WO2023100094A1

WO2023100094A1 - An optical system for emission spectroscopy in deep ultraviolet wavelength range

Info

Publication number: WO2023100094A1
Application number: PCT/IB2022/061579
Authority: WO
Inventors: Priyadarshan Divyadarshan Pant; Santosh Thumma
Original assignee: Metal Power Analytical Private Limited
Priority date: 2021-12-01
Filing date: 2022-11-30
Publication date: 2023-06-08

Abstract

The present disclosure relates to the field of spectroscopy and discloses a compact high-resolution optical spectrometer system (100) for emission spectroscopy in deep ultraviolet range. The system (100) comprises a source (1), a spectrometer optics assembly (3) with or without a coupling optics (9), and a signal analysis sub-system (13). A light emitted by the source (1) passes through a slit (4) onto a collimating unit (5) of the spectrometer optics assembly (3), where the light is collimated and directed to a dispersing element (6). The dispersing element (6) diffracts the collimated light into its constituent wavelengths which are focused by a focusing unit (7) onto an array detection sub-system (8). The detection sub-system (8) generates a signal corresponding to each incident wavelength simultaneously. The signal analysis sub-system (13) collects, processes, and analyzes the signals to generate an output. The system (100) has low-footprint and provides improved light-throughput and high-resolution.

Description

AN OPTICAL SYSTEM FOR EMISSION SPECTROSCOPY IN DEEP

ULTRAVIOLET WAVELENGTH RANGE

FIELD

The present invention generally relates to the field of atomic emission spectroscopy. More particularly, the present invention relates to an optical system for emission spectroscopy in deep ultraviolet wavelength range.

BACKGROUND

The background information herein below relates to the present disclosure but is not necessarily prior art.

In high-resolution spectrometer instrumentation, it is important to have small and environmentally durable spectrometer optics, particularly when it is used for deep ultraviolet wavelength analysis. Generally, these high-resolution spectrometer optics configurations demand optics designs with large footprints, expensive inert gas purging or vacuum generation systems, and complex environmental control systems which make the systems more complex, bulky, and expensive.

Furthermore, these emission spectrometers in portable or hand-held instrument configurations for metal sorting applications demand spectrometer optics with light weight, high resolution, wide wavelength range coverage and short stabilization times.

Along with that, the optics modules with larger footprints especially when used in portable spectroscopy instrumentation demand higher inert gas consumption, longer duration to create inert gas environment and longer stabilization times.

Maintaining the spectrometer optics at a constant temperature to achieve higher precision is important, however, for achieving high level of thermal stability within small footprint, quicker thermal stabilizations times are crucial for the portable instrumentations. These can be compensated mathematically by using complex algorithms, but those are meant for mere compensations rather than actual stability of the instruments.

Optics modules with large footprints suffer with another limitation of poor light throughput, as the light throughput is inversely proportional to the second power of the distance from the light source. So, smaller focal length optics designs are crucial, especially for higher light throughputs and smaller footprints. There is a scope to improve signal electronically, but it suffers with increased noise.

Many improvements are being made in the field of spectroscopy to achieve smaller footprint spectrometer optics without complex scanning mechanisms, higher resolutions, shortened stabilizations times, lower inert gas consumptions and the like, especially for ultraviolet wavelength ranges.

For example, the publication US9502229B2, titled ‘Ultra Compact Plasma Spectrometer’ discloses a plasma spectrometer with an energy analyzer array which is of an array of conducting material stacked one on another to collect and focus the particles on to a detector plate. This compact spectrometer is fundamentally used to detect the energy of the particles instead of energy of the radiation. Moreover, the energy analyzer array is a combination of multiple electrical conducting plates made from a silicon wafer. This publication does not address the limitations recited above.

Further, the US publication US6151112A, titled ‘High Resolution Compact intracavity laser spectrometer’ discloses a compact spectrometer with multiple dispersing elements and single photodiode detector to achieve higher resolutions for single wavelength. By maintaining certain symmetry in the design, this prior art could achieve higher resolutions of the incident laser beam having single wavelength. However, the spectrometer disclosed in this publication does not facilitate capturing wide wavelength ranges with higher resolutions for the ultraviolet emission source.

