Radially homogeneous high energy density UV sample ablating laser radiation in "pure" solid to gas sample preparation , for analysis by ICP-MS and ICP-OES

A laser ablation system for analyzing sample system material comprising in any functional order:

• a 200-380 nm UV wavelength laser source which is capable of providing pulse(s) or CW electromagnetic radiation (LS);
• beam expanding means (BE);
• beam collimating means (BC);
• beam homogenizing means (H);
• beam condenser means (C);
• aperture means (A);
• optionally beam directing mean (BDM);
• beam demagnifying means (BDM);
• means for supporting a sample system;
• and
• a plasma based analysis system;
• said beam homogenizing means comprising a system comprising at least one beam splitting means and at least one Gaussian profile inverting optic and at least one beam recombining means, such that electromagnetic radiation entering thereinto is caused to interact with said at least one beam splitting means, with approximately half of said electomagnetic radiation being caused thereby to pass through said at least one Gaussian profile inverter and subsequently be re-combined with the other approximately half of electromagnetic radiation which does not pass through said at least one Gaussian profile inverter, by said at least one beam recombining means;
• such that in use said UV wavelength laser source provides electromagnetic radiation which, in radial cross-section, presents with an essentially Gaussian radial energy distribution;
• and
• said electromagnetic radiation being expanded by said beam expander;
• and
• said beam collimating means collimates said expanded electromagnetic radiation;
• and
• said collimated electromagnetic radiation being caused to pass through said beam homogenizing means and emerge as essentially constant radial energy distribution electromagnetic radiation;
• and
• said essentially constant radial energy distribution electromagnetic radiation being caused to converge by said condenser;
• and
• pass through said aperture;
• and
• be directed to impinge on a sample system placed on said means for supporting a sample system, said electromagnetic radiation substantially homegeneously providing at least 30 J/cm2 over an area with a cross sectional diameter of at least 40 microns, thereby causing ablation of sample system material substantially by an optically induced direct solid-to-gas laser ablation mechanism;
• at least some of said ablated sample system material being caused to enter said plasma based analysis system wherein it is analyzed.

A laser ablation system for analyzing sample system material comprising in any functional order:

• a 200 nm or greater UV wavelength laser source which is capable of providing pulse(s) or CW electromagnetic radiation (LS);
• beam homogenizing means (H);
• means for supporting a sample system;
• and
• a system selected from the group consisting of:
• an (ICP-OES) optical emission system,
• an (ICP-MS) mass spectrometer system,
• a (MIP-OES) optical emission system, and
• a (MIP-MS) mass spectrometer system;
• said beam homogenizing means being comprised of at least one multifaceted “fly's eye” array optic which comprises a multiplicity of essentially evenly spatially distributed effective optical lenses or facets;
• such that in use said 200 nm or greater UV wavelength laser source provides electromagnetic radiation);
• and
• said electromagnetic radiation is caused to pass through said beam homogenizing means;
• and
• be directed to impinge on a sample system placed on said means for supporting a sample system, thereby causing ablation of sample system material substantially by an optically induced direct solid-to-gas laser ablation mechanism;
• at least some of said ablated sample system material being caused to enter said system selected from the group consisting of:
• an (ICP-OES) optical emission system,
• an (ICP-MS) mass spectrometer system,
• a (MIP-OES) optical emission system, and
• a (MIP-MS) mass spectrometer system;
• wherein it is analyzed.

A laser ablation system for analyzing sample system material comprising in any functional order:

• a 200 nm or greater UV wavelength laser source which is capable of providing pulse(s) or CW electromagnetic radiation (LS);
• beam homogenizing means (H);
• means for supporting a sample system;
• and
• a system selected from the group consisting of:
• an (ICP-OES) optical emission system,
• an (ICP-MS) mass spectrometer system,
• a (MIP-OES) optical emission system, and
• a (MIP-MS) mass spectrometer system;
• said beam homogenizing means comprising a system comprising at least one beam splitting means and at least one Gaussian profile inverting optic and at least one beam recombining means, such that electromagnetic radiation entering thereinto is caused to interact with said at least one beam splinting means, with approximately half of said electromagnetic radiation being caused thereby to pass through said at least one Gaussian profile inverter and subsequently be re-combined with the other approximately half of electromagnetic radiation which does not pass through said at least one Gaussian profile inverter, by said at least one beam recombining means;
• such that in use said 200 nm or greater UV wavelength laser source provides electromagnetic radiation;
• and
• said collimated electromagnetic radiation is caused to pass through said beam homogenizing means and emerge as essentially constant radial energy distribution electromagnetic radiation;
• and
• be directed to impinge on a sample system placed on said means for supporting a sample system, said electromagentic radiation substantially homogensously providing at least 30 J/cm2 over an area with a cross sectional diameter of at least 40 microns, thereby causing ablation of sample system material substantially by an optically induced direct solid-to-gas laser ablation mechanism;
• at least some of said ablated sample system material being caused to enter said system selected from the group consisting of:
• an (ICP-OES) optical emission system,
• an (ICP-MS) mass spectrometer system,
• a (MIP-OES) optical emission system, and
• a (MIP-MS) mass spectrometer system;
• wherein it is analyzed.

A laser ablation system for analyzing sample system material comprising in any functional order:

• a 200 nm or greater UV wavelength laser source which is capable of providing pulse(s) or CW electromagnetic radiation (LS);
• and at least one beam homogenizing means (H) selected from the group consisting of:
• a multimode laser head and a near field aperture located with respect thereto so that electromagnetic radiation exiting said multimode laser head has an essentially constant radial energy content profile and prior to becoming other than of essentially constant radial energy density content passes through said aperture, with said aperture being imaged with demagnification;
• a non-homogeneous laser head and a beam-coring aperture dimensioned and positioned to extract a limited section of electromagnetic radiation exiting said non-homogeneous laser head which has an approximately constant radial energy density content profile;
• at least one multifaceted “fly's eye” array optic which comprises a multiplicity of essentially evenly spatially distributed effective optical lenses or facets;
• and
• a system comprising at least one beam splitting means and at least one Gaussian profile inverting optic and at least one beam recombining means, such that electromagnetic radiation entering thereinto is caused to interact with said at least one beam splitting means, with approximately half of said electromagnetic radiation being caused thereby to pass through said at least one Gaussian profile inverter and subsequently be re-combined with the other approximately half of electromagnetic radiation which does not pass through said at least one Gaussian profile inverter, by said at least one beam recombining means;
• said laser ablation system for analyzing sample system material further being in functional combination with a selection from the group consisting of:
• an (ICP-OES) optical emission system,
• an (ICP-MS) mass spectrometer system,
• a (MIP-OES) optical emission system, and
• a (MIP-MS) mass spectrometer system;
• such that, in use, said 200 nm or greater UV wavelength laser source of electromagnetic radiation is caused to provide electromagnetic radiation to a sample system via said at least one beam homogenizing means, from which sample system material is ablated, said ablated material being caused to enter said system selected from the group consisting of:
• an (ICP-OES) optical emission system,
• an (ICP-MS) mass spectrometer system,
• a (MIP-OES) optical emission system, and
• a (MIP-MS) mass spectrometer system;
• wherein said ablated material is analyzed.

A method of preparing and analyzing sample system material comprising the steps of:

• a. providing a laser ablation system for analyzing sample system material comprising in any functional order:
• a 200-380 nm UV wavelength laser source which is capable of providing pulse(s) or CW electromagnetic radiation (LS);
• and at least one beam homogenizing means (H);
• said laser ablation system for analyzing sample system material further being in functional combination with a plasma based analysis system such that, in use, said 200-380 nm UV wavelength laser source of electromagnetic radiation is caused to provide electromagnetic radiation substantially homogeneously providing at least 30 J/cm2 over an area with a cross sectional diameter of at least 40 microns to a sample system via said at least one beam homogenizing means, from which sample system material is ablated, at least some of said ablated material being caused to enter said plasma based analysis system wherein it is analyzed;
• b. providing a sample system (SS);
• c. causing said 200-380 nm UV wavelength laser source of electromagnetic radiation to provide electromagnetic radiation to a sample system via said at least one beam homogenizing means such that sample system material is ablated substantially by an optically induced direct solid-to-gas laser ablation mechanism;
• and
• d. causing at least some of said ablated sample system material to enter said plasma based analysis system to the end that it is analyzed.

