CN101751148A - Capturing device and capturing method for non-deformable light spots - Google Patents

Abstract

The invention discloses a capturing device and a capturing method for non-deformable light spots, which use high-coherency light to irradiate the surface of an object so as to produce scattered light and capture light spot images produced by the scattered light at the position where the difference between a scattering angle and a reflecting angle is about 10 degrees. A light limiting module for limiting an incidence vision angle is designed in the light spot capturing device, the light spots on the image plane move when the capturing device and the object plane have relative shift, but the shape and strength of the light spots are nearly kept unchangeable, so the light spot capturing device is quite favorable for identification and positioning of precise light spot pictures.

Description

A kind of image-taking device of indeformable hot spot and method

Technical field

The present invention relates to the image-taking device and the method for the indeformable hot spot of diffraction and interference effect, especially a kind of scattered light produces diffraction light by the small-bore light limiting module, and diffraction light interferes with each other the formation hot spot again, and the apparatus and method of capture in addition.

Background technology

When two the bundle high same tone light beam superposition together, and its optical path difference (OPD) is during less than people having the same aspiration and interest length (coherentlength), can produce interference effect, and interference effect is divided into constructive interference and destruction interference, it is bright that constructive interference makes the light intensity behind the two light beam superpositions, destruction interference then is dark, so interference effect can cause distribution of light intensity to become the figure of bright dark arrangement.Interfere relevant with optical path difference, when two light beams meet, if its optical path difference is the odd integer multiple of half-wavelength, then can produce destruction interference, when if its optical path difference is the even integer multiple of zero or half-wavelength, then produce constructive interference, therefore, it is the sensing precision of half-wavelength that the conoscope image of bright dark arrangement can provide the optical path difference variable quantity.Because light wavelength is quite short, is about 0.4 to 0.7 μ m as wavelength of visible light, so the sensing precision of half-wavelength is quite sensitive, also therefore, interference effect often is applied to various occasions widely.

When more coarse surperficial of the light incident one of high same tone, just can make high same tone light produce scattering (scattering) because of coarse surface, scattered light is propagated toward any direction, if wherein arbitrarily the scattered light superposition of two-supremes same tone together and its optical path difference during again less than people having the same aspiration and interest length just can produce stable interference.The scattered light of these high same tones interferes with each other, and forms the image of many bright spots and dim spot, and we claim that this image is laser facula (Laser Speckle).

Hot spot do not finding with before displacement is relevant, is considered as information in the optical system by the people, and still, after having the people to find that displacement and hot spot have correlativity, hot spot just becomes a kind of measurement technology.Recently, someone has used the characteristics of hot spot, detection technology during as movement of objects at U.S. Patent Publication No. US6642506B1 (hereinafter to be referred as 506 cases) in 2003, is described and is utilized people having the same aspiration and interest light source, aperture and imaging len to obtain the measurement of hot spot image as object one dimension displacement amount.506 cases are selected suitable aperture size, obtain the sensing cell size of spot size more than or equal to sensor, and emphasize aperture is placed imaging len focus place, and the vertical object plane of observing of the optical axis of imaging len and aperture, can reduce the measuring error that the up and down change vertical with the object plane moving direction caused.For another No. 20050024623 patent of U.S. Patent Publication No. (hereinafter referred to as 623 cases), disclose a kind of optical displacement method and apparatus, utilization has same tone light emitted one same tone light, incident one surface, then leave this surface via reflection, and the rough sensor that on catoptrical path, is provided with, to accept this reflected light.When the angle on reflected light and surface equals the angle on incident light and surface, be to be so-called direct reflection (specular reflection).Because sensor has been accepted reflected light and scattered light simultaneously, and interference effect makes on sensor and to produce many hot spot images, so via judging contained hot spot image in this reflected light, with before moving with move after image compare, can judge that just direction that hot spot moves is with big or small.

Also having a correlation technique is the patent application case of Patent Cooperation Treaty (PCT), its publication number is WO2004075040 patent (hereinafter referred to as 040 case), disclose a kind of optical signal disposal route and device of optical mouse of electric numerical data processing, be to utilize to collect the signal that hot spot moves, with the laser light signal of reaction mouse and the relative displacement vector of the irradiated body surface that produces hot spot, built-in amplification and the shaping module of handling the photoelectricity signal in the mouse body, take one's bearings and count module and computer interface circuit, and comprising a LASER Light Source and the photo switches, photo sensors that receives the laser facula signal, the photoelectricity signal that this photo switches, photo sensors receives will be transmitted and be input into above-mentioned amplification, in the shaping module.

