The technology relates to medical devices for monitoring and assessing vascular health. In one embodiment, the technology is an apparatus that attaches to a subject's finger comprising a heating and cooling component, a coherent source, a temperature sensor, an image detector, and/or a component for data control and management. In another embodiment, there is a component that alters local blood flow in the subject, and laser speckle contrast and photoplethysmography (PPG) signals from the altered blood flow in the subject are compared to monitor the vascular health of the subject.