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Telecentric Lenses are used for specific applications such as measurement in machine vision systems. To understand the difference between telecentric lenses and regular lenses, pay attention to this mock-up, which has four different features:
- Train
- Three chairs placed at equal distances with people sitting on them.
- Four trees with varying heights.
- Telephone lines
The mock-up appears the same from both sides, which is why a telecentric lens is placed on one side and a regular lens on the other.
Comparison of Train Image in Telecentric Lens and Regular Lens
When looking at a moving train with a Telecentric lens, the image has the following characteristics:
- The direction of train movement and its distance from the lens are not discernible.
- The size of the train remains unchanged as it moves.
- The side view of the train is not visible, and only the front of the train is visible.
In contrast, with a regular lens, the direction of train movement is discernible, and we can see the side view of the train.
Comparison of Chair Images in Telecentric Lens and Regular Lens
With a Telecentric lens, only one chair with a person seated on it is visible, but with a regular lens, all three chairs and the people on them are visible.
Note that in the mock-up, the distance between the chairs is the same, but in the image taken with a regular lens, the distance between the first and second chairs appears much greater than the distance between the second and third chairs.
Difference in Tree Images with Each Lens Type
With a Telecentric lens, we can see all four trees in the image, but with a regular lens, we can only see three trees.
Additionally, in the image taken with a telecentric lens, we can identify the tallest tree, but changes in object distance with the lens cause their size to change, making it impossible to identify the tallest tree in images taken with regular lenses.
Comparison of Telephone Line Images
Telephone lines are arranged in a row, so with a Telecentric lens, we can only see one of them, whereas with a regular lens, all telephone lines are visible. However, due to the presence of trees, the top part of the telephone lines is not visible.