The publication US9683891B1, titled ‘Compact Spectrometer for Two - Dimensionally Sampling’ teaches a Fourier Transform Spectrometer with multiple mirrors and prisms which create an interferogram by incidenting two light sources having adjustable phase shift with a fixed incident angle. This spectrometer fundamentally makes interferograms and works for visible to infrared wavelength regions with resolutions in the range of 0.2 nm to 10 nm, however, it is not capable of achieving a high resolution in the deep ultraviolet wavelength range.

The publication US2021/0302305A1, titled ‘Ultra Miniature Spatial Heterodyne Spectrometer’ discloses a Spatial Heterodyne Spectrometer (SHS) with multiple dispersing elements, prisms, and beam splitters. The SHS is basically used to capture the fringe pattern by adjusting the optical paths between the reference and captured images in terms of the modulation frequencies. Generally, by principle this applies to visible wavelength range and has very narrow wavelength bands. In this prior art, the wavelength range is mentioned as 3O67A⁰ to 3O98A⁰ i.e., wavelength difference is 30A° and the resolution is ~0.085A°. In nm, the wavelength difference is 3 nm and the resolution is -0.08 nm. This spectrometer is generally used in topographical and velocity sensitive applications where a very narrow wavelength band is to be studied.

The publication US7369228 B2 discloses a compact spectrometer optics with a dispersing element and a detector without collimating and focusing optics. This spectrometer is of Rowland circle optics configuration and usually has focal length of more than 150 mm. This prior art does not address the limitations of deep ultraviolet emission detection and ultracompact, lightweight, and high resolution optics.

Furthermore, the publication US11067446B2 teaches a compact spectrometer module with an LED source and a Fabry-Perot interferometer component. This spectrometer gets the spectrum by applying Fourier transforms to the interferogram created by Fabry Perot interferometer. This prior art has a fixed LED source. The LED light excites the pharmaceutical sample and captures the emitted infrared light with Fabry Perot component. This generally operates in the visible to infrared wavelength ranges. So, this invention cannot achieve emission spectrometers operating in ultraviolet wavelength ranges with higher resolutions and wider wavelength ranges. Moreover, it cannot be coupled with various sources like emission, absorption, spark, and the like.

Therefore, there is a need in the art for an optical system for emission spectroscopy in deepultraviolet wavelength range and a method thereof.

OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

It is an object of the present disclosure to ameliorate one or more problems of the prior part or to at least provide a useful alternative.

An object of the present disclosure is to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range. Another object of the present disclosure is to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range that has a small footprint.

Still another object of the present disclosure to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range that does not have any moving or scanning elements.

Yet another object of the present disclosure to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range that gives high light throughput.

A further object of the present disclosure to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range that provides good repeatability in measurement within short duration of time.

Still another object of the present disclosure to provide an optical system for emission spectroscopy that minimizes the effect of environmental factors such as temperature and pressure fluctuations on the measurement in the ultraviolet range.

Yet another object of the present disclosure to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range that reduces potential leakages of inert gas or vacuum which can affect the stability of the signal in both short term and long term by allowing no or very less access points.

Still another object of the present disclosure to provide an optical system for emission spectroscopy that reduces efforts in making an inert gas environment for the system and also reduces an inert gas consumption to detect the UV wavelength signals.

Yet another object of the present disclosure to provide an optical system for emission spectroscopy in deep ultraviolet wavelength range that provides short stabilization times, high stability, and good control over thermal stability.

Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

The present disclosure envisages an optical system for emission spectroscopy in deep ultraviolet wavelength range. The system comprises a source, a spectrometer optics assembly, and a signal analysis system. The source is configured to emit a light. The source can be selected from the group consisting of an emission source, an absorption source, a laser induced source, a glow discharge source, an inductively coupled plasma (ICP) source, and a direct current (DC) plasma source that can generate at least one of a plasma, a spark, and an arc. The spectrometer optics assembly comprises an entrance slit, a collimating unit, a dispersing element, a focusing unit, and one or more detectors comprised in said array detection sub-system. The configuration of the spectrometer optics assembly is selected from the group consisting of Czerny Turner, Crossed Czerny Turner, Ebert-Fastie and Monk- Gillieson. The entrance slit is configured to provide a passage to the light emitted by the source and further configured to limit the throughput of the light. The collimating unit is configured to collimate the light received through the slit and direct the collimated light to a desired direction. The dispersing element is configured to receive the collimated light and diffract the incident collimated light into its constituent wavelengths. The focusing unit is configured to focus the constituent wavelengths onto an array detection sub-system. Each of the detectors of the array detection sub-system is sensitive to ultraviolet radiation and is configured to generate a signal corresponding to each incident wavelength simultaneously. The array detection sub-system comprises detectors selected from the group consisting of linear array detectors, 2D array detectors, array of photodiodes, array of charge-coupled devices (CCDs), and array of complementary metal-oxide semiconductor (CMOS) detectors. The signal analysis sub-system is configured to collect the generated signals from the array detection sub-system and is further configured to process and analyze the collected signals to generate an analysis output.

In an embodiment, the focusing unit is a lens having a spherical surface or a toroidal surface.

In an embodiment, the relation between:

1. a distance ‘D’ between a center of said source (1) and said entrance slit (4) of said spectrometer optics assembly (3),

2. a distance ‘F’ between said entrance slit (4) and said collimating unit (5), and

3. a distance ‘L’ between the center of said source (1) and said collimating unit (5) is 0.2 < D/L < 0.8 and 0.2 < F/L < 0.8.

In an embodiment, the focal length ‘F’ of the spectrometer optics assembly is in the range of 48 mm to 53 mm, the source distance ‘D’ is in the range of 48 mm to 53 mm, and the resolution is in the range of 46pm to 67pm. In an embodiment, the collimating unit and the focusing unit are selected from the group consisting of a focusing lens, a group of focusing lenses, a combination of lenses and mirrors, a spherical concave mirror, and a toroidal mirror.

In an embodiment, the system includes a primary coupling optics configured to enhance, filter, or mask the light received from the source. The primary coupling optics comprises at least one of a focusing lens, a mirror, a group of focusing lenses, a group of mirrors, or a combination of lenses and mirrors.

In another embodiment, the system includes a primary coupling optics configured to enhance, filter, or mask the light received from the source. The primary coupling optics comprises at least one of a focusing lens, a mirror, a fiber optic cable, a group of focusing lenses, a group of mirrors, a group of fiber optic cables, or a combination of lenses, mirrors, and fiber optic cables. The primary coupling optics is further selected from the group consisting of a plane mirror, a concave mirror, a combination of a plane and concave mirrors, with at least one of focusing lenses, focusing mirrors, folding mirrors, and fiber optic cables to guide the light to said spectrometer optics assembly.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

An optical system for emission spectroscopy in deep ultraviolet wavelength range of the present disclosure will now be described with the help of the accompanying drawing, in which:

Figure 1 illustrates a schematic diagram of an optical system for emission spectroscopy in deep ultraviolet wavelength range with direct light collection from the source for the benchtop instruments, in accordance with a first embodiment of the present disclosure;

Figure 2 illustrates a schematic diagram of an optical system for emission spectroscopy in deep ultraviolet wavelength range with light collection through primary coupling optics for the benchtop instruments, in accordance with the first embodiment of the present disclosure;

Figure 3 illustrates a schematic diagram of an optical system for emission spectroscopy in deep ultraviolet wavelength range with direct light collection from the source for the portable instruments, in accordance with a second embodiment of the present disclosure; and

Figure 4 illustrates a schematic diagram of an optical system for emission spectroscopy in deep ultraviolet wavelength range with light collection through primary coupling optics for the portable instruments, in accordance with the second embodiment of the present disclosure.

LIST OF REFERENCE NUMERALS

100 - System

1- Source

2 - Source chamber

3 - Spectrometer optics assembly

4 - Entrance slit

5 - Collimating unit

6 - Dispersing element

7 - Focusing unit

8 - Array detection sub-system

9 - Primary coupling Optics

10 - Fiber optics cable

11 - Folding mirror

12 - Gun-shaped housing

13 - Signal analysis system

14 - Application

DETAILED DESCRIPTION

Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

Embodiments are provided to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details, are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

When an element is referred to as being "mounted on," “engaged to,” "connected to," or "coupled to" another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.

As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.

The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element or component from another element or component. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.

Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.

