Microbiology Lab 2 V-Scope and Microscopy

Describe the stage adjustment knobs

The stage adjustment knobs (upper and lower) are used to center the slide on the stage prior to focusing. The upper knob adjusts the stage right and left, and the lower knob moves the stage forward and backward

What are the stage adjustment knobs used for on a microscope?

The stage adjustment knobs are used to center the slide on the stage prior to focusing

What is the stage of a microscope?

The stage is the flat platform with stage clips to hold the slide in place. A mechanical stage is a movable platform that allows the user to move the slide left and right, or forward and backward, by turning the stage adjustment knobs. This feature is useful for moving a slide in small increments, and also for recording and relocating the slide to a specific point of interest.

What does the turret allow for?

The turret allows the lenses to be easily rotated to select the lens that offers the necessary power of magnification.

What are the 3 main categories of microscopes?

There are three main categories of microscopes: optical, electron, and scanning probe.

How many objective lenses are there usually on a microscope?

There are typically three to four objective lenses on a microscope, ranging in power from 4X to 100X. The lowest power objective lens (4X) is the scanning power lens, the medium strength objective lens (10X) is the medium power lens, and the highest strength objective lens (40X) is the high power lens.

The total magnification for a slide viewed with the high power lens should be reported as _____.

600x

What is resolution limited by?

As compound microscopes utilize reflected visible light, the resolution of the microscope is limited by the wavelength of the visible light.

Describe total magnification factor

Calculated by multiplying the magnification of the ocular lens with the objective lens

If the magnification of a compound microscope is increased from 10x to 100x, the field of view will _____.

Decrease

What is depth of field?

Depth of field refers to the distance range that is in focus at a given time. one can adjust the depth of focus to have either a shallow focus that will emphasize a subject, or a greater focus, that will focus to include much of the foreground and background. Like field of view, the depth of view is dependent on the total magnification factor. Compound microscopes have an inherently shallow depth of field, on the order of only a few micrometers. In short: Distance range that is in focus at a given time

The main component of an optical microscope that is used to focus an image at a high power of magnification is the _____.

Fine adjustment knob

What is the fourth objective lens if found?

If a fourth objective lens is present it is typically the 100X oil immersion lens. Oil immersion lenses are typically spring-loaded and retractable, so that the end of the lens will retract if it comes into contact with the object, protecting both the slide and the lens from damage. Additionally, an oil immersion lens is generally sealed, keeping the oil from seeping into the lens. The total magnification factor of a microscope is calculated by multiplying the magnification of the ocular lens with the magnification of the objective lens.

How to estimate the size of cocci

If you count the number of cocci bacteria that you see going across the field of view (this is an estimate), then it will estimate the size. Example, if you estimate around 100 cocci would fit across the FOV, then your estimation would be 0.9 micrometers (90 micrometers / 100 cocci = 0.9 micrometers/cocci).

Depth of field is dependent on what?

Like field of view, the depth of field is dependent on the total magnification factor.

Describe optical/light mircroscopes

Optical microscopes, also referred to as light microscopes, use reflected visible light and a series of two or more convex lenses to magnify and focus an object.

What is resolving power?

Resolving power is the ability to discern two objects as separate and is limited by the wavelength of light.

The oil immersion lens provides optimal viewing of what size specimens?

Small

The slide is placed on the _____ of an optical microscope.

Stage

Describe the arm and base of a microscope

The arm of a microscope supports the lenses of the microscope and connects them to the base of the microscope. The base is the bottom of the microscope, which provides support to the instrument.

What does the coarse knob do?

The coarse focus knob raises and lowers the microscope stage and is used to initially focus on low power. The stage should always be lowered before selecting a new slide.

Describe the two functions of the coarse focus knob on the SI V-Scope.

The coarse focus knob raises and lowers the stage of the microscope. It is also used to focus low power before adjustment by the fine focus knob. When selecting a new slide, the stage should always be lowered and then you can use the coarse focus knob to get into near focus.

What is the condenser lens?

The condenser lens sits just below the stage and focuses the light from the illuminator onto the slide

The coverslip of a wet mount slide should be added how?

The coverslip should be added at an angle to reduce the amount of bubbles produced

Describe the diaphragm of a microscope

The diaphragm sits below the stage and the condenser lens. It is composed of overlapping pieces of metal or plastic that move to vary the amount of light projected toward the condenser lens. Microscopes with a diaphragm have a small lever that is used to change the size of the opening, which adjusts the intensity of light.

What does the fine focus knob do?

The fine focus knob is used to focus an image when viewing a slide with the medium and high power objective lenses. This is the only focus knob required when using these objective lenses.

What is field of view?

The higher the total magnification factor, the smaller the field of view For example, imagine looking at a book at a distance of 3 feet. At this distance there is a large field of view, or the visible area that can be observed. In this case, the entire book is visible, along with its location relative to other objects. This is analogous to viewing an object with a microscope: by increasing the magnification, the field of view (or amount of the object seen) is smaller, and more detail is visible. In short: Visible area of a slide that can be observed

What is the most common light microscope?

The most common type of light microscope is the compound microscope, which utilizes a lens of short focal length and a second lens of a longer focal length. The short lens forms and focuses the image, and the longer lens magnifies and further focuses the image. Compound microscopes are able to resolve objects to a resolution of approximately 200 nm (0.2 μm).

What does the turret control?

The objective lenses

Where are objective lenses found?

The objective lenses of a microscope are found closest to the stage and are held by the turret, or revolving nose piece.

What is the ocular lens? List the typical power of an ocular lens

The ocular lens is located at the top of the microscope. This short lens is termed "ocular" as it is the lens that one looks through in order to view the image. An ocular lens is typically 10X or 15X power and is often referred to as the eye piece. A microscope with one ocular lens is called a monocular microscope, a microscope with two ocular lenses is called a binocular microscope (as shown in Figure 1), and a microscope with two ocular lenses and a location for a camera is called a trinocular microscope.