What are Compound Microscopes?
Most of the microscopes used today are compound.
A compound microscope features two or more lenses.
A hollow cylinder called the tube connects the two lenses.
The top lens, the one people look through, is called the eyepiece.
The bottom lens is known as the objective lens.
Below the two lenses is the stage, with the illuminator below that.
Compound microscopes were among the first magnifying instruments invented.
Two Dutch eyeglass makers named Zaccharias and Hans Janssen are credited with making the first compound microscope in 1590 by putting one lens at the top of a tube and another at the bottom of the tube.
Their idea was fleshed out by others scientists over the next several centuries, but the basic design remained very similar.
The eyepiece, also known as the ocular lens, is at the top of the compound microscope.
It is not adjustable, that is, it only has one strength.
Most ocular lenses are 10x, meaning that they magnify objects to ten times their normal size.
People look in through the eyepiece through the tube and out through the objective lens.
A compound microscope normally contains several objective lenses.
The objective lenses are different lengths, with the longer ones being the strongest.
The lenses are situated on a round disk below the tube.
Viewers choose which strength lens they want and place it below the tube by turning the disk until the desired lens is in place.
The stage and illuminator are below the objective lens.
Specimens are placed over a translucent part of the stage.
Light provided by the illuminator shines through the clear part of the stage, making it easier for the viewer to see the magnified details of the specimen.
Two adjustment knobs help focus the object on the stage by bringing the lenses and the stage closer together.
Compound microscopes have been around for hundreds of years and are still very useful.
A number of scientific disciplines use compound microscopes to discover the wonders of the microscopic world..
Contact Lenses and Dry Eyes
Contact Lenses and Dry EyesBy
Until recently, contact lenses and dry eyes seemed to come hand in hand. Modern technology, however, has developed several ways for contact lens wearers to deal with dry eyes. When eyes become dry, they can be irritable, bloodshot and in severe cases, vision can become impaired. What Causes Dry Eyes?Dry eyes occur for a number of reasons, although there is thought to be a particular link between extended contact lenses and dry eyes. Dry eyes are also prevalent with older contact lens wearers as tear ducts become less effective with age.
Problems with contact lenses and dry eyes become exacerbated when wearers spend a considerable length of time in front of a computer screen or in an air-conditioned environment.Specific Contact Lenses for Dry EyesThere are some manufacturers that deal specifically with the problem of contact lenses and dry eyes. For example biomedics offer their own range of frequency 55 contact lenses for dry eyes. The higher...
Contact Lenses and Dry Eyes
Contact lenses > Contact Lenses and Dry Eyes
Crazy Contact Lenses - Making Them Look Deep Into Your Eyes
They say eyes are windows to the soul. So if you are creatively stylish with your makeup, clothes, shoes, or hairdo, why not do the same with your eyes? Even if you have 20/20 vision, you can still be a part of the fashion trend of crazy contact lenses.
Don't just change the color of your eye, change the design! You don't even need a prescription.
But if you do have prescribed contact lenses, why not experiment a little? Remember when you were younger and wore orange and black wired braces for the month of Halloween? Well, how about on October 31st you wear a really spooky pair of contact lenses?
There are all sorts of crazy contact lenses out there. You can make your eyeballs look entirely green or you can appear to have cat eyes.
Maybe you want to wear crazy contact lenses for Halloween, a night out on the town, or perhaps you prefer a subtler, but equally awesome look for your daily life. The possibilities are endless. Get wild, weird,...
Crazy Contact Lenses - Making Them Look Deep Into Your Eyes
Contact lenses > Crazy Contact Lenses - Making Them Look Deep Into Your Eyes
Disposable Contact Lenses
People must take good care of their contact lenses. Cleaning the contact lenses and storing them in solution must be a daily ritual to keep them clean and soft and not let them get dry. Also, this would ensure that the lenses are dust free and would not cause any irritation or itchiness in the eyes.
An alternative to this is to use disposable ones. Even though there are contact lenses that can be disposed after a day's use, they might be very expensive and many people can't afford them.
Contact lens that can be disposed once a week, or a month, or six months or a year are the most popular and affordable types of disposable contact lenses.
Disposable contacts must not be used after the expiration date since this might result in complications in the vision or the eyes. They are also convenient to use and so most physicians tend to prescribe these to the patients. Most popular among the disposable variety are the ones that can be replaced once in every...
Contact lenses > Disposable Contact Lenses
Discount Color Contact Lens
Colored contact lenses are very popular among the young and fashion-conscious of today. They let you change your eye color to match your mood and dressing. There are basically four types of colored lenses: opaque color tints, visibility tints, light-filtering tints and enhancement tints. Most of the colored lenses are available without visual correction; however, they are also available for those with astigmatism and bifocal corrections.
Opaque color tints give you a dramatic change to your eye color and are obtainable in a variety of colors like gray, blue, violet and hazel.
Visibility tints are light-colored tints added to the lens.
They are normally light green or blue, and do not affect your eye color. Light-filtering tints are specially designed for sports purposes, as they enhance certain colors like optic yellow or green in tennis and softballs and even golf balls. What they do is actually make the other surrounding colors dull, and enhance the color...
Contact lenses > Discount Color Contact Lens