The presented spectral measurement system for the atomic emission spectrometer for vacuum ultra violet wavelength application includes an emission source which can generate the spark or arc emissions by various method of sample excitation methods and a light collection optics which includes focusing lenses or lens groups to enhance the ultra violet wavelength signal and a spectrometer with crossed Czerny Turner optics which includes the a slit, spherical concave collimating mirror, a plane grating, a spherical concave focusing mirror and a photodiode array detection system. Arc/Spark spectrometer includes an emission source to generate the emission light by generating the arc/spark at solid sample surface, optical system which can disperse the light into different wavelengths depending upon the elements present in the sample and a detection system to capture the wavelengths, converting them into electrical signals, processing and analyzing the data to estimate the elemental concentrations in the sample.

Optical system further consists of a light collection optics which includes focusing lenses or lens groups to enhance the ultra violet wavelength signal and a spectrometer with crossed Czerny Turner optics which includes a slit, spherical concave collimating mirror, a plane grating, a spherical concave focusing mirror and a photodiode array detector.

Furthermore, these emission spectrometers in portable or hand-held instrument configurations for metal sorting applications demand spectrometer optics with light weight, high resolution, wider wavelength range coverage and short stabilization times.

Along with that, the optics modules with larger footprints especially when used in portable spectroscopy instrumentation demand higher inert gas consumptions, longer durations to create inert gas environment and longer stabilization times.

Maintaining the spectrometer optics at a constant temperature to achieve higher precision is important, however, for achieving high level of thermal stability within small footprint, quicker thermal stabilizations times are crucial for the portable instrumentations. These can be compensated mathematically by using complex algorithms, but those are meant for mere compensations rather than actual stability of the instruments. Optics modules with large footprints suffer with another limitation of poor light throughput, as the light throughput is inversely proportional to the second power of the distance from the light source. So, smaller focal length optics designs are crucial, especially for higher light throughputs and smaller footprints. There is a scope to improve signal electronically, but it suffers with increased noise.

To address all the above issues associated with the conventional spectrometer optics systems and methods, the present disclosure envisages an optical system (hereinafter referred to as “system 100”) for emission spectroscopy in deep ultraviolet wavelength range. The system 100 is a compact high-resolution spectrometer optical system in the field of atomic emission spectroscopy with a small footprint of its kind without any moving or scanning elements, which helps to achieve high light throughput, better repeatability in the measurement within short duration of time and minimizes the effects of the environmental factors such as temperature and pressure fluctuations on the measurement in the ultraviolet wavelength range and helps to make key configurations to have unique advantages.

The system 100 is now being described with reference to Figure 1 through Figure 4.

Referring to Figure 1, the system 100 comprises a source 1, a spectrometer optics assembly 3, and a signal analysis sub-system 13. The source 1 is disposed in a source chamber 2 and is configured to emit a light. Typically, the emission source 1 consists of a cathode and a sample as an anode. The anode is kept a few millimeters away from the cathode. The source 1 is excited by applying controlled high voltages in an inert gas or vacuum environment. Based on the excitation method, the source 1 can be selected from the group consisting of, but not limited to, an emission source, an absorption source, a laser induced source, a glow discharge source, an inductively coupled plasma (ICP) source, and a direct current (DC) plasma source that can generate at least one of a plasma, a spark, and an arc.

The spectrometer optics assembly 3 comprises an entrance slit 4, a collimating unit 5, a dispersing element 6, a focusing unit 7, and an array detection sub-system 8. The entrance slit 4 is configured to provide a passage to the light emitted by the source 1 and is further configured to limit the throughput of the light. The collimating unit 5 is configured to collimate the light received through the slit 4 and direct the collimated light to a desired direction, i.e., onto the dispersing element 6. The dispersing element 6 is configured to receive the collimated light and diffract the incident collimated light into its constituent wavelengths. The dispersing element 6 is typically a diffraction grating. The collimated light gets diffracted at different diffraction angles depending on its wavelength and incident angle. The configuration is selected such that the grating diffracts the wide wavelength region with high resolution in a small footprint. The focusing unit 7 is configured to focus the constituent wavelengths onto an array detection sub-system 8. The array detection sub-system 8 comprises one or more detectors. Each of the detectors is sensitive to the ultraviolet radiation and is configured to generate a signal corresponding to each incident wavelength simultaneously.

