A lens and reflector unit for optical measurements, comprising: - a first convex surface section (502, 801) of said lens and reflector unit, wherein said first convex surface section (502, 801) and a plane that intersects said first convex surface section (502, 801) at its circumferential rim delimit a first lens that has a first optical axis (503, 706), - a second convex surface section (504, 803) of said lens and reflector unit, wherein said second convex surface section (504, 803) and a plane that intersects said second convex surface section (504, 803) at its circumferential rim delimit a second lens that has a second optical axis (505, 707), - a first flat surface section (506, 802) of said lens and reflector unit, said first flat surface section (506, 802) having a normal direction that divides an angle between said first and second optical axes (503, 706, 505, 707) into equal halves at a point of said first flat surface section (506, 802) where said first and second optical axes (503, 706, 505, 707) intersect, characterized in that: - the lens and reflector unit comprises a third convex surface section of said lens and reflector unit, wherein said third convex surface section and a plane that intersects said third convex surface section at its circumferential rim delimit a third lens that has a third optical axis that has a common point with said second optical axis (505, 707) at a point that is also a focal point of said second and third lenses, - the lens and reflector unit comprises a fourth convex surface section of said lens and reflector unit, wherein said fourth convex surface section and a plane that intersects said fourth convex surface section at its circumferential rim delimit a fourth lens that has a fourth optical axis, - the lens and reflector unit comprises a second flat surface section of said lens and reflector unit, said second flat surface section having a normal direction that divides an angle between said third and fourth optical axes (708, 709) into equal halves at a point of said second flat surface section where said third and fourth optical axes (708, 709) intersect, - the lens and reflector unit comprises a first transparent body and a second transparent body different than said first transparent body, - said first convex surface section (502, 801), said second convex surface section (504, 803) and said first flat surface section (506, 802) are surface sections of the first transparent body, and - said third convex surface section, said fourth convex surface section and said second flat surface section are surface sections of the second transparent body. - a first convex surface section (502, 801) of said lens and reflector unit, wherein said first convex surface section (502, 801) and a plane that intersects said first convex surface section (502, 801) at its circumferential rim delimit a first lens that has a first optical axis (503, 706), - a second convex surface section (504, 803) of said lens and reflector unit, wherein said second convex surface section (504, 803) and a plane that intersects said second convex surface section (504, 803) at its circumferential rim delimit a second lens that has a second optical axis (505, 707), - a first flat surface section (506, 802) of said lens and reflector unit, said first flat surface section (506, 802) having a normal direction that divides an angle between said first and second optical axes (503, 706, 505, 707) into equal halves at a point of said first flat surface section (506, 802) where said first and second optical axes (503, 706, 505, 707) intersect, - the lens and reflector unit comprises a third convex surface section of said lens and reflector unit, wherein said third convex surface section and a plane that intersects said third convex surface section at its circumferential rim delimit a third lens that has a third optical axis that has a common point with said second optical axis (505, 707) at a point that is also a focal point of said second and third lenses, - the lens and reflector unit comprises a fourth convex surface section of said lens and reflector unit, wherein said fourth convex surface section and a plane that intersects said fourth convex surface section at its circumferential rim delimit a fourth lens that has a fourth optical axis, - the lens and reflector unit comprises a second flat surface section of said lens and reflector unit, said second flat surface section having a normal direction that divides an angle between said third and fourth optical axes (708, 709) into equal halves at a point of said second flat surface section where said third and fourth optical axes (708, 709) intersect, - the lens and reflector unit comprises a first transparent body and a second transparent body different than said first transparent body, - said first convex surface section (502, 801), said second convex surface section (504, 803) and said first flat surface section (506, 802) are surface sections of the first transparent body, and - said third convex surface section, said fourth convex surface section and said second flat surface section are surface sections of the second transparent body.