WO2002007229A1 - Light emitting diode arrangements - Google Patents

Light emitting diode arrangements Download PDF

Info

Publication number
WO2002007229A1
WO2002007229A1 PCT/GB2001/003172 GB0103172W WO0207229A1 WO 2002007229 A1 WO2002007229 A1 WO 2002007229A1 GB 0103172 W GB0103172 W GB 0103172W WO 0207229 A1 WO0207229 A1 WO 0207229A1
Authority
WO
WIPO (PCT)
Prior art keywords
arrangement according
substrate
light emitting
emitting diode
reflector
Prior art date
Application number
PCT/GB2001/003172
Other languages
French (fr)
Inventor
Neil Thomson Gordon
Stanley Desmond Smith
Charles Thomas Elliott
Harvey Hardaway
Fedor Vladimir Karpushko
Original Assignee
Qinetiq Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Qinetiq Limited filed Critical Qinetiq Limited
Priority to AU2001270823A priority Critical patent/AU2001270823A1/en
Publication of WO2002007229A1 publication Critical patent/WO2002007229A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/20—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • H01L33/60—Reflective elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/40—Materials therefor
    • H01L33/405—Reflective materials

Definitions

  • the present invention relates to light emitting diodes (LEDs). It is particularly but not exclusively directed to LEDs which emit electromagnetic radiation through a -side surface of the semiconductor structure which lies parallel to the diode junction.
  • Light emitting diodes have many applications, including telecommunications, spectroscopy and gas sensing.
  • a recent development is that of room temperature infra-red light emitting diodes which cover the 3 to 12 micron spectral region where gases such as carbon dioxide, carbon monoxide, nitrogen oxides, sulphur oxides and carbohydrates have strong selective absorption bands enabling quantitative gas detection.
  • a major reason for the low output power is the inefficiency in transmitting the light generated at the diode junction to the exterior, and a principal cause thereof is total internal reflection within the device.
  • light can only pass from an optically dense medium (high real refractive index of value n) to air (where n is nominally unity) if its angle of incidence is no greater than sin ⁇ l/n), and it otherwise undergoes total internally reflection.
  • the present invention is directed to reducing the mount of light lost due to reflection within LEDs, and/or to increasing the directionality of light emitted from LEDs.
  • the first step should reduce the optical output power necessary from the diode junction for a given device overall output, or should increase the device overall output for a given output from the diode junction.
  • the second step should reduce the optical output power necessary from the diode junction for a given device output in a predetermined direction, or should increase the device output in a predetermined direction for a given output from the diode junction.
  • the present invention provides a light emitting diode arrangement comprising a light emitting diode on or in a semiconductor substrate, a first side of the diode which faces away or outwardly from the substrate being provided with a reflector, wherein the semiconductor substrate includes an optical focussing, interference or diffractive element adjacent a second side of the diode opposed to the first side.
  • optical element with well defined light directing properties (for example either a grating type structure or a lens) it is possible to arrange that the number of reflections before a light beam leaves the device is minimised, so reducing losses due to optical abso ⁇ tion within the device inter alia.
  • much of the light which does not leave at first incidence on the optical element output surface is redirected to the reflector with a much reduced angle of incidence whereby after reflection it is much more likely to be able to leave via the optical element.
  • the element is a grating
  • the light returning therefrom does not necessarily have the same (reflected) angle as the light incident thereon.
  • the focussing element may comprise a curved surface for example a part spherical or hemispherical surface.
  • the interference element may comprise a Fresnel lens.
  • the latter could also be regarded as a focussing element.
  • the diffractive element may be a simple one dimensional diffraction grating or a Fresnel lens, but preferably it is a three dimensional grating (regions of differing heights with differing periodicities - equivalent to the superposition of two or more one or two dimensional gratings), or a two dimensional grating.
  • the diffractive element grating may be defined by periodically varying thicknesses of transparent material.
  • the optical element may do so in analogue manner, as in the part spherical or hemispherical lens mentioned above, or in a diffraction grating.
  • adjacent regions of the optical element may take discrete values of thickness, and this is preferred when a diffractive or interference element is used. Most simply there are only two thickness values, but preferably there are 3, 4, or even 8, since increasing the number of values can assist in efficiently light extraction.
  • the focussing, interference or diffractive element is preferably formed within the thickness of the semiconductor substrate, e.g. by being formed from the material of the substrate.
  • the substrate is etched downward from the face opposed to the LED to define the element.
  • the element may be formed from a separate material on the semiconductor substrate in optical contact therewith.
  • a further semiconductor layer may be deposited on the substrate and be shaped to provide a focussing interference or diffractive element, for example by etching or in milling.
  • a separate layer of material may be secured in optical contact with the substrate and be shaped to provide a focussing or diffractive element either before or after the securing step.
  • the securing may be effected by a sufficiently thin layer of adhesive using special tooling and controlled pressure.
  • optical contact is meant that the gap between the device and the element is no greater than one quarter of the LED wavelength within the material (i.e. vacuum wavelength divided by n), thus providing a condition in which total internal reflection is effectively prevented and permitting light generated within the device to penetrate through the element surface over a wide range of incident angles.
  • a separate element preferably has a refractive index differing from that of the adjacent semiconductor substrate by no more than 1, more preferably no more than 0.5, even more preferably no more than 0.3. Most preferably, the two indices are substantially equal, e.g. by using the same material.
  • the reflector may be provided by the supporting substrate itself, if it is formed of a material which is reflective per se, or includes a reflective coating. Alternatively a reflective coating may be applied to the LED surface.
  • the reflector may provide specular or diffuse reflection.
  • the supporting substrate is etched to form a curved surface, for example ellipsoidal or part spherical, and the adjacent LED surface is shaped correspondingly.
  • the resulting directed reflection can improve efficiency of light extraction.
  • Figure 1 shows a first embodiment of the invention in diagrammatic cross-section
  • Figure 2 shows a second embodiment of the invention in diagrammatic cross-section.
  • Figure 1 shows a first arrangement according to the invention in which an LED mesa 1 is formed upon (and normally integrally with) a semiconductor substrate 2.
  • the exterior face of the mesa 1 is in contact with a reflective (mirror) electrode 3 on and supported by a further substrate 4.
  • a microlens 5 having a part spherical surface 6 is defined within the substrate 2 by etching down from the surface opposed to the LED mesa.
  • Figure 2 is similar to Figure 1, except that the lens 5 is replaced by a two or three dimensional height stepped diffraction grating 7.
  • the reflector may be a coating on the appropriate face of the LED.