Above-mentioned signal interpretation mode, all be that interpretation is by in the sensor institute picked image, the bright dark variation of hot spot, with mobile direction and the distance of converting, 040 case simple in structure, if but the surface of incident is very smooth, the hot spot spot size that produces will become very little, and thus, the interpretation of the bright dark variation of hot spot also and then becomes and is not easy very much, so that resolution declines to a great extent, and sensitivity simultaneously is also influenced.

And 623 case sensors receive is reflected light near mirror, therefore, received signal can be divided into direct current portion and exchange portion, direct current portion signal is from catoptrical uniform luminance, and the bright dark variation of hot spot is interchange portion signal, when the size of hot spot too hour, the signal of interchange portion changes and just is difficult to distinguish, therefore, interpretation is more difficult.

Other 506 cases place aperture on the imaging len focus, constitute telecentric iris projection system (a telecentricprojection system), though removed the susceptibility of distance between object plane and the optical system, but the aperture of this kind structure is the function of object plane capture scope without limits, that is the scattered light incident field angle function that enters sensor without limits, though so the method has the function of control hot spot mean size, the situation of distortion takes place in the time of can't avoiding hot spot to move.

Therefore, want the important key of accurate correct identification two dimensional spot image figure to be whether spot size is appropriate, whether constructive hot spot is bright and strong with the background information contrast, the more important thing is, whether the hot spot image can be out of shape, have only indeformable spot pattern that correct guide to visitors identification and precision positioning function just can be provided, and be widely used in computer mouse, finger navigator, smart card, three-dimensional fingerprint identity identification device, machine-tool or mechanical arm Precision Position Location System etc.

Summary of the invention

In view of above problem, fundamental purpose of the present invention is, a kind of indeformable light-spot view-finding device and method are provided, and gives reasonable solution at laser facula easy deformation and the too little problems such as identification that are difficult for of spot size.Utilize non-mirror reflection two dimensional spot image-taking device, measure laser facula, and introduce the incident field angle that aperture restriction face to be illuminated scattered light enters two-dimentional sensor, promptly limited object plane capture scope in the position that scattering angle and reflection angle differ about 10 °.Suitably integrate parameters such as spot size, taking lens focal length, capture angle and object plane capture scope, can obtain the almost indeformable effect of hot spot image that produces on the picture plane.So-called hot spot is indeformable is meant, when image-taking device and object plane relatively move, also and then move as the hot spot on the plane, but from the process of observation scope that two-dimentional sensor occurs shifting out, light spot shape and intensity is not variation almost.Because the obtained hot spot of light-spot view-finding device of the present invention and method can not be out of shape, therefore be very beneficial for accurate hot spot Figure recognition and location when mobile.

Can be about the advantages and spirit of the present invention by following detailed Description Of The Invention and appended graphic being further understood.

Description of drawings

Figure 1A, Figure 1B and Fig. 1 C: be to show that the present invention calculates the light path synoptic diagram of the relative optical path difference of hot spot image.

Fig. 2 A: be the structural representation that shows a preferred embodiment of the present invention.

Fig. 2 B: be the light path synoptic diagram that shows another preferred embodiment of the present invention.

Fig. 2 C, Fig. 2 D: be the structural representation that shows the other preferred embodiment of the present invention.

Fig. 3: be the structural representation that shows another preferred embodiment of the present invention.

Fig. 4 A: be to show that the present invention produces the synoptic diagram of rescattering light.

Fig. 4 B: be the light path synoptic diagram that shows another preferred embodiment of the present invention.

Fig. 4 C: be the structural representation that shows another preferred embodiment of the present invention.

Fig. 5: be to show that the present invention captures indeformable hot spot striograph.

Fig. 6 A, Fig. 6 B: be to show that the present invention is applied to the synoptic diagram of laser mouse.

Fig. 7 A, Fig. 7 B and Fig. 7 C: be to show light-spot view-finding method synoptic diagram of the present invention.

Embodiment

For making the present invention can reach the indeformable function of hot spot image, so when this describes light-spot view-finding device in detail and relatively moves with object plane, move the metering formula of the relative optical path difference of front and back hot spot image.