In an embodiment, the array detection sub-system 8 comprises detectors selected from the group consisting of, but not limited to, linear (ID) array detectors, 2D array detectors, array of photodiodes, array of charge -coupled devices (CCDs), and array of complementary metal- oxide semiconductor (CMOS) detectors.

The spectrometer optics assembly 3 has a configuration selected from the group consisting of, but not limited to, Czerny Turner, Crossed Czerny Turner, Ebert-Fastie and Monk-Gillieson which uses plane grating, either ruled or holographic.

The signal analysis sub-system 13 is configured to collect the generated signals from the array detection sub-system 8 and is further configured to process and analyze the collected signals to generate an analysis output. In an embodiment, the analysis output is a data identifying the constituent components of a sample and their proportion in the sample. For example, the analysis output may be used to determine the elemental composition of a broad range of metals. The signal analysis system 13 comprises a series of data acquisition electronics boards, which is responsible for capturing, amplifying, and processing the data from the array detection sub-system 8 and reduce the noise to achieve a desired signal to noise ratio (SNR).

The system 100 further includes an application 14 installable in an electronic device. The application 14 is configured to communicate with the signal analysis sub-system 13 through a communication means to receive and display the analysis output to a remote user. The communication means refers to a means for transmitting and receiving electronic data. The communication means may include, for example, the Internet, the World Wide Web, an intranet, cable (including fiber optic cable), magnetic communications, electromagnetic communications (including RF, microwave, and infrared communications), and electronic communications. Wireless communication means can support various wireless communication network protocols and technologies such as Near Field Communication (NFC), Wi-Fi, Bluetooth, 4G Long Term Evolution (LTE), Code Division Multiplexing Access (CDMA), Universal Mobile Telecommunication System (UMTS) and Global System for Mobile Telecommunication (GSM).

In an embodiment, the focusing unit 7 is a lens having a spherical surface or a toroidal surface.

The system 100 envisages two embodiments, wherein the first embodiment is for a regular benchtop instrumentation (shown in Figures 1 and 2) and the second embodiment (shown in Figures 3 and 4) is for a portable or hand-held instrumentation.

In the first embodiment, the system 100 includes a primary coupling optics 9 configured to enhance, filter, and/or mask the light received from the source 1. The primary coupling optics 9 comprises at least one of a focusing lens, a mirror, a group of focusing lenses, a group of mirrors, or a combination of lenses and mirrors. The spectrometer optics 3 is combined with the source 1 either by direct light path or by a primary coupling optics 9.

In an embodiment, the distance between a center of the source 1 and the entrance slit 4 of the spectrometer optics assembly 3 is ‘D’, the distance between the center of the source 1 and the collimating unit 5 is ‘L’ , and the distance between the entrance slit 4 and the collimating unit 5 is ‘F’; wherein the relation between ‘D’, ‘F’ and ‘L’ is 0.2 < D/L < 0.8 and 0.2 < F/L < 0.8. The focal length ‘F’ of the spectrometer optics assembly 3 is in the range of 48 mm to 53 mm. The source distance ‘D’ is in the range of 46 mm to 57 mm, and the resolution is in the range of 0.04 nm to 0.15 nm. This embodiment helps to achieve shorter or superior stabilizations times, higher stability, better control over thermal stability, lower the consumption of the inert gas environment and higher light throughput. This is achieved by making the spectrometer optics 3 too compact which further can be achieved by careful selection of the incident angles and configuration of the optical design forms to trade-off the distances and angles between the inter components. This compactness in the design allows simpler mechanical housings to make and protect them from the potential inert gas leakages, thermal and pressure variations. In short, the maintenance and controlling of the smaller footprint optics is much simpler compared that of traditional long footprint optics. By careful selection of incident angles, distances, and configurations of the spectrometer optics 3, it is made possible to get the smaller footprint spectrometer optics 3, which further opens useful embodiments to cater different industrial requirements. The collimating unit 5 and the focusing unit 7 are selected from the group consisting of a focusing lens, a group of focusing lenses, a combination of lenses and mirrors, a spherical concave mirror, and a toroidal mirror. Typically, the collimating unit 5 and the focusing unit 7 include concave mirrors which have a radius of curvature equal to twice the focal length of the spectrometer optics assembly 3. Usage of toroidal mirrors reduces the astigmatism and improves the signal strength considerably.

