A tissue oximeter device comprising: a probe for taking oximeter measurements; a panel connector for interfacing a connection interface to a unit; the connection interface for coupling the probe to the unit and allowing through the panel connector coupling of the probe to a first radiation source, a second radiation source, a first photodetector, and a second photodetector, wherein the first radiation source, second radiation source, first photodetector, and second photodetector are external to the probe; and a sensor head comprising a first source structure and a second source structure for emitting light and a first detector structure and a second detector structure for detecting light, the first and second source structures being arranged to be coupled to the first and second radiation sources (116, 120) via the connection interface, and the first and second detector structures being arranged to be coupled to the first and second photodetectors via the connection interface, wherein the first and second detector structures are arranged to define a first axis that passes through a centerpoint of each detector structure (208a, 208b), a distance from a centerline that passes through a centerpoint of the first source structure to the first axis defines a first line segment, a distance from a centerline that passes through a centerpoint of the second source structure to the first axis defines a second line segment, which is parallel to the first line segment, wherein each of the centerlines and the first axis are approximately parallel to an x-axis and wherein the centerline of the first source structure is parallel to, but not coincident with, the centerline of the second source structure and the lengths of the first and second line segments along a y-axis are not equal; and wherein the unit is configured to house the first radiation source, second radiation source, first photodetector, and second photodetector, wherein the unit is external to the probe, the first radiation source is for generating first light, the second radiation source is for generating second light, the first photodetector is for detecting third light, the second photodetector is for detecting fourth light, and the unit houses a beam combiner for coupling the first and second radiation source (116, 120), the beam combiner being external to the probe. a probe for taking oximeter measurements; a panel connector for interfacing a connection interface to a unit; the connection interface for coupling the probe to the unit and allowing through the panel connector coupling of the probe to a first radiation source, a second radiation source, a first photodetector, and a second photodetector, wherein the first radiation source, second radiation source, first photodetector, and second photodetector are external to the probe; and a sensor head comprising a first source structure and a second source structure for emitting light and a first detector structure and a second detector structure for detecting light, the first and second source structures being arranged to be coupled to the first and second radiation sources (116, 120) via the connection interface, and the first and second detector structures being arranged to be coupled to the first and second photodetectors via the connection interface, wherein the first and second detector structures are arranged to define a first axis that passes through a centerpoint of each detector structure (208a, 208b), a distance from a centerline that passes through a centerpoint of the first source structure to the first axis defines a first line segment, a distance from a centerline that passes through a centerpoint of the second source structure to the first axis defines a second line segment, which is parallel to the first line segment, wherein each of the centerlines and the first axis are approximately parallel to an x-axis and wherein the centerline of the first source structure is parallel to, but not coincident with, the centerline of the second source structure and the lengths of the first and second line segments along a y-axis are not equal; and wherein the unit is configured to house the first radiation source, second radiation source, first photodetector, and second photodetector, wherein the unit is external to the probe, the first radiation source is for generating first light, the second radiation source is for generating second light, the first photodetector is for detecting third light, the second photodetector is for detecting fourth light, and the unit houses a beam combiner for coupling the first and second radiation source (116, 120), the beam combiner being external to the probe.