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Power Engineering (AREA)
  • Led Device Packages (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Led Devices (AREA)

Abstract

To increase the amount and/or directionality of light from a light emitting diode (LED) 1 located on or in a semiconductor substrate (2), a first side of the diode which faces away from the substrate is provided with a reflector (3) (shown as a mirror electrode on a second larger substrate (4), but it may be a specular coating on the LED), and the substrate (2) includes an optical focussing (e.g. Lens), interference (e.g. Fresnel lens) or diffractive (e.g. grating) element (5) adjacent a second side of the diode opposed to the first side. Preferably the element (5) is formed within the thickness of the substrate (2) by etching downwards from the surface remote from substrate (4). The height variation in a grating element (5) may be binary or multi-valued, and the grating may be one two or three-dimensional. The side of the LED adjacent reflector (3) may be curved.

Description

Light Emitting Diode Arrangements
The present invention relates to light emitting diodes (LEDs). It is particularly but not exclusively directed to LEDs which emit electromagnetic radiation through a -side surface of the semiconductor structure which lies parallel to the diode junction.
Light emitting diodes have many applications, including telecommunications, spectroscopy and gas sensing. A recent development is that of room temperature infra-red light emitting diodes which cover the 3 to 12 micron spectral region where gases such as carbon dioxide, carbon monoxide, nitrogen oxides, sulphur oxides and carbohydrates have strong selective absorption bands enabling quantitative gas detection.
It is clearly advantageous to be able to maximise the optical output power of a light emitting diode. For example in infra-red gas sensing at low concentrations, such as in the parts-per-billion (ppb) to parts-per-million (ppm) range, the output powers of existing devices are not sufficient to provide conditions allowing a good signal-to- noise ratio.
A major reason for the low output power is the inefficiency in transmitting the light generated at the diode junction to the exterior, and a principal cause thereof is total internal reflection within the device. As is well known, light can only pass from an optically dense medium (high real refractive index of value n) to air (where n is nominally unity) if its angle of incidence is no greater than sin ^l/n), and it otherwise undergoes total internally reflection. Thus, for a side emitting LED based on indium antimonide (InSb), where n = 4, and assuming a uniform angular distribution of optical emission from the diode junction over a solid hemispherical angle 2π towards a planar side surface of the device, only 3% of the light emitted within the junction is directly transmitted through the planar surface.
Additionally, the latter small amount of light is emitted over a large solid angle. It is commonly difficult or impractical to collect light within a large solid angle by the use of external optics, thereby adding to the disadvantages when a directed beam of light is required. The present invention is directed to reducing the mount of light lost due to reflection within LEDs, and/or to increasing the directionality of light emitted from LEDs. The first step should reduce the optical output power necessary from the diode junction for a given device overall output, or should increase the device overall output for a given output from the diode junction. The second step should reduce the optical output power necessary from the diode junction for a given device output in a predetermined direction, or should increase the device output in a predetermined direction for a given output from the diode junction.
It is known to provide an LED between a reflector and a textured surface, one example being described in "Compound Semiconductors" 6(4), May/June 2000, page 55. However, the textured surface is generally random, and does not provide optimal light directing properties for efficient light extraction therethrough.
It is also known to provide a Fresnel lens as a separate layer on the underside of a semiconductor substrate on the other side of which is an LED (see US 5,181,220). While this may improve light extraction, there appears to be no clear disclosure of an underlying reflector.
The present invention provides a light emitting diode arrangement comprising a light emitting diode on or in a semiconductor substrate, a first side of the diode which faces away or outwardly from the substrate being provided with a reflector, wherein the semiconductor substrate includes an optical focussing, interference or diffractive element adjacent a second side of the diode opposed to the first side.
