Seven Key Considerations for Selecting Industrial Lenses

Seven Key Considerations for Selecting Industrial Lenses

In a machine vision system, the lens plays a crucial role in capturing images, making its proper selection critical. Based on years of experience with customer cases, DZO Optical has outlined seven key considerations for choosing industrial lenses in machine vision systems.

1. Client's Special Requirements

Firstly, it's crucial to consider any specific client requirements. This includes any additional components between the lens and the workpiece, such as lenses, mirrors, or glass, and the working environment of the machine vision lens. The following aspects should be confirmed:

• Installation Space Limitations: The size, length, and other parameters of the machine vision lens.
• Fixed Camera Hanging Lens: In some cases, heavier lenses may not be suitable for suspension.
• Camera System Motion: High-speed motion can lead to system shifts due to inertia.
• Spectral Response Requirements: For example, ordinary glass lenses will absorb most ultraviolet light in UV environments.
• Adding Light Sources: Based on the scene's lighting needs, additional light sources might be required.
• Price Requirements: Consider budget constraints.
• Working Environment: Ensure the lens is suitable for the environmental conditions.
• Other Special Components: Any additional requirements.

2. Need for Telecentric Lenses

Precision measurement systems often require telecentric lenses, designed to overcome perspective distortion. This lens type maintains consistent magnification despite varying distances. Given their fixed focal length and working distance, telecentric lenses can be large and heavy. The choice of telecentric lenses should consider field of view, working distance, spatial limitations, and motion control requirements.

3. Depth of Field (DOF) in Machine Vision Lenses

Some visual systems require a greater depth of field, especially when industrial cameras are positioned at an angle or when the object isn't on a single plane. Factors affecting DOF include shorter focal lengths, smaller apertures, and longer distances from the lens to the object. However, smaller apertures can compromise detail, and larger camera sensor pixels contribute to greater DOF.

4. Sensor Size Compatibility

Each lens has a maximum compatible sensor size. It's crucial to ensure that the industrial lens can accommodate the camera's sensor size. Using a lens with a smaller maximum compatible sensor size can cause severe distortion and aberration.

5. Machine Vision Lens Interfaces

The compatibility between lens and camera is crucial. Common interface types include C, CS, F, and others. A lens with a C interface, for example, is only compatible with cameras using the same interface.

6. Focal Length of the Machine Vision Lens

Focal length impacts the field of view and working distance. Determining the focal length should consider factors like field of view, working distance, and camera sensor size.

7. Distortion in Machine Vision Lenses

Distortion results from inconsistencies in magnification, causing image warping. Distortion is unavoidable to some extent due to manufacturing processes, but high-quality lenses minimize it. When precision is required, such as in measurement systems, lens distortion must be carefully considered. Selecting the right lens involves considering all these parameters in the context of the actual project requirements.