CN1141664C - Fingerprint image sensor based on waveguide holographic technique and method for acquiring finigerprint image - Google Patents
Fingerprint image sensor based on waveguide holographic technique and method for acquiring finigerprint image Download PDFInfo
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- CN1141664C CN1141664C CNB011181362A CN01118136A CN1141664C CN 1141664 C CN1141664 C CN 1141664C CN B011181362 A CNB011181362 A CN B011181362A CN 01118136 A CN01118136 A CN 01118136A CN 1141664 C CN1141664 C CN 1141664C
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Abstract
The present invention belongs to the field of photoelectric image sensors, which comprises the following steps: a semiconductor laser linear array emit collimation coherent light for lighting through a microlens linear array; an optical waveguide utilizes a total reflection mechanism to form a closed light path system; a waveguide holographic grating element is used for coupling an incident light beam out of a waveguide substrate; the total reflection mechanism is utilized for obtaining fingerprint images and carrying out wave front reconstruction to an emergent beam; an optical fiber cluster is used as an optical transmitting and imaging element; a CMOS imaging chip is utilized for collecting the fingerprint images which are transmitted to a computer in a digital video format. The core waveguide holographic grating optical element is prepared by using Ar<+> laser light with an exposure method of interference fringes.
Description
Technical field the invention belongs to the electro-optical imaging sensors field, particularly is used to survey the preparation and the application of the holographic micro optical element of waveguide of somatic fingerprint surface topography.
The background technology fingerprint identification technology is the high reliability identity recognizing technology of a widespread use.The fingerprint image that uses fingerprint image sensor to obtain high resolving power, high-contrast, low distortion is to realize the prerequisite of fingerprint recognition accurately.The fingerprint collecting equipment of widespread use at present mostly is total reflection type prism photoelectricity fingerprint image sensor, and general volume, weight, power consumption are bigger, the manufacturing cost height.Therefore develop a kind of novel high-performance, integrated micro photoelectricity fingerprint image sensor is subjected to domestic and international expert's attention day by day cheaply.
At present, it is several that fingerprint image sensor mainly contains photo-electric, capacitor array formula, thermally sensitive array formula etc.Wherein the most perfect, the most widely used total reflection type prism photoelectricity fingerprint image sensor principle of work of development is described below as shown in Figure 1 and Figure 2:
The parallel incident beam 2 after collimating that is sent with expansion light source 1 by illumination is in the right-angle side entrance prism of total reflection prism 3.Adopted finger 4 and pressed on the prism hypotenuse.Wherein fingerprint ditch position 5 does not contact with prism surface, and incident beam 2 at this total reflection takes place; Total reflection condition is destroyed on contact prism surface, fingerprint ridge 6 position, and incident beam 2 will be scattered.Thus, incident beam 2 is just formed the outgoing beam 7 that carries fingerprint image by the modulation of fingerprint pattern, enters image-taking system 8, through obtaining the image of fingerprint after further handling.
In above-mentioned method, because each optical element is discrete, and adopts the open space light path, the complex structure volume is bigger, and is subject to the background noise interference.
Summary of the invention the object of the invention is to overcome the weak point of prior art, a kind of fingerprint image sensor based on the waveguide holographic technique is proposed, use the waveguide holographic optical elements (HOE), take micro integrated closed light path design, it is little to make it have a volume, be not subject to background noise and disturb, preparation cost is low, the characteristics that are suitable for producing in enormous quantities.
The present invention proposes a kind of fingerprint image sensor based on the waveguide holographic technique, it is characterized in that, comprises
Be formed slopely the optical waveguide plate and the waveguide hologram sheet that is close to its upper surface of reconstruct angle of light on one side, the end that this optical waveguide is tilted is equipped with diode laser array and microlens array, the reconstruct angle of light of the operation wavelength of this semiconductor laser and said optical waveguide plate is complementary, the big end of the lower surface of this waveguide plate and optical fiber bunch closely pastes, the small end and the cmos imaging chip of this optical fiber bunch closely paste, and this cmos imaging chip is installed on signal condition and the interface card.
The said waveguide hologram sheet of the present invention is made up of with the holographic grating two parts on the silver halide emulsion layer that is positioned at thick 5～15 μ m of being produced on of one side surface the optical glass base plate of thick 1.8～2.5mm.
Theoretical and the waveguide holographic theory according to holographic diffraction grating, the refractive index of choosing the sensitive emulsion layer on the waveguide hologram sheet is slightly smaller than the optical waveguide plate, therefore the holographic grating organizator holographic structure of producing.
