The document discusses autocollimators, which are optical instruments used to measure small angular differences through non-contact means. There are two main types: visual autocollimators, which measure angles through an eyepiece and graduated reticle; and digital autocollimators, which use photodetectors and provide precise, real-time measurements through a user-friendly interface. Autocollimators have applications in measuring straightness, flatness, and other precision angles and are advantageous for higher accuracy alignment and dimensional assessment.

1. MALAVIYA NATIONAL INSTITUTE OF TECHNOLOGY
AUTOCOLLIMATOR

2. INTRODUCTION OF AUTOCOLLIMATOR :-
 A general discussion of autocollimators is found in the
book Engineering Optics by K. J. Habell and Arthur Cox,
published by Pitman (London), 1948 .
 Autocollimator is an optical instrument used for the
measurement of small angular differences.
 For small angular measurement , it provides a very
sensitive and accurate approach.
 It is a non-contact measurement of the angles.

4.  oo’ = (2*θ)*(f)
where f = focal length ( distance between
source and lens )
 Autocollimator responds only to reflector tilt ( theta) .

5.  TYPES OF AUTOCOLLIMATOR :-
• Visual Autocollimators
• Digital Autocollimators

6. 1) VISUAL AUTOCOLLIMATOR :-
• Visual autocollimators measure the
angle of optically flat (1/4 wave or
better), reflective surfaces in arc
seconds by viewing a graduated
reticle through an eyepiece.
• The longer the focal length of the
visual autocollimator, the greater
the angular resolution and the
smaller the field of view.

7. 2) DIGITAL AUTOCOLLIMATOR :-
• Autocollimators are PC-based instruments which are
designed to operate in the lab as well as in a
machine shop environment.
• use an electronic photodetector to detect the
reflected beam.
• No external controller is required.
• Advantages:
1) High precision.
2) Real-Time measurements.
3) User – friendly interface.
4) Creating data reports and transferring in
other programes.

8. APPLICATONS :-
 Measurement of straightness and flatness .
 Precise angular indexing in conjuction with polygons .
 Comparative measurement using master angles .
 Assessment of squareness and parallelism of
components .
 Measurement of small linear dimensions .

10. ADVANTAGES :-
Measure the Straightness and Flatness .
Used for higher accuracy measurement .
To check squareness and parallelism.
Easy to setup and operate.
Used to align components.
Measuring small angles.

11. DISADVANTAGES :-
 regular maintenance is required.
Difficulty in positioning and identification.
Time consuming.
Requires sample cutting and processing for tracing
by the detector.

12. OTHER MEASURING DEVICES :-
 Protractor
 Clinometer
 Sine Bar
 Angle Guages