Radiant energy – Invisible radiant energy responsive electric signalling – Ultraviolet light responsive means
Patent
1995-02-13
1996-07-16
Fields, Carolyn E.
Radiant energy
Invisible radiant energy responsive electric signalling
Ultraviolet light responsive means
2503581, 356 30, G01N 2187
Patent
active
055369430
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus for examining objects by irradiating them with radiation and analyzing the transmitted or emitted radiation. The invention also relates to a method and apparatus for classifying diamonds.
Normally, apparatus for examining objects using radiation comprises a source, which may be a laser of a particular wavelength or a broad-band illuminator such as a tungsten lamp, means for controllably exposing the object to the radiation and means for collecting radiation transmitted or emitted by the object. The transmitted or emitted radiation may be filtered to exclude the illuminating wavelength or to transmit a single wavelength of interest, the radiation passed by the filter being passed to a detector.
Such an apparatus may be used for examining diamonds, the information obtained depending on the wavelength of radiation studied.
It is desired to provide a method and apparatus for examining objects in which the intensity of the irradiating radiation may be measured, the path for measuring the irradiating radiation being as similar as possible to the path of the radiation to the object. Furthermore, it is desired to minimize the number of parts required and to simplify the apparatus generally.
THE INVENTION
The first aspect of the invention provides apparatus for and a method of examining an object. The method and apparatus of the first aspect of the invention allow the intensity of radiation used to irradiate the object to be detected. Accordingly, temperature variations or other variations in the spectrum of the radiation source can be allowed for when interpreting the results. The apparatus can be small and simple. The same reflective member is used in the path of radiation from the sample to the detector and the source to the detector.
In the second position of the reflective member, a signal can be produced dependent upon the intensity of light which is reflected by the object, transmitted by the object, reflected through the object or emitted by the object by luminescence.
The radiation path from the source to the reflective member, from the reflective member to the object or from the reflective member to the detector is preferably as simple as possible, involving the smallest number of optical elements, to reduce the amount of radiation lost at each optical element. However, any radiation path may be used and may comprise a plurality of reflective devices. The reflective member may comprise a plurality of components but the change from the first position to the second position is achieved in this case substantially by changing the position of the reflective member as a whole or as a unit.
For simplicity, only one reflective member should be used. This is possible, because the apparatus can be set up such that radiation directed to the object and (a portion of) the radiation emanating from the object intersect the same reflective member. Preferably, the path of irradiating radiation is coincident with the path of radiation emanating from the object which intersects the reflective member. In this case, a beam splitter may be used to direct light to the detector.
Using the beam splitter allows the apparatus to be set up very simply, as it uses the principle of reversability of light. Whatever path the irradiating radiation takes (reflected back by the reflective member or reflected onto the sample), reflected radiation must be able to travel back along the path of the irradiating radiation. It will then be interrupted by the beam splitter and so directed to the detector.
The beam splitter is preferably placed before the reflective member in the path of radiation coming from a source, the radiation coming from the source not being directed to the detector by the beam splitter. In this configuration, the first position of the reflective member may correspond to the reflective member being normal to the direction of radiation from the source so that the radiation is reflected back onto the beam splitter which will then deflect the beam
REFERENCES:
patent: 4236076 (1980-11-01), Judge et al.
patent: 4291975 (1981-09-01), Raccah
patent: 4394580 (1983-07-01), Gielissa
patent: 4511800 (1985-04-01), Harbeke et al.
patent: 4578762 (1986-03-01), Wong
patent: 5028800 (1991-07-01), Wulf et al.
Extract from GEM Testing (Tenth Edition) by B. W. Anderson and E. J. Jobbins, Preface and pp. 96-97, 124-125, and 202-205.
Smith Martin P.
Welbourn Christopher M.
Fields Carolyn E.
Gersan Establishment
Glick Edward J.
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