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Measurement of Straightness Using Auto Collimator AIM: To Measure The Flatness With The Use of Auto-Collimator Apparatus Required

The document describes a procedure to measure flatness using an auto-collimator. An auto-collimator and straight edge are used to take readings at 100mm intervals along the straight edge. The differences between readings are calculated and converted to microns of rise or fall per 100mm. These values are summed in a column to determine the cumulative variation in flatness over the length measured. By plotting the cumulative values, the overall flatness of the surface can be determined.

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sindhu elshaddaiengg
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496 views3 pages

Measurement of Straightness Using Auto Collimator AIM: To Measure The Flatness With The Use of Auto-Collimator Apparatus Required

The document describes a procedure to measure flatness using an auto-collimator. An auto-collimator and straight edge are used to take readings at 100mm intervals along the straight edge. The differences between readings are calculated and converted to microns of rise or fall per 100mm. These values are summed in a column to determine the cumulative variation in flatness over the length measured. By plotting the cumulative values, the overall flatness of the surface can be determined.

Uploaded by

sindhu elshaddaiengg
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOC, PDF, TXT or read online on Scribd
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MEASUREMENT OF STRAIGHTNESS USING AUTO COLLIMATOR

AIM:
To measure the flatness with the use of Auto-Collimator

APPARATUS REQUIRED:
 Auto collimator
 Straight edge with 100mm marked intervals.

SPECIFICATIONS:
Objective focal length : 300 mm.
Objective clear aperture : 25 mm
Barrel dia : 38 mm
Barrel length : 200 mm
Eyepiece magnification : 10x
Measuring range : 25 minutes
Read out : on direct graticule AT 1’
Telescope length : 380 mm
Illuminating bulb rating : 6 volts, 10 watts comes with transformer
Dimensions of base : solid rugged C.I base (75x 250mm)

PROCEDURE:
1. Clean the surface plate or table.

2. Position the auto-collimator in line with the reflector. Switch on the lamp in the

3. The alignment between the auto-collimator and reflector should be checked at


both extremes of the operational distance to make certain that the target graticule
is contained within the eyepiece field.

4. Fix a guide strip to control the horizontal displacement of the reflector and
minimize the movement of the target graticule.

New No. 3, Old no. 2, S.V . Koil Street, Sekar Nagar, Ashok Nagar, Chennai – 600 083
Phone: +91 (044, 4352 1779 | Cell: (+91) 9789976777, 9789975777& 9940077338
Email: sales@elshaddaiengg.com, support@elshaddaiengg.com www.elshaddaiengg.com
5. Mark off the positions along the surface plate equal to the pitch positions on the
reflector base (in this case 100 mm). Column 1 should indicate this position.

6. At the initial position takes the reading and tabulates (column 2)

7. Move the carriage (reflector) to the next position and again tabulate the reading.

8. This method is to continue until the final outward position is recorded.

9. The remainder of the table should be filled by adopting the following procedure:
 Column 3: This is the variations of the tilt occurring between the position at
which the reading is taken and the original position.
 Column 4: The angular position in column 3 is converted into a linear measure (1
second = 0.5 micro m). Insert a zero at the top of the column to represent the
datum.
 Column 5: This is the cumulative algebraic sum of the displacements. Calculate
the mean displacement this is the amount by which the displacement must be
adjusted to relate them to the zero datum.
 Plot the values of column 5 versus column 1.

OBSERVATION:

1 2 3 4 5

Reflector Autocollimator Difference From Rise Or Fall Cumulative


Carriage Reading 1st Reading Per 100mm Rise Or Fall
mm Seconds Seconds μm μm
0 0 0

0-100

100-200

200-300

300-400

400-500

New No. 3, Old no. 2, S.V . Koil Street, Sekar Nagar, Ashok Nagar, Chennai – 600 083
Phone: +91 (044, 4352 1779 | Cell: (+91) 9789976777, 9789975777& 9940077338
Email: sales@elshaddaiengg.com, support@elshaddaiengg.com www.elshaddaiengg.com
500-600

600-700

700-800

800-900

900-1000

RESULT:

Thus the flatness of the surface is determined using autocollimator.

New No. 3, Old no. 2, S.V . Koil Street, Sekar Nagar, Ashok Nagar, Chennai – 600 083
Phone: +91 (044, 4352 1779 | Cell: (+91) 9789976777, 9789975777& 9940077338
Email: sales@elshaddaiengg.com, support@elshaddaiengg.com www.elshaddaiengg.com

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