Intelligent Lens System Improves Integration in Machine Vision Systems

By Mark Peterson, VP Advanced Technology and Andrea Van, VP Business Development. Theia Technologies. © 2024.
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Theia Technologies’ IQ Lens™ System brings together a motorized lens, motor control board, average calibration data, and software with graphical user interface (GUI) to form a modular, highly configurable system. Until recently, the user needed to develop their own motor control software. Theia’s IQ Lens™ System software application and intuitive graphical user interface saves the user considerable development effort and cost, speeding time to market. The IQ Lens™ calibration data provides intelligence that enables optimal image quality and easy imaging system setup. The compact, lightweight varifocal lens and motor control board provide for remote operation in hard to reach or mobile environments. Combined, these elements allow for convenient and cost-effective integration into the imaging system.

Remote Access and Control

Theia’s motorized lenses and motor control board are designed for integration into vision systems for a variety of machine vision applications and use stepper motors to operate the zoom, focus, iris, and filter of the lens (see Fig. 1). The lenses simplify camera setup and installation in applications that have remote or difficult to access set up locations, such as autonomous mobile robots (AMRs) and Uncrewed Aerial Vehicles (UAVs).

Figure 1. Theia’s IQ Lens™ System integrated into robotics application. Image courtesy of Staubli.

The lenses are highly versatile, providing the ability to adjust the zoom and focus remotely, offering enormous flexibility in the placement of imaging systems requiring variable camera positions and/or object distances. Remote zoom and focus permit fine tuning of object resolution in dynamic environments and applications including in Cobots and robotic assisted medical procedures, as well as in automated and remotely operated laboratory testing for example.

Theia’s motorized lenses can also be switched between transmitting visible light and transmitting Near IR light for detecting water levels in tissue, agricultural crops, and other media, enabling high image detail in multi-spectral applications (see Fig. 2). This capability can also be used for enabling accurate color rendition in visible light and improved sensitivity in NIR light (with or without additional NIR illumination) such as in license plate reading applications.

Figure 2. Theia's motorized lenses focus visible and Near IR light to the same plane as seen in this beverage inspection simulation.

Plug and Play

Until recently, using Theia’s motorized lens and motor control board together required the user to develop software to translate desired engineering parameters into motor steps and motor steps into lens commands. Theia’s new IQ™ Lens System comes with a software development kit (SDK) that allows for quick and easy integration into the imaging system.

Many users want to set a field of view, depth of field, or object distance. With the IQ Lens™ System’s SDK, these engineering units are automatically converted from intuitive concepts into motor steps using Theia’s available lens control library and graphical user interface (GUI), the IQ Lens(tm) can be controlled without the need for complicated external calculations, curve fitting, and interpolation and without requiring the user to look up which motor step correlates to what FOV, or which iris step equates to what F/# (see Fig. 3).

Figure 3. Theia IQ Lens™ control software's graphical user interface.

The new IQ Lens™ System also includes the MCR IQ™ Motor Control Board with software application and GUI to convert motor steps into machine commands that move the lens to desired positions. The board communicates via USB, UART or i2c protocols for flexibility in integration.

Purchase of the IQ Lens™ and MCR IQ™ Motor Control Board includes a royalty free license to use the software applications.

Both software applications are available as Python modules for program development. In addition, there is a convenient GUI application allowing user access to the modules. These modules save the user considerable effort, time and money, keeping the user from needing to develop their own software, greatly speeding system development, integration and time to market.

Lens Intelligence

The Theia IQ Lens™ includes calibration data in a computer-readable data format to enable enhanced image performance and image processing speed.

With varifocal lenses, changing the focal length will cause the image to lose focus and so setting the best focus for a desired field of view (focal length) is an iterative process. Theia’s IQ Lens™ calibration data includes an average measured zoom/focus tracking curve which can be used to keep the lens in focus while changing zoom position, or to set the focus at a known zoom position. This zoom/focus curve is kept up to date as a rolling average of lenses in production (see Fig. 4)

Figure 4. Focus / Zoom Tracking Curve of a 12-50mm focal length lens, showing different focal length’s focus/zoom motor positions

Knowing this relationship allows the user to remotely program the focus and zoom motor position to enable image optimization in difficult-to-access and/or mobile cameras such as with AMRs and UAVs for example.

Accurate field of view setup can be achieved by knowing the relationship of focal length to zoom motor step position. In applications such as remote operation and guidance of pick and place automation equipment, and mobile speed cameras where the field of view and object distance must change because the camera is not in a fixed position, this focal length and focus adjustability allows the image to be optimized for any object distance from the camera.

The calibration curves are monitored from lens lot to lot to verify the continued accuracy of the curves. When a Theia IQ Lens™ is purchased, the most recent average data file is provided, available from online download.

Theia’s IQ Lens™ also includes design data that is common across lenses in the same family including aperture size, geometrical distortion, and relative illumination which can be used to enhance image processing.

Aperture size design data enables control over lighting in outdoor applications with limited lighting control. Applications such as Automated Number Plate Recognition (ANPR), aerial crop monitoring, and infrastructure monitoring can benefit from increased depth of field through more precise aperture control (see Fig. 5).

Figure 5. Motorized iris control allows users precise control over aperture size, useful in ANPR applications as illustrated here.

Geometrical distortion design data for multiple focal lengths permits positional corrections. Imaging applications requiring known object positions such as 3D mapping, situational awareness, navigation of AMRs or UAVs, image stitching and de-warping, can be set up without complicated distortion mapping illumination grid jigs.

Relative illumination design data allows corner image brightness to be adjusted for uniformity at different focal lengths and F/# settings, great for applications needing a uniformly exposed scene such as, inspection and grading applications.

This data is available for download from Theia’s cloud database with application notes providing instructions and suggestions for using the data. The calibration data frames are provided in a JSON format data file.

Modular Design

Theia’s IQ Lens™ System offers a modular design with separate components allowing flexible configuration inside the hardware envelope (see Fig. 6). The motorized varifocal lenses are compact at less than a 52mm lens length and Theia’s motor control board is only 25x60mm to fit into small enclosures and lightweight to be used in mobile or uncrewed applications like AMRs or UAVs and mobile monitoring or inspection systems for optimal maneuverability.

Figure 6. Theia's modular IQ Lens™ System is highly configurable, able to integrate into complex imaging systems, as shown here.

Conclusion

Theia’s IQ Lens™ System with motorized varifocal lens, motor control board, average calibration data, and software application provide convenience, flexibility and optimized image quality in a cost-effective package to support today’s demanding machine vision applications (see Fig. 7).

Fast. Intelligent. Cost-effective. Just plain Smart!

Figure 7. Theia's IQ Lens System includes a motorized lens, motor control board, average calibration data, and software with graphical user interface.

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