1991 Fiscal Year Final Research Report Summary
Laser Holographic Observation of Submicron Particles
| Project/Area Number |
02650031
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理計測・光学
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| Research Institution | Kobe Design University (1991)
Kyushu University (1990) |
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Principal Investigator |
MURAKAMI Terutoshi Kobe Design University, Faculty of Design, Professor, 芸術工学部, 教授 (70037696)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAYAMA Kunihito Kyushu University, Faculty of Engineering, Professor, 工学部, 助教授 (20040446)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Sub-micron Particle / Holography Measurement / Laser Diagnostics / Aerosol / Hologram of Small Particle |
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| Research Abstract |
The purpose of this research is to find the spacial distribution of sub-micron particles dispersed in atmosphere. For this aim, a new Laser holographic recording method has been developed.
When the Particle size is comparable with or less than the wave length, it is difficult to obtain the inline hologram of the particle by the conventional method. By the computer simulation based on the Hie theory, we have found that the difficulty is caused by weakness of scattered light by such a small object, and that the object light may be buried in a reference light. If the strongly focused light is used to irradiate the particles at right angle to the reference beam, the side scattered light of comparable intensity with the reference light can be obtained on the photo plate, and the hologram is recorded.
The experiment has been done by using a ruby laser for smoke of a stick of incense or the dioctyl phthalate (DOP) aerosol. The Particle sizes of smoke and DOP aerosol were estimated by means of size classification using the Andersen particle sampler. It was confirmed that the size of 98 percent particles on the number is under 0.7mum, and that the new method is usefull to record the hologram of submicron particles. The three dimensional depth from the recording plane has been detemined by optical reconstruction of the hologram. The size of each particle could not be determined by the reconstruction.
From the computer simulation, it is seen that the hologram of good visibility is obtained under the proper intensity ratio of tlie irradiation to the reference light, and that the ratio depends sharply on the particle size.
After this, we would develop a new method to detemine tlie particle diameter from the analysis of above relation.
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