High resolution surface particle detector
A particle counting device includes a scanner probe having a first opening for receiving particles from a sample surface and second openings. Pumps produce a first airstream flowing from the first opening and a second airstream flowing to the second openings. A flow device splits the first airstream into third and fourth airstreams. A first particle detector detects particles in the third airstream. The first particle detector is capable of detecting particles within a first range of particle sizes. A second particle detector detects particles in the fourth airstream. The second particle detector is capable of detecting particles within a second range of particle sizes different from the first range of particle sizes. Control circuitry controls the flow device and the pumps to provide a first flow rate of the third airstream and a second flow rate of the fourth airstream that is larger than the first flow rate.
1. A device for counting particles on a sample surface, comprising:
a scanner probe having a first opening for receiving particles from a sample surface and one or more second openings;
one or more pumps for producing a first airstream flowing from the first opening and a second airstream flowing to the one or more second openings;
a flow device for splitting the first airstream into a third airstream and a fourth airstream;
a first particle detector for receiving and detecting particles in the third airstream, wherein the first particle detector is capable of detecting particles within a first range of particle sizes;
a second particle detector for receiving and detecting particles in the fourth airstream, wherein the second particle detector is capable of detecting particles within a second range of particle sizes which is different from the first range of particle sizes;
a control circuitry for controlling the flow device and the one or more pumps to provide a first flow rate of the third airstream and a second flow rate of the fourth airstream, wherein the first flow rate is smaller than the second flow rate;
a first sensor for measuring the first flow rate; and
a second sensor for measuring the second flow rate;
wherein the control circuitry controls the flow device based on measured first and second flow rates by the first and second sensors.
2. The device of claim 1 , further comprising:
a second flow device for adding air from an air source to the fourth airstream to form the second airstream.
3. The device of claim 2 , further comprising:
a filter for filtering particles from the second airstream.
4. A device for counting particles on a sample surface, comprising:
a scanner probe having a first opening for receiving particles from a sample surface and one or more second openings;
one or more pumps for producing a first airstream flowing from the first opening and a second airstream flowing to the one or more second openings;
a flow device for splitting the first airstream into a third airstream and a fourth airstream;
a first particle detector for receiving and detecting particles in the third airstream, wherein the first particle detector is capable of detecting particles within a first range of particle sizes;
a second particle detector for receiving and detecting particles in the fourth airstream, wherein the second particle detector is capable of detecting particles within a second range of particle sizes which is different from the first range of particle sizes;
a control circuitry for controlling the flow device and the one or more pumps to provide a first flow rate of the third airstream and a second flow rate of the fourth airstream, wherein the first flow rate is smaller than the second flow rate;
wherein the control circuitry determines a total particle count by:
determining a corrected particle count for the first detector by multiplying a particle count from the first particle detector by a ratio of a third flow rate of the first airstream over the first flow rate;
determining a corrected particle count for the second detector by multiplying a particle count from the second particle detector by a ratio of the third flow rate over the second flow rate; and
adding the corrected particle count for the first detector and the corrected particle count for the second detector.
5. The device of claim 1 , wherein the first and second particle detectors and the one or more pumps are disposed in a housing, and wherein the device further comprises:
a first tube extending between the housing and the scanner probe for conveying the first airstream; and
a second tube extending between the housing and the scanner probe for conveying the second airstream.
6. The device of claim 5 , further comprising:
a modulator for modulating a flow rate of the second airstream.
7. The device of claim 6 , wherein the modulator is disposed in the housing.
8. The device of claim 6 , wherein the modulator is disposed in the scanner probe.
9. The device of claim 6 , wherein the modulator modulates the flow rate of the second airstream at a fixed frequency.
10. The device of claim 6 , wherein the modulator modulates the flow rate of the second airstream at a frequency that varies over time.
11. A device for counting particles on a sample surface, comprising:
a scanner probe having a first opening for receiving particles from a sample surface and one or more second openings;
one or more pumps for producing a first airstream flowing from the first opening and a second airstream flowing to the one or more second openings;
a flow device for splitting the first airstream into a third airstream and a fourth airstream;
a particle detector for receiving and detecting particles in the third airstream;
a control circuitry for controlling the flow device and the one or more pumps to provide a first flow rate of the third airstream and a second flow rate of the fourth airstream, wherein the first flow rate is smaller than the second flow rate;
a first sensor for measuring the first flow rate; and
a second sensor for measuring the second flow rate;
wherein the control circuitry controls the flow device based on measured first and second flow rates by the first and second sensors.
12. The device of claim 11 , further comprising:
a second flow device for adding air from an air source to the fourth airstream to form the second airstream.
13. The device of claim 12 , further comprising:
a filter for filtering particles from the second airstream.
14. The device of claim 11 , wherein the particle detector and the one or more pumps are disposed in a housing, and wherein the device further comprises:
a first tube extending between the housing and the scanner probe for conveying the first airstream; and
a second tube extending between the housing and the scanner probe for conveying the second airstream.
15. The device of claim 14 , further comprising:
a modulator for modulating a flow rate of the second airstream.
16. The device of claim 15 , wherein the modulator is disposed in the housing.
17. The device of claim 15 , wherein the modulator is disposed in the scanner probe.
18. The device of claim 15 , wherein the modulator modulates the flow rate of the second airstream at a fixed frequency.
19. The device of claim 15 , wherein the modulator modulates the flow rate of the second airstream at a frequency that varies over time.