Radiant energy – Electrically neutral molecular or atomic beam devices and...
Patent
1994-08-30
1997-11-18
Porta, David P.
Radiant energy
Electrically neutral molecular or atomic beam devices and...
359350, H05H 304
Patent
active
056891091
DESCRIPTION:
BRIEF SUMMARY
The invention relates to apparatus for the manipulation, processing and observation of small particles, in particular biological particles, comprising at least one first laser, which generates light beams in a first wavelength region that are focused by a first optical device with sufficient convergence to form an optical trap in a given region; an object holder to contain particles, in particular biological particles; a light source for observation light; and observation and recording devices with which to observe the particles in the object holder and record their behavior.
The invention further relates to a method for the manipulation, processing and observation of small particles, in particular biological particles, in which the objects in an object holder are fixed in an optical trap by at least one first laser, which generates light beams in a first wavelength range, and the objects are observed and/or their behavior recorded with observation and recording devices.
Apparatus of this kind is known, for example, from U.S. Pat. No. 4,893,886, which employs a so-called optical trap that uses a strongly focused laser beam with an intensity profile having an approximately Gaussian distribution. In these optical traps the components of radiation pressure, namely scattering force and gradient force, are combined with one another to form a point of stable equilibrium situated close to the focus of the laser beam. Here the scattering force is proportional to the optical intensity and acts in the direction of the incident laser light. The gradient force is proportional to the optical intensity and points in the direction of the intensity gradient.
Details of such optical traps and their physical bases are given, for example, in the publication "Optical Trapping and Manipulation of Single Living Cells Using Infra-Red Laser Beams", A. Ashkin et al. in BERICHTE DER BUNSEN-GESELLSCHAFT FOR PHYSIKALISCHE CHEMIE, March 1989, pp. 254-260.
Apparatus of this kind can be used to capture, fix and manipulate small particles, in particular biological particles, which can otherwise move freely in a fluid within the object holder. One difficulty that arises here is that of simultaneously observing the particles as they are being manipulated in order to enable precise processing.
The invention is therefore directed to the problem of providing an apparatus and a method by which well-directed and exact manipulation, processing and observation of small particles, in particular biological particles, can be achieved.
Thus, in accordance with the present invention there is provided an apparatus of the kind mentioned at the outset characterised in that of at least one second laser is provided, which generates light beams in a second wavelength range that are focused by a second optical device with sufficient convergence to manipulate particles present in the region of the object holder; in that the optical devices for the light beams in the first wavelength range, for the light beams in the second wavelength range and for the beams of the observation light are each separate and can be positioned and focused independently of one another; and in that the light beams in the first wavelength range, the light beams in the second wavelength range and the beams of the observation light are focused in the same object plane of the object holder at the beginning of the manipulation and observation, regardless of their wavelengths.
As a further development of the apparatus in accordance with the invention, it is provided that each of the first lasers is of an adjustable-wavelength type as appropriate, in particular an IR laser, and that each of the second lasers is an adjustable-wavelength UV laser as appropriate, in particular a pulsed UV laser. By this means the particles can be fixed suitably for practical purposes while the actual manipulation is performed with the UV laser, with no danger that excessive amounts of energy will be applied, which could otherwise cause undesirable damage to the particles.
According to a special embodiment of t
REFERENCES:
patent: 4893886 (1990-01-01), Ashkin et al.
Steubing et al., SPIE, vol. 1202, 272-280 (1990).
Ashkin et al., NATURE, vol. 330, 769-771 (1987).
Ashkin et al., Ber. Bunsenges. Phys. Chem., 254-260 (1989).
Hanig Richard
Linek Ernest V.
Porta David P.
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