The operation wavelength of said diode laser array is a 650nm ruddiness, and the reconstruct angle of light of optical waveguide plate is 70 °.
The present invention also proposes the method that a kind of fingerprint image sensor is gathered fingerprint image, it is characterized in that, by the optical waveguide plate of one side through being formed slopely the reconstruct angle of light and the waveguide hologram sheet that is close to its upper surface, diode laser array, the fingerprint image sensor that cmos imaging chip and signal condition and interface card are formed, gather fingerprint image and specifically may further comprise the steps:
1) fingerprint image sensor and host computer are online, and the finger concora crush of fingerprint to be collected is in waveguide hologram sheet top;
2) fingerprint image sensor is lighted lighting source, send incident beam and enter the waveguide hologram sheet by the substrate optical plate glass, according to the principle that fingerprint image is gathered in total reflection, outgoing beam carries fingerprint image, and by waveguide holographic raster the time, diffraction takes place and cause wavefront reconstruction;
3) outgoing beam behind the wavefront reconstruction images on the cmos imaging chip by an optical fiber bunch convergence;
4) computer control cmos imaging chip obtains fingerprint image in the snapshot mode;
5) fingerprint image sensor is transferred to computing machine by transmission cable with the fingerprint of digital format.
The principle that the present invention obtains fingerprint image is: the semiconductor laser light source sends the incident angle incident to be complementary with incident light centre wavelength of substrate optical plate glass one end of incident beam through tiltedly splitting that centre wavelength is positioned at red range.Incident beam enters the waveguide hologram sheet by the substrate optical plate glass, and total reflection takes place on the surface thereon.Outgoing beam will be made amplitude modulation(PAM) by fingerprint, carry fingerprint image.Outgoing beam is when the holographic grating layer by waveguide hologram sheet lower surface, diffraction will take place and cause wavefront reconstruction, thereby the change direction of propagation, to under enter optical fiber bunch, and assemble and to image on the photosensitive unit array of cmos imaging chip, light intensity signal is sent to computing machine or other central controller with video format after conditioning and interface circuit conditioning.
Characteristics of the present invention comprise:
1, uses optical waveguide, utilize total reflection mechanism to form closed optical path;
2, use diode laser array and lenticule linear array to form the collimated coherent optical beam illumination;
3, use the waveguide holographic raster element that incident beam is coupled out waveguide, form total reflection and obtain fingerprint image, and to the outgoing beam wavefront reconstruction;
The invention has the advantages that:
1, adopts closed light path design, can effectively shield the noise that the environment veiling glare is introduced;
2, integrated optics and fiber optic components are used in effective integration, and the system compact volume is little;
3, core waveguide holographic element preparation cost is low, is suitable for producing in enormous quantities.
Description of drawings
Fig. 1 is present total reflection type prism photoelectricity fingerprint image sensor principle of work.
Fig. 2 is to use the take the fingerprint principle of image of total reflection method.
Fig. 3 is the holographic integrated finger print image sensor system assemblies figure of waveguide of the present invention.
Fig. 4 is the principle of work of waveguide holographic element of the present invention.
Fig. 5 is the preparation facilities figure of waveguide holographic element.
The embodiment of embodiment a kind of fingerprint image sensor based on the waveguide holographic technique of the present invention is described with reference to the accompanying drawings as follows:
The fingerprint image sensor structure embodiment that the present invention proposes is as shown in Figure 3, Figure 4:
The core optical element of this fingerprint image sensor is on one side through 70 ° of optical waveguides of tiltedly splitting 11 and the waveguide hologram sheet 12 that is close to its upper surface.Guarantee fitting tightly of the two with refractive index match by 13 between waveguide hologram sheet 12 and the optical waveguide 11.The end that optical waveguide is tiltedly split is equipped with diode laser array (centre wavelength 650nm) 9, and utilization lenticule linear array forms illuminating bundle to laser beam datum.The big end of the lower surface of waveguide plate and optical fiber bunches 16 closely pastes and installs, and the small end of optical fiber bunch closely pastes and installations with cmos imaging chip 17.The cmos imaging chip is installed on signal condition and the interface card 18.Core optical element of the present invention is a waveguide hologram sheet 12, is made up of optical glass base plate and the holographic grating layer two parts that are positioned at the thick 6 μ m of its lower surface of thick 2mm.Theoretical and the waveguide holographic theory according to holographic diffraction grating, holographic grating organizator holographic structure on this element, the refractive index of promptly choosing photosensitive emulsion is slightly smaller than the waveguide sheet.In operation wavelength is 650nm ruddiness, and the reconstruct angle of light is 70 °, and under the situation that the thing angle of light is 0 °, the fringe spacing of holographic grating 15 is:
The spatial frequency of corresponding holographic grating 15 is
For obtaining high-contrast and high-resolution fingerprint image, should make incident beam 10 close by the diffraction efficiency of holographic grating 15, so the diffraction efficiency of corresponding holographic grating 15 should be 0.4～0.6 by the transmissivity and the outgoing beam 14 of holographic grating 15.
