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
  • G01J3/12—Generating the spectrum; Monochromators
  • G01J3/18—Generating the spectrum; Monochromators using diffraction elements, e.g. grating
  • G01J3/1804—Plane gratings
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/106—Beam splitting or combining systems for splitting or combining a plurality of identical beams or images, e.g. image replication
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/1086—Beam splitting or combining systems operating by diffraction only
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/1086—Beam splitting or combining systems operating by diffraction only
  • G02B27/1093—Beam splitting or combining systems operating by diffraction only for use with monochromatic radiation only, e.g. devices for splitting a single laser source
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/12—Beam splitting or combining systems operating by refraction only
  • G02B27/126—The splitting element being a prism or prismatic array, including systems based on total internal reflection
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
  • G02B27/4233—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element [DOE] contributing to a non-imaging application
  • G02B27/4244—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element [DOE] contributing to a non-imaging application in wavelength selecting devices
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
  • G02B27/4272—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having plural diffractive elements positioned sequentially along the optical path
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping

Definitions

• the invention relates to a dispersive optical device for use such as a spectroscope, polarizer, monochromator or the like, of for use as a basic component for a monochromator, spectograph, spectophotometer, polarizer or the like.
• One object of the invention is to propose a dispersive device which can have small physical dimensions, is robust, can be produced at a relatively low cost, and has relatively high light strength and high resolution.
• Another object of the invention is to propose a dispersive device which furthermore allows through-sighting with transmission of an image which is in scale. Further objects and advantages of the invention will be apparent from the following.
• the inventive dispersive optical device includes a dispersi ⁇ e optical member comprising a first and a second grating applied to planar parallel substrate surfaces, preferably reflection gratings which have the same grating frequency and have parallel grating scores or rulings, the second grating being adapted for being struck by a portion of the light defracted by the first grating, so that light which is defracted by the second grating is parallel with light incident on the first grating. Since a greater defraction angle gives a greater angular dispersion, the angle between a normal to a grating and a line between the gratings should attain at least 60 o and preferably at least 70 o. The upper limit of the angle is 90 o, for natural reasons, but attains in practice to about 88 o . The angle is selected to advantage within the interval 80-85°.
• the angular variation will be small for rays between the gratings. This signifies that only a correspondingly small spectrum portion of parallel light incident on the first grating will strike the second grating. Since the gratings are mutually the same, light defracted by the -second grating will be parallel to the light incident on the first grating. By measuring the angle of the member (i.e. the grating) to incident light, an indication can be obtained of the wavelength of the light observed at the member output.
• the member when the member is utilized as a monochromator, for example, it can be arranged for light of a predetermined wavelength range to leave the output of the member by setting a given angle between incident light and the member.
• a focussing lens can be arranged behind the member output with a slit after the lens, suitably at its focal point, so that aligning errors are eliminated, as well as extraneous light wavelengths, only the whole of the pertinent pencil of rays being looked after.
• the dispersive member can be provided with a wavelength scale which is readable at the output from the second grating, so that the wavelength of the light observed at the output of the second grating can be read off by eye directly.
• the gratings can be arranged opposite, and adjacent each other between a first and a second planar parallel substrate, the substrates being arranged mutually parallel and adjacent.
• a third planar parallel substrate is preferably arranged perpendicular to said thereof first and second substrate at one end / ⁇ mirror means can hereby be arranged at the free surface of the third substrate.
• Light which is defracted by the first grating can thus be arranged for total reflection at the free surface of the first substrate, for subsequently striking the first mirror means, whereat it is directed towards the free surface of the second substrate for being totally reflected there.
• the light can subsequently be arranged for directing towards the second grating, where it is defracted and departs from the member.
• the departing light will, however, be mirror-inverted in relation to the light incident on the first grating, although the member can be made such that light which is totally reflected at the free surface of the second substrate strikes a second, mirror means at the free end of the second substrate, for direction towards the second grating with an angle of incidence corresponding to the defraction angle at the first grating.
• both gratings of the member are adapted mutually adjacent and opposite, the source of the light incident on the first grating can be observed with full sharpness and substantially without parallax.
• Said first and second gratings can possibly constitute opposing sides of a single grating element.
• a light- absorbent coating should be arranged to surround the member excepting the substrate surfaces which form the input and output of the member and the substrate surfaces at which said total reflections are arranged to occur.
• Fig. 1 schematically illustrates a first embodiment of a dispersive member incorporated in the device in accordance with the invention.
• Fig. 2 illustrates an alternative embodiment of the device in accordance with the invention.
• Fig. 3 illustrates an embodiment of the device according to Fig. 1.
• Fig. 4 illustrates a device in accordance with the invention, utilizable as a monochromator and including the member according to Fig. 1.
• Fig. 5 is a section taken along the line V-V in Fig. 4.
• Figs 6 and 7 illustrate members according to Fig. 1, incorporated in a spectrograph and a spectrophotometer, respectively.
• Fig. 8 illustrates a member in accordance with the invention, provided with an angle scale.
• Fig. 9 illustrates a monochromator in accordance with the invention containing two members according to Fig. 1.
• a dispersive member 1 is illustrated in Fig. 1, and includes a transparent substrate 2, e.g. of float glass, with planar parallel chief surfaces 21,22. At one end zone of the member 1 there is a first refletion grating 3 arranged on the surface 22. At the other end zone of said member there is a second reflection grating 4 arranged on the surface 21.
• the substrate 2 and gratings 3,4 are. outwardly covered by a light-absorbent medium 5, e.g. a black paint, with a refractive index as near to that of the substrate as possible, excepting at the substrate surfaces 6,7 opposite the respective grating 3,4.
