Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/28—Investigating the spectrum
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/02—Details
  • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
  • G01J3/0208—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/02—Details
  • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
  • G01J3/024—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using means for illuminating a slit efficiently (e.g. entrance slit of a spectrometer or entrance face of fiber)

Definitions

• the present invention relates to a light collection system. It applies in particular to optical spectrometric analysis. 0 More specifically, the present invention relates, in the field of optical paths, to a combination of mirrors with different technical characteristics.
• mirrors are combined in a particular system which constitutes an optical system for collecting light from a light source and sending it to " a light detection device, which can be used at least in the context of optical spectrometric analysis, even in 0 other optical applications.
• FIG. 1 schematically illustrates a light collection system 2, placed between a light source 4 and a light detection device 6 which is pierced with a light entry slot 8.
• the light path has reference 10.
• the light collection systems used depend on: - the nature of the incident light, that is to say the wavelengths of the light rays composing this incident light, the distance separating the light source from the detection device, and the dimensions and the shape of the light source and detection device.
• the current light transmission and collection systems are constituted either of a blade with parallel faces or of a plano-convex or biconvex focusing lens or of a set of two plano-convex focusing lenses.
• FIG. 2 shows the path 12 of the light in the case of a light transmission system consisting of a blade with parallel faces 14.
• the references 16, 18, 20, 22 and 23 respectively represent the light source, the device detection, the entry slit of the latter, the path of light and the light brush which enters the detection device.
• FIG. 3 shows the light path 24 in the case of a light collection system consisting of a biconvex focusing lens 26.
• FIG. 4 shows the light path 28 in the case of a light collection system made up of a set of two plano-convex focusing lenses 30 and 32.
• the system of Figure 2 transmits light without focusing it, that is to say without amplifying the light flux.
• the systems of FIGS. 3 and 4 collect the maximum light from the source 16 before focusing, that is to say concentrating, this light on the input slit 20 of the detection device 18 by amplifying the light flux.
• the system which implements a set of lenses In the case where the light collection system is further from the detection device than the light source, the system which implements a set of lenses
• FIG. 4 makes it possible to transmit light in a substantially parallel beam between the two lenses 30 and 32 and therefore to minimize the risks of poor focusing on the entry slit 20.
• blade with parallel faces or lenses more or less absorb light radiation, depending on the wavelength of the latter. This absorption is sometimes negligible, in particular in the case of visible light passing through, for example, a magnesium fluoride lens. This absorption is often greater for radiation located in the far ultraviolet (corresponding to wavelengths less than 200nm).
• 40, 42, 44, 46, and 48 respectively represent the polychromatic incident light, the focal point of the light with the shortest wavelength, the focal point of the light with the longest wavelength, the detection device, the entry slit of this light device detection, the image spot for the lowest wavelength and the image spot for the highest wavelength.
• Figure 5 shows the partial closure thus existing at the entrance slot. This problem of different focal point depending on the wavelength is all the more important as the range of wavelengths observed is wide and induces a difference in sensitivity of the detection device as a function of the wavelengths.
• the light flux is not the same for each of the wavelengths at a given position on the optical axis. It can be maximum if the entry slit is placed on the focal point of one of the two wavelengths, but it is necessarily lower for the second wavelength.
• the known light collection systems comprising focusing lenses, partially meet the needs for amplification of the light fluxes, they do not make it possible to maximize this amplification simultaneously for all the wavelengths of a light polychromatic. This is due, on the one hand, to the absorption, sometimes significant, of the light induced by the material constituting the lens and, on the other hand, to the longitudinal chromatic aberrations (differences between the positions, on the optical axis, of the luminous flux maxima).
• Its object is an optical system which is capable of solving both the problems of light absorption and the problems of chromatic aberration while meeting the needs for amplification of light fluxes (of all kinds and wavelengths) between one or more light sources and one or more detection devices.
• the subject of the present invention is a light collection system, this system being intended to collect the light emitted by at least one light source and to focus the collected light on at least one light detection device, this system being characterized in that it comprises at least two mirrors, namely first and second mirrors, the first mirror being able to collect the light emitted by the light source and to focus the collected light on the second mirror, this second mirror being able to focus the light it receives from the first mirror on the light detection device, this system being an amplifier, achromatic and of reduced absorption, particularly in the ultraviolet, and in that the system is provided
• the light detection device may or may not have an entry slit.
