An optical module for reading a test region of an assay, the optical module comprising: • a first light source for illuminating the test region of the assay; • an optical detector, comprising an optical input for receiving light emitted from the test region of the assay and an electrical output; • a substrate for mounting the first light source and the optical detector; • a housing defining a first opening for providing a first optical path from the first light source to the test region and from the test region to the optical detector; ∘ wherein the housing and the substrate enclose and positionally align the first light source and the optical detector relative to the first opening; • a second light source for illuminating a control region of the assay; ∘ wherein the second light source is mounted on the substrate, ∘ wherein the housing comprises a second opening for providing a second optical path from the second light source to the control region and from the control region to the optical detector, and ∘ wherein the housing and the substrate further enclose and positionally align the second light source relative to the first and second openings (106, 107), and the optical detector; • one or more first baffles positioned on the substrate between the optical detector and the first light source to block direct propagation of light from the first light source to the optical detector; characterized in that the optical module further comprises angled pillars extending from an inside surface of the housing between the first and second openings (106, 107) to the first baffles, wherein the angled pillars are positioned at an optimum position where signal to noise ratio is highest. • a first light source for illuminating the test region of the assay; • an optical detector, comprising an optical input for receiving light emitted from the test region of the assay and an electrical output; • a substrate for mounting the first light source and the optical detector; • a housing defining a first opening for providing a first optical path from the first light source to the test region and from the test region to the optical detector; ∘ wherein the housing and the substrate enclose and positionally align the first light source and the optical detector relative to the first opening; ∘ wherein the housing and the substrate enclose and positionally align the first light source and the optical detector relative to the first opening; • a second light source for illuminating a control region of the assay; ∘ wherein the second light source is mounted on the substrate, ∘ wherein the housing comprises a second opening for providing a second optical path from the second light source to the control region and from the control region to the optical detector, and ∘ wherein the housing and the substrate further enclose and positionally align the second light source relative to the first and second openings (106, 107), and the optical detector; ∘ wherein the second light source is mounted on the substrate, ∘ wherein the housing comprises a second opening for providing a second optical path from the second light source to the control region and from the control region to the optical detector, and ∘ wherein the housing and the substrate further enclose and positionally align the second light source relative to the first and second openings (106, 107), and the optical detector; • one or more first baffles positioned on the substrate between the optical detector and the first light source to block direct propagation of light from the first light source to the optical detector;