US3850524A - Counter for condensation nuclei in air - Google Patents

Abstract

The condensation chamber of a recording counter for small airborne dust particles is first flushed with the air to be tested by drawing the air through inlet and discharge valves by a suction pump, the chamber is sealed, and its contents are saturated with moisture while being compressed isothermally in a ratio of 1:1.18 to 1.25. Upon subsequent adiabatic decompression through a suddenly opened valve of relatively large flow section, water droplets form on the nuclei provided by dust particles and are photographed so that they may be counted on the developed film. The apparatus is operated automatically in cycles at chosen intervals.

Description

United States Patent 91 Kanter [4 Nov. 26, 1974 COUNTER FOR CONDENSATION NUCLEI 27, No. 5, May 1956, pp. 273-7.

IN AIR Junge et al., Journal of Meteorol gy, Vol. 18, No. 1, [75] Inventor: Hans Joachim Kanter, February, 1961, pp. 81-108.

Garmisch-Partenkirchen, Germany [73] Assignee: Max-Planck-Gesellschaft zur Primary Examiner-Ronald L. Wibert Forderund der Wissenschaften e.v., Assistant ExaminerR. J. Webster Gottingen, Germany Attorney, Agent, or FirmHans Berman 22 Filed: Mar. 16, 1973 v 1 pp 341,989 [57 ABSTRACT The condensation chamber of a recording counter for [30] Foreign Apphcatlon Pnomy Data small air-borne dust particles is first flushed with the Mar. 24. 1972 Germany 2214463 air to be tested by drawing the air through inlet and discharge valves by a suction pump, the chamber is [52]- U-S. Cl 356/3 25 3, 356/103 sealed, and its contents are saturated with moisture [51] Int. Cl. ..G0lm1/00,G0lm 21/00. while being compressed isothermally in a ratio of [58] Field of Search 356/37, 103, 107, 108; 1:1.18 to 1.25. Upon subsequent adiabatic decompres- 8, 573-577 sion through a suddenly opened valve of relatively large flow section, water droplets form on the nuclei [56] References Cited provided by dust particles and are photographed so UNITED STATES PATENTS that they may be counted onthe developed film. The 3.756.720 9/1973 Skala 356/37 apparatus is Operated automatically in cycles at OTHER PUBLICATIONS Saunders, The Review of Scientific Instruments, Vol.

chosen intervals.

10 Claims, 7 Drawing Figures PROGRAMMING mm WQ' AL lfi 53 51. 3 1F 57 53 55 l l 1 r L g PUWER numn MUTUR V SUPPLY MElIHM STARTER 13 17 36 a -1. 7%,, that. W 151 7 1a 22 Ll] VALVE 55 2 CONTROLLER 21 cLncK 55 l SHEET 10F 4 EE 2 e :3. a W $258 3 a Z 5%; as: v 5 m3 E: 22:22:

PATEHTL T'T'ivzs m4 Fig.6

SHEET a or 4 sucnuu VALVE (m DECUMPRESSIUN 17 VALVE 1 FLASH TUBE CAMERA FLASH TUBE MIRRUR WATER VALVE cmnRuLT PISTON 5 MUTUR STARTER (5B) 4 mm VALVE (m T T T T T T T EH 9 LE EL-..

compression seconds t COUNTER FOR CONDENSATION NUCLEI IN AIR This invention relates to a counter for condensation nuclei in air, and particularly to a modification of the nuclei counter of John Aitken which permits automatic and periodic determination of submicroscopic condensation nuclei in air.

In a known modification of Aitkens original counter (J. of Meteorology 18 [1961] 81-108), a normally closed receiver is provided with a piston or plunger arranged for movement into and out of the receiver and for thereby changing the effective capacity of the receiver cavity, an inlet valve for admitting air to the receiver, a discharge valve for releasing the air, and a water supply system for saturating the air in the receiver with moisture. A camera is focused on a plane in the receiver cavity, and its field may be illuminated instantaneously by a flash of light to produce a photographic image. The nuclei are visible on the photographic record as images of spherical condensation droplets, and the diameters of the images increase by lack of sharpness with their distance from the plane of sharp delination toward or away from the objective lens system of the camera. The relationship between the size of the circles of confusion representing the droplets and the distance of the nuclei from the plane of sharp delineation is determined by calculation or by experimental calibration.