• the first and second mirrors have the same axis, this same axis constituting the optical axis of the system, and the focal points respective first and second mirrors are located on this optical axis.
• the first mirror may include a central bore which is capable of letting the light focused by the second mirror pass to the light detection device.
• the first and second mirrors are offset with respect to each other, at least one of the first and second mirrors being off-axis.
• Each of the first and second mirrors can be chosen from spherical mirrors, parabolic mirrors and ellipsoidal mirrors.
• Each of the first and second mirrors can be covered with a metallic or chemical deposit.
• the light detection device may include an entry slit and the second mirror is then provided to focus the light it receives from the first mirror on this entry slit.
• the light detection device can be an optical spectrometric analysis device comprising an entry slit and the second mirror is then provided for focusing the light which it receives from the first mirror on this entry slit.
• the light source can be a polychromatic source. The light emitted by this light source may contain one or more ultraviolet components.
• This light source can be a glow discharge lamp.
• FIG. 1 schematically illustrates a system for collecting light placed between a light source and a light detection device and has already been described
• Figure 2 schematically illustrates the path of light in the case of a known light transmission system, consisting of a blade with parallel faces , and has already been described
• FIG. 3 diagrammatically illustrates the light path in the case of a known light transmission system, consisting of a biconvex focusing lens, and has already been described
• FIG. 1 schematically illustrates a system for collecting light placed between a light source and a light detection device and has already been described
• Figure 2 schematically illustrates the path of light in the case of a known light transmission system, consisting of a blade with parallel faces , and has already been described
• FIG. 3 diagrammatically illustrates the light path in the case of a known light transmission system, consisting of a biconvex focusing lens, and has already been described
• FIG. 4 illustrates schematically the light path in the case of a known light transmission system, consisting of a set of two focusing lenses p lan-convex, and has already been described
• FIG. 5 schematically illustrates the partial obturation which exists at the level of the entry slit of the detection device in the case of FIGS. 3 and 4, for a polychromatic light, and has already been described
• FIG. 6 is a schematic view of a first particular embodiment of the optical system which is the subject of the invention, using two mirrors placed on the optical axis, in the case of a light source which is large relative to the size of these mirrors, FIG.
• FIG. 7 is a schematic view of a second particular embodiment of the optical system object of the invention, using two mirrors placed on the optical axis, in the case of a light source which is small compared to the size of these mirrors
• Figure 8 is a schematic view of a third particular embodiment of the optical system object of the invention, using two mirrors of which at least one is off axis ("off axis")
• Figure 9 illustrates schématiqueme nt the light transmission in an installation comprising a source of glow discharge light, a system for collecting 'mirrors to light according to the invention and a light detection device consisting of an optical emission spectrometer, and
• FIG. 10 is a schematic view of another system according to the invention, using more than two mirrors.
• first mirror two mirrors are preferably used, respectively called “first mirror” and “second mirror”.
• the shapes and characteristics of these two mirrors are predefined and one can form, or not, on these mirrors, a metallic or chemical deposit.
• This metallic or chemical deposit is intended to protect the mirror on which it is formed against possible mechanical or chemical attack and to minimize the absorption of light radiation.
• the first mirror is provided to collect the maximum light from the light source, after which the optical system is placed, and to ensure the focusing, on the second mirror, of the light thus collected.
• This second mirror then focuses the light it receives on the light detection device which follows the optical system.
• This device generally comprises an entry slit and the second mirror then makes it possible to focus the light which it receives on this slit.
• this device is an optical emission spectrometer which actually includes such a slot.
• the size of the mirrors is dependent on the power and size of the light source, the distance between the latter and the mirrors and the distance between the 'latter and the detection device' or, more precisely, the slot of this device.
• the first and second mirrors are focusing, which makes it possible to amplify the light fluxes.
• first and second mirrors instead of lenses, solves the light absorption problems mentioned above.
