You searched for: “aeroscloscope
aeroscope, aeroscloscope (s) (noun); aeroscopes; aeroscloscopes (pl)
An apparatus for gathering bacteria, dust, etc. from the air: An auroscope is a device which is used for microscopic examination after collecting bacteria from the air.

An auroscope is an instrument, usually electronic, used to count microscopic dust and other suspended matter in the air for purposes of analysis.

The differences in intensity of the light reflected from each particle facilitates the identification of the pieces of dust.