It has been proposed to operate the known apparatus automatically, but the known automatic operating arrangements have been found to be complex and correspondingly costly when reliable, and unsatisfactory in their reliability and precision if simple in their construction.

The primary object of the invention is the provision of an automatically operated nuclei counter satisfying requirements for high precision while being of sufficiently simple construction to operate reliably over extended periods of time without being attended.

The improved counter arrangement of the invention has a receiver additionally provided with a decompression valve leading directly into the ambient atmosphere for expansion of a tested air sample previously compressed in the receiver, a receptacle in the receiver communicating with a water supply line controlled by a valve in response to the water level in the receptacle, and with a programming mechanism which energizes the electrically operated parts of the counter arrangement in a timed cycle. The inlet and discharge valves are opened first and the piston or plunger is withdrawn from the receiver cavity for flushing the latter with ambient air drawn through the valves by suction, and the water level control device is energized. Thereafter the inlet and discharge valves are closed, thepiston or plunger is moved inward of the receiver for compressing the air sample, whereafter the decompression valve is opened for sudden expansion of the air sample, and ultimately the flash illuminator is energized while the camera shutter is open to produce a latent image on the photosensitive film or other material in the camera. The operating cycle is terminated by closing the decompression valve, and the apparatus is ready for the next cycle.

The submicroscopic condensation nuclei which are of interest are recorded selectively when the ratio of the effective capacities of the receiver capacity in the two terminal positions of the plunger or piston is between 1:l.18 and 111.25.

The nuclei are uniformly distributed in the receiver, and particularly in the portion of the receiver accessible for recording, when the receiver cavity has a cylindrical shape, and is bounded axially by the piston or plunger at one axial end and by an observation window for the camera at the other end, and when the orifices of the inlet and discharge valves are located in the receiver wall at diagonally opposite points of a plane parallel to the cavity axis.

It is not normally required to count condensation nuclei at intervals as short as the duration of one operating cycle, and the programming mechanism preferably includes an interval timer which starts respective operating cycles at intervals longer than one operating cycle and capable of being adjusted.

For reasons not yet fully explored, the photographic records obtained in tests repeated under identical conditions are most precisely reproduced if the piston or plunger moves inward of .the receiver during its compression stroke at a constant speed.

The apparatus of the invention has been found emi- 4 nently suitable for recording condensation nuclei having each a radius of 10' to 10 cm and being present in the atmosphere at a concentration of 200 to 600 nuclei per cubic centimeter. Such conditions are characteristic of pure air over the ocean or over the continents at altitudes above 3,000 meters. Because of its operating characteristics, the apparatus is well suited for unmanned exploration of the atmosphere. It is accurate enough to provide a reference standard for less sophisticated nuclei counters.

Other features, additional objects, and many of the attendant advantages of this invention will readily become apparent from the followingdetailed description of a preferred embodiment when considered in connection with the appended drawing in which:

FIG. 1 shows a counter arrangement of the invention in elevational section, electrical and optical devices being represented in a conventional manner;

FIG. 2 shows a portion of the arrangement of FIG. 1 on a larger scale and in greater detail in section on the line II-II in FIG. 3;

FIG. 3 shows a portion of the device of FIG. 2 in plan section;

FIG. 4 illustrates a part of the device of FIG. 3 on a further enlarged scale;

FIG. 5 diagrammatically illustrates the image recording process in the counter;

FIG. 6 is a timing diagram of the programming unit in the apparatus of FIG. 1; and

FIG. 7 shows an auxiliary device for use with the apparatus of FIG. 1 in a conventional manner.

Referring now to the drawing in detail, and initially to FIG. 1, there are seen a condensation chamber assembly l, a photographic recording unit 2, and a programming mechanism 3 which constitute the principal elements of the counter arrangement.

The condensation chamber assembly 1 includes a receiver 4 having a cylindrical cavity bounded in one axial direction by a piston 5 so that the effective capacity of the cavity may be decreased or increased by movement of the piston 5 into and out of the receiver 4. In the illustrated terminal position of the piston 5, the cavity capacity is at its maximum.