• the surface 6 can be the input of the member, in which case the surface 7 constitutes its output.
• the gratings 3,4 have the same grating frequency, and mutually parallel scores or rulings, extending normal to the plan of the Fig. 1.
• the function of the member is as follows. Assume that white light strikes the substrate surface 6 at an angle of incidence of ⁇ 1 . The light is refracted there so that the angle of incidence will be ⁇ 2 to the grating 3.
• ⁇ 2 is defined by the expression arcsin ((sin ⁇ 1 )/n 2 ), n 2 being the substrate refractive index.
• b 1 width of grating 3
• b 2 width of grating 4
• the grating 4 will only be struck by light with a wavelength between ⁇ m ax and ⁇ min . ( ⁇ and ⁇ min are obtained by insertion of ⁇ max and ⁇ min in the grating formula above.) A portion of the light incident on the grating 4 will be defracted. If grating 4 has the same frequency as grating 3, the defraction angle will be equal to the angle of incidence on the grating 3. i.e. ⁇ 2 . The light leaving the grating 4 will thus be parallel to the light incident on the grating 3.
• t.he dispersive member according to Fig. 1 is utilizable as a spectroscop and is directly readable by the human eye.
• Fig. 4 illustrates a member 1 according to Fig. 1, which is pivotably mounted about a shaft substantially in the plane of the grating parallel to the grating lines, and at half the width of the grating 3.
• the member 1 is enclosed in a housing 30 having an opening 31 opposite the grating 3.
• transmission gratings 3', 4' are utilized, which are applied to the substrate 2. Otherwise, the same conditions apply as for Fig. 1.
• the member according to Fig. 3 includes two planar parallel substrates 102,103, on which the gratings 3,4 are applied directly opposite each other.
• the substrates 102, 103 are placed one against the other.
• a third substrate 104 is abutted tightly against the ends of the substrates 102, 103.
• Both ends of the substrate 104 are provided with a reflecting coating 107,108 to form mirrors at right angles to the plane of the gratings 3,4.
• a light-absorbing coating 5 is applied to the member, excepting .at its input 6 and output 7, and possibly the positions 105 and 106.
• the free surfaces of the substrares 102,103 may be coated to allow total reflection of light defracted by the grating 3, as is illustrated by the dashed ray path.
• a medium with a lower refractive index than that of the substrate can be applied at the positions 105,106, whereat the coating 5 can be applied to the medium in the positions 105,106.
• Incident light is defracted at the grating 3, mirrored at the position 105 at the mirror 107, and at the position 106 at the mirror 108 to strike the grating 4 at an angle of incidence corresponding to the defraction angle at the grating 3.
• Figs. 4 and 5 illustrate a device in accordance with the invention, which includes a member according to Fig. 1 and is adapted for utilization as a monochromator and/or spectrograph or the like.
• a mirror 32 is arranged to deflect incident light by 90°.
• a mirror 33 parallel to the mirror 32, deflects the light to the incident direction.
• the mirror 33 is arranged parallel displaceable at right-angles, to the incident light.
• the mirror 33 is arranged to direct incident light to the input 6 of the element 1.
• the member 1 is pivotably mounted on a shaft 34, which is mounted in the plane of the grating 4 at half the width thereof.
• the shaft 34 extends, in the normal plane to Fig. 4.
• the focussing lens 3-5 is arranged opposite the output 7 of the member 1 to focus departing light towards a slit 36 in the housing 30.
• the slit 56 is in a position defined by a line through the shaft 34 parallel to the incident light.
• a screw 37 is connected to the member 1 in a position at a distance from the shaft 34.
• the screw 37 is adapted to provide pivoting of the member 1 about the shaft 34 when the screw is turned.
• the screw 37 or the member 1 is connected to the mirror 33 to provide parallel displacement of the mirror 33, so that light deflected by the mirror 53 strikes the input 6 of the member 1 irrespective of the pivotal position of the member.
• the screw 37 has a wheel 39 and is connected to a revolution counter indicating the angle of the member 1, and thus the light wavelength passing through the slit 36.
• Fig. 5 illustrates a mirror 41, pivotably mounted on a shaft 40 with an operating wheel 43.
• An eyepiece 42 is mounted in the upper part of the housing 30.
• the lens 35 focusses in front of the eyepiece 42, and a graduation scale 49 is arranged at the focus of the lens 35.
• the scale 49 extends normal to the plane of the Fig. 5.
• the mirror 40 and eyepiece 42 thus allow visual scanning of the light, and the scale provides an indication of the wavelength in question.
• Fig. 6 illustrates an apparatus housing 50 with an opening 51 , in the housing 50 there is a member 1 according to. Fig. 1, mounted with the input 6 opposite the opening 51,so that light coming through the opening strikes the input 6 substantially normal to the grating 3.
• a focussing lens 55 is arranged at the output 7 of the member 1 , and a diode array 59 is arranged after the lens 55. This diode array can then sense the focussing position, and thereby register the detected wavelength.
• the apparatus according to Fig. 6 thus constitutes a spectograph.
• Fig. 7 illustrates a spectrophotometer
• a detector means 156 which is pivotable about a shaft through the centre of the grating 4.
• the means 156 contains a focussing lens 155 and a detector 159.
• the angle of the means 156 to the grating 4 is red so that a purposeful registration of the scanned spectrum can be obtained.
• Figs. 6,7 illustrate only two examples of a plurality of possible applications, wherein the member in accordance with the invention can be utilized.
• Fig. 8 schematically illustrates a member according to Fig. 1 with an angle scale 81 and a focussing member 82 depicting the scale at infinity in front of the input 6.
• the scale 81 is suitably arranged visible in a marginal area of the image field.
• the angle scale 81 and member 82 can of course be arranged in the apparatuses according to Figs. 2 and 3 also.
• the monochromator according to Fig. 9 can be said to contain two series-connected members according to Fig. 1.
• the departing light is caused to be coaxial with the incident light, and the wavelength of departing light can easily be adjusted by the angular setting of both members 1 , whereby the member on the input side is pivotable about a shaft 71 at the centre of the grating 3 and the other member 1 is pivotable about a shaft 72 at. the centre of the other grating 4.
• Pivoting both members is arranged to be done simultaneously and to the same extent, so that the angle to Incident light of the first member is always the same as the angle of the second member to departing light.
• No focussing member is required in the apparatus according to Fig. 9.
• a focussing lens 75 with large focal length, which Is arranged between the output of the first member and the input of the second member, has been found to almost double the light intensity of the monochromator, simultaneously as resolution is more or less doubled.
• the lens 75 is arranged at an angle of about 55 to the ray path.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Electromagnetism (AREA)
• Nonlinear Science (AREA)
• Plasma & Fusion (AREA)
• Engineering & Computer Science (AREA)
• Diffracting Gratings Or Hologram Optical Elements (AREA)
• Spectrometry And Color Measurement (AREA)
• Lasers (AREA)
• Laser Surgery Devices (AREA)
• Analysing Materials By The Use Of Radiation (AREA)