In the second embodiment, the system 100 includes a primary coupling optics 9 configured to enhance, filter, or mask the light received from the source 1. The primary coupling optics 9 comprises at least one of a focusing lens, a mirror, a fiber optic cable, a group of focusing lenses, a group of mirrors, a group of fiber optic cables, or a combination of lenses, mirrors, and fiber optic cables. The primary coupling optics 9 is further selected from the group consisting of a plane mirror, a concave mirror, a combination of a plane and concave mirrors, with at least one of focusing lenses, focusing mirrors, folding mirrors 11, and fiber optic cables to guide the light to the spectrometer optics assembly 3. Thus, the spectrometer optics 3 is combined with emission source 1 of portable or hand-held instrumentation through the primary coupling optics 9. The fiber optics cable 10 is useful when the spectrometer optics 3 needs to be mounted at an appropriate location as per the convenience. This fiber optics cable 10 is considered as the part of the primary coupling optics 9. All these arrangements are generally housed inside a gun-shaped housing 12 which is convenient in portable instruments.

As shown in the Figure 4, the spectrometer optics 3 can be placed as per the convenience. For example, it can be housed inside the gun-shaped housing 12. This embodiment addresses the limitations with large format spectrometer optics 3 and helps in achieving higher levels of thermal stability within small footprint and quicker thermal stabilizations times for the portable instrumentations. This embodiment also helps to achieve shorter or superior stabilizations times, higher stability, better control over thermal stability, lower the consumption of the inert gas environment and higher light throughput.

Further embodiments are also possible to scale the advantages to its maximum levels, for example addition of multiple spectrometer optics modules 3 side-by-side or stack one over another depending on the application whether it is bench top instrumentation or portable instrumentation and by using appropriate primary coupling optics 9 to enhance the wavelength ranges and resolutions in the smallest footprints possible. With the abovementioned embodiments, the results achieved in contrast to the footprint of its counterpart designs such as Rowland circle and conventional Czerny-Turner optical systems are - the resolution is increased by three times, the wavelength range is increased by three times, the light throughput in increased by nine times, the inert gas consumption and volume is reduced by ten times, and the thermal stabilization times are improved by three times.

In an operative embodiment, the spectrometer optical system 100 for emission or absorption spectroscopy for deep ultraviolet wavelength range comprises the source 1 which generates one of a plasma, a spark, or an arc by exciting a sample under test using various excitation techniques. The system 100 optionally comprises the primary coupling optics 9 which includes a focusing lens, a group of focusing lenses, or a combination of lenses and mirrors to enhance, filter, and/or mask the light and the spectrometer optics 3 with Czerny Turner optics which includes the slit 4, the collimating unit 5, the dispersing element 6, the focusing optics 7, one or more detectors 8 which are of ID or 2D array detectors, and the signal analysis subsystem 9.

The ultraviolet light generated by the source 1 is directed towards the spectrometer optics 3 either directly or by using a primary coupling optics 9. The slit 4 in the spectrometer optics 3 limits the light throughput and acts as an object for spectrometer optics 3 to image. The collimating unit 5, which is typically a collimating mirror, collimates the light received from slit 4 and directs to the dispersing element 6 which is typically a diffraction grating. This grating diffracts the incident collimating light into its constituent wavelengths and directs them on to the focusing unit 7 which is typically a focusing mirror. The focusing unit 7 focusses the constituent wavelengths on the detectors 8 which are either array of ID or 2D array detectors or array of photodiodes.

When the compact high-resolution spectrometer optical system (CHSS) 100 for emission spectroscopy is being operated in deep ultraviolet region down to 140 nm, the CHSS reduces the potential leakages of the inert gas or vacuum environment, which affects the stability of the signal in both short term and long term by allowing no or very less access points. Due to its compactness, the efforts to make the inert gas environment for the instrument and the inert gas consumption to detect the UV wavelength signals are drastically reduced.

The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

TECHNICAL ADVANCEMENTS

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of an optical system for emission spectroscopy in deep ultraviolet wavelength range that:

• has a small footprint in the range of 50mm.

