Patent ID: 8736837

Claim:
A flow cell for characterizing particles in a sample solution, the flow cell comprising: an excitation fiber having a core for transporting an excitation light, the excitation fiber defining a channel transversal to its core for directing a flow of the sample solution there through; and at least one collection fiber adjacent to the channel, the at least one collection fiber collecting light scattered or emitted by the particles flowing through the channel and excited by the excitation light; wherein the excitation fiber, the channel and the at least one collection fiber characteristics are selected and the excitation fiber, the channel and the at least one collection fiber are proportioned and positioned relative to each other so as to allow the scattered or emitted light to enter and be guided by the at least one collection fiber, the scattered or emitted light forming a circle at an entrance of the at least one collection fiber, the circle having a diameter defined by a numerical aperture of the at least one collection fiber, the characteristics, proportions and positions of the excitation fiber, of the channel and of the at least one collection fiber meeting a condition to generate collected light of a non-Gaussian temporal intensity profile, the condition being: r + NA ⁡ [ ( 2 ⁢ t - r ) n t 2 - NA 2 + R ′ - t n f 2 - NA 2 + g n 0 2 - NA 2 ] R < 1 wherein: NA is equal to √{square root over (n 1 2 −n 2 n )} and is the numerical aperture of the at least one collection fiber, n 1 is a refractive index of a core of the at least one collection fiber, n 2 is a refractive index of a cladding of the at least one collection fiber, n f is a refractive index of the core of the excitation fiber, n t is a refractive index of the sample solution in the channel, n o is a refractive index of a medium in a gap between an endface of the at least one collection fiber and the excitation fiber, g is a size of the gap between the endface of the at least one collection fiber and the excitation fiber, t is a half-width of the channel in a direction perpendicular to the endface of the at least one collection fiber, R′ is a half-width of the excitation fiber core in the direction perpendicular to the endface of the at least one collection fiber, R is a half-width of the at least one collection fiber in a direction parallel to a flow of the sample solution through the channel in the excitation fiber, and r is a half-width of the particles in the direction parallel to a flow of the sample solution through the channel in the excitation fiber.