The piston may be pushed inward of the receptacle 4 and into its other, non-illustrated terminal position by a radial cam 7 which engages a cam follower roller 8 on the piston rod 6. A helical compression spring holds the cam follower 8 in engagement with the cam 7. The cam 7 is pivoted back and forth by a reversing gear motor 64 after the starter controls 58 for the motor 64 are energized by a programming unit 53 in the mechanism 3 which also includes an interval timer 54.

Three solenoid valves communicate with the cavity of the receiver 4, and are operated by the programming unit 53. A two-way inlet valve 13 normally directs air drawn from the ambient atmosphere through a by-pass conduit 15 to a suction pump 16 equipped with a builtin electric motor so that the valve 13 is swept free of deposited dust particles. When the solenoid of the valve 13 is energized by the programming unit 53, the valve 13 admits air from the atmosphere to the receiver 4. A normally closed discharge or suction valve 14, when operated by the unit 53, connects the receiver 4 directly to the suction pump 16. A normally closed decompression valve 17 having a flow section much greater than that of the valves 13, 14 permits the receiver cavity to be brought into direct communication with the ambient atmosphere for quick release of superatmospheric pressure.

Air in the receiver 4 may be saturated with moisture from a receptacle 18 in which the water level is sensed by a detector 22 connected to a controller 56 for a normally closed, solenoid-operated water valve 21. When the controller 56 is activated by the unit 53, and the detector 22 senses a water level below a set level in the receptacle 18, the valve 21 is opened to admit water from a water line, not shown in detail, to the receptacle 18, and the valve 21 closes the water line when the desired level is reached in the receptacle 18.

A portion of the cavity in the receiver 4 may be illuminated by means of a circular, electronic flashtube 26, and the illuminated cavity portion may be photographed by means of a camera 36 when a mirror 41 is tilted out of the field of the camera 36 by an electromagnetic tilting mechanism 63 controlled by the unit 53 in parallel circuit with the decompression valve 17 and with the power supply 57 of the flash tube 26 which includes a time delay circuit.

In the illustrated position, the mirror 41 reflects into the camera 36 an image of the dial on a clock 45 when the clock is illuminated by an electronic flash tube 65 whose non-illustrated power supply is connected to a flash terminal on the camera 36 in a manner not specifically shown, the camera being operated electrically from time to time by the programming unit 53. The film transport mechanism, not itself illustrated, in the camera 36 is electrically operated and provided with an emergency shut-off unit 51 connected to a temperature sensor 52. If the film jams the transport mechanism, the temperature in the motor of the latter rises, and the temperature increase is sensed by the sensor 52 which causes the shut-off unit 51 to open the energizing circuit of the electric motor in the film transport mechamsm.

As is better seen in FIGS. 2 and 3, a 120 portion of the cam face on the radial cam 7 spirals away from the axis of cam rotation in such a manner that the piston 5 is moved inward of the receiver 4 at a uniform linear speed when the shaft 7' of the cam 7 is moved at uniform angular velocity by the gear motor 64. The portions of the cam face merging with either end of the spiralling portion are circular about the axis of the shaft 7', and the piston stands still in its terminal positions while the cam follower 8 travels over the circular cam face portions during acceleration and deceleration of the motor 64. Two limit switches, obscured by the cam 7, are operated by an abutment on the shaft 7' in the terminal piston positions. When the piston 5 reaches the illustrated position, one limit switch reverses the motor 64 and opens a holding circuit in the starter 58, so as to stop the motor, and the other limit switch reverses the motor 64 in the non-illustrated piston position of minimum cavity volume.

For the convenience of manufacture, the receiver 4 consists of three flangedly connected, axial parts 12, 11, 1 l' which are coaxial, cylindrical tubes of the same diameter. The part 12 is closed by a radial end wall 9 in which the piston rod.6 is slidably sealed. An elongated, wide slot 19 in the bottom of the central receiver part 11 is closed in a radially outward direction by a shallow trough 20 welded to the outer face of the receiver 4 so that the slot 19 and the trough 20 jointly bound a receptacle 18, the valve 21 communicating with the bottom of the trough 20.

