FA Lens - Shenzhen Yixian Sensing Technology Co., Ltd

FA Lens FAQs

What Is an FA Lens?

An FA lens refers to a specialized lens for Factory Automation, serving as a core component of machine vision systems. Specifically designed for industrial scenarios, it is engineered to meet the rigorous demands of automated production and quality control.

FA lenses feature high resolution, stable imaging quality, and a large depth of field—capabilities that enable them to accurately capture clear images even in complex industrial environments (e.g., high dust, variable lighting, or high vibration), ensuring reliable inspection precision. Their interfaces and parameters are fully compatible with industrial cameras, facilitating efficient integration into machine vision workflows for seamless visual inspection.

Across industries such as electronics manufacturing, automotive production, and food packaging, FA lenses are widely used in automated production and quality control processes, including PCB board inspection, component dimension measurement, and product sorting. By delivering clear, high-fidelity images, they provide machine vision systems with reliable image data, making them an essential tool for achieving high-precision inspection and production in the field of factory automation.

What Are the Differences Between FA Lenses and Telecentric Lenses?

1. Imaging Principle

FA Lenses (Industrial Lenses) adopt a conventional imaging optical path design. When the object distance (distance between the lens and the object) changes, the imaging magnification changes accordingly—this variation directly leads to measurement errors. For example, if an FA lens is used to measure the diameter of a mechanical part, a small shift in the part’s position (e.g., 1mm closer to the lens) will cause the part’s image on the sensor to enlarge slightly, resulting in an overestimated diameter reading.
Telecentric Lenses are categorized into object-side telecentric, image-side telecentric, and double-sided telecentric types. Taking the most common object-side telecentric lens as an example: its entrance pupil (the point where light rays converge before entering the lens) is located at infinity, and the principal rays (the central rays of light bundles) enter parallel to the optical axis. This design ensures that even if the object shifts within a certain depth of field range (e.g., moving up or down along the Z-axis), the imaging magnification remains almost unchanged. This eliminates magnification errors caused by object position fluctuations, greatly improving measurement accuracy.

2. Performance Differences

The two lens types differ significantly in distortion control, depth of field, and measurement accuracy—key performance indicators for industrial imaging:

Performance Indicator	FA Lenses	Telecentric Lenses
Distortion Control	While designed to minimize distortion, they still exhibit higher distortion compared to telecentric lenses, especially in the edge areas of the image. For instance, when capturing a large flat panel with an FA lens, the edges of the panel may appear slightly curved (barrel or pincushion distortion), affecting the accuracy of edge dimension measurements.	Feature ultra-low distortion (often <0.1%, far lower than FA lenses). The parallel principal ray design ensures uniform imaging across the entire field of view, even at the edges—critical for applications requiring strict shape fidelity, such as measuring the outline of a semiconductor chip.
Depth of Field	Have a relatively limited depth of field. If the detected object is thick (e.g., a 5mm-thick plastic part) or shifts along the Z-axis, parts of the object may appear blurred, requiring frequent refocusing.	Offer a much larger depth of field. Even if the object moves slightly along the Z-axis (e.g., ±2mm), the entire object remains in sharp focus. This is ideal for inspecting objects with varying thicknesses, such as 3D printed parts or stacked electronic components.
Measurement Accuracy	Magnification changes with object distance, leading to larger errors in high-precision measurements. They are typically suitable for applications requiring accuracy within ±0.1mm, not micron-level precision.	Stable magnification ensures high-precision measurements (often down to ±1μm). They are the preferred choice for scenarios like measuring the pitch of tiny PCB pins or the thickness of smartphone screen glass, where micron-level accuracy is mandatory.

3. Application Scenarios

Their performance differences directly determine their suitability for distinct industrial scenarios, balancing accuracy requirements, imaging speed, and cost:

FA Lenses: Widely used in industrial automation scenarios where ultra-high precision is not required. These applications prioritize fast imaging speed and cost-effectiveness.
- Typical use cases:
  - General appearance defect inspection (e.g., detecting scratches on plastic casings, missing screws on assembly lines).
  - Barcode/QR code recognition in logistics (e.g., scanning package labels on conveyor belts, where only clear reading of the code is needed, not precise dimension measurement).
  - Low-precision positioning (e.g., guiding a robot to pick up large, non-critical parts like plastic containers).
Telecentric Lenses: Primarily applied in high-precision measurement and precision assembly guidance scenarios, where imaging accuracy and stability are paramount.
- Typical use cases:
  - Semiconductor manufacturing (e.g., measuring the size of chip bonding pads, inspecting wafer edge defects).
  - Display panel inspection (e.g., verifying the width of LCD/OLED screen borders, detecting micro-cracks in glass substrates).
  - Precision component assembly (e.g., guiding a robot to align tiny connectors on a circuit board, where sub-millimeter positioning accuracy is required).

