What is a telecentric lens used for?

Telecentric lenses are often used for precision optical two-dimensional measurements or reproduction and other applications that are sensitive to the image magnification or the angle of incidence of light. The simplest way to make a lens telecentric is to put the aperture stop at one of the lens’s focal points.

Are microscope objectives telecentric?

The aperture stop in a microscope is located at the back focal plane of the microscope objective. This makes the microscope objective telecentric in object space. Therefore, in microscopy, the object is observed with constant magnification, even for defocused object planes.

What is telecentric illumination?

A telecentric illuminator increases edge contrast and measurement accuracy by decreasing diffuse reflections from the object. Collimated light rays exit the illuminator and remain collimated as they strike an object’s surface (Figure 2).

Do telecentric lenses have distortion?

Because telecentric lenses tend to have such low distortion, they are more prone to having non-monotonic wave/mustache distortion than fixed focal length lenses, as shown in Figure 2.

What is entrance and exit pupil?

In an optical system, the entrance pupil is the optical image of the physical aperture stop, as ‘seen’ through the front (the object side) of the lens system. The corresponding image of the aperture as seen through the back of the lens system is called the exit pupil.

What is magnification in telecentric lens?

Telecentric lenses are designed to have a constant magnification regardless of the object’s distance or location in the field of view. This attribute is ideal for many machine vision measurement applications, as measurements of an object’s dimension will be independent of where it is located.

How do I choose a telecentric lens?

Choosing the right telecentric lens is easy: we must find the magnification under which the image fit the sensor. Example. We need to measure the geometrical feature of a mechanical part (nut) using a telecentric lens and a 2048 x 2048, 5.5 µm sensor.

Why is exit pupil important?

Why is the Exit Pupil Important? It is important because the only light rays which pass through this virtual aperture can exit the system and enter your eyes. Therefore with all else being equal, the larger the exit pupil diameter, the more amount of light will be delivered to your eye.

What is exit pupil on a scope?

The exit pupil is the width of the beam of light leaving the eyepiece, usually measured in millimeters (mm). The larger the exit pupil, the brighter the image will be under low-light conditions. Exit pupil size is calculated by dividing the objective lens size by the magnification power.

What is the ideal exit pupil?

The ancient dogma on this topic, printed in countless books, says “The human pupil dilates to a maximum diameter of 7 millimeters.” Therefore 7 mm is supposed to be the ideal maximum size for the exit pupil of binoculars or a telescope.

How important is exit pupil size?