By providing an optical element with well defined light directing properties (for example either a grating type structure or a lens) it is possible to arrange that the number of reflections before a light beam leaves the device is minimised, so reducing losses due to optical absoφtion within the device inter alia. Ideally much of the light which does not leave at first incidence on the optical element output surface is redirected to the reflector with a much reduced angle of incidence whereby after reflection it is much more likely to be able to leave via the optical element. For example, where the element is a grating, the light returning therefrom does not necessarily have the same (reflected) angle as the light incident thereon. The focussing element may comprise a curved surface for example a part spherical or hemispherical surface.
The interference element may comprise a Fresnel lens. The latter could also be regarded as a focussing element.
The diffractive element may be a simple one dimensional diffraction grating or a Fresnel lens, but preferably it is a three dimensional grating (regions of differing heights with differing periodicities - equivalent to the superposition of two or more one or two dimensional gratings), or a two dimensional grating.
The diffractive element grating may be defined by periodically varying thicknesses of transparent material.
Where the optical element varies in thickness it may do so in analogue manner, as in the part spherical or hemispherical lens mentioned above, or in a diffraction grating. However, adjacent regions of the optical element may take discrete values of thickness, and this is preferred when a diffractive or interference element is used. Most simply there are only two thickness values, but preferably there are 3, 4, or even 8, since increasing the number of values can assist in efficiently light extraction.
The focussing, interference or diffractive element is preferably formed within the thickness of the semiconductor substrate, e.g. by being formed from the material of the substrate. In a preferred embodiment, the substrate is etched downward from the face opposed to the LED to define the element.
Alternatively, however, the element may be formed from a separate material on the semiconductor substrate in optical contact therewith. For example a further semiconductor layer may be deposited on the substrate and be shaped to provide a focussing interference or diffractive element, for example by etching or in milling. Alternatively a separate layer of material may be secured in optical contact with the substrate and be shaped to provide a focussing or diffractive element either before or after the securing step. The securing may be effected by a sufficiently thin layer of adhesive using special tooling and controlled pressure. By "optical contact" is meant that the gap between the device and the element is no greater than one quarter of the LED wavelength within the material (i.e. vacuum wavelength divided by n), thus providing a condition in which total internal reflection is effectively prevented and permitting light generated within the device to penetrate through the element surface over a wide range of incident angles.
Where a separate element is provided it preferably has a refractive index differing from that of the adjacent semiconductor substrate by no more than 1, more preferably no more than 0.5, even more preferably no more than 0.3. Most preferably, the two indices are substantially equal, e.g. by using the same material.
The reflector may be provided by the supporting substrate itself, if it is formed of a material which is reflective per se, or includes a reflective coating. Alternatively a reflective coating may be applied to the LED surface.
The reflector may provide specular or diffuse reflection.
In one embodiment, the supporting substrate is etched to form a curved surface, for example ellipsoidal or part spherical, and the adjacent LED surface is shaped correspondingly. The resulting directed reflection can improve efficiency of light extraction.
Further details and advantages of the invention will become apparent upon a reading of the appended claims, to which the reader is referred, and upon a consideration of the following description of embodiments of the invention made with reference to the accompanying drawing, in which:
Figure 1 shows a first embodiment of the invention in diagrammatic cross-section; and
Figure 2 shows a second embodiment of the invention in diagrammatic cross-section.
Figure 1 shows a first arrangement according to the invention in which an LED mesa 1 is formed upon (and normally integrally with) a semiconductor substrate 2. The exterior face of the mesa 1 is in contact with a reflective (mirror) electrode 3 on and supported by a further substrate 4. A microlens 5 having a part spherical surface 6 is defined within the substrate 2 by etching down from the surface opposed to the LED mesa.
Figure 2 is similar to Figure 1, except that the lens 5 is replaced by a two or three dimensional height stepped diffraction grating 7.
Although a supporting substrate 4 is provided in the embodiments, it will be appreciated that this feature may be unnecessary if alternative means, for mounting the LED/substrate 2 is provided. In such a case the reflector may be a coating on the appropriate face of the LED.