The preparation method embodiment of core optical element waveguide hologram sheet 12 as shown in Figure 5 among the present invention.This method uses commercial holographic dry plate 19 (emulsion layer thickness 6 μ m) that one side scribbles even photosensitive emulsion coating to the making that exposes of waveguide holographic interference pattern.Use the Ar of wavelength as λ '=514nm
+Laser instrument 20 is made light source.For satisfying the parameter d in (1), when then making the waveguide hologram sheet, the angle of thing light and reference light should be:
Ar
+The light beam of laser instrument 20 is at first by a pinhole filter elimination high frequency noise of being made up of microcobjective 21 and pin hole 22, form collimated light beam 24 by spherical convex lens 23 then, be divided into thing light 26 and 27 liang of bundles of reference light by beam splitter 25, being adjusted to angle through level crossing is 53.9 °, and uses cylindrical mirror 29 adjustment that thing light and reference light hot spot area coverage are roughly overlapped.After holographic dry plate 19 fully exposes, after development, photographic fixing, oven dry, can obtain meeting the amplitude formula waveguide hologram sheet of parameter request.
For obtaining high-contrast and high-resolution fingerprint image, need that in post-production holographic grating is bleached processing and form the phase holographic grating, to improve the diffraction efficiency of holographic grating.
Extract somatic fingerprint with method of the present invention and can make light source with centre wavelength 650nm red light-emitting diode linear array, optical fiber bunch can use the product P art No.52362 of Edmund Scientific Co. company, cmos imaging chip and subject signal modulate circuit thereof use the OmniVision OV7710 of company black and white cmos image sensing chip and signaling interface disposable plates thereof, with USB (USB (universal serial bus)) and computer interconnection.The flat waveguide hologram sheet upper surface that presses on of tested finger, provide the instruction that takes the fingerprint by computing machine, the finger print image that the cmos image sensing chip can obtain to the computing machine transmission with per second 15 frame sampling speed by signaling interface disposable plates and usb bus can stop to gather when stopping acquisition instructions when computing machine provides.The present invention is that 3: 1 optical fiber bunch is made the imaging system using two ends area ratio, use the photosensitive unit number greater than 640 * 480, the digital quantization degree of depth is during greater than the face battle array cmos imaging chip of 8bit, can obtain resolution greater than 600dpi, contrast is better than 250: 1, and aberration rate is less than 1% fingerprint image.
Claims (5)
1, a kind of fingerprint image sensor based on the waveguide holographic technique, it is characterized in that, comprise: the optical waveguide plate of one side through being formed slopely the reconstruct angle of light and the waveguide hologram sheet that is close to its upper surface, the end that this optical waveguide is tilted is equipped with diode laser array, the reconstruct angle of light of the operation wavelength of this semiconductor laser and said optical waveguide plate is complementary, the big end of the lower surface of this waveguide plate and optical fiber bunch closely pastes, the small end and the cmos imaging chip of this optical fiber bunch closely paste, and this cmos imaging chip is installed on signal condition and the interface card.
2, fingerprint image sensor as claimed in claim 1, it is characterized in that said waveguide hologram sheet is made up of with the holographic grating two parts on the sensitive emulsion layer that is positioned at thick 5～15 μ m of being produced on of one side surface the optical glass base plate of thick 1.8～2.5mm.
3, fingerprint image sensor as claimed in claim 1 is characterized in that, the refractive index of choosing the sensitive emulsion layer on the waveguide hologram sheet is slightly smaller than the optical waveguide plate, therefore the holographic grating organizator holographic structure of producing.
