Classifications

• • 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
• • 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
  • G01J3/10—Arrangements of light sources specially adapted for spectrometry or colorimetry
• • 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
  • G02B27/4233—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
  • G02B27/425—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 illumination systems
• • 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
  • G02F1/33—Acousto-optical deflection devices

Definitions

• Present invention relates to the devices intended for formation of directed optical irradiation that possesses spectral, power, spatial, polarization, and temporal characteristics given beforehand, and that can be used in different areas, such as in medical applications, in optical instrumentation, in optical information processing, or in light and illumination technology.
• a multi-purpose Light-Emitting-Diodes (LED) based lamp which contains several light sources, reflector, optical system, battery, and switch, wherein the light source is the LED-containing board having the shape of parabolically bent narrow stripe, equipped with the collimator and light waveguide.
• the light source with LEDs is located inside a solid plastic housing, which has a form of a sector with the convex side bent as a parabola or paraboloid, and equipped with LEDs, and the narrow stripe is truncated and connected with collimator or lens (Russian Federation Patent No. 2194212, published 2002.12.10).
• Disadvantage of the abovementioned device is impossibility to control the characteristics of output irradiation in a wide range. Particularly, spatial distribution of the emitted light remains uncontrolled.
• An assembly of LEDs is known that includes housing, the lenses for vertical and horizontal light directions from LEDs, the devices for control the LEDs bias current, and power source unit (USA Patent No. 5765940, published 1998.06.16). Disadvantage of this device is impossibility to control output irradiation characteristics in a wide spectral range because the LEDs spectrum is too narrow and there is no possibility to control their spatial characteristics.
• a broadband source of light is a key device needed for carrying out different spectrographic analyses. Such analysis provides, among others, measurements of constitutes of agricultural products and the composition and property of chemical substances. Spectrographic analysis instruments operating in visible range also have important use in analysis and matching of color documents. Efficient broadband source of light for a spectrometer is disclosed in the USA patent No.
• a spectrometer comprising a broadband light source is known, said light source comprising an array of LEDs where each LED emits a narrow wavelength band but the combination of them emits a desired range of wavelengths, switch means controlling whether the separate LED is on or off in any given time, and multiplexing means for controlling said switch means so as to produce a desired total wavelength range (USA Patent No. 5475221, published 1995.12.12).
• the present invention provides the multi-purpose source of polychromatic optical irradiation with spatial shape of output power distribution of the light beam remaining stable in a wide spectral range.
• the device comprises an array of LEDs operating at different wavelengths which are situated in the positioning assembly so that their irradiation is incident in a diffraction element under the angle specific for each wavelength in such a way that the diffracted or refracted beams propagate in one common direction composing the total luminous flux in which the directed optical irradiation with characteristics given beforehand, is provided.
• the multi-purpose source of polychromatic optical irradiation comprises housing, a power source unit, an array of LEDs with respective electronic circuits providing control of the bias current through each LED, and an optical component to control the geometrical characteristics of the beam.
• the device for LEDs positioning with three degrees of freedom, and the diffraction element are additionally installed into the housing.
• the array of light emitting elements is mounted inside the housing by means of bonding elements so that to provide adjustment of each light emitting element.
• the diffraction element for example, diffraction grating
• Said diffraction grating provides selection of certain part of the spectrum from each LED as well as formation of output light irradiation according to the given beforehand characteristics.
• said diffraction grating serves to converge n light beams with different ⁇ ,-, which provides formation of the total light flux and propagation of the deflected irradiation with given beforehand spectral, spatial and temporal characteristics.
• several chips comprising small-size unpackaged LEDs are arranged in one line in the direction being normal to the diffraction plane of the diffraction element.
• the plurality of such lines being parallel to each other provides the assembly of line-shaped light emitting elements that operates by the same way as the point-shape light emitting elements in the first embodiment of the invention providing the line- shaped cross section of the output luminous flux.