The flanges 29 which axially connect the receiver parts 11, 11' in axially spaced relationship provide an annular chamber in which the flash tube 26 is mounted. The chamber is sealed from the receiver cavity by a short, cylindrical glass tube 27 flush with the inner walls of the receiver parts 1 l, l 1'. The inner wall of the receiver part 11 is lined with a non-illustrated, black velvet which dips into the receptacle 18 and acts as a wick for humidifying air in the receiver. Openings in the velvet expose the orifice 13' of the valve 13 and the much greater orifice 17 of the valve 17.

The axial end of the receiver part 11' remote from the piston 5 is sealed by a radial glass plate 23 held in position by an annular cap 24. The light reaching the glass plate 23 from the flash tube 26 is limited to those rays which are deflected in a portion of the receiver cavity indicated by the broken line 25 by a stop arrangement 28 consisting of three centrally apertured plates 31, 32, 33 axially interposed between the cavity portion 25 and the glass plate 23.

The lens barrel 34 of the camera 36 is sealed into the central opening of the cap 24 and encloses the objective lens system 35 of the camera. The rear end of the barrel 34 is fixedly attached to one tubular part 38 of rigid bellows 37, the other tubular part 39 telescoping in the part 38 in light-tight engagement and being attached to the body 36' of the camera 36 for exposure of film 43 in the camera body which is that of a conventional, electrically operated 16 mm movie camera equipped for single-frame exposure by electric remote control, and for film advance after each exposure. The camera body, which may be a staple article of commerce, has not been illustrated in detail. It may be shifted toward and away from the barrel 34 in a conventional manner, not shown.

A side tube 44 projecting from the bellows tube 39 at right angles to the optical axis of the objective lens system 35, which coincides with the axis of the receiver 4, encloses another objective lens 42 and carries at its far end the electric clock 45 indicating the date, hour,

and minute on its non-illustrated dial. The afore-' described tiltable mirror 41 is arranged in the bellows 37 for either reflecting an image of the illuminated dial on the clock 45 or for permitting the recording of events in the cavity portion 25.

As is shown in even greater detail in FIG. 4, beveled annular edges 30 of the receiver parts 11, 11' project toward each other so as further to shield the camera 36 from stray light of the flash tube 26. Light reaching the glass plate 23 and transmitted thereby to the camera is limited to a circular area of diameter 46 in the center of the plate 23, and such light is deflected by particles in the cavity portion 25.

As is diagrammatically illustrated in FIG. 5, the objective lens system 35 is focussed on a plane 49, and a condensed water droplet formed on a speck of dust as a nucleus during decompression of the receiver cavity appears sharp on the film 43 after the latter is developed. The images of droplets in front or behind the plane 49 are larger, as is indicated by light rays represented by fully drawn and broken lines respectively. The diameter D of a circle 50 indicating a condensed droplet in planes 47, 48 located at a selected known distance from the plane 49 is readily calculated from the known parameters of the optical system. The number of nuclei in a volume of air axially bounded by the planes 47, 48 and radially bounded by a cylinder whose diameter may be derived from the diameter 46 is determined by counting on the developed film 43 all spots whose diameter is equal to or smaller than D. This volume of air occupies the portion 25 of the receiver cavity, so that this portion constitutes an optically defined test cell within the cavity. The test cell is located in the center of the area illuminated by the tube 26.

The manner in which a typical nuclei counter arrangement of the invention is automatically operated by the programming unit 53 is evident from the timing schedule of FIG. 6 which assumes an operating cycle of 60 seconds. The unit 53 may consist of a rotary, multiple-deck switch driven by a gear motor which is energized by the timer 54 for turning the rotary switch through one revolution, and by associated relays, as is conventional in itself.

At the time t =0, the piston 5 is in the non-illustrated position nearest the camera 36. When the motor of the programming unit 53 is started, and its relays are connected to a battery or the like, by the interval timer 54, the solenoids of the valves l3, 14 are energized to open the valve 14 and to connect the receiver cavity to the atmosphere through the valve 13, and the pump 16 is energized so that a stream of the ambient air to be tested is drawn through the receiver 4. After seconds from the start of the cycle, the motor 64 is started by its control 58, and the cam 7 starts turning toward the illustrated position, thereby permitting the spring 10 to withdraw the piston 5 towards the position shown in the drawing and thereby to increase the receiver capacity by a factor of 1.21:1. Shortly before the terminal position of the piston 5 is reached, at t sec., the water valve controller 56 is energized and opens the valve 21 to bring the water in the receptacle 18 to its prescribed level. If the water level were not set at this stage, the air volume in the receiver 4 after complete withdrawal of the piston 5 would not be precisely defined. The discharge valve 14 is closed at t 28 sec., and the valve controller 56 is simultaneously deenergized. Because the pump 16 maintained slightly subatmospheric pressure in the receiver 4 while the valve 14 was open, the valve 13 is closed only at t sec., when the air, in the receiver has reached atmospheric pressure.

