In this merric webinar, Laser, powder-blown directed energy deposition (DED) has been recognized for its flexibility in geometry and materials. Despite being widely used in various industries, such as automotive, aerospace, and medical, challenges remain in ensuring uniformity in the manufactured parts. To address this issue, coaxial monitoring in DED typically involves implementing a beam splitter (or dichroic mirror) within the laser optic train which redirects light emitted or reflected from the melt pool to a sensor (infrared, CCD, pyrometer, etc.). This talk will introduce implementing a coaxial photodiode array in a custom-built DED machine in order to capture melt pool information at fast rates (~100 kHz). In addition, a simulation-guided feedforward-feedback control framework will be discussed to effectively control the melt pool temperature in DED processes.