Abstract: A portable ambient air quality monitor having an enclosure to enclose and protect the monitor from an ambient environment and an airflow intake for controllably allowing ambient air to enter the monitor. A photodiode is disposed at a location downstream from a fan. The airflow from the fan is laminarized by a mesh or baffle to allow a thin stream of air to flow over the photodiode. A sensing region is defined by an intersection of an airflow sampling path and an optical path. The sensing region is also disposed above the photodiode. The airflow sampling path is configured to receive laminar airflow from the airflow intake and for directing the laminar airflow into the sensing region. A light beam is generated from a laser to reflect the light beam for reducing the required area of the sensing region to detect and measure the particles floating in the ambient air.

Abstract: A portable ambient air quality monitor having an enclosure to enclose and protect the monitor from an ambient environment and an airflow intake for controllably allowing ambient air to enter the monitor. A photodiode is disposed at a location downstream from a fan. The airflow from the fan is laminarized by a mesh or baffle to allow a thin stream of air to flow over the photodiode. A sensing region is defined by an intersection of an airflow sampling path and an optical path. The sensing region is also disposed above the photodiode. The airflow sampling path is configured to receive laminar airflow from the airflow intake and for directing the laminar airflow into the sensing region. A light beam is generated from a laser to reflect the light beam for reducing the required area of the sensing region to detect and measure the particles floating in the ambient air.