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Condensermicroscope function

An objective lens is the most important optical unit that determines the basic performance/function of an optical microscope To provide an optical performance/function optimal for various needs and applications (i.e. the most important performance/function for an optical microscope), a wide variety of objective lenses are available according to the purpose.

While two lenses are necessary for a basic compound microscope to work, a light source is also a key factor. Many microscopes today have their own light sources, but a mirror behind and below the objective lens makes a great light source that can be angled to hit the object precisely.

Stage clipsmicroscope function

In a basic compound microscope, the lens at the bottom of the tube which is closest to the object is the objective lens. This lens takes the light rays that bounce off the object and spreads them apart through a convex lens so they appear bigger. When they appear bigger, we can see them in greater detail than we could without the aid of the lenses.

Low power objectivemicroscope function

Objective lenses are roughly classified basically according to the intended purpose, microscopy method, magnification, and performance (aberration correction). Classification according to the concept of aberration correction among those items is a characteristic way of classification of microscope objectives.

Because microscopes are so useful, they’ve become an essential tool in many fields of science and have helped us understand how the world works. But how do microscopes work, and are they all the same?

The basics of how a compound microscope works are the same ones that are used in other microscopes. Compound microscopes are still a very important and powerful tool, and they’re used regularly, but there are some advances that have occurred in the more than 400 years since the first microscope, and we have some other options available.

The very first microscope was invented in the late 1500s, and although technology and computers have advanced the field of microscopy today, some of the basic principles of how a microscope works have stayed the same.

Ocular lensmicroscope function

High power objectivemicroscope function

These eyeglass makers realized that if they put one lens at the bottom of a tube and one at the top, they could use the power of both lenses to see tiny objects more clearly. These original microscopes were the first examples of compound microscopes, which are microscopes that use more than one lens to view objects. An even more basic microscope is a single convex lens, which we call a magnifying glass.

That’s the basic premise behind a microscope; it’s pretty simple with two lenses and a light source. Let’s look at it one step at a time to further understand what’s happening. We’ll use a basic compound microscope with two lenses to continue the explanation.

Photography or image pickup with a video camera has been common in microscopy and thus a clear, sharp image over the entire field of view is increasingly required. Consequently, Plan objective lenses corrected satisfactorily for field curvature aberration are being used as the mainstream. To correct for field curvature aberration, optical design is performed so that Petzval sum becomes 0. However, this aberration correction is more difficult especially for higher-magnification objectives. (This correction is difficult to be compatible with other aberration corrections) An objective lens in which such correction is made features in general powerful concave optical components in the front-end lens group and powerful concave ones in the back-end group.

These are a few of the more common microscopes available, but there are many more to choose from. The field of microscopy has become very specialized, allowing for detailed analysis in a variety of professions. If you’re interested in purchasing a microscope, connect with New York Microscope Company to find just the right microscope for your needs and budget.

Armmicroscope function

The purposes of optical microscopes are broadly classified into two; "biological-use" and "industrial-use". Using this classification method, objective lenses are classified into "biological-use" objectives and "industrial-use" objectives. A common specimen in a biological use is fixed in place on the slide glass, sealing it with the cover glass from top. Since a biological-use objective lens is used for observation through this cover glass, optical design is performed in consideration of the cover glass thickness (commonly 0.17mm). Meanwhile, in an industrial use a specimen such as a metallography specimen, semiconductor wafer, and an electronic component is usually observed with nothing covered on it. An industrial-use objective lens is optically designed so as to be optimal for observation without any cover glass between the lens end and a specimen.

Stagemicroscope function

Meanwhile, an objective lens for which the degree of chromatic aberration correction to the secondary spectrum (g ray) is set to medium between Achromat and Apochromat is known as Semiapochromat (or Flulorite).

In the optical design of microscope objectives, commonly the larger is an N.A. and the higher is a magnification, the more difficult to correct the axial chromatic aberration of a secondary spectrum. In addition to axis chromatic aberration, various aberrations and sine condition must be sufficiently corrected and therefore the correction of the secondary spectrum is far more difficult to be implemented. As the result, a higher-magnification apochromatic objective requires more pieces of lenses for aberration correction. Some objectives consist of more than 15 pieces of lenses. To correct the secondary spectrum satisfactorily, it is effective to use "anomalous dispersion glass" with less chromatic dispersion up to the secondary spectrum for the powerful convex lens among constituting lenses. The typical material of this anomalous dispersion glass is fluorite (CaF2) and has been adopted for apochromatic objectives since a long time ago, irrespective of imperfection in workability. Recently, optical glass with a property very close to the anomalous dispersion of fluorite has been developed and is being used as the mainstream in place of fluorite.

An optical microscope is used with multiple objectives attached to a part called revolving nosepiece. Commonly, multiple combined objectives with a different magnification are attached to this revolving nosepiece so as to smoothly change magnification from low to high only by revolving the nosepiece. Consequently, a common combination lineup is comprised from among objectives of low magnification (5x, 10x), intermediate magnification (20x, 50x), and high magnification (100x). To obtain a high resolving power particularly at high magnification among these objectives, an immersion objective for observation with a dedicated liquid with a high refractive index such as immersion oil or water charged between the lens end and a specimen is available. Ultra low magnification (1.25x, 2.5x) and ultra high magnification (150x) objectives are also available for the special use.

Types ofmicroscope objectives

Axial chromatic aberration correction is divided into three levels of achromat, semiapochromat (fluorite), and apochromat according to the degree of correction. The objective lineup is divided into the popular class to high class with a gradual difference in price. An objective lens for which axial chromatic aberration correction for two colors of C ray (red: 656,3nm) and F ray (blue: 486.1nm) has been made is known as Achromat or achromatic objective. In the case of Achromat, a ray except for the above two colors (generally violet g-ray: 435.8nm) comes into focus on a plane away from the focal plane. This g ray is called a secondary spectrum. An objective lens for which chromatic aberration up to this secondary spectrum has satisfactorily been corrected is known as Apochromat or apochromatic objective. In other words, Apochromat is an objective for which the axial chromatic aberration of three colors (C, F, and g rays) has been corrected. The following figure shows the difference in chromatic aberration correction between Achromat and Apochromat by using the wavefront aberration. This figure proves that Apochromat is corrected for chromatic aberration in wider wavelength range than Achromat is.

A variety of microscopy methods have been developed for optical microscopes according to intended purposes. The dedicated objective lenses to each microscopy method have been developed and are classified according to such a method. For example, "reflected darkfield objective (a circular-zone light path is applied to the periphery of an inner lens)", "Differential Interference Contrast (DIC) objective (the combination of optical properties with a DIC( Nomarski）prism is optimized by reducing lens distortions)", "fluorescence objective (the transmittance in the near-ultraviolet region is improved)", "polarization objective (lens distortions are drastically reduced)", and "phase difference objective (a phase plate is built in) are available.

At the top of the compound microscope is another lens which is called the eyepiece. This lens also magnifies the image coming from the objective lens to give you a more detailed and clearer view of the subject.

The very first microscopes weren’t very effective, but they’re a good illustration of how a microscope works. They were created by opticians who were used to grinding glass into lenses for people who needed eyeglasses.

In the most basic sense, a microscope is a tool that’s used to see objects that are too small to be seen by the eye alone. There are many things happening in the world around us and inside of us that we simply can’t see, although we know that they happen. Blood cells move through the body carrying nutrients and oxygen, but without a microscope, we can’t see those individual blood cells.