The present invention provides methods and systems for particle detection and analysis using two-dimensional optical imaging to access enhanced detection sensitivity and expanded sensing functionality relative to conventional point and array detection-based optical particle counters. Methods and systems of the present invention provide a two-dimensional optical imaging-based particle sensing platform wherein system components and specifications are selected to generate reproducible and readily identifiable signals, including particle detection signatures, from optical scattering or emission from particles provided to the system. Systems and methods of the present invention are capable of accurately and sensitively detecting, identifying, and characterizing (e.g., determining the size of) particles in liquid phase or gas phase samples.