Priority Applications (2)

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Publications (1)

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Citations (10)

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• 1980
  • 1980-05-28 SE SE8003968A patent/SE421568B/sv not_active IP Right Cessation
• 1981
  • 1981-03-30 AT AT81900924T patent/ATE9041T1/de not_active IP Right Cessation
  • 1981-03-30 AU AU70361/81A patent/AU7036181A/en not_active Abandoned
  • 1981-03-30 EP EP81900924A patent/EP0059706B1/en not_active Expired
  • 1981-03-30 US US06/346,044 patent/US4591270A/en not_active Expired - Fee Related
  • 1981-03-30 DE DE8181900924T patent/DE3165503D1/de not_active Expired
  • 1981-03-30 WO PCT/SE1981/000101 patent/WO1981003552A1/en not_active Ceased
  • 1981-03-30 JP JP56501208A patent/JPS57500998A/ja active Pending
  • 1981-05-26 WO PCT/SE1981/000156 patent/WO1981003551A1/en not_active Ceased
  • 1981-05-26 US US06/346,041 patent/US4397525A/en not_active Expired - Fee Related
  • 1981-05-26 JP JP56501751A patent/JPS57500951A/ja active Pending
  • 1981-05-26 EP EP81901289A patent/EP0058667B1/en not_active Expired
  • 1981-05-26 AT AT81901289T patent/ATE8938T1/de not_active IP Right Cessation
  • 1981-05-26 DE DE8181901289T patent/DE3165378D1/de not_active Expired

Patent Citations (10)

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