Polarizing Microscope Interference Figures

An "Interference Figure" is a phenomena which details what a specimen produces at the rear focal plane of a transmitted light lens system. This colorful figure is used for material diagnosis and identification. The Bertrand lens on a polarizing microscope is used to perform conoscopic observation to view interference figures. Interference figures are achieved with certain specimens like crystals whose field of view becomes extinct when viewed under cross polars.

When setting up your polarizing microscope, in order to make sure the polars are crossing correctly you will want to use an interference figure slide. This is a slide that is purchased separately from the microscope.

Place the interference figure slide on the stage and make sure the 40x objective lens is in place. Bring the specimen into focus and turn up the transmitted light to its brightest setting. Engage the analyzer and swing the polarizer into place (usually it is located above the light source). While you are looking through the eyetubes rotate the polarizer and find the point where the field becomes darkened (this is the back of the focal plane). Engage the Bertrand lens. Immediately you should observe some type of interference figure with colors and patterns. As you rotate the stage to create the correct cross pattern the colors will change.

 Ultimately you want to achieve images such as these - sharp and colorful four part images.

Polarizing interference figures seen through the MT9200 polarizing microscope.

Ant Facts

Ants are fascinating insects, and smart too! They communicate with each other, can carry 20x their own body weight and are of course, always interesting to view under a microscope. A few random facts about ants:

• An ant has 6 legs, each with 3 joints
• Average life expectancy of an ant is 45-60 days
• Adult ants can not chew and swallow solid food
• Ants have 2 stomachs

Ant captured at 100x magnification using the BA310 biological microscope and the MW5.1 CCD microscope camera.

Optic Nerve Under the Microscope

The optic nerve is the second of twelve paired cranial nerves and is considered part of the central nervous system. Fiber tracks of this central nervous system are incapable of regeneration unlike some in the peripheral nervous system, and therefore optic nerve damage can produce irreversible blindness. The fibers from the retina run along the optic nerve to nine primary visual nuclei in the brain where a major relay inputs into the primary visual cortex.

Illustration courtesy lithograph plate from Gray's Anatomy

Each human optic nerve contains between 770,000 and 1.7 million nerve fibers, which are axons of the retinal ganglion cells of one retina. 

Optic nerve captured at 40x magnification using the BA310 biological microscope and a 5 mega pixel CCD microscope camera.

Damage to the optic nerve typically causes permanent and potentially severe loss of vision. The three most common injuries to the optic nerve are from glaucoma, optic neuritis, and anterior ischemic optic neuropathy.

Optic nerve captured at 200x magnification using the BA310 biological microscope and a 5 mega pixel CCD microscope camera.

Science Project: Growing Crystals for Microscope Viewing

Viewing crystals under a microscope is fascinating. Something as simple as table salt or sugar provides beautiful images when placed under a biological microscope or even a polarizing microscope!

Table salt captured under the MT9300 polarizing microscope.

This science project involves making some of your own crystals, prior to viewing them under the microscope. Gather some table salt, sugar, epsom salt, fresh lemon juice and fresh orange juice. Place a teaspoon of hot water in a small bowl, slowly adding salt until nothing else will dissolve. Put this mixture on a clean glass depression slide and set your slide in direct sunlight so the liquid will evaporate (a window ledge is a good place to leave the slides). Continue this process for each of your samples, making sure to label your slides after preparing them.

 

Once the liquid has evaporated from your samples, look at each slide under the microscope, starting with the lowest magnification (40x) and working your way up to the highest power. Notice how different the crystals appear. Salt typically forms small cubed-shaped crystals, but you might notice some hexagon shaped crystals from the Epsom salts.

 

If the crystals are hard to view and you do not have access to a polarizing microscope, you can use polarizing film to obtain the same affect. You will need two pieces of polarizing film. Place one piece over the light beneath the microscope, and the other piece over the slide on top of the stage. Make sure that the polarizing film over the slide is at a right angle to that beneath the stage.

 

As the water evaporates from your substances, the particles from sugar, salt, etc. have bonded together to create crystals. When viewing with polarization, the light is split into different colors, making the crystals easier to view.

 

Sugar captured at 200x magnification with a polarizing light microscope.

 

Take note of the types of crystals you view through the microscope and how the samples differ from each other.

Kids Science Affordable Gift Ideas

As the holidays approach, consider a few of the gift ideas below for your younger budding scientists. You are guaranteed to give a unique gift, and quite possibly one that will encourage learning as a fun activity.

Until recently parents had to choose between a low power stereo microscope for viewing specimens such as rocks, leaves, flowers, etc. and a high power biological microscope for viewing pond water and bacteria. However, this holiday season brings with it an affordable priced combination microscope with both low and high magnifications in one microscope. Introducing the ESH101 Kids Microscope.

High and Low Power Microscope in One: $89

This combo microscope has a light above the stage and allows for room to place larger specimens such as seashells and flowers while viewing at 40x magnification.  The light beneath the stage is perfect for the higher magnifications (100x and 400x) and allows you to view slides with pond water, cheek cells, or other microscopic specimens.

Microscope Prepared Slides: $19.95

Microscope prepared slide kits are available in a number of different options including botany, histology and zoology. Each slide kit contains a variety of prepared and labeled slides, ready to place under the microscope.

