The work piece to be checked is arranged in the path of
the rays of the lighting equipment.
It produces a shadow image, which is viewed with the
microscope eyepiece having either a suitable mark for
aiming at the next points of the objects or in case of
often occurring profiles. e.g. Threads or rounding –
standard line pattern for comparison with the shadow
image of the text object is projected to a ground glass
The text object is shifted or turned on the measuring in
addition to the comparison of shapes.
The addition to this method (shadow image
method), measuring operations are also possible by
use of the axial reaction method, which can be
recommended especially for thread measuring.
This involves approached measuring knife edges
and measurement in axial section of thread
according to definition.
This method permits higher precision than shadow
image method for special measuring operations.
The large tool maker’s microscope is suitable for the
following fields of applications;
•Length measurement in cartesian and polar co-ordinates.
•Angle measurements of tools; threading tools punches
and gauges, templates etc.
•Thread measurements i.e., profile major and minor
diameters, height of lead, thread angle, profile position
with respect to the thread axis and the shape of thread.
(rounding, flattering, straightness of flanks)
•Comparison between centres and drawn patterns and
drawing of projected profiles.
• Examination of form tools, plate and template
gauges, punches and dies, annular grooved and
threaded hobs etc.
• Measurement of glass graticules and other surface
• Elements of external thread forms of screw plug
gauges, taps, worms and similar components.
• Shallow bores and recesses.
An Profile Projector (often simply called a optical
comparator in context) is a device that applies the
principles of optics to the inspection of manufactured
In a comparator, the magnified silhouette of a part is
projected upon the screen, and the dimensions and
geometry of the part are measured against prescribed
Profile Projector Applications
intended for the routine inspection of machined parts,
was a natural next step in the era during which applied
science became widely integrated into industrial
It’s also employed for inspecting and comparing very
small and complex parts, which play very significant
role in system’s structure, as an application of quality.
Profile Projector Advantages
• Profile Projector can reveal imperfections such as
burrs, scratches, indentations or undesirable chamfers
which both micrometers or calipers can’t reveal.
• They’re able to measure in 2-D space. Unlike
micrometers and calipers, which measure one
dimension at a time, where comparators measure
length and width simultaneously.
• Cost savings:
• Optical comparators save time. Ease-of-use factors
and ergonomic designs reduce the inspection time,
retraining costs and operator fatigue, all while
• Custom hard gages are subject to wear and need
frequent recertification, which takes them out of
service and adds an additional cost.
Profile Projector Disadvantage
The limitation of using profile projector as a fixed
device forms a disadvantage of it, while instruments
such micrometer or calipers can be used to reach for
measuring far and joint accessible components and it is
large and bulky and usually require a cart to transport
from place to place, also the device requires power for
The scanning electron microscope (SEM) uses a focused
beam of high-energy electrons to generate a variety of
signals at the surface of solid specimens.
The signals that derive from electron-sample interactions
reveal information about the sample including external
morphology (texture), chemical composition, and
crystalline structure and orientation of materials making up
In most applications, data are collected over a selected area
of the surface of the sample, and a 2-dimensional image is
generated that displays spatial variations in these properties.
Areas ranging from approximately 1 cm to 5 microns in
width can be imaged in a scanning mode using conventional
SEM techniques (magnification ranging from 20X to
approximately 30,000X, spatial resolution of 50 to 100
The SEM is also capable of performing analyses of
selected point locations on the sample; this approach is
especially useful in qualitatively or semi-quantitatively
determining chemical compositions (using EDS),
crystalline structure, and crystal orientations (using
The design and function of the SEM is very similar to
the EPMA and considerable overlap in capabilities
exists between the two instruments.
• In addition to topographical, morphological and
compositional information, a Scanning Electron
Microscope can detect and analyze surface fractures,
provide information in microstructures, examine
surface contaminations, reveal spatial variations in
chemical compositions, provide qualitative chemical
analyses and identify crystalline structures.
• SEMs can be as essential research tool in fields such
as life science, biology, gemology, medical and
forensic science, metallurgy.
• In addition, SEMs have practical industrial and
technological applications such as semiconductor
inspection, production line of miniscule products and
assembly of microchips for computers.
Advantages of a Scanning Electron Microscope include its wide-
array of applications, the detailed three-dimensional and
topographical imaging and the versatile information garnered
from different detectors.
