# Extended Reality: Types and Applications
## 4 Hardware in Extended Reality
### Existing Main Forms of Interface  
After analyzing the articles, the most popular devices for x-ray visualization were identified and will be described and compared below. Extended reality gives a variety of ways to interact with graphical, audial, or sensory information. Examples of XR headsets that are mostly used as hardware are shown in Figure 8.  
All-In-One HMD--The Meta Quest is a standalone mixed reality HMD device with an integrated IMU and camera system for visual SLAM localization. The cameras can detect user hand gestures to control visualization without controllers. The integrated CPU is powerful enough to run medium-quality mixed reality simulations and games, but the battery life is about 2.5 h. Also, the headset supports connection to the computer via Wi-Fi. Connecting via cable removes the battery limitations, but limits the user's movements [67]. This device is quite advanced, especially for the price of USD 500. It is also quite compact and ergonomic, weighing 515 g [68]. HMD with Sensors--HTC Vive Pro 2 is also an HMD device with an integrated IMU and camera system. It also works on MR, AR, and VR modes, but it does not have an integrated CPU. This headset always needs to be connected to the PC and provides high-quality visualizations or precisely calculated simulations. The disadvantage is only that user is always connected to a PC and limited in movements. The device costs USD 800 and is quite large in size, weighing 850 g, which is heavy for the head [69]. HMD without Sensors--The Oculus rift is only an HMD headset. This device only has a screen and uses infrared (IR) LED throughout the entire body for tracking, so it only provides a VR experience. For tracking the position of this system, an external IR camera is used to track IR points of a headset. An example of such a device is the first versions of the Oculus Rift DK1 and DK2. The weight of the device is 470 g, and the price is USD 300. Standalone with Prismatic Combiner--Microsoft HoloLens is an AR and MR headset where the user always sees a real world, and virtual data are projected through a special prism. The two types of views are combined to provide the look of a real world with a virtual object. It uses cameras and IMU to localize the position of the headset [67; 70]. This technology is used in the Microsoft HoloLens headset, which is often used in scientific papers and experiments due to its good support, with a cost of USD 3500. The device is compact and ergonomic and weighs 566 g [71]. Smartphones--Modern smartphones are also suitable for use in VR and AR visualization. They have sufficiently powerful processors and high-quality cameras to process data in real time. For AR use, just a smartphone is enough. However, for VR use, it needs a special adapter with lenses, like Google Cardboard or Samsung Gear VR, for comfortable use. Also, due to their low weight, about 100-300 g, such devices are ergonomic, which makes their use comfortable. This is the cheapest method to get the VR experience, from EUR 10 without including the smartphone [2], but it has the disadvantages of low screen resolution and a low battery life due to the heavy load on the phone's processor. There are also usually no spatial controllers, or there is only one, like in Samsung Gear VR, which worsens control and immersion in the VR environment. Regular Monitor and Camera--This is an old and straightforward way to get the AR experience. Usually, they used a graphic marker printed on paper, which was read by a program using a web camera. The computer processed everything and displayed a picture from the camera on the monitor on which a virtual object was superimposed. Figure 8: Examples of XR headsets: 1. Meta Quest 3 [68], 2. HTC Vive [69], 3. Microsoft HoloLens [70], 4. Samsung Gear VR [72]. Extended reality systems have several types of user interfaces with headsets.