A device for detection of internal bleeding in a patient's body is provided. An optical interface for transmitting IR light through an area of a skin of a patient and to collect IR light from the area of the skin, is provided. In some embodiments the optical interface includes one or more delivery components and one or more collection components. The delivery component includes a plurality of first optical channels configured to transmit the IR light through a plurality of respective first sub-areas on the area of the skin, into an internal layer of the body. The collection component includes a plurality of second optical channels, configured to collect IR light from a plurality of respective second sub-areas on the area of the skin.
