公开(公告)号：US20200064249A1

公开(公告)日：2020-02-27

申请号：US16547466

申请日：2019-08-21

Applicant: Apple Inc.

Inventor： Omid MOMTAHAN ,  Mehmet Mutlu ,  Miaolei Yan ,  Richard Yeh

IPC: G01N15/02 ,  G01N15/14

Abstract: An apparatus for particulate matter (PM) measurement includes a first light source to generate a first light beam and a second light source disposed at a first distance from the first light source to generate a second light beam in parallel to the first light beam to illuminate a PM. The apparatus further includes a first light detector to measure a first timing corresponding to a first self-mixing signal resulting from a reflection and/or back-scattering of the first light beam from a PM, and a second light detector to measure a second timing corresponding to a second self-mixing signal resulting from a reflection and/or back-scattering of the second light beam from the PM. A processor can determine a first velocity of the PM based on a spatial separation between centers of the first light beam and the second light beam and a temporal separation between the first timing and the second timing.