Infrared laser Laser's track movements in virtual and augmented reality

The latest virtual and augmented reality systems offer the most intuitive ways currently available for humans to interact with machines. They use sensors to track human movements.

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FAULHABER Antriebssysteme

ROHM Semiconductor GmbH

OSRAM Opto Semiconductors GmbH

When you see someone using the latest virtual or augmented reality systems, it almost looks as though they are dancing. Wearing a headset or special glasses, they weave around the place, waving their hands in the air – and none of it seems to make sense to the outside observer. However, what you’re actually looking at is the most modern and intuitive way for someone to interact with a computer game or indeed software in general.

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Sensors – usually based on infrared light – track the user’s positions, movements and gestures, which the system then responds to or even integrates into the action as it unfolds. Virtual reality (VR) users are completely immersed in another world. The systems generate a simulated environment and integrate the users as active participants. Today’s VR offerings predominantly target the games market, but the list of potential industrial applications is long. Examples range from virtual tours of holiday resorts or new properties through urban design to training scenarios for complex work environments.

The own smartphone as the display

From a technical perspective, VR systems consist of a headset with two lenses, through which you see the same scene from two different perspectives. This creates the impression of depth for the user. Many solutions use the participant’s own smartphone as the display, tracking their head movements via sensors in the phone or headset. The latest breakthroughs include devices with special head-up displays. These visually isolate the user from their real surroundings and are connected to high-performance gaming computers or consoles. They use specially developed sensors to track the user’s position and orientation in the gaming space, sometimes also registering their hand movements separately, and transfer this information to the virtual environment. Users find themselves completely transported into the simulated setting – they see their hands, for instance, and are able to grasp objects.

To track a user’s movements in a gaming space, these systems employ a combination of infrared light and cameras or photodetectors. One option is to mount infrared LEDs around the headset, which emit points of light in a specific pattern. A front camera records these light markers, and algorithms calculate the user’s position and movements from the pattern as it changes. To generate the light, compact and efficient emitters are required, reducing stray light to a minimum. A wavelength of 850 nanometers (nm) is suitable for this purpose, since the emitted light should ideally be invisible to the user, while matching the spectral sensitivity of the camera. The small SFH 4053 Chipled (1.0 mm x 0.5 mm x 0.45 mm) is a good choice, for instance, delivering 35 milliwatts optical power at a current of 70 milliamps.

A 850 nm laser diode

Other solutions take the opposite approach, instead illuminating the gaming area from two opposing directions using infrared light. The headset is mounted with photodetectors that detect this light. Algorithms calculate the user’s position and orientation by analyzing all detector signals. Hand movements are also registered in this way: participants can use handheld controllers to perform specific actions in the virtual world.

These controllers similarly equipped with photodetectors so they can be integrated into the simulation. The illumination units are equipped with powerful, high-efficiency infrared LEDs in the 850 nm wavelength, such as the Oslon Black Series emitters. These are among the most powerful and efficient devices for infrared illumination on the market today, generating optical power of up to or even beyond 1.3 watts at a current of 1 amp, depending on the chip type. Surface-mountable standard photodiodes are suitable for use as detectors. To avoid users colliding with real objects, the VR systems assess the gaming space using an 850 nm laser diode. If the user approaches a wall, for instance, a corresponding barrier is inserted in the virtual setting.

Augmented or mixed reality – overlaid with information

Augmented reality (AR) enriches the real world with additional, contextual information. The main demand for these solutions previously came from industrial applications. Users working on complex systems, for instance, could view superimposed details about specific components or the relevant process step. As with virtual reality, AR applications are now being developed for a much wider audience – from adverts that pop up during shopping trips to navigation services for pedestrians. In summer 2016, AR suddenly gained widespread recognition with the smartphone game Pokémon Go, where players set out to catch virtual cartoon creatures appearing in their real surroundings.

Many AR systems display their information on smartphone screens and use the phone’s sensors to adapt the depicted environment to the user’s position. Data glasses – also known as smart glasses – are another alternative, projecting the additional information directly into the user’s field of view. This leaves their hands free so they can interact with the program intuitively using gestures.

These AR systems detect the user’s gestures using integrated miniaturized 3D cameras. There are essentially two methods of achieving this. Time-of-flight cameras record the time required for a laser pulse to travel from the camera to an object and then reflect back from it. The distance between object and sensor is thus calculated pixel by pixel.

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