• does not have any moving or scanning elements.

• gives high light throughput.

• provides good repeatability in measurement within short duration of time, Relative Standard Deviations <2%.

• minimizes the effect of environmental factors such as temperature and pressure fluctuations on the measurement in the ultraviolet range.

• reduces the potential leakages of inert gas or vacuum environment which affect the stability of the signal in both short term and long term by allowing no or very less access points;

• reduces the efforts in making an inert gas environment for the system and also reduces an inert gas consumption to detect the UV wavelength signals; and

• provides short stabilization times of around 5min, high stability, and good control over thermal stability.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

The use of the expression “at least” or “at least one” suggests the use of one or more elements or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:

1. An optical system (100) for emission spectroscopy in deep ultraviolet wavelength range, said system (100) comprising:

• a source (1) configured to emit a light;

• a spectrometer optics assembly (3) comprising: i. an entrance slit (4) configured to provide a passage to the light emitted by said source (1) and further configured to limit the throughput of said light; ii. a collimating unit (5) configured to collimate the light received through said slit (4) and direct the collimated light to a desired direction; iii. a dispersing element (6) configured to receive said collimated light and diffract said incident collimated light into its constituent wavelengths; iv. a focusing unit (7) configured to focus said constituent wavelengths onto an array detection sub-system (8); and v. one or more detectors comprised in said array detection sub-system (8), each of said detectors being sensitive to ultraviolet radiation and configured to generate a signal corresponding to each incident wavelength simultaneously, and

• a signal analysis sub-system (13) configured to collect said generated signals from said array detection sub-system (8) and further configured to process and analyze said collected signals to generate an analysis output wherein the relation between:

• a distance ‘D’ between a center of said source (1) and said entrance slit (4) of said spectrometer optics assembly (3),

• a distance ‘F’ between said entrance slit (4) and said collimating unit (5), and

• a distance ‘L’ between the center of said source (1) and said collimating unit (5) is 0.2 < D/L < 0.8 and 0.2 < F/L < 0.8.

2. The system (100) as claimed in claim 1, wherein said source (1) is selected from the group consisting of an emission source, an absorption source, a laser induced source, a glow discharge source, an inductively coupled plasma (ICP) source, and a direct current (DC) plasma source that can generate at least one of a plasma, a spark, and an arc.

3. The system (100) as claimed in claim 1, wherein said focusing unit (7) is a lens having a spherical surface or a toroidal surface.

4. The system (100) as claimed in claim 1, wherein the focal length ‘F’ of said spectrometer optics assembly (3) is in the range of 48 mm to 53 mm, the source distance ‘D’ is in the range of 46 mm to 57 mm, and the resolution is in the range of 0.04 nm to 0.15 nm.

5. The system (100) as claimed in claim 1, wherein said spectrometer optics assembly (3) has a configuration selected from the group consisting of Czerny Turner, Crossed Czerny Turner, Ebert-Fastie and Monk-Gillieson.

6. The system (100) as claimed in claim 1, wherein said array detection sub-system (8) comprises detectors selected from the group consisting of linear array detectors, 2D array detectors, array of photodiodes, array of charge-coupled devices (CCDs), and array of complementary metal-oxide semiconductor (CMOS) detectors.

7. The system (100) as claimed in claim 1, which includes a primary coupling optics (9) configured to enhance, filter, or mask the light received from said source (1), said primary coupling optics (9) comprising at least one of a focusing lens, a mirror, a group of focusing lenses, a group of mirrors, or a combination of lenses and mirrors.

8. The system (100) as claimed in claim 1, wherein said collimating unit (5) and said focusing unit (7) are selected from the group consisting of a focusing lens, a group of focusing lenses, a combination of lenses and mirrors, a spherical concave mirror, and a toroidal mirror.

9. The system (100) as claimed in claim 1, which includes a primary coupling optics (9) configured to enhance, filter, or mask the light received from said source (1), wherein said primary coupling optics (9) is selected from the group consisting of a plane mirror, a concave mirror, a combination of a plane and concave mirrors, with at least one of focusing lenses, focusing mirrors, folding mirrors, and fiber optic cables to guide the light to said spectrometer optics assembly (3).

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