A new system that projects an image of a patient's veins onto their skin will soon be tested in a US hospital. Finding veins for injections and IVs can be a hassle, but the system captures a real-time near-infrared image of the patient's veins and displays the enhanced picture on the patient's body. From New Scientist:
The tricky part is making sure the image of the veins is projected in exactly the right place. Get this wrong, and the system becomes worse than useless. The key is device called a "hot mirror", which is transparent to visible light but reflects infrared (hot) wavelengths.
The video projector and camera are set at 90 degrees to each other facing the mirror, which is set at 45 degrees to both of them. After calibration, this ensures that a vein always appears within 0.06 millimetres of its correct position…
