object offset when using AR headset

Hi,

I am a newbie to programminga and augmented reality, I bought this AR headset ( https://www.amazon.co.uk/Docooler-Headset-Augmented-Holographic-Projector/dp/B074MY8JSF ) . I followed the tutorials for vuforia on unity , and it works perfectly ( 3d model is shown on the marker exactly as its placed in the unity editor ) when seeing through the phone. The problem arises when I use the phone in the headset, the model position is offseted when I view through the visor. . .. . .can anyone help me how to accurately caluclate the offset and make the change in the imagetarget script.

Regards,

Krishna.