How to Select the Appropriate Focal Length for an FA Lens Based on Requirements?

When choosing the focal length of an FA lens (Industrial Lens), three core factors must be considered: the size of the inspection target, working distance, and field of view (FOV).

For inspecting small targets at close range (e.g., detecting surface defects on microchips, measuring the size of tiny electronic components), a short focal length lens (typically 4mm–16mm) is preferred. Short focal lengths enable a wider field of view in limited working spaces (e.g., 10mm–50mm working distance), ensuring the entire small target is clearly imaged on the camera sensor without the need to move the lens or target repeatedly.
For inspecting large targets at long distances (e.g., checking the assembly status of large mechanical parts on a production line, identifying barcodes on pallets in logistics), a long focal length lens (usually 50mm–200mm or longer) is more suitable. Long focal lengths can "zoom in" on distant large targets, ensuring that key details (e.g., screw tightness, barcode clarity) are captured with sufficient resolution, even when the lens cannot be placed close to the target (due to space constraints or safety requirements).

To determine the exact focal length, you can use the industrial lens focal length calculation formula:
Focal Length (f) = (Working Distance (WD) × Sensor Size (H/V)) / Field of View (FOV)
In this formula:

"Sensor Size (H/V)" refers to the horizontal or vertical dimension of the camera’s image sensor (e.g., 1/2.3-inch sensor ≈ 6.17mm horizontal size);
"Field of View (FOV)" is the actual size of the area you need to capture on the target (e.g., FOV = 100mm for inspecting a 100mm-wide mechanical part).

If you are unsure about parameter definitions or formula application, you can consult our engineers. They will combine your specific application scenarios (e.g., target material, lighting conditions, inspection speed) to provide accurate focal length recommendations, avoiding mismatches that lead to blurred imaging or incomplete field of view.

Do FA Lenses Require Matching with Specific Industrial Cameras?

Yes, FA lenses (Industrial Lenses) need to be used with matching industrial cameras. The key compatibility factors to consider are:

Interface Type: Common interfaces include C-mount and CS-mount—FA lenses and cameras must share the same interface to ensure physical connection and optical alignment (e.g., a C-mount FA lens cannot be directly used with a CS-mount camera without an adapter, which may cause focus errors).
Sensor Size (Image Circle): The FA lens’s image circle (the maximum sensor size it can cover) must match or be larger than the camera’s sensor size. If the lens’s image circle is too small, it will cause vignetting (dark edges in the image), affecting detection accuracy.
Pixel Size: The FA lens’s optical resolution should align with the camera’s pixel density. For example, a high-pixel camera (e.g., 20MP) requires an FA lens with high resolution to avoid “pixel waste” (the lens cannot resolve details that the sensor could capture), ensuring optimal imaging performance for accurate visual inspection.

Does Distortion of FA Lenses Greatly Affect Inspection Results? How to Correct It?

Yes, FA lens distortion significantly impacts inspection results. Distortion (e.g., barrel or pincushion distortion) deforms the image—for example, making a straight edge appear curved or a square object look trapezoidal. This directly leads to errors in critical tasks like dimension measurement (e.g., overestimating/underestimating part sizes) and defect localization (e.g., misjudging the position of scratches), especially in high-precision scenarios (e.g., PCB pin inspection, semiconductor chip measurement).

To correct distortion:

Hardware Solution: Prioritize low-distortion FA lenses (typically with distortion <0.1%) for precision-demanding tasks—their optical design (e.g., multi-element lens groups, aspherical lenses) inherently minimizes distortion.
Software Correction: For lenses with existing distortion, use image processing software (e.g., Halcon, OpenCV). First, capture images of a standard calibration board (with known grid sizes) to obtain distortion parameters; then apply geometric transformations (e.g., polynomial correction algorithms) to the image, restoring the true shape and dimensions of the inspected object.