Simultaneously, the piston 5 starts moving inward of the receiver 4 under the action of the cam 7 to compress the air sealed in the receiver cavity. The piston moves at uniform linear speed for 20 seconds during its compression stroke. The piston movement is slow enough and the heat capacity of thereceiver 4 suffi cient to keep the air temperature constant during compression. The sealed body of air is being saturated with moisture from the receptacle 18. At t 55 sec., the programming unit 53 opens the non-illustrated shutter of the camera 36, and the flash tube 65 is simultaneously energized by way of the synchronizing contact of the camera so as to illuminate the dial of the clock 45.

At t 55.5 sec., the programming unit 53 closes the energizing circuits of the mirror tilting mechanism 63, of the decompression valve 17, and of the power supply 57 for the flash tube 26. The mirror 41 is tilted out of the optical axis of the objective lens system 35, and the wide opening of the valve .17 causes sudden, and practically adiabatic, expansion of the air in the receiver 4. The air temperature drops, and the air becomes supersaturated with water. The submicroscopic nuclei accumulate respective, visible droplets of water.

Because of the delay circuit in the power source 57, the flash bulb 26 is energized only 0.4 seconds after the opening of the decompression valve, and the latent image of the droplets within the field of the objective lens system 35 is superimposed on the previously formed image of the clock 45. The film 43 is advanced in the camera body 36' by one frame.

At t 59 sec., the solenoid of the valve 17 is deenergized, and the valve is closed by its return spring. Simultaneously, the'mirror tilting mechanism 63 is deen-v ergized, letting the mirror 41 return to its starting position by gravity. The camera also is deenergized to close the shutter and thereby to advance the film 43 by one frame. At t 60 sec., the starting condition of the apparatus is restored, and the programming unit is ready to begin another cycle upon a signal from the interval timer 54, the latter being a rotary timing switch continuously operated at low speed.

In the counter arrangement whose operation has been described above with reference to FIG. 6, the axial boundaries of the portion 25 of the receiver cavity may be'selected for a testcell volume of about 0.15 to 0.3 cm. The objective lens system 35 is achromatic and has a resolution power of approximately 300 lines per millimeter, approximately equal to the resolution power of the photosensitive emulsion on the film 43. The glass of the window 23 absorbs all light of wavelengths for which the objective lens system 35 is not fully corrected, particularly ultraviolet radiation.

The apparatus described so far is capable of furnishing a readily evaluated photographic record of condensation nuclei up to a concentration of 2,000 per cubic centimeter. It is preferred, however, to dilute the tested air when the concentration of nuclei exceeds 1,200 per cm". A suitable diluting attachment 59 for the inlet valve 13 is shown in FIG. 7. It consists essentially of a dustfilter 61 and a throttle valve 62 connected to a mixing vessel 60, the intake ends of the filter 61 and the valve 62 being open to the ambient atmosphere, and the mixing vessel 60 being connected to the valve 13.

The suction of the pump 16 draws air into the mixing vessel 60 in either position of the valve 13 through the filter 61 and the valve 62 so that the ambient air entering through the valve 62 is diluted with air substantially completely stripped of nuclei by the filter 61. It is preferred to set the valve 62 for the same pressure drop under normal operation conditions as occurs in the filter 61.

When equipped with the diluting attachment of FIG. 7, the useful range of the counter arrangement is expanded substantially beyond 2,000 nuclei per cm. The lower useful counting limit is at aproximatly 20 nuclei per cm and far below the range of 200 to 600 condensation nuclei to be expected in pure air.