• the diffraction grating can be substituted by acousto-optic Bragg cell supported with electronics means for excitation and control the diffraction grating running inside said cell.
• the mirror is located in the light beam path by such a way that the light reflected from this mirror is incident to the diffraction element according to the mentioned above expression.
• the positioning device provides the necessary adjustment of the LEDs according to the expression mention above in order to obtain the total device spectral characteristic equal to that given beforehand.
• the presence of the said mirror provides the size minimization of the total device.
• Said acousto-optic Bragg cell provides not only the total light flux formation but also control of the output light power of any spectral component.
• Yet another embodiment of the invention comprises a sequence of the diffraction grating and the acousto-optic Bragg cell arranged in such a way that a part of light-emitting elements is optically connected with said diffraction grating and another part is optically connected with said acousto- optic Bragg cell providing that irradiation emitted by any of light-emitting elements propagates in the same direction as from other elements after said consequence of the diffraction grating and the acousto-optic Bragg cell.
• Figure 1 illustrates the schematic of the multi-purpose source of polychromatic optical irradiation with stable spatial mode of output light beam in a wide spectral range.
• Figure 2 demonstrates the schematic of the multi-purpose source of polychromatic optical irradiation in which an acousto-optic Bragg cell is applied as a diffraction element instead of diffraction grating.
• Figure 3 shows the schematic of the multi-purpose source of polychromatic optical irradiation in which both diffraction grating and acousto-optic Bragg cell are used as diffraction elements.
• Figure 4 shows the schematic of the source of polychromatic optical irradiation generating the light beam of the line-shaped cross section, which shape remains the same in the wide spectral range.
• FIG. 1 illustrates schematic of a preferred embodiment according to the invention in which multi-purpose source of polychromatic optical irradiation comprises housing (10), an array of light-emitting elements (12 ⁇ ,12 2 , ... 12,,), a micro-optical assembly (13) for formation of spatial characteristics of light beams emitted either by LEDs or by light-emitting crystals, a mirror (15), a diffraction element (16), an optical assembly for formation of the output beam (17), and adjustment elements (11) for adjustment of light-emitting elements, as well as the electronic control device (14).
• the housing (10) contains small platforms (11) for spatial positioning and fixing of the light- emitting elements (12). These platforms can be fabricated in the housing (10) by mechanical processing or vacuum casting.
• the angle between the plane of each platform (11) and the plane of the diffraction element (16) is to be calculated before fabrication of the housing (10) with said small platforms. This angle particularly depends on the wavelength of the light emitted by the elements (12).
• the thin layer of insulator for example, AI 2 O 3
• a micro-optical assembly (13) is mounted after the light emitting elements (12) are fixed in the housing (10) and electrical connection is supplied to all light-emitting elements (12).
• the device shown in Fig.l operates by the following way.
• Adjustment elements (11) also provide that the projection of the incident light-beam axis on the plane of the diffraction grating (16) is orthogonal to the grating grooves. Moreover, the adjustment elements (11) provide the spatial coincidence of all the light beams emitted by different light-emitting elements (12) in the plane of the diffraction grating (16). Light beams from n light-emitting elements (12 ⁇ , ...
• the mirror (15) can be installed in the way of the said light beams propagation to provide compactness of the device. Since the diffraction angle ( ⁇ ) is the same for all wavelengths, n light beams diffracted from the diffraction grating (16) propagate in the same direction forming the output beam.
• the total luminous flux of the output beam consists of light beams emitted by n light-emitting elements.
• the output light beam is characterized now by any arbitrary combination of the wavelengths emitted from n light-emitting elements because any of these elements can be switched on/off independently. Intensity of total luminous flux as well as any of its spectral components can be controlled by the driving current of the light-emitting elements (12). Note that the spatial distribution of the output power remains the same for all spectral components of the luminous flux.
• the solid angle ⁇ ou t of the output irradiation is defined by the spatial parameters of the optical assembly and by the shape of the diffraction grating.
• An additional feature of the multi-purpose source of polychromatic irradiation is possibility to introduce a modulation of both the total output power and the power of any spectral component or their arbitrary combination.
• Such power modulation is achieved due to modulation of the driving current of the light-emitting elements (12).
• the driving current of each light emitting element is controlled by means of the control device (14).
• a programmable microcomputer can be used as the control unit (14). The microcomputer allows control of each light-emitting element irradiation time, the order of switching on/off each light-emitting element or their combination, and the modulation of both the total luminous flux and each spectral component of the output beam.
• Either light-emitting diodes or light-emitting crystals can be used as the light- emitting elements (12).
• FIG. 2 Another preferred embodiment of the invention is shown in Fig. 2 where an acousto-optic Bragg cell serves as the diffraction element (26).
• the Bragg cell (26) is supported with electronic means (28) for excitation inside the cell an acoustic wave. This wave modulates the refractive index of the Bragg cell (26) providing formation of the running diffraction grating, which operates as a diffraction element.
• the spacing ( ⁇ ) of the running diffraction grating is defined by the parameters of the acoustic waves and can be controlled by said electronics means.
• the multi-purpose source of the polychromatic light with the acousto-optic Bragg cell operates in the following way.
• a is the angle of incidence measured between the normal to the Bragg cell (26) and the direction of the beam emitted from /-th light emitting element
• ⁇ is the angle of light diffraction from the Bragg cell
• m is an integer
• A,- is the wavelength of the light emitted by /-th light-emitting element.
• Schematic of the light source shown in Fig. 3 represents yet another embodiment of the invention. Because of the similarity of light beam diffraction from the diffraction grating and from the acousto-optical Bragg cell, the light beams emitted by a part of light-emitting elements [for example, elements from (12 ⁇ ) to (12,) as shown in Fig.3] are directed to the diffraction grating (16) while the other part [elements from (12 /+ ⁇ ) to (12 ⁇ )] is optically connected with the acousto-optic Bragg cell (26).
• a part of light-emitting elements for example, elements from (12 ⁇ ) to (12,) as shown in Fig.3
• the other part is optically connected with the acousto-optic Bragg cell (26).
• the diffraction grating and Bragg cell are installed in a consecutive sequence in such a way that any light beam diffracted from the diffraction grating (16) and any light beam diffracted from the acousto-optic Bragg cell (26) propagates in one and the same direction.
• the control device (14) keeps the Bragg cell non-excited and simultaneously activates any or several light-emitting elements of array (12 ⁇ ) ... (12,).
• the light beam emitted by these activated elements diffracts from the diffraction grating (16) to propagate at one and the same angle ⁇ and then freely propagates through non-activated Bragg cell (26).
• the control device (14) activates one of the light- emitting elements from the array (12 ⁇ i) ... (12 / 0 and simultaneously the control device (14) communicates with electronic means (28) so as to provide excitation of the acoustic wave with the spacing ⁇ corresponding to the desired output wavelength similarly as it was explained in the previous paragraph for embodiment shown in Fig.2.
• This configuration allows minimization of the light power losses, and, consequently, it increases the efficiency of the object illumination.
• the diffraction grating can be replaced by another Bragg cell or even by several Bragg cells providing that the diffracted beams from any Bragg cell propagate in one and the same direction. Synchronization of proper light-emitting element's activation and excitation of the acoustic wave with proper spacing in proper Bragg cell is carried out by the control device (14) through the respective electronic means (28). In this case the sequence of several Bragg cells serves as the diffraction element.
• a source of polychromatic optical radiation shown in Fig. 4 operates in the way, which is very similar to that described for the light source described by Fig. 1.
• the arrays of light emitting elements (42 ⁇ ) ... (42,,) play the same role as the separate light emitting elements (12 ⁇ ) ... (12 ⁇ ) shown in Fig. 1.
• Each array (42) consists of a set of unpackaged light-emitted elements arranged in the line. All elements in any array of (42) emit light of almost the same wavelength. However, the wavelength of the light emitted by a line-shaped array (42,) may be different from the wavelength emitted by another array (42,7, for example).
• the line-shaped arrays (42) are preferably situated parallel one to another.
• the arrays (42) are installed in the support for adjustment (41), which in its turn is fixed to the base of the housing (40).
• the light emitted by the line-shaped arrays (42) of light emitting elements is transmitted through the optical means (43), which concentrate the light in the diffraction element (44).
• the diffraction element (43) is mounted so that the plane of light diffraction is orthogonal to the main direction of the arrays (42) of light emitting elements.
• ⁇ is the diffraction angle
• m is an integer
• ⁇ ,- is the wavelength of the light emitted by /-th array of the light emitting elements.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Optical Couplings Of Light Guides (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)

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Citations (2)

• 2004
  • 2004-02-17 RU RU2004105078/28A patent/RU2287736C2/ru not_active IP Right Cessation
• 2005
  • 2005-02-08 WO PCT/FI2005/050020 patent/WO2005078484A1/en active Application Filing

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