SEMs are also easy to operate with the proper training and
advances in computer technology and associated software make
This instrument works fast, often completing SEI, BSE and EDS
analyses in less than five minutes. In addition, the technological
advances in modern SEMs allow for the generation of data in
Although all samples must be prepared before placed in the
vacuum chamber, most SEM samples require minimal
•The disadvantages of a Scanning Electron Microscope start with
the size and cost.
•SEMs are expensive, large and must be housed in an area free of
any possible electric, magnetic or vibration interference.
•Maintenance involves keeping a steady voltage, currents to
electromagnetic coils and circulation of cool water.
•Special training is required to operate an SEM as well as prepare
•The preparation of samples can result in artifacts. The negative
impact can be minimized with knowledgeable experience
researchers being able to identify artifacts from actual data as
well as preparation skill. There is no absolute way to eliminate or
identify all potential artifacts.
•In addition, SEMs are limited to solid, inorganic samples small
enough to fit inside the vacuum chamber that can handle
moderate vacuum pressure.
•Finally, SEMs carry a small risk of radiation exposure
associated with the electrons that scatter from beneath the sample
The transmission electron microscope (TEM) operates
on the same basic principles as the light microscope but
uses electrons instead of light. What you can see with a
light microscope is limited by the wavelength of light.
TEMs use electrons as "light source" and their much
lower wavelength makes it possible to get a resolution a
thousand times better than with a light microscope.
You can see objects to the order of a few angstrom (10-
Transmission electron microscopy (TEM) is a
microscopy technique whereby a beam of electrons is
transmitted through an ultra-thin specimen, interacting
with the specimen as it passes through. An image is
formed from the interaction of the electrons transmitted
through the specimen; the image is magnified and
focused onto an imaging device, such as a fluorescent
screen, on a layer of photographic film, or to be
detected by a sensor such as a CCD camera.
•A Transmission Electron Microscope is ideal for a number of
different fields such as life sciences, nanotechnology, medical,
biological and material research, forensic analysis, gemology and
metallurgy as well as industry and education.
•TEMs provide topographical, morphological, compositional and
•The images allow researchers to view samples on a molecular
level, making it possible to analyze structure and texture.
•This information is useful in the study of crystals and metals, but
also has industrial applications.
•TEMs can be used in semiconductor analysis and production
and the manufacturing of computer and silicon chips.
• Technology companies use TEMs to identify flaws,
fractures and damages to micro-sized objects; this data can
help fix problems and/or help to make a more durable,
• Colleges and universities can utilize TEMs for research and
• Although electron microscopes require specialized training,
students can assist professors and learn TEM techniques.
• Students will have the opportunity to observe a nano-sized
world in incredible depth and detail.
•A Transmission Electron Microscope is an impressive
instrument with a number of advantages such as:
•TEMs offer the most powerful magnification, potentially over
one million times or more
•TEMs have a wide-range of applications and can be utilized in
a variety of different scientific, educational and industrial
•TEMs provide information on element and compound
•Images are high-quality and detailed
•TEMs are able to yield information of surface features, shape,
size and structure
•They are easy to operate with proper training
•TEMs are large and very expensive
•Laborious sample preparation
•Potential artifacts from sample preparation
•Operation and analysis requires special training
•Samples are limited to those that are electron transparent, able to
tolerate the vacuum chamber and small enough to fit in the
•TEMs require special housing and maintenance
•Images are black and white
•Electron microscopes are sensitive to vibration and
electromagnetic fields and must be housed in an area that isolates
them from possible exposure.
•A Transmission Electron Microscope requires constant upkeep
including maintaining voltage, currents to the electromagnetic
coils and cooling water.
Straight edge is a measuring tool which consists of a
length of steel or other suitable material usually of
narrow and deep section and vary in length from
several millimeters to a few meters.
The object of the deep and narrow section is to
provide considerable resistance to bending in the
plane of measurement without excessive weight
The accuracy of the straight edge should be high and
permissible deviation of the measuring edge from the
true straight line should not exceed
+ (0.001+ L/500000)mm
• A surface plate is a solid, flat plate used as the main
horizontal reference plane for precision inspection,
marking out (layout), and tooling setup.
• The surface plate is often used as the baseline for all
measurements to the workpiece, therefore one
primary surface is finished extremely flat with
accuracy up to 0.00001 in/0.00025 mm for a grade
AA or AAA plate. Surface plates are a very common
tool in the manufacturing industry and are often
permanently attached to robotic type inspection
devices such as a coordinate-measuring machine.