• the first mirror a spherical, parabolic or ellipsoidal mirror is preferably used. It is the same for the second mirror.
• the first mirror can be pierced with a hole to allow the passage of the light from the 'second mirror to the light detection device (case of the examples of figures 6, 7 and 10).
• the optical system 50 which is schematically represented in FIG. 6, is placed between a light source 52 and a light detection device 54 whose entry slot has the reference 56.
• the first mirror 58 of the system 50 is concave while the second mirror 60 of this system is convex.
• the light 62 emitted by the source 52 is captured by the mirror 58 and focused by the latter towards the mirror 60 which in turn focuses it on the slot 56.
• the size of the light source 52 is comparable to that of the mirrors 58 and 60. However, it could be larger.
• the optical axis of the system 50 has the reference XI. It can be seen that the mirror 58 is much larger than the mirror 60, is located between the latter and the device 54 and has a hole 64 allowing the passage of the light that the mirror 60 focuses on the slot 56.
• the mirrors 58 and 60 are of the spherical type, for example, have the same axis which coincides with the axis XI and their respective foci Fl and F2 are on this axis XI.
• the focal distances of the mirrors 58 and 60 are respectively denoted dl and d2, with dl greater than d2.
• the foci Fl and F2 are distinct in the example of FIG. 6 but could be confused in other examples.
• the optical system 66 which is schematically represented in FIG. 7, is placed between a light source 68 and a light detection device 70 whose entry slot has the reference 72.
• the first mirror 74 of the system 66 is concave while the second mirror 76 of this system is convex.
• the light 78 emitted by the source 68 is picked up by the mirror 74 and focused by the latter towards the mirror 76 which focuses it at its turn on slot 72.
• the size of the light source 68 is small compared to the size of the mirrors 74 and 76. It can be, for example, 16 times smaller.
• the optical axis of the system 66 has the reference X2. It can be seen that the mirror 74 is much larger than the mirror 76, is located between the latter and the device 70 and has a hole 80 allowing the passage of the light that the mirror 76 focuses on the slot 72.
• the mirrors 74 and 76 are of the spherical type, for example, have the same axis which coincides with the axis X2 and their respective focal points F3 and F4 are on this axis X2.
• the focal distances of the mirrors 74 and 76 are respectively denoted d3 and d4, with d3 greater than d.
• the foci F3 and F4 are distinct in the example of FIG. 7 but could be confused in other examples.
• the optical system 80 according to the invention which is schematically represented in FIG. 8, is placed between a light source 82 and a light detection device 84 whose entry slot has the reference 86.
• the first mirror 88 of the system 80 is concave while the second mirror 90 of this system is convex.
• the light 92 emitted by the source 82 is captured by the mirror 88 and focused by the latter towards the mirror 90 which in turn focuses it on the slit 86.
• the two mirrors 88 and 90 are offset relative to each other and off-axis ("off axis") relative to the optical axis.
• the mirrors 74 and 76 are of the spherical type for example and their respective focal points are merged at the same point F.
• the focal distances of the mirrors 74 and 76 are respectively denoted d5 and d ⁇ , with d5 greater than d6.
• any polychromatic light emitted by any of the sources 52, 68 and 82 is focused on the entry slit of the corresponding light detection device.
• This type of light source emits polychromatic light, the rays of which, after entering the detection system, are dispersed as a function of their wavelengths.
• FIG. 9 where we see a glow discharge lamp 94, an optical emission spectrometer 96, which is dipersive in wavelength, and a system 98 for collecting light with mirrors, in accordance with l 'invention.
• the path followed by the light in the set 94-96-98 of FIG. 9 has the reference 100.
• the use of mirrors makes it possible to amplify the luminous fluxes and to solve in particular the problems of absorption and chromatic aberration mentioned previously.
• the assembly 94-96-98 of FIG. 9 can be used for the lights of respective wavelengths 121.567nm, 130.217nm, 149.262nm and 15 ⁇ , 144nm, respectively emitted by the elements hydrogen, oxygen, nitrogen and carbon during of their radiative de-excitation within the glow discharge cell.