The structural features of the counting arrangement and the mode of operation described above by way of example permit selective counting of condensation nuclei having diameters between 10 to 4 10' cm which are of special interest to meteorologists. Nuclei constituted by small ions having radii smaller than 8 X 10 are not recorded, nor is the record falsified by larger particles. At the preferred compression or expansion ratio between 1: 1.18 and 121.25, only condensed droplets not produced by homogeneous condensation of water molecules are detected. As has been shown above, the counter arrangement of the invention permits operation under conditions in which the droplets cannot fall by gravity from the test cell 25 at the moment at which the photographic record is produced, and while they are still distributed in the test cell at random.

Such a distribution is initially produced by the fact that the orifices of the valves 13,14 in the receiver cavity are located in axially spaced portions of a plane parallel to the cavity axis, and are oppositely spaced from the axis, that is, diagonally spaced from each other in the rectangular plane. As is evident from FIG. 3, the plane preferably includes the cavity axis, and such an arrangement has been found to improve reproducibility of test results.

It should be understood, of course, that the foregoing disclosure relates only to a preferred embodiment of the invention, and that it is intended to cover all changes and modifications in the example of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

l. A counter arrangement for counting condensation nuclei in ambient air comprising, in combination:

a. a receiver bounding a cavity therein;

b. inlet valve means operable for admitting said air to said cavity when said valve means is open;

c. suction means for withdrawing admitted air from said cavity;.

(1. decompression valve means operable to be opened for directly connecting said cavity to said ambient air;

e. a piston member movable into and outward of said receiver between two terminal positions for decreasing and increasing the efi'ective capacity of said cavity;

f. saturating means for saturating said air in said cavity with moisture, said saturating means including a receptacle, and level control means operable for maintaining in said receptacle a constant level of water exposed to said cavity;

g. a camera focused on a portion of said cavity;

h. illuminating means operable for illuminating said portion of said cavity; and

i. programming means for cyclically operating said inlet valve means, said suction means, said decompression valve means, said piston member, said saturating means, and said illuminating means in timed sequence. 0

2. An arrangement as set forth in claim 1, wherein the effective flow section of said decompression valve means is substantially greater than the effective flow section of said inlet valve means.

3. An arrangement as set forth in claim 2, wherein said effective capacity of said cavity in said one terminal position of said piston member is 1.18 to 1.25 times the effective capacity of said cavity in said other terminal position of said piston member.

4. An arrangement as set forth in claim 2, wherein said cavity has an axis and is cylindrical about said axis, said cavity being bounded in one axial direction by said piston member, said receiver including a window bounding said cavity in the other axial direction, said camera being focussed on said portion through said window, said inlet valve means and said suction means communicating with said cavity through respective orifices in said receiver located in a common plane parallel to saidaxis and oppositely offset from said axis in respective portions of said plane axially spaced from each other.

5. An arrangement as set forth in claim 2, further comprising interval timing means operatively connected to said programming means for starting respective cycles of operation thereof at predetermined intervals.

6. An arrangement as set forth in claim 2, further comprising drive means operated in response to said programming means and operatively connected to said piston member for moving the same between said terminal positions thereof at uniform linear speed.

7. An arrangement as set forth in claim 2, further comprising stop means preventing light of said illuminating means from by-passing said portion of the cavity and directly entering said camera.

8. An arrangement as set forth in claim 2, further comprising a source of visible indicia, light deflecting means movable between two positions for alternatively directing light from said portion of said cavity and from said source to said camera, said programming means including means for moving said light deflecting means in timed sequence with said illuminating means for thereby deflecting light from said portion to said camera while said illuminating means are energized while deflecting light from said source to said camera when said illuminating means are not energized.

9. An arrangement as set forth in claim 2, further comprising diluting means for diluting said ambient air with a gas substantially free from said nuclei prior to the admitting of said air to said cavity by said inlet valve means.

