Patent ID: 8189187

Claim:
A method for making a transparent, monolithic optical flow cell of the type used to characterize formed bodies passing through it, said optical flow cell having formed therein a prismatic internal flow channel defined by at least three intersecting substantially planar surfaces, whereby said prismatic internal flow channel has a transverse cross-section that is substantially polygonal in shape, said method comprising the steps of: (a) providing a monolithic glass preform comprising a glass tube having a central, axially-extending prismatic internal flow channel therethrough, said channel exhibiting a substantially uniform transverse cross-section of a desired polygonal shape; (b) heating said monolithic glass preform to a predetermined temperature above the softening temperature of said glass tube; (c) axially drawing said monolithic glass preform at a controlled rate, for a controlled time and at a constant angular orientation, to achieve a desired transverse cross-sectional area of said prismatic internal flow channel, thereby creating a drawn monolithic glass preform.