Question

An imaginary line joining the point of intersection of the cross-hairs of the diaphragm and the optical center of the object glass is called as .......

• A. fundamental line
• B. axis of telescope
• C. axis of level tube
• D. line of collimation

Hint:

The line of collimation} is critical for accurate survey measurements. Any misalignment in this line leads to collimation error.

Answer 1

The Correct Option is D

Step 1: Understand the terms involved
- The diaphragm in a telescope has cross-hairs used for sighting.
- The object glass is the objective lens of the telescope.
- The line joining the intersection of the cross-hairs and the optical center of the objective is crucial in aligning and aiming the instrument.
Step 2: Define the correct term
- The line described above is called the line of collimation, also known as the line of sight.
- It is used as a reference for taking angular and linear measurements in surveying instruments.
Step 3: Final Answer
The correct term for this imaginary line is line of collimation.