound light microscopes

Other types include electron microscopes, fluorescent microscopes, phase-contrast microscopes, and dark field microscopes, which are used in research settings or reference laboratories.

Question 2

What is the optical tube length of a compound light microscope?

Answer 2

160 mm in most

This is the distance between the objective lens and the eyepiece.

Question 3

What are the two separate lens systems in a compound light microscope?

Answer 3

Ocular and Objective

The ocular lens is located in the eyepiece, while the objective lens consists of multiple lenses with different magnifications.

Question 4

What is the magnification of the ocular lens in a binocular compound light microscope?

Answer 4

Usually x10

Binocular microscopes have two eyepieces, while monocular microscopes have one.

Question 5

List the common objective lens magnifications found in a compound light microscope.

Answer 5

• x4 – scanning (not common)
• x10 – low power
• x40 – high dry
• x100 – oil immersion
• x50 – low oil immersion (optional)

Each lens serves a different purpose for varying levels of detail.

Question 6

How is total magnification calculated in a microscope?

Answer 6

Multiply the ocular magnification by the objective magnification power

For example: x10 (ocular lens) x x40 (objective lens) = x400 total magnification.

Question 7

What is the function of the mechanical stage in a microscope?

Answer 7

Holds the slide and allows movement back and forth, and left to right.

Question 8

What does the substage condenser do?

Answer 8

Consists of two lenses that focus light from the light source on the object.

Question 9

What is the purpose of the aperture diaphragm in a microscope?

Answer 9

Opens and closes to control the amount of light illuminating the object.

Question 10

Fill in the blank: To adjust the Köhler Illumination, one must first secure the slide on the microscope stage and adjust the light source to approximately _______.

Answer 10

half of its total brightness.

Question 11

What should be used to clean the lenses of a microscope?

Answer 11

High quality lens paper

The only solvent recommended is methanol or specially designed products.

Question 12

What maintenance steps should be taken for a microscope?

Answer 12

• Follow manufacturer guidelines
• Rotate lenses while looking through them
• Annual cleaning by a professional
• Protect from excessive heat and humidity
• Carry with both hands

Excessive oil can be removed with xylene.

Question 13

What is the first step in operating a microscope?

Answer 13

Lower the stage to its lowest point.

Question 14

What should be done when using the x40 (high-dry) objective lens?

Answer 14

• Look for a suitable examination area using the x10 (low-power) objective lens
• Use the fine adjustment knob to focus on the image
• Do not use oil on the slide
• Do not use the coarse adjustment knob

This ensures the specimen is focused correctly.

Question 15

What is the purpose of calibration in microscopy?

Answer 15

Important in identifying objects on the slides

Size differences can help identify similar-looking parasite ova.

Question 16

What is digital microscopy?

Answer 16

Use optics and a camera to capture an image

Photomicrographs can be added to patient files and this technology is becoming more affordable.

Question 17

What should be done after finishing the use of a microscope?

Answer 17

• Turn the light off
• Lower the stage completely
• Rotate the nosepiece to the low-power objective lens
• Remove the specimen
• Clean the oil-immersion lens if necessary
• Cover the microscope.