Structure andfunction of an eyepiece in a microscope

Transmitted Illumination Since most specimens examined on a stereo microscope are opaque, a top light (Transmitted Illumination) is used to shed light on the specimen. Some stereo microscopes also include a bottom light (Incident Illumination).

Armmicroscope function

As in a compound microscope, there are two optical systems in a compound microscope: Eyepiece Lenses and Objective Lenses.

It has a p+ i-p-n+ Configuration as shown in the diagram. The construction of PIN photodiode and APD is similar is contains two heavily doped and two lightly doped regions. p+ and n+ are the heavily dopes regions whereas i and p are lightly doped regions. In the intrinsic region(i), the depletion layer width is fairly thinner in this photodiode as compared to PIN photodiode. Here p+ region acts like anode and n+ region acts like cathode. Here this p layer is having high resistivity, so all the reverse bias is mostly applied across p and n+ region. When the reverse bias is increased, the width of the depletion layer also gets increased.

The structure is similar to that of silicon APD whereas the key difference is in the intrinsic layer, material used is Germanium (Ge) which has smaller bandgap compared to silicon.

Working Stage is where the specimen to be viewed is placed. Pole and track stands have simple stages since lower magnification powers require less subtle movements than high power microscopes.

Here in this type the basic structure is almost similar to silicon APD and the difference is there is a multiplication layer is added which is doped with Indium Phosphide (InP) material, through which device performance is enhanced by amplification of the electric field strength, having improved gain, lesser noise, and optimized for specific wavelength sensitivity. The intrinsic layer is doped with Indium Gallium Arsenide (InGaAs) material. The p layer which is lightly doped is also doped with a layer of InP material.

Microscopeparts and functions

An Avalanche photodiode (APD) is a highly sensitive semiconductor detector that uses the photoelectric effect to convert optical signals into electrical signals. In case of conventional photodiodes, PIN photodiodes operate in a linear mode and the output current is very small and also has limited gain. Whereas the APD operates in reverse bias and uses avalanche breakdown to amplify weak optical signals for higher sensitivity due to this process of detecting even the faint signals, the output currents are very large. It is also called a reach-through APD because this photodiode allows the electric field to extend or reach through the entire depletion region.

Function ofbody tubein microscope

Turn on The Transmitted/Oblique illuminator. Place a small solid specimen onto the stage such as a card, coin or any other flat, detailed object.

Nosepiecemicroscope function

Diopter adjustment ring that allows for the possible inconsistencies of our eyesight in one or both eyes. Binocular microscopes also swivel (Interpupillary Adjustment) to allow for different distances between the eyes of different individuals.

What iseyepiece in microscope

Adjust the microscope down to the lowest magnification using the Magnification adjustment knob. The image could be slightly out of focus.

Function of an eyepiece in a microscopepdf

Adjust the eyepieces for the correct interpupillary distance to suit you. Do this by moving the eyepieces closer together or farther apart until a single field of view is observed (B). Now, set the Dioptric adjustment rings on both eyepieces to the zero position (A).

Do not adjust the focus with the focusing knob.  Adjust the focus for each eye separately using the eyepiece Dioptric adjustment rings.  Your microscope is now "parfocal". This means that as the microscope is zoomed from high to low magnification the image will stay in focus throughout the entire range. Each individual will have a different setting.

Use the Magnification adjustment knob to set the highest magnification. Bring the image into focus with the focusing knob.  Center the image on some clear point of detail on the specimen.

The Reverse bias is applied to the photodiode which is near to the breakdown value. The incident light produces the electron hole pairs and these carriers travels with their saturation velocity. Now when they travel with the maximum velocity, they will colloid with the lattice. So new electron hole pairs are generated. These newly generated carriers travels along with initial carriers. Thus the multiplication of charge carriers takes place which increases the current. This process of generating more number of charged carriers is called as impact ionization.

Objective lensmicroscope function

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Objective Lenses are the primary optical lenses on a microscope. In a low power microscope, they provide fixed magnification or zoom magnification. Zoom magnification is typically offered in a Greenough design or with a Common Main Objective.

A low power or stereo microscope typically employs objective lenses of 50x or less. It is used to view specimens that are visible to the naked eye such as insects, crystals, circuit boards and coins.

Eyepieces or Oculars are what you look through at the top of the microscope. Typically, standard eyepieces have a magnifying power of 10x. Optional eyepieces of varying powers are available, typically from 5x-30x.

Indium Gallium Arsenide (InGaAs) APDs are suitable for use in near-infrared to short-wave infrared range, which is about 900-1700 nm.

Stereo microscopes are increasingly modular. This means that the same head can be used in conjunction with different focus blocks and stands. For example, Microscope.com offers a range of pole stands, track stands and boom stands.

It has p+ i-p-n+ construction, contains highly doped p+ and n+ regions and lightly doped I and p regions. The intrinsic (i) layer is where the main depletion region where photon absorption and electron-hole pair generation occur and the material used in intrinsic layer is silicon (Si). The p+ and n+ contacts are connected to provide efficient charge collection and to create electric field which is necessary for Avalanche multiplication process.