TLens® compared to VCM

While Voice Coil Motor (VCM) is widely used in today’s camera modules, the poLight® TLens technology out-competes most traditional VCM features, and a migration from VCM technology to the new poLight technology is foreseen for smartphones and accessories/wearables, as well as for demanding industry applications. The fundamental structure of the TLens is very different from the VCM technology: Whereas the VCM technology has to move the full lens package to create focus, the TLens alters the shape of the lens at an extremely rapid speed, thereby tuning the optical characteristics.

Illustrating the difference between TLens and VCM technology, the video below clearly illustrates the advantages poLight’s TLens technology can bring to the smartphone camera experience. Shown on the left, TLens focuses extremely fast, with no field-of-view variation. The example is shot with a mid-tier phone, with the TLens mounted on a fixed-focus camera, and using a contrast-based autofocus algorithm.

The video to the right was shot with a high-end smartphone that uses a VCM with PDAF. Notice that the focusing speed is significantly lower, that the camera is sometimes unable to focus, and that the use of VCM technology causes a “pumping” effect”.

Typical Characteristics (1/4” sensor)

TLens® VCM
Response time 1 ms 5 to 15 ms
Power consumption <5mW 220 mW
Field of view No AF pumping AF pumping
Smallest Footprint (typical 1/4′ sensor) 4.4x4.9 mm >7.5×7.5 mm
Magnetic Interference No Yes

The TLens (Tunable Lens) doesn’t just replace traditional VCM technology for autofocus. Instead it enables a range of entirely new experiences, use cases, and ways to build innovation and help you differentiate. TLens®’s unique features include:

  • Instant focus – enabling recording of several images, to be combined into one, all-in-focus image, featuring instant focus above and beyond competing technologies. This unique feature may be used in back/main cameras, as well as in front-facing cameras. The TLens is up to 10 times faster than competing technologies.
  • Constant field of view – provides smooth and accurate focusing as the image or video is recorded. Unlike with VCM, the zoom effect is not visible as focus changes. Constant field of view significantly reduces the complexity of image stitching and bracketing, which is relevant for both single and multi-camera systems.
  • High optical axis stability – is a characteristic of the TLens design, which, unlike VCM, is not affected by gravity, thermal and mechanical shocks. As a result, complex calibration procedures are not necessary, and the lens performs stably over its lifetime, rendering the manufacturing process less complex, and delivering higher image quality over time. From an application point of view, this significantly reduces the complexity of image stitching and bracketing for both single and multi-camera systems.
  • Extremely low power consumption – is an important quality for new applications in smartphones and wearables, as well as for industry applications that require low power consumption. TLens’ low power consumption also means that, unlike with VCM, the image sensor’s temperature will remain stable when focusing, improving image quality.
  • More efficient AF camera module manufacturing – the Packaged TLens® will enable efficient manufacturing of camera modules, resulting in better yield at camera module level. The Packaged TLens® minimises dust contamination, whereas VCM keeps open access to the image sensor. The integration of camera modules with TLens can also easily be fully automated, providing improved yield and more cost-effective processes.
  • Easy integration of camera into phones – as the small footprint enables TLens-based cameras to fit more easily into the phone – front and back. The TLens® design, without coils or springs, also eliminates interference issues.
    The Test and Calibration procedures can be minimized due to the few moving parts, high optical stability, and low power consumption, etc.
  • Dual and multi-camera implementation – are a feature of the mobile unit eco-system. With the small footprint of the TLens, the cameras can be placed close together, which is good for high resolution, extended dynamic range, optical zoom, and more. The TLens’ constant field of view, high optical axis stability, instant focus, elimination of electromagnetic interference, and low power consumption will also improve the multi-camera system performance.
  • No magnetic interference - as the TLens does not have coils or springs, the magnetic interference is negligible, permitting two auto-focus cameras to be placed in close proximity without interference. This provides OEMs with extensive design autonomy, and minimises interference with other coils and RF parts.