A method of preparing and analyzing sample system material comprising the steps of:

• a. providing a laser ablation system for analyzing sample system material comprising in any functional order:
• a 200-380 nm UV wavelength laser source which is capable of providing pulse(s) or CW electromagnetic radiation (LS);
• at least one beam homogenizing means (H) selected from the group consisting of:
• a multimode laser head and a near field aperture located with respect thereto so that electromagnetic radiation exiting said multimode laser head has an essentially constant radial energy content profile and prior to becoming other than of essentially constant radial energy density content passes through said aperture, with said aperture being imaged with demagnification;
• a non-homogeneous laser head and a beam-coring aperture dimensioned and positioned to extract a limited section of electromagnetic radiation exiting said non-homogeneous laser head which has an approximately constant radial energy density content profile;
• at least one multifaceted “fly's eye” array optic which comprises a multiplicity of essentially evenly spatially distributed effective optical lenses or facets;
• and
• a system comprising at least one beam splitting means and at least one Gaussian profile inverting optic and at least one beam recombining means, such that electromagnetic radition entering thereinto is caused to interact with said at least one beam splitting means, with approximately half of said electromagnetic radiation being caused thereby to pass through said at least one Gaussian profile inverter and subsequently be re-combined with the other approximately half of electromagnetic radiation which does not pass through said at least one Gaussian profile inverter, by said at least one beam recombining means;
• said laser ablation system for analyzing sample system material further being in functional combination with a plasma based analysis system such that, in use, said UV wavelength laser source of electromagnetic radiation is caused to provide electromagnetic radiation substantially homogeneously providing at least 30 J/cm2 over an area with a cross sectional diameter of at least 40 microns to a sample system via said at least one beam homogenizing means, from which sample system material is ablated, at least some of said ablated material being caused to enter said plasma based system wherein it is analyzed;
• b. providing a sample system;
• c. causing said UV wavelength laser source of electromagnetic radiation to provide electromagentic radiation to substantially homogeneously provide at least 30 J/cm2 over an area with a cross sectional diameter of at least 40 microns to a sample system via said at least one beam homogenizing means such that sample system material is ablated substantially by an optically induced direct solid-to-gas laser ablation mechanism;
• and
• d. causing at least some of said sample system ablated material to enter said plasma based analysis system to the end that it is analyzed.

A method of ablating material from a sample system such as precious gems for analysis, in a way which is undetectable comprising:

• a. providing a laser ablation system for analyzing sample system material comprising in any functional order:
• a laser source which is capable of providing pulse(s) or CW, electromagnetic radiation (LS);
• at least one beam homogenizing means (H);
• and
• means for supporting a sample system;
• said laser ablation system for analyzing sample system material further being in functional combination with a plasma analysis systems such that, in use, said laser source electromagnetic radiation is caused to provide electromagnetic radiation to a sample system via said at least one beam homogenizing means, from which sample system material is ablated, at least some of said ablated material being caused to enter said plasma analysis system wherein it is analyzed;
• b. providing a sample system (SS);
• c. causing said laser source of electromagnetic radiation to provide electromagnetic radiation to a sample system via said at least one beam homogenizing means such that sample system material is substantially uniformly ablated over an area of between 50 and 700 microns diameter, and to a uniform depth of less than 2 microns, said ablation being substantially by an optically induced direct solid-to-gas laser ablation mechanism;
• and
• d. causing at least some of said ablated sample system to enter said plasma based analysis system to the end that it is analyzed;
• and
• e. optionally applying polishing techniques to said sample system to the end that effects of said ablation procedure are not detectable by observation and/or conventional weighing techniques.

