Sensing a narrow frequency band of radiation and gemstones

Apparatus for examining a large number of objects distributed over an area or for examining an article in association with means for irradiating a line across the objects or article, the apparatus comprising viewing means for viewing all or an extended part of said line and sensing a narrow frequency band of radiation emitted by specific objects or zones of the article on excitation by radiation irradiated by said irradiating means, the viewing means comprising:

• narrow band pass filter means which, within a specific angle of incidence, substantially filter out all but said narrow frequency band;
• collection means which allow to pass through the filter means both rays which are within said angle of incidence and rays which are outside said angle of incidence;
• and
• means for stopping any rays which have passed through the filter means outside said specific angle of incidence.

A method of identifying specific discrete objects or specific zones of an article, comprising:

• projecting exciting radiation to strike the objects or article along an extended line;
• viewing all the line or an extended part thereof using collection means which extends substantially parallel to the line, radiation from each part of the line, as seen looking at 90.degree. to the line, passing through narrow band pass filter means which, within a specific angle of incidence, passes substantially only radiation of a narrow frequency band;
• stopping radiation which has passed through the filter means outside said angle of incidence;
• and
• sensing radiation which has passed through the filter means within said angle of incidence to identify the specific objects or zones which emit a frequency within said narrow band.

A method of sorting diamonds or other specific luminescing minerals from ore particles over a wide feed path, the method comprising:

• irradiating a line across said feed path in order to excite luminescence in the diamonds or luminescing minerals;
• detecting luminescence emitted from a said diamond or luminescing mineral using detecting means responsive to luminescence emitted by a diamond or a said other luminescing material anywhere on said line or on an extended part thereof, and responsive to the location from which the luminescence is emitted;
• and
• scanning the response of the detecting means and thereby identifying the location of diamond or luminescing mineral from the position of the scan at the instant of detection of the emitted luminescence.

Monitoring means for an apparatus for performing an examination and which includes scanning means for scanning incident radiation along a line, the monitoring means comprising:

• a first zone on said line, which first zone emits radiation when it receives the incident radiation;
• a second zone on said line which second zone absorbs at least a large proportion of the incident radiation and emits at the most little radiation, at least in a predetermined frequency band, when it receives the incident radiation;
• and
• sensing means for sensing radiation emitted from the first zone and from the second zone, and giving a signal when the radiation sensed from either zone differs from predetermined values.

A method of identifying specific discrete objects or specific zones of an article, comprising:

• projecting exciting radiation to strike the objects or the article along an extended line;
• collecting radiation emitted by the objects or the zones along all said line or an extended part thereof;
• forming the collected radiation into generally parallel rays;
• passing the generally parallel rays through narrow band pass filter means for filtering the generally parallel rays and allowing only radiation of a selected frequency to pass;
• sensing the selected frequency radiation which has passed through the filter means;
• and
• indicating the specific objects or zones which emit the selected frequency radiation.

A method of identifying specific objects or zones which respond to an exciting radiation by emitting at least two luminescences, namely a weaker luminescence which is more characteristic of the specific object or zone to be identified, and a stronger luminescence which is less characteristic of the object or zone to be identified, the method comprising:

• subjecting a plurality of the objects or zones to the exciting radiation;
• detecting the weaker luminescence to indicate the presence of a specific object or zone to be identified;
• detecting the stronger luminescence,
• and identifying the location from which the stronger luminescence was emitted and hence the location of the specific object or zone to be identified.

Apparatus for identifying specific objects or zones, which respond to an exciting radiation by emitting at least two luminescences, namely a weaker luminescence which is more characteristic of the specific object or zone to be identified, and a stronger luminescence which is less characteristic of the object or zone to be identified, the apparatus to be used in association with means for subjecting a plurality of objects or zones to the exciting radiation, the apparatus comprising:

• first means for detecting the weaker luminescence to indicate the presence of a specific object or zone to be identified;
• second means for detecting the stronger luminescence and identifying the location from which the stronger luminescence was emitted and hence the location of the specific object or zone to be identified;
• and
• means for giving a signal when the first and second detecting means detect at the same instant.

