# Engineering Metrology Questions and Answers – Circular Scanning

This set of Engineering Metrology Multiple Choice Questions & Answers (MCQs) focuses on “Circular Scanning”.

1. What is mathematical morphology?
a) Method of image rendering
b) Method of image processing and analysis
c) Method of image compression
d) Method of image formation

Explanation: Mathematical morphology is a method of image analysis and processing which is based on set theoretical descriptions of image measurements and transformations. It uses the concept of a structuring element, a predefined shape which is employed as a probe to test out the spatial nature of a pattern.

2. What is not true for circular scanning?
a) They are solid state device
b) They are used for line following
c) They are used for surface inspection
d) They are used for evaluation

Explanation: Circular scanning devices are used for surface inspection of bore and cylinder outside diameter, angular position measurement, line following etc. Circular scanning is a solid state device that is configured as a light sensitive discretely segmented annular ring.

3. Circular scanners are consists of which type of diodes?
a) Monolithic arrays of silicon photodiodes
b) Silicon avalanche photodiodes
c) Multi element silicon photodiodes
d) Two dimensional arrays of silicon photodiodes

Explanation: Circular scanners devices consist of monolithic arrays of silicon photodiodes. These are self-scanned photodiode arrays which have their geometry, (like a number of elements, aperture width, angular resolution, element spacing etc.) defined.

4. On which factor does the output of photodiode in circular scanners depends upon?
a) Frequency of illumination incidented
b) Frequency of illumination reflected
c) Amplitude of illumination incidented
d) Amplitude of illumination reflected

Explanation: In circular scanners, each photodiode site will output a signal that is directly proportional in amplitude to the illumination incident upon it. This output is a serial analog data stream whose rate is determined by the input clock frequency.

5. What are the factors which are responsible for the time required to read out the number of elements in a circular scan?
a) Size of scanner
b) Property of photodiode
c) Average scan time for reading
d) Frequency of input clock and number of elements

Explanation: The requirements of light intensity are a function of the circular scan time and the physical size of each photodiode. The total time required to read out the number of elements is a function of the input clock and the number of elements in the array.
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6. What is not a function of circular scanning?
a) Tracking
b) Slicing of 3D object into 2D image
c) Displacement
d) Cylindrical bore inspection

Explanation: The various applications of circular scanning could be for detecting presence/absence of a feature, cylindrical bore or other defect inspection, displacement, tracking, location recognition, etc.

7. What is tracking?
a) Obtaining coordinates of a particular object in an image
b) Obtaining a path followed by a moving object
c) Obtaining the coordinate data necessary to position the sensing system along defined patterns
d) Obtaining the coordinates of a frame that is captured

Explanation: Tracking and cylindrical bore or other defect inspections are the applications of circular scanning. In circular scanning, tracking means obtaining the coordinate data necessary to position the sensing system along defined patterns.

8. What is displacement?
a) Calibration, verification, and alignment of an object moving in an angular motion about a pivotal centre
b) Verification and alignment of an object moving in an angular motion about a pivotal centre
c) Calibration and alignment of an object moving in an angular motion about a pivotal centre
d) Calibration and verification of an object moving in an angular motion about a pivotal centre

Explanation: Displacement and location recognition are the applications of circular scanning. Displacement in circular scanning refers to calibration, verification, and alignment of an object moving in an angular motion about a pivotal centre.

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