Systems and methods for a multiple angle light scattering (MALS) instrument having two-dimensional detector array
View Patent ↗A particle detection system uses a reflective optic comprising a curved surface to detect high angle scattered light generated by a particle in a liquid medium, when a laser beam is incident on the particle. When the particles transit the laser beam, light is scattered in all directions and is described by MIE scattering theory for particles about the size of the wavelength of light and larger or Rayleigh Scattering when the particles are smaller than the wavelength of light. By using the reflective optic, the scattered light can be detected over angles that are greater than normally obtainable.
1. A system for detecting and identifying a particle in a liquid, the system comprising:
a target zone comprising a liquid medium, the particle carried into the target zone by the liquid medium;
a light source configured to generate a light beam and to direct the light beam through the target zone, the light beam incident at an angle such that the light beam is internally reflected by the interface of the liquid medium with the atmosphere after it has traveled through the target zone, thus eliminating the need for a beam stop to deflect the light beam after it has traveled through the target zone;
an optic configured to collect and reflect light scattered by a particle in the target zone; and
a 2-dimensional detector camera configured to detect the reflected light.
2. The system of claim 1 , wherein the 2-dimensional detector camera provides a frame rate from about 1000 frames per second to 10000 frames per second.
3. The system of claim 1 , wherein the 2-dimensional detector camera comprises a square array of photodiodes.
4. The system of claim 3 , wherein the square array of photodiodes comprises 256 active elements arranged in a 16×16 square grid.
5. The system of claim 4 , wherein each of the 256 active elements comprises a size of approximately 1.1 mm2.
6. The system of claim 5 , wherein the 256 active elements comprise a layout having about 1.5 mm center-to-center spacing between elements.
7. The system of claim 3 , wherein the 2-dimensional detector camera further comprises a signal conditioning and digitizing board connected to the array of photodiodes.
8. The system of claim 7 , wherein the board comprises a plurality of transimpedance amplifiers, wherein a plurality of photodiodes are connected to each transimpedance amplifier.
9. The system of claim 8 , wherein each of the pluralities of photodiodes are connected to their respective trans-impedance amplifier via a multiplexer.