• the optical system 98 can process, in addition to the light coming from the source 94, the light which comes from another light source 102 and to which the same path 100 is imposed by means of a semi-transparent mirror 104 adapted to the lights considered.
• the light or lights from the optical system 98 can be treated by a spectrometer 106, in addition to the spectrometer 96.
• a suitable semi-transparent mirror 108 is then provided to send the light or lights coming from the system 98 to the slot 110 of the spectrometer 106.
• the system which is the subject of the invention is capable of allowing considerable gains in terms of light flux transmitted and collected and in terms of spectral domains observable simultaneously.
• This system is not limited to a number of mirrors equal to two (see the description of FIG. 10). In addition, it is not limited to the use of spherical, parabolic or ellipsoidal mirrors.
• FIG. 10 is an alternative embodiment of FIG. 6, in which one uses, in addition to the mirrors 58 and 60, another mirror 112 making it possible to reflect the light coming from the system 50 towards the slot 56 of the device 54.
• Such an arrangement is for example usable when this device cannot be placed in alignment with the source 52.
• a polychromatic light source in particular a polychromatic light source whose spectrum contains one or more ultraviolet components. This possibility has already been considered above, in particular in the case where the source is a lamp, or cell, with luminescent discharge.
• an enclosure which is opaque to any light, in particular to ultraviolet radiation, and in which the source, the detection device and the mirrors are placed. Means are also provided for creating a vacuum in this enclosure or to fill it with a gas which is transparent to ultraviolet radiation.
• FIG. 6 This is • schematically illustrated in FIG. 6 where we see an enclosure 114 which is tight and opaque to any light and in which the source 52, the mirrors 58 and 60 and the device 54 are located.
• This enclosure is for example in a metal such as stainless steel.
• Pumping means 116 are provided to create a vacuum in this enclosure, so as to eliminate any gas, such as water vapor or dioxygen, capable of absorbing ultraviolet radiation.
• the enclosure 114 and the pumping means 116 are also schematically represented in FIGS. 9 and 10.
• these pumping means are replaced by means for filling the enclosure 114 with a gas which is transparent to ultraviolet radiation and contains, for example, neither water nor oxygen.
• the gas used is, for example, pure dinitrogen or a rare gas such as argon.
• These means for filling the enclosure 114 with gas comprise means 118 for injecting this gas into the enclosure.
• a hole 119, distant from the place of arrival of the gas in the enclosure, is provided in the wall thereof to allow the gas to escape therefrom (after which this gas can be pumped by means not shown). ).
• a gas circulation is thus established in the enclosure.
• the enclosure is rigid. However, one can also use a “flexible” enclosure.
• FIG. 8 This is schematically illustrated by FIG. 8 where the enclosure is in several parts: a main enclosure 120 is used, which contains the mirrors, and an auxiliary enclosure 122 which contains the source 82 and which is tightly connected to the enclosure 120 by a metal bellows 124.
• the detection device 84 is itself in a sealed enclosure 126 and the latter is connected in sealed manner to the enclosure 120 by another metallic bellows 128.
• the device, the mirrors and the source are thus in a “flexible” enclosure thanks to the bellows. This allows in particular to move the mirrors to refine the focus settings.
• such a "flexible" enclosure can also be used in the examples of FIGS. 6, 7, 9 and 10.
• a rigid enclosure is used, for example in the form of a tube, containing the source and the mirrors, and this enclosure is connected in a sealed manner, by a rigid or flexible conduit (bellows) , to another • sealed enclosure, containing the detection device.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Spectrometry And Color Measurement (AREA)
• Lenses (AREA)

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• 2002
  • 2002-10-08 FR FR0212467A patent/FR2845487B1/fr not_active Expired - Fee Related
• 2003
  • 2003-10-07 WO PCT/FR2003/002947 patent/WO2004034119A1/fr not_active Application Discontinuation
  • 2003-10-07 US US10/530,608 patent/US7492454B2/en not_active Expired - Fee Related
  • 2003-10-07 CA CA002501441A patent/CA2501441A1/fr not_active Abandoned
  • 2003-10-07 JP JP2004542562A patent/JP2006502399A/ja active Pending
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