Microscope camera: $99

Have multiple kids and don't want to have to purchase multiple microscopes? Consider the MW1-LD2 microscope camera - it hooks directly up to the USB port on the computer and allows you to view a live image on the computer. Capture and save images directly to the computer.

View more holiday educational gift ideas for children here.

Kids Science Project: Indentifying Counterfeit $

Have you ever looked closely at a dollar bill? There are many parts to this currency that keep illegal counterfeiters from reproducing the bills. The higher the dollar amount of the bill, the more complex it gets.

For this particular science project you will want to gather several different bills: $1, $5, $10, $20, along with a stereo (dissecting) microscope.

One of the ways that counterfeit bills are discovered is by the type of paper that is used. Take one of your bills and notice the texture. Have you ever seen a wet dollar bill? It does not fall apart like standard paper does. Try to find a bill with a small tear in it and place it under the microscope. What do the paper fibers look like at higher magnifications? Do you notice any red or blue fiber threads in the dollar bill? These are used to prevent counterfeiting.

Next, start with a single $1 bill. How many number and letter combinations do you see on this bill? Now put this bill under the microscope and notice the ink in the printing of the bill. Can you see any other small details that might not have been noticeable without the microscope?

$1 captured at 40x magnification with the MW1-LD1 digital kids microscope.

Next, let's move on to the $20. Hold the bill up to the light. Do you notice any watermarks (lightly colored images) that were not visible without light shining through the bill? On the face side of the bill, look at the number in the bottom right hand corner. If you tilt the bill or shine a light on it, notice that the colors change!

$20 captured at 5x magnification.

Place the $20 under your stereo microscope and look closer at the edges of the pictures on the face side of the bill. Do you see any hidden words or phrases?

What details do you notice in the White House?

Make a list of some of the details you discover under the microscope. Then have other family members or classmates look at the dollar bills and see if they can discover all the same details!

Micro Fiber Cloth Under Microscope

This lens cleaning micro fiber cloth was placed under our MW5-L5 stereo zoom microscope. The first shot was captured at maximum magnification (40x). Then the 1.5x auxiliary lens was added to the microscope increasing the magnification even more. Images were captured with the MW5.1 CCD microscope camera.

Micro Fiber Cloth

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60x Magnification

80x Magnification

SLR Camera T-Mount Adapters

T-Mount

Connecting an SLR or digital SLR camera to a microscope is a fairly simple process that requires the use of a T-Mount adapter (also referred to as a T-ring).

Each brand of microscope has a slightly different way that the camera connects to the trinocular port, but below is an illustration that shows the process used for the Meiji microscopes.

If you have any lenses on your SLR camera you will want to remove them. Each brand of SLR camera has a different specific T-Mount adapter that is made for the brand. You will need the correct brand-specific T-mount. For example, if you are using a Nikon SLR camera, you need to use the corresponding Nikon T-Mount. There are several Olympus cameras that require an additional part called the MF-1 OM. You can view a list here to see if your Olympus camera is one that requires this piece.

The T-mount adapter bayonette mounts onto the body of the SLR camera and then threads directly on to the camera attachment. The camera attachment is a microscope specific part that connects the threads from your T-mount and securely attaches the camera setup to the trinocular port on the microscope.

Finally, there is typically a photo eyepiece that must be placed inside the camera attachment. Remember that when you look through the microscope you are looking through magnified eyepieces. Similarly, the camera also needs to view some magnification so that the image your camera captures will closely match up to the magnification viewed through the microscope eyepieces. Keep in mind that because the SLR camera already provides a bit of magnification based on the chip size in the camera, the magnification of the photo eyepiece will not be identical to your microscope eyepieces. For example, when using 10x eyepieces in the microscope, you might use a 2.5x photo eyepiece in order to get the same magnification at the camera.

You can find more information about the SLR camera parts required for a Meiji microscope here.

String under the Microscope

If you have kids you can spend hours finding interesting things to look at under a stereo microscope. Our most recent microscope analysis involved a pen with a rope attached to it.

Pen you can wear around your neck.

Using the MW5-L5 stereo zoom microscope along with the MW5.1 CCD microscope camera, the string was analyzed at several magnifications.

20x Magnification

40x Magnification

60x Magnification

80x Magnification

Notice how as the magnification increases, the field of view decreases. The image also becomes a bit darker. (Light becomes more important at the higher magnifications!) The items you can find around your house to place under a stereo microscope are endless. If you own a stereo microscope, have your kids gather some everyday household items and take a look at them under the microscope - it can provide hours of entertainment! Microscopes make great holiday gifts - consider giving one to your child or grandchild this season.

Carpet under the Microscope

Microscope World has a customer that manufacturers plush carpet. During the manufacturing process, they use the MW5-LD2 digital stereo microscope to examine the carpet fibers. Below are the carpet images captured with the digital stereo zoom microscope. The customer uses the included microscope software to capture and save the images, making it easy to email the photos both inter-office as well as within manufacturing facilities. The included microscope software also has a measuring feature that is often used to measure carpet fibers and the space between the weave of the carpet fiber. Notes are often made directly on the captured microscope photos before they are emailed or saved to a file - this ensures that valuable data is not lost or confused.

10x Magnification

20x Magnification

30x Magnification

40x Magnification