Laser facula is the scattered light of photographed object, to two-dimentional sensor, produce the intensity distributions image of interfering gained via image-taking device diffraction, its common and LASER Light Source characteristic, photographed object face characteristic, the arrangement of image-taking device, and factor such as two-dimentional sensor size all has relation, needs precisely to analyze its blind spot and degree of difficulty, but can be analyzed by some reasonable assumptions.We suppose that LASER Light Source is a uniform source of light that high same tone is arranged, so light source characteristic can satisfy hot spot and interferes required condition.The object plane feature is the most difficult grasp, we can't do the delicate nature analysis to each object plane, but there is any to emphasize, we are when measuring the hot spot image, often with the strongest hot spot of size maximum, intensity as evaluating objects, give up and be easy to mix and increase the weak and little hot spot of False Rate with background information.Spot intensity is relevant with interference condition, the hot spot image that only constructive interference just can obtain becoming clear.And the hot spot mean size is relevant with the characteristic of photographed object face, and the hot spot average-size can be write as: 2 δ ≈, 2 λ L/D, wherein 2 δ are the hot spot mean diameter, λ: the laser light wavelength, D: the aperture of image-taking device, L: the aperture is to the distance of sensor.Scattered light on from a certain scattering point of object plane and adjacent area thereof to sensor is if be constructive interference all, then the hot spot image can be very bright and also bigger than average light spot size, if destruction interference, then the hot spot image can die down and diminish, even disappear, so we can suppose that the interference approach of big and bright hot spot image satisfies constructive interference condition.What we will compare is before image-taking device moves and the correlativity (correlation) of mobile back two hot spot images, so we can write down the image of first hot spot image earlier, observe a certain bright hot spot that satisfies constructive interference condition in this image, then if we calculate after the image-taking device displacement d, in second the hot spot image that is presented, what this bright hot spot has and changes, and is analyzed as follows:

(i) in order to obtain minimum image-taking device, we select for use the 4-f lens imaging system to analyze, and wherein f is the focal length of imaging len.4-f imaging design, its object distance is identical with image distance, is the enlargement ratio M=1 that unites, so shown in Figure 1A, γ wherein _A=γ _B,γ _{A '}=γ _{B '}, γ _{A "}=γ _{B "}

(ii) the size of hot spot on imaging surface B point can be made as average-size 2 δ of diffraction effect, because imaging is that the system enlargement ratio is 1, therefore be the center at object plane with the A point, δ is that any point all will be with the size 2 δ ≈ 2 λ L/D of diffraction limit Airy Disk on the object plane of radius region, be imaged near the position of the correspondence of the answering picture plane B point, and interfere with the Airy Disk superposition of other imaging point.If the B point is the scattered light of radius region with δ for bright spot is illustrated in the A point, all equals or be close to 0 or the integral multiple of wavelength because of diffraction arrives optical path difference that B orders.Modern consider that the A point on the object plane may become A ' or A with respect to the position of image-taking device when image-taking device or backward after the displacement d forward "; Its corresponding picture point is B ' or B ".

We can reasonable assumption,

γ _A＞＞d＞＞δ.

Shown in Figure 1B, at first calculating with the A point is the center, and δ is in the scope of radius, issuable maximum optical path difference, γ _{A+ δ}With γ _A-δPoor: (with γ, θ _A, δ represents)

${\mathrm{\γ}}_{A+\mathrm{\δ}}=\sqrt{{\mathrm{\γ}}^2+{({\mathrm{\γ}\tan \mathrm{\θ}}_A+\mathrm{\δ})}^2}=\mathrm{\γ}\sqrt{{1+(\tan {\mathrm{\θ}}_A+\frac{\mathrm{\δ}}{\mathrm{\γ}})}^2}$

${\mathrm{\γ}}_{A-\mathrm{\δ}}=\sqrt{{\mathrm{\γ}}^2+{({\mathrm{\γ}\tan \mathrm{\θ}}_A-\mathrm{\δ})}^2}=\mathrm{\γ}\sqrt{{1+({\tan \mathrm{\θ}}_A-\frac{\mathrm{\δ}}{\mathrm{\γ}})}^2}$