A method of identifying objects or zones of an article, comprising:

• projecting modulated incident radiation to strike the objects or zones along an extended line, which radiation will cause radiation to be emitted by the objects or zones to be identified, the modulation frequency of the incident radiation changing along the line;
• sensing the emitted radiation;
• and
• using the frequency of the emitted radiation to identify the position from which the radiation has been emitted.

A method of identifying specific objects or zones which respond to an exciting radiation by emitting luminescence, the method comprising:

• subjecting a plurality of the objects or zones to the exciting radiation;
• detecting emitted luminescence using a detecting means in which the response is located in dependence on the location of the object or zone emitting the luminescence;
• scanning the response of the detecting means, the location from which the luminescence was emitted being determined from the position of the scan at the instant of detection of the emitted luminescence;
• providing monitoring means adjacent said objects or zones which monitoring means are fixed in relation to said detecting means, and which monitoring means emit luminescence in response to said exciting radiation;
• detecting the latter said luminescence by said detecting means;
• and
• giving a signal if said latter luminescence changes substantially.

Apparatus for identifying specific objects or zones which response to an exciting radiation by emitting luminescence, for use in association with means for subjecting a plurality of the objects or zones to the exciting radiation, the apparatus comprising:

• detecting means for detecting emitted luminescence, the response being located in the detecting means according to the position of the object of zone emitting the luminescence;
• means for scanning the response of the detecting means;
• means for determining from the position of the scan at the instant of detection of the emitted luminescence, the location of a specific object or zone to be identified;
• monitoring means illuminated by said exciting radiation and fixed in relation to said detecting means, which monitoring means emit luminescence in response to said exciting radiation, which latter said luminescence is detected by said detecting means;
• and p1 means for giving a signal if said latter luminescence changes substantially, to thereby give said signal when overall performance of said apparatus changes.

A method of identifying among ore particles diamonds or other specific luminescing minerals which respond to an exciting radiation by emitting luminescence, comprising:

• subjecting the ore particles to said exciting radiation;
• detecting luminescence emitted from a zone at a first time due to excitement by said exciting radiation;
• detecting luminescence emitted from said zone a at second time after the first time due to excitement by said exciting radiation;
• and
• sensing any difference in the emitted luminescence at the two times to thereby identify ore particles which provide said difference and hence identify diamonds or other specific luminescing particles among the ore particles.

Apparatus for sorting diamonds or other specific luminescing minerals from a large number of ore particles distributed over a wide feed path, the apparatus comprising:

• means for conveying the ore particles along a wide feed path;
• means for irradiating a line across the feed path in order to excite Raman emission from the diamonds or specific luminescing minerals;
• collection means into which will pass emission from the ore particles, the collection means providing an aperture having an f number of one or less in the view looking across the feed path;
• a narrow band pass filter arrangement arranged to filter out all of the emission from the ore particles except said Raman emission and such broad band luminescence as has frequencies in said narrow band;
• sensing means for giving a signal responsive to the emission which has passed through the filter arrangement;
• means for subtracting from said signal the effect of said broad band luminescence which has frequencies in said narrow band, thereby providing a signal indicating the presence of the diamond or specific mineral;
• means responsive to the location from which the Raman emission is emitted, for identifying the location of the diamond or specific mineral;
• and
• sorting means responsive to said location responsive means for separating the diamond or specific mineral from the other ore particles.

A method of sorting diamonds or other specific luminescing minerals from a large number of ore particles distributed over a wide feed path, the method comprising:

• converting the ore particles along the wide feed path;
• irradiating a line across the feed path in order to excite Raman emission from the diamonds or specific luminescence minerals;
• collecting emission from the ore particles using collection means providing an aperture having an f number of one or less in the view looking across the feed path;
• using a narrow band pass filter arrangement to filter out all emission from the ore particles except said Raman emission and such broad band luminescence as has frequencies in said narrow band;
• giving a signal responsive to the emission which passes through the filter arrangement;
• subtracting from said signal the effect of said broad band luminescence which has frequencies in said narrow band;
• sensing the presence of the diamond or specific mineral;
• identifying the location of the diamond or specific mineral;
• and
• responsive to the identification of the location of the diamond or specific mineral, separating the diamond or specific mineral from the other ore particles.