Flowcells and Raman analysis systems provide improved signal collection dynamics through increased solid-angle geometries and improved numerical aperture for near-diffraction-limited performance. A combined excitation/collection beam passes through a first optical material, a sample conduit and a second optical material. A concave reflective aspheric surface focuses and re-collimates the combined beam to and from a region of the sample within the conduit. The optical materials may comprise separate windows or may integrally form sidewalls the conduit. The reflective surface may be spaced apart from the second window or may be integrally formed with the second optical material. The focused region in the sample may approximate a point or a line, and at least a portion of the interior wall of the conduit may be reflective, causing the combined beam to pass through the sample region more than once to enhance collection efficiency.