Utilize Taylor ' s series, it is above every to ignore secondary,

$f\left(\frac{\mathrm{\δ}}{\mathrm{\γ}}\right)\≅f\left(0\right)+\frac{f\′\left(0\right)}{1!}\left(\frac{\mathrm{\δ}}{\mathrm{\γ}}\right)$

$\sqrt{{1+({\tan \mathrm{\θ}}_A+\frac{\mathrm{\δ}}{\mathrm{\γ}})}^2}$

$\&cong;\sqrt{1+{\mathrm{<figure-callout\; id="2"\; label="tan"\; filenames="H2008101828377E0000011.png,H2008101828377E0000021.png"\; state="\{\{state\}\}">tan</figure-callout>}}^2{\mathrm{\&theta;}}_A}+\frac{{\tan \mathrm{\&theta;}}_A}{\sqrt{{1+\mathrm{<figure-callout\; id="2"\; label="tan"\; filenames="H2008101828377E0000011.png,H2008101828377E0000021.png"\; state="\{\{state\}\}">tan</figure-callout>}}^2{\mathrm{\&theta;}}_A}}\&CenterDot;\frac{\mathrm{\&delta;}}{\mathrm{\&gamma;}}=\frac{1}{{\cos \mathrm{\&theta;}}_A}+\sin {\mathrm{\&theta;}}_A\&CenterDot;\frac{\mathrm{\&delta;}}{\mathrm{\&gamma;}}$

$\stackrel{\&CenterDot;}{\&CenterDot;\&CenterDot;}{\mathrm{\&gamma;}}_{A+\mathrm{\&delta;}}=\mathrm{\&gamma;}\sqrt{{1+({\tan \mathrm{\&theta;}}_A+\frac{\mathrm{\&delta;}}{\mathrm{\&gamma;}})}^2}\&cong;\frac{\mathrm{\&gamma;}}{{\cos \mathrm{\&theta;}}_A}+{\mathrm{\&delta;}\&CenterDot;\sin \mathrm{\&theta;}}_A$

$\stackrel{\&CenterDot;}{\&CenterDot;\&CenterDot;}{\mathrm{\&gamma;}}_{A-\mathrm{\&delta;}}=\mathrm{\&gamma;}\sqrt{{1+({\tan \mathrm{\&theta;}}_A-\frac{\mathrm{\&delta;}}{\mathrm{\&gamma;}})}^2}\&cong;\frac{\mathrm{\&gamma;}}{{\cos \mathrm{\&theta;}}_A}-{\mathrm{\&delta;}\&CenterDot;\sin \mathrm{\&theta;}}_A$

$\stackrel{\&CenterDot;}{\&CenterDot;\&CenterDot;}{\mathrm{\&gamma;}}_{A+\mathrm{\&delta;}}-{\mathrm{\&gamma;}}_{A-\mathrm{\&delta;}}\&cong;2\mathrm{\&delta;}\&CenterDot;\sin {\mathrm{\&theta;}}_A$

Then calculate, when object plane and image-taking device relative displacement, the mobile d of A point distance is during to the position of A ' point (hot spot that still original A point object plane feature of observation is presented, imaging point is at B ' at this moment), with A ' point is the center, and δ is γ by issuable maximum optical path difference in the radius _{A '+δ}With γ _{A '-δ}Poor, shown in figure 1C:

$\stackrel{\&CenterDot;}{\&CenterDot;\&CenterDot;}{\mathrm{\&gamma;}}_{A\&prime;+\mathrm{\&delta;}}-{\mathrm{\&gamma;}}_{A\&prime;-\mathrm{\&delta;}}\&cong;2\mathrm{\&delta;}\&CenterDot;\sin {\mathrm{\&theta;}}_{A\&prime;}$

Shown in Fig. 1 C, when the mobile d distance of object plane A point is put to A ', be that center δ is the maximum optical path difference (γ in the radius with A ' point _{A '+δ}-γ _{A '-δ}) be that center δ is the maximum optical path difference (γ in the radius with the A point _{A+ δ}-γ _A-δ), the optical path difference change amount between two light paths is (γ _{A '+δ}-γ _{A '-δ})-(γ _{A+ δ}-γ _A-δ):