10. An arrangement as set forth in claim 1, wherein said programming means include 1. means for opening said inlet valve means and actuating said suction means for flushing said cavity with said air,

2. means for moving said piston member after said opening of said inlet valve means outward of said receiver into one of said terminal positions, and for actuating said level control means,

3. means for deactivating said suction means and member,

closlng Sald f valve means after 531d outward 6. means for energizing said illuminating means after movmg of the Piston m m said opening of said decompression valve means, 4. means for moving said piston member inward of and said receiver into the other terminal position after Said closing of Said inlet valve means, 7. means for closing said decompression valve means 5. means for opening said decompression valve after Said energizingmeans after said inward moving of said piston UNETED STATES PATENT OFFICE I CERTIFLCATE @E CGRREQTWN Patent No. '8 Dated November w 1-974 iinventms) ms JOACHIM KAWER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, line {737, change Mam-Plenck sesellsehaft 2m:

Farrier-and. der Wissenschaften ecv. to

' Max Plenck-G esellsahaft zur Forderunq der Wissenschaften e.V.

Signed and sealed this 18th day of February 1975.

(SEAL) Attest: Ca MARSHALL DANN RUTH C. MASON I Commissioner of Patents Attesting Officer and Trademarks USCOMM-DC 60376-1 69 e vs. GOVERNMENT PRINTING OFFICE 1959 o-ase-ssa.

| FORM F'O-IOSO (10-69)

Claims (16)

1. A counter arrangement for counting condensation nuclei in ambient air comprising, in combination: a. a receiver bounding a cavity therein; b. inlet valve means operable for admitting said air to said cavity when said valve means is open; c. suction means for withdrawing admitted air from said cavity; d. decompression valve means operable to be opened for directly connecting said cavity to said ambient air; e. a piston member movable into and outward of said receiver between two terminal positions for decreasing and increasing the effective capacity of said cavity; f. saturating means for saturating said air in said cavity with moisture, said saturating means including a receptacle, and level control means operable for maintaining in said receptacle a constant level of water exposed to said cavity; g. a camera focused on a portion of said cavity; h. illuminating means operable for illuminating said portion of said cavity; and i. programming means for cyclically operating said inlet valve means, said suction means, said decompression valve means, said piston member, said saturating means, and said illuminating means in timed sequence.

2. means for moving said piston member after said opening of said inlet valve means outward of said receiver into one of said terminal positions, and for actuating said level control means,

2. An arrangement as set forth in claim 1, wherein the effective flow section of said decompression valve means is substantially greater than the effective flow section of said inlet valve means.

3. An arrangement as set forth in claim 2, wherein said effective capacity of said cavity in said one terminal position of said piston member is 1.18 to 1.25 times the effective capacity of said cavity in said other terminal position of said piston member.

3. means for deactivating said suction means and closing said inlet valve means after said outward moving of the piston member,

4. means for moving said piston member inward of said receiver into the other terminal position after said closing of said inlet valve means,

4. An arrangement as set forth in claim 2, wherein said cavity has an axis and is cylindrical about said axis, said cavity being bounded in one axial direction by said piston member, said receiver including a window bounding said cavity in the other axial direction, said camera being focussed on said portion through said window, said inlet valve means and said suction means communicating with said cavity through respective orifices in said receiver located in a common plane parallel to said axis and oppositely offset from said axis in respective portions of said plane axially spaced from each other.

5. An arrangement as set forth in claim 2, further comprising interval timing means operatively connected to said programming means for starting respective cycles of operation thereof at predetermined intervals.

5. means for opening said decompression valve means after said inward moving of said piston member,

6. means for energizing said illuminating means after said opening of said decompression valve means, and

6. An arrangement as set forth in claim 2, further comprising drive means operated in response to said programming means and operatively connected to said piston member for moving the same between said terminal positions thereof at uniform linear speed.

7. An arrangement as set forth in claim 2, further comprising stop means preventing light of said illuminating means from by-passing said portion of the cavity and directly entering said camera.

7. means for closing said decompression valve means after said energizing.

8. An arrangement as set forth in claim 2, further comprising a source of visible indicia, light deflecting means movable between two positions for alternatively directing light from said portion of said cavity aNd from said source to said camera, said programming means including means for moving said light deflecting means in timed sequence with said illuminating means for thereby deflecting light from said portion to said camera while said illuminating means are energized while deflecting light from said source to said camera when said illuminating means are not energized.

9. An arrangement as set forth in claim 2, further comprising diluting means for diluting said ambient air with a gas substantially free from said nuclei prior to the admitting of said air to said cavity by said inlet valve means.

10. An arrangement as set forth in claim 1, wherein said programming means include

Images