The present invention relates to a device for measuring blood and physiological characteristics by passing light through human tissue that is configured for deployment on a human finger. The device includes a lower finger-trough configured in the main housing of the device a hingedly attached closeable lid that has an upper finger-trough configured for deployment of at least one finger stabilizing element, the lid being latchable in a closed position a finger stabilizing element made of a material having flexibly soft malleable characteristics so as to sealingly engage the top of the finger a light source that is deployed in the sloped end wall of the lower finger-trough adjacent to the lower portion of the finger tip and an end cap the is deployable on the open end of the device when the lid is in the closed position, which enables calibration of the device with a minimum of light wave "noise" from ambient light.