Make θ _{A '}=θ _A+ Δ θ, Δ θ are the very small angles variable quantity

$({\mathrm{\&gamma;}}_{A\&prime;+\mathrm{\&delta;}}-{\mathrm{\&gamma;}}_{A\&prime;-\mathrm{\&delta;}})-({\mathrm{\&gamma;}}_{A+\mathrm{\&delta;}}-{\mathrm{\&gamma;}}_{A-\mathrm{\&delta;}})$

$=2\mathrm{\&delta;}\sin {\mathrm{\&theta;}}_{A\&prime;}-2\mathrm{\&delta;}\sin {\mathrm{\&theta;}}_A$

$=2\mathrm{\&delta;}\sin ({\mathrm{\&theta;}}_A+\mathrm{\&Delta;\&theta;})-2\mathrm{\&delta;}\sin {\mathrm{\&theta;}}_A$

$=2\mathrm{\&delta;}({\sin \mathrm{\&theta;}}_A\cos \mathrm{\&Delta;\&theta;}+{\cos \mathrm{\&theta;}}_A\sin \mathrm{\&Delta;\&theta;})-{2\mathrm{\&delta;}\sin \mathrm{\&theta;}}_A$

$\&cong;2\mathrm{\&delta;}({\sin \mathrm{\&theta;}}_A+{\cos \mathrm{\&theta;}}_A\&CenterDot;\mathrm{\&Delta;\&theta;})-2\mathrm{\&delta;}\sin {\mathrm{\&theta;}}_A$

$=2\mathrm{\&delta;}\cos {\mathrm{\&theta;}}_A\&CenterDot;\mathrm{\&Delta;\&theta;}$

Because $\mathrm{\&Delta;\&theta;}\&ap;\frac{d\&CenterDot;\cos {\mathrm{\&theta;}}_A}{{\mathrm{\&gamma;}}_A},$ Again ${\mathrm{\&gamma;}}_A=\frac{\mathrm{\&gamma;}}{\cos {\mathrm{\&theta;}}_A},$ So

$({\mathrm{\&gamma;}}_{A\&prime;+\mathrm{\&delta;}}-{\mathrm{\&gamma;}}_{A\&prime;-\mathrm{\&delta;}})-({\mathrm{\&gamma;}}_{A+\mathrm{\&delta;}}-{\mathrm{\&gamma;}}_{A-\mathrm{\&delta;}})$

$\&ap;2\mathrm{\&delta;}\frac{d}{\mathrm{\&gamma;}}{\cos }^3{\mathrm{\&theta;}}_A$

The scattered light that our hypothesis order at object plane A through the 4f lens imaging in sensor B point position, in like manner, A ', A " put then image in B ', B respectively " point.Diffraction effect is told us, is the center with the B point, δ be radius (radius of Airy Disk, that is hot spot mean radius) all energy coupling is arranged as the plane each point with the B point, all can produce interference at B point.Add the image-forming condition of enlargement ratio M=1, if the B point is a bright spot, expression is the center with the A point, δ is that the optical path difference that the scattered light arrival B of the object plane of radius is ordered has constituted constructive interference, can suppose that its optical path difference equivalence value is 0, in other words originally calculating with the A point is the center, and δ is that the maximum optical path difference that the object plane zone arrival B of radius is ordered is n (γ _{A+ δ}+ γ _{B+ δ})-n (γ _A-δ+ γ _B-δ) be about 4 δ * sin (θ _A) (refractive index of air, n=1), because of the potential inclination texture of photographed object rough surface has compensated-4 δ * sin (θ naturally _A) optical path difference, make the bright spot that is imaged as constructive interference that B is ordered.The present d distance if light source and face to be illuminated relatively move, this moment, the condition of original object plane there is no change, put maximum optical path difference and then became but arrive new hot spot B ': (γ _{A '+δ}+ γ _{B '+δ})-(γ _{A '-δ}+ γ _{B '-δ}).What we took notice of is how many this new optical path differences has with original optical path difference change amount between the two, because this change amount is if be about half-wavelength, original constructive interference will become destruction interference, so both optical path difference change amounts will be the new hot spot image intensity greatest factor of influence.According to above-mentioned calculating, the relative optical path difference change in hot spot path the amount [(γ that this produces because of mobile d _{A '+δ}+ γ _{B '+δ})-(γ _{A '-δ}+ γ _{B '-δ})]-[(γ _{A+ δ}+ γ _{B+ δ})-(γ _A-δ+ γ _B-δ)] value be about 4 δ * d*cos ³(θ _A)/γ, if this is worth much smaller than λ, the capture zone of being considered on the expression object plane, originally the hot spot point B of ordering at A, move to A ' point and formed new hot spot B ' point, interference condition between the two is almost constant, so if original B point bright spot also must be bright spot to B ' point, so that when light source and face to be illuminated have relative displacement, the image intensity changes in distribution is little, and the hot spot image just follows displacement not change, that is reaches the requirement of indeformable light-spot view-finding.Obtain from practical experience, as 4 δ * d*cos ³(θ _AThe value of)/γ is less than λ/5, and the indeformable effect of light-spot view-finding is just very obvious, and wherein λ is the wavelength of high same tone light 100.

Seeing also Fig. 2 A, is the structural representation of a preferred embodiment of the present invention.As shown in the figure, the invention provides a kind of indeformable light-spot view-finding device, it comprises an optical transmitting set 10, a light limiting module 12 and a sensor 14.Parallel beam 100 to one body surfaces 2 of this optical transmitting set 10 and collector lens 11 combined transmit one high same tone, this optical transmitting set 10 can be wall emission laser (Vertical Cavity Surface Emitting Laser, VCSEL), the limit penetrate type laser (Edge Emission Laser, EEL), the Solid State Laser of the gas laser of high same tone, high same tone maybe can launch narrow frequency light and have the light-emittingdiode of high same tone.The area of these high same tone light 100 these body surfaces 2 of irradiation is distances of adjusting this optical transmitting set 10 and collector lens 11 according to default area size.And this light limiting module 12 comprises an aperture 121 and an imaging len 122, and this aperture 121 is located between this imaging len 122 and this body surface 2, and this sensor 14 is located at after this light limiting module 12, and it is an one dimension or two-dimentional sensor, as: CCD or CMOS.

When this optical transmitting set 10 is launched these high same tone light 100 to this body surface 2, produce at least one scattered light 102, the characteristic of this at least one scattered light 102 is to decide along with the roughness of this body surface 2, as: when this body surface 2 is a shiny surface (minute surface), this high same tone light 100 is projected to the scattered light 102 that this body surface 2 produced will focus on a reflection direction and identical with these high same tone 100 energy; Perhaps this body surface 2 is uneven surface (cloudy surface), after this high same tone light 100 is projected to this body surface 2, produces the scattered light 102 of all directions.

From the above, if this body surface 2 has a rugged three dimensional change for coarse, will cause these high same tone light 100 projections after, produce this at least one scattered light 102, and this at least one scattered light 102 is propagated toward any direction, and then produce the hot spot that is easy to identification.

Hold above-mentioned, after this high same tone light 100 is projected to this body surface 2, produce this at least one scattered light 102, utilize this light limiting module 12 to accept this at least one scattered light 102, and this light limiting module 12 comprises an aperture 121 and an imaging len 122, this imaging len 122 is located at after this aperture 121, promptly be located between this aperture 121 and this sensor 14, this light limiting module 12 limits the incident field angle that this at least one scattered light 102 enters this sensor 14, the size of incident field angle is decided by the distance of this aperture 121 and this imaging len 122, and the diameter of this aperture 121 and this imaging len 122, aperture because of this aperture 121 makes this at least one scattered light 102 produce diffraction light again, this diffraction light produces hot spot by this imaging len 122, and can control its spot size according to the pore size of this aperture 121, and this hot spot images in this sensor 14.Suitably integrating parameters such as spot size, taking lens focal length, capture angle and capture object plane scope, satisfy the relative optical path difference change in hot spot path and measure 4 δ * d*cos ³(θ _AThe value of)/γ then can produce an indeformable hot spot figure less than λ/5 as the plane, wherein λ is the wavelength of high same tone light 100.

In order to obtain three-dimensional object plane feature signal is converted to the optimum efficiency of indeformable hot spot image, the present invention's design is measured scattered light 102 in the direction of θ r=θ i ± 10 °, and wherein θ i is the incident angle that the high same tone light 100 of incident is incident in object plane 2.Utilize the optical axis of light limiting module 12 of the present invention can accurately obtain the scattered light 102 of θ i ± 10 ° direction.When the high same tone light of incident to shine an object plane near directional light, its scattered energy distributes and occupies more ratio in