A method of ablating material from a sample system which -minimizes variation of results over time comprising the steps of:

• a. providing a sample system (SS);
• b. placing said sample system into a system for ablating sample systems with electromagnetic radiation;
• c. while monitoring sample system ablation results over time, applying pulses of electromagnetic radiation to said sample system which are characterized by a first combination of values for:
• wavelength;
• degree of homogenization;
• fluence (energy density);
• pulse duration;
• pulse repetition rate;
• total number of pulses applied to a location on a sample system;
• pulse(s) of electromagnetic radiation;
• and
• diameter of electromagnetic radiation pulses at a location at which they impinge on a sample system;
• d. while varying selections from the group consisting of:
• wavelength;
• degree of homogenization;
• fluence (energy density);
• pulse duration;
• pulse repetition rate;
• total number of pulses applied to a location on a sample system;
• pulse(s) of electromagnetic radiation;
• and
• diameter of electromagnetic radiation pulses at a location at which they impinge on a sample system;
• continuing to note sample system ablation results over time and identifying combinations of said selections which provide desired ablation results.

A method of ablating material from a sample system comprising applying electromagnetic radiation pulse(s) from a 200-380 nm UV wavelength laser source of electromagnetic radiation to a sample system, wherein said pulse(s) are characterized by a combination of wavelength, degree of homogenization, fluence (energy density), pulse duration, pulse repetition rate, total number of pulse(s) applied to a location on a sample system, and diameter of electromagnetic radiation pulses at a location at which they impinge on a sample system;

• such that the results of ablation indicate at least one selection from the group consisting of:
• ablation was by an essentially pure optical mechanism as determined by any technique;
• ablation was by an essentially pure optical direct solid-to-gas phase transition mechanism as evidenced by ratios (ICP-OES), (ICPMS), (MIP-OES) or (MIP-MS) intensity of ablated high to low melting and/or boiling point elements or compounds remaining essentially constant over time;
• substantially uniform ablation depth occurred over the diameter of the ablated region;
• the ablation provides an ablated region in the sample system with an aspect ratio of diameter to depth of at least 0.8;
• and
• the electromagnetic radiation pulse(s) present with at least 85% homogenization as evidenced by measured radial energy uniformity.

A method of analyzing ablated material from a sample system comprising applying electromagnetic radiation pulse(s) from a 200-380 nm UV wavelength laser source of electromagnetic radiation to a sample system, wherein said pulse(s) are characterized by a combination of wavelength, degree of homogenization, fluence (energy density), pulse duration, pulse repetition rate, total number of pulse(s) applied to a location on a sample system, and diameter of electromagnetic radiation pulse(s) at a spot location at which they impinge on a sample system;

• said method comprising:
• providing laser electromagnetic radiation pulse(s) of 200-380 nm UV wavelength, which have 2-20 nsec duration as a single shot or at a repetition rate corresponding to 1-30 Hz, and
• which laser electromagnetic radiation pulse(s) have a degree of homogenization of 85% or greater, and
• which laser electromagnetic radiation pulse(s) have a fluence (energy density) of 30 J/cm2 or greater, and
• which laser electromagnetic radiation pulse(s) have a diameter, at the spot location at which they are caused to impinge on a sample system, of at least 40 microns;
• causing said laser electromagnetic radiation pulse(s) of 200-380 nm UV wavelength electromagnetic radiation to impinge on a sample system such that material is ablated therefrom thereby;
• and
• entering at least some of the material ablated from said sample system to an (ICP-OES), (ICP-MS), (MIP-OES) or (MIP-MS) system in which it is analyzed.

A laser ablation system for applying a beam of electromagnetic radiation to a sample system comprising a beam homogenizing means (H) having at least two stages, each stage being independently selected from the group consisting of:

• a multifaceted “fly's eye” array optic which comprises a multiplicity of essentially evenly spatially distributed effective optical lenses or facets;
• and
• a system comprising at least one beam splitting means and at least one Gaussian profile inverting optic and at least one beam recombining means, such that electromagnetic radiation entering thereinto is caused to interact with said at least one beam splitting means, with approximately half of said electromagnetic radiation being caused thereby to pass through said at least one Gaussian profile inverter and subsequently be re-combined with the other approximately half of electromagnetic radiation which does not pass through said at least one Gaussian profile inverter, by said at least one beam recombining means;
• said laser ablation system further comprising, in functional combination therewith, a plasma based analysis system.