4, fingerprint image sensor as claimed in claim 1 is characterized in that, the operation wavelength of said diode laser array is positioned at red range, and the reconstruct angle of light of optical waveguide plate is complementary with it
5, a kind of fingerprint image sensor is gathered the method for fingerprint image, it is characterized in that, by the optical waveguide plate of one side through being formed slopely the reconstruct angle of light and the waveguide hologram sheet that is close to its upper surface, diode laser array, the fingerprint image sensor that cmos imaging chip and signal condition and interface card are formed, gather fingerprint image and specifically may further comprise the steps:
1) fingerprint image sensor and host computer are online, and the finger concora crush of fingerprint to be collected is in waveguide hologram sheet top;
2) fingerprint image sensor is lighted lighting source, send incident beam and enter the waveguide hologram sheet by the substrate optical plate glass, according to the principle that fingerprint image is gathered in total reflection, outgoing beam carries fingerprint image, and by waveguide holographic raster the time, diffraction takes place and cause wavefront reconstruction;
3) outgoing beam behind the wavefront reconstruction images on the cmos imaging chip by an optical fiber bunch convergence;
4) computer control cmos imaging chip obtains fingerprint image in the snapshot mode;
5) fingerprint image sensor is transferred to computing machine by transmission cable with the fingerprint of digital format.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB011181362A CN1141664C (en) | 2001-05-18 | 2001-05-18 | Fingerprint image sensor based on waveguide holographic technique and method for acquiring finigerprint image |
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| CNB011181362A CN1141664C (en) | 2001-05-18 | 2001-05-18 | Fingerprint image sensor based on waveguide holographic technique and method for acquiring finigerprint image |
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| CN1141664C true CN1141664C (en) | 2004-03-10 |
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Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100410964C (en) * | 2003-04-28 | 2008-08-13 | 北京海鑫科金高科技股份有限公司 | Acquisition and splicing method of three-face rolling fingerprint |
| CN101169824B (en) * | 2006-10-25 | 2011-04-20 | 原相科技股份有限公司 | Fingerprint identification device and method |
| KR101179559B1 (en) * | 2009-12-18 | 2012-09-04 | 주식회사 유니온커뮤니티 | Fingerprint Recognition Apparatus for Distinguishing Forged Fingerprint and Method therof |
| CN101866141B (en) * | 2010-05-25 | 2012-02-22 | 上海理工大学 | Method for manufacturing diagonal stripe holographic waveguide device with high refractive index modulating degree |
| CN102383669A (en) * | 2011-10-21 | 2012-03-21 | 昆明理工大学 | Holographic optical lock |
| US10146988B2 (en) | 2013-06-24 | 2018-12-04 | Blackberry Limited | Obtaining a biometric image and handling damaged biometrics |
| CN104751121B (en) * | 2015-03-05 | 2019-04-05 | 上海交通大学 | Light wave conduction fingerprint recognition system based on optical grating construction |
| KR101928319B1 (en) | 2015-06-18 | 2018-12-12 | 선전 구딕스 테크놀로지 컴퍼니, 리미티드 | Multifunction fingerprint sensor with photo sensing capability |
| US10437974B2 (en) | 2015-06-18 | 2019-10-08 | Shenzhen GOODIX Technology Co., Ltd. | Optical sensing performance of under-screen optical sensor module for on-screen fingerprint sensing |
| CN105260708B (en) * | 2015-09-25 | 2020-07-24 | 联想(北京)有限公司 | Detection device, electronic equipment and information processing method |
| CN105759330B (en) * | 2016-03-16 | 2018-04-17 | 上海交通大学 | Fingerprint recognition system based on optical grating construction and microprism array |
| CN109154869B (en) * | 2016-06-07 | 2021-02-05 | 深圳市汇顶科技股份有限公司 | Optical collimator of optical sensor module under screen for on-screen fingerprint sensing |
| CN106022323B (en) * | 2016-07-26 | 2019-09-10 | 昆山龙腾光电有限公司 | Finger recognition system and finger identification method and fingerprint identification device |
| KR102630571B1 (en) * | 2016-11-29 | 2024-01-30 | 엘지디스플레이 주식회사 | Flat Panel Display Embedding Optical Imaging Sensor |
| CN108241839A (en) * | 2016-12-23 | 2018-07-03 | 创智能科技股份有限公司 | Biological identification device |
| WO2018152740A1 (en) * | 2017-02-23 | 2018-08-30 | 深圳市汇顶科技股份有限公司 | Sensing unit |
| CN108664855A (en) * | 2017-03-30 | 2018-10-16 | 上海箩箕技术有限公司 | Fingerprint imaging module and electronic equipment |
| CN109786577B (en) * | 2019-01-30 | 2020-12-11 | 固安翌光科技有限公司 | OLED screen body for fingerprint identification device and fingerprint identification device |
| DE102019206363B3 (en) * | 2019-05-03 | 2020-07-09 | Audi Ag | Motor vehicle with a device for color-dependent detection of image content and a computing device |
| CN111061089B (en) * | 2019-12-13 | 2021-04-27 | 武汉华星光电技术有限公司 | Display device |
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