Claims

1. A light emitting diode arrangement comprising a light emitting diode on or in a semiconductor substrate, a first side of the diode which faces away from the substrate being provided with a reflector, wherein the semiconductor substrate includes an optical focussing interference or diffractive element adjacent a second side of the diode opposed to the first side.
2. An arrangement according to claim 1 wherein said focussing element includes a curved surface.
3. An arrangement according to claim 2 wherein said focussing element includes a part spherical or hemispherical surface.
4. An arrangement according to claim 1 wherein said diffractive element is a grating.
5. An arrangement according to claim 4 wherein said grating is a two or three dimensional grating.
6. An arrangement according to claim 1 wherein said interference element is a Fresnel lens.
7. An arrangement according to any one of claims 4 to 6 wherein said element is a variable height element of transparent material.
8. An arrangement according to claim 7 wherein adjacent regions of the diffractive element take discrete values of thickness.
9. A light emitting diode according to claim 8 wherein there are two said values.
10. A light emitting diode according to claim 8 wherein there are four said values.
11. An arrangement according to any preceding claim wherein said element is formed within the thickness of said semiconductor substrate.
12. An arrangement according to claim 11 wherein said element is formed from said semiconductor substrate.
13. An arrangement according to any preceding claim wherein said first side is supported on a supporting substrate.
14. An arrangement according to claim 13 wherein the supporting substrate and said first face are shaped to provide contact therebetween substantially over the whole first face.
15. An arrangement according to claim 13 or claim 14 wherein the supporting substrate is said reflector, being of reflective material or comprising a reflective coating.
16. An arrangement according to any one of claims 1 to 14 wherein the reflector is a coating on said first side.
17. An arrangement according to any preceding claim wherein the first side of the diode is curved.
18. An arrangement according to any preceding claim wherein said reflector is specular.
19. A method of making a light emitting diode arrangement comprising providing a light emitting diode between a reflector and a semiconductor substrate, and removing material from the surface of the substrate opposed to the LED to define therein a focussing, interference or diffractive optical element.
20. A method according to claim 19 wherein the element is shaped to provide different thicknesses.
21. A method according to claim 20 wherein said different thicknesses take discrete values.
PCT/GB2001/003172 2000-07-19 2001-07-18 Light emitting diode arrangements WO2002007229A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001270823A AU2001270823A1 (en) 2000-07-19 2001-07-18 Light emitting diode arrangements

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0017655A GB0017655D0 (en) 2000-07-19 2000-07-19 Light emtting diode arrangements
GB0017655.2 2000-07-19

Publications (1)

Publication Number Publication Date
WO2002007229A1 true WO2002007229A1 (en) 2002-01-24

Family

ID=9895907

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2001/003172 WO2002007229A1 (en) 2000-07-19 2001-07-18 Light emitting diode arrangements

Country Status (3)

Country Link
AU (1) AU2001270823A1 (en)
GB (1) GB0017655D0 (en)
WO (1) WO2002007229A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002056390A1 (en) * 2001-01-15 2002-07-18 Osram Opto Semiconductors Gmbh Light-emitting diode and method for the production thereof
US6995360B2 (en) 2003-05-23 2006-02-07 Schlumberger Technology Corporation Method and sensor for monitoring gas in a downhole environment

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1487024A (en) * 1974-09-10 1977-09-28 Northern Telecom Ltd Integral lens light emitting diode
JPS58137271A (en) * 1982-02-10 1983-08-15 Toshiba Corp Light-emitting diode
JPS61121373A (en) * 1984-11-17 1986-06-09 Oki Electric Ind Co Ltd Surface light-emitting element and manufacture thereof
JPH01228181A (en) * 1988-03-08 1989-09-12 Furukawa Electric Co Ltd:The Semiconductor light emitting element
US5181220A (en) * 1985-07-16 1993-01-19 Mitsubishi Denki Kabushiki Kaisha Semiconductor light emitting light concentration device
GB2311413A (en) * 1996-03-22 1997-09-24 Hewlett Packard Co Light emitting devices

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1487024A (en) * 1974-09-10 1977-09-28 Northern Telecom Ltd Integral lens light emitting diode
JPS58137271A (en) * 1982-02-10 1983-08-15 Toshiba Corp Light-emitting diode
JPS61121373A (en) * 1984-11-17 1986-06-09 Oki Electric Ind Co Ltd Surface light-emitting element and manufacture thereof
US5181220A (en) * 1985-07-16 1993-01-19 Mitsubishi Denki Kabushiki Kaisha Semiconductor light emitting light concentration device
JPH01228181A (en) * 1988-03-08 1989-09-12 Furukawa Electric Co Ltd:The Semiconductor light emitting element
GB2311413A (en) * 1996-03-22 1997-09-24 Hewlett Packard Co Light emitting devices

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 007, no. 251 (E - 209) 8 November 1983 (1983-11-08) *
PATENT ABSTRACTS OF JAPAN vol. 010, no. 306 (E - 446) 17 October 1986 (1986-10-17) *
PATENT ABSTRACTS OF JAPAN vol. 013, no. 551 (E - 857) 8 December 1989 (1989-12-08) *
WINDISH R ET AL: "High-efficiency surface-textured LEDs", COMPOUND SEMICONDUCTOR, MAY-JUNE 2000, FRANKLIN PUBLISHING, USA, vol. 6, no. 4, pages 55 - 58, XP001033639, ISSN: 1096-598X *
YANG O-SEUNG ET AL: "Integration of microlensed LED and double heterojunction bipolar transistors for transmitter OEIC", ELECTRONICS LETTERS, IEE STEVENAGE, GB, vol. 32, no. 19, 12 September 1996 (1996-09-12), pages 1821 - 1823, XP006005702, ISSN: 0013-5194 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002056390A1 (en) * 2001-01-15 2002-07-18 Osram Opto Semiconductors Gmbh Light-emitting diode and method for the production thereof
US7015514B2 (en) 2001-01-15 2006-03-21 Osram Opto Semiconductors Gmbh Light-emitting diode and method for the production thereof
US6995360B2 (en) 2003-05-23 2006-02-07 Schlumberger Technology Corporation Method and sensor for monitoring gas in a downhole environment

Also Published As

Publication number Publication date
AU2001270823A1 (en) 2002-01-30
GB0017655D0 (en) 2000-09-06

Similar Documents

Publication Publication Date Title
US5779924A (en) Ordered interface texturing for a light emitting device
US6015719A (en) Transparent substrate light emitting diodes with directed light output
US5229614A (en) Method of coupling radiation in an infrared detector, and an arrangement herefor
US5793062A (en) Transparent substrate light emitting diodes with directed light output
US5705834A (en) Increased efficiency LED
US11592726B2 (en) Lighting device comprising LED and grating
WO2006036587A2 (en) Light recycling illumination systems having restricted angular output
US7492024B2 (en) Reflector for a double-pass photodetector
JP2004505434A (en) Micro light-emitting diode array with improved light extraction
JP2001102676A5 (en)
EP2418693B1 (en) Luminescent solar concentrator with distributed outcoupling structures and microoptical elements
WO2012083821A1 (en) Multi-band light collecting and energy conversion module
EP1202405B1 (en) Optical device for emitting/detecting a luminous signal and protective/insulating package for a light beam emission source
US5506419A (en) Quantum well photodetector with pseudo-random reflection
WO2002007228A1 (en) Light emitting diode with lens
WO2002007229A1 (en) Light emitting diode arrangements
JP7123599B2 (en) Light receiving and emitting device and optical density measuring device
CN115210886A (en) Miniature LED equipment
JPH02165684A (en) Semiconductor laser device
KR101499973B1 (en) Apparatus for solar power generation and device for concentrating light
WO2002007230A1 (en) Light emitting diodes
CN114400265B (en) Photoelectric conversion device for solar photovoltaic power generation
JPH01241184A (en) Reflection type photosensor
JP6981074B2 (en) Optical element
JP2004272931A (en) Light guide body and optical position detector

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP