Hi @hang, please be aware that the Tobii Eye Tracker 5 is designed for interaction and gaming purposes only.
The use of the ET5 for academic or research purposes is only permitted in rare circumstances and requires the purchase of a special license to do so.
You can enquire about this @ https://developer.tobii.com/license-agreement/contact/
For advanced metrics, eye images, and research use, we offer the Tobii 5L which you can read more about @ https://tech.tobii.com/products/eye-tracker-5l/