A specular variable angle absolute reflectometer (400, 500, 1200), comprising: a light source (402, 1202); a detector (412, 1212); a sample mount configured to position an optically reflective sample (502, 1206) at a plane containing a rotation axis (414, 1211) such that the sample (502, 1206) is rotatable by a first angle about the rotation axis (414, 1211); a mirror system (406, 1204) in a light path of the light source (402, 1202), the mirror system (406, 1204) configured to reflect a light beam from the light source (402, 1202) towards the sample (502, 1206); a roof mirror (408, 1208) disposed in the light path after the sample (502, 1206), the roof mirror (408, 1208) configured to reflect the light beam reflected by the sample (502, 1206) back towards the sample (502, 1206) and wherein the roof mirror (408, 1208) comprises a "V" shaped wedge with an inner angle of the "V" shaped wedge facing the sample (502, 1206); a mechanism connected to the roof mirror (408, 1208), the mechanism being configured to rotate the roof mirror (408, 1208) by a second angle about the rotation axis (414, 1211), the second angle being about twice the first angle; wherein the detector (412, 1212) is arranged in the light path after the roof mirror (408, 1208) and is configured to receive light that has been reflected from the roof mirror (408, 1208), thence back to the sample (502, 1206), thence back to the mirror system (406, 1204), and thence to the detector (412, 1212); wherein the specular variable angle absolute reflectometer further comprises: a light trap associated with the mirror system (406, 1204); and a movement system connected to the mirror system (406, 1204) and configured to move the mirror system (406, 1204) such that the light trap intercepts the light from the light source (402, 1202) with a forward movement of the mirror system (406, 1204) and a direct path from the light source (402, 1202) to the detector (412, 1212) when the mirror system (406, 1204) is retracted from intercepting the light from the light source (402, 1202). a light source (402, 1202); a detector (412, 1212); a sample mount configured to position an optically reflective sample (502, 1206) at a plane containing a rotation axis (414, 1211) such that the sample (502, 1206) is rotatable by a first angle about the rotation axis (414, 1211); a mirror system (406, 1204) in a light path of the light source (402, 1202), the mirror system (406, 1204) configured to reflect a light beam from the light source (402, 1202) towards the sample (502, 1206); a roof mirror (408, 1208) disposed in the light path after the sample (502, 1206), the roof mirror (408, 1208) configured to reflect the light beam reflected by the sample (502, 1206) back towards the sample (502, 1206) and wherein the roof mirror (408, 1208) comprises a "V" shaped wedge with an inner angle of the "V" shaped wedge facing the sample (502, 1206); a mechanism connected to the roof mirror (408, 1208), the mechanism being configured to rotate the roof mirror (408, 1208) by a second angle about the rotation axis (414, 1211), the second angle being about twice the first angle; wherein the detector (412, 1212) is arranged in the light path after the roof mirror (408, 1208) and is configured to receive light that has been reflected from the roof mirror (408, 1208), thence back to the sample (502, 1206), thence back to the mirror system (406, 1204), and thence to the detector (412, 1212); wherein the specular variable angle absolute reflectometer further comprises: a light trap associated with the mirror system (406, 1204); and a movement system connected to the mirror system (406, 1204) and configured to move the mirror system (406, 1204) such that the light trap intercepts the light from the light source (402, 1202) with a forward movement of the mirror system (406, 1204) and a direct path from the light source (402, 1202) to the detector (412, 1212) when the mirror system (406, 1204) is retracted from intercepting the light from the light source (402, 1202). a light trap associated with the mirror system (406, 1204); and a movement system connected to the mirror system (406, 1204) and configured to move the mirror system (406, 1204) such that the light trap intercepts the light from the light source (402, 1202) with a forward movement of the mirror system (406, 1204) and a direct path from the light source (402, 1202) to the detector (412, 1212) when the mirror system (406, 1204) is retracted from intercepting the light from the light source (402, 1202).