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    Please follow the instructions from the Installation and User Guide carefully. Check whether your VR connected by USB cable is recognized by the PC. Make sure that the Developer mode is activated in the VR device. Also, access from the PC must be allowed in the VR device. Therefore, in case of any difficulties during installation, wear the VR on your head while it is on and approve all security requests by clicking on them. It is possible that several security requests will appear one after the other.

    There are two basic gestures to distinguish: (A) "Grabbing" is done with the "grip" button, which is typically located on the side of VR controllers and is operated with the middle finger. One can imagine closing the hand and holding the object in the "closed fist" as in reality. (B) Fine-tuning is done with the "trigger" button, which is typically located at the front of VR controllers and operated with the index finger. You can think of this as holding a fine-thread screw between your index finger and thumb, just like in reality. In both cases (A or B), the hand must be brought close enough to the object or screw for the action to be performed. The correct position is confirmed by "highlighting" of the object or screw. So you should bring your hand close enough until the highlighting occurs, then press the grab or trigger button and hold it down for further interaction. If you still cannot pick up an optical element, it may be locked down.

    We use a mixture of geometrical optics (to track the direction of propagation) and wave optics (to describe Gaussian beams and interference). Interaction with matter is implemented by a response-function formalism. A detailed discussion of the physical-mathematical basis is planned for scientific publications (currently in preparation).

    We are working on a number of additional exciting features for future releases. Some of them are listed in the feature list as "under development", others are in an earlier stage. If you have a specific suggestion, let us know.

    In the case of a divergent beam, the beam radius becomes larger and larger. Therefore, it could potentially hit a rapidly growing number of optical elements, even if they are very far laterally from the center of the divergent beam. Algorithmic tracking of all possibilities then becomes impractical. Therefore, the rendering of a beam in femtoPro is terminated when its beam radius exceeds a threshold value. This situation is analogous to the real laboratory. There, too, a strongly divergent beam is usually no longer perceived above a certain radius. Its cross-section is then so large that the scattered light quantity is too small to be directly perceived. Nevertheless, this situation should be avoided for laser safety reasons. For this reason, an optical and acoustic warning signal sounds in femtoPro when a beam radius becomes too large. This beam should be intercepted by a "beam blocker" to stop the warning signal.

    No. But we are working on an interface so that users will be able to create and share their own scenes in the future, for example to create new problems for teaching and training or to share plans and instructions for experimental setups.

    A full version is  available for free  for a limited time (until October 31, 2022). The necessary VR set typically costs around 400-600 € and can of course also be used for other software.

    We welcome requests to contribute. There are several opportunities we can discuss. Please feel free to contact  us.

    Write an email to femtopro@uni-wuerzburg.de. If it is helpful for understanding, send a suitable "screenshot" along. Screenshots can be taken directly in VR. With Oculus VR, the submenu for selecting screenshot or video recording opens by clicking the "Oculus" button on the right controller, with Pico VR by double-clicking the "Pico" button. The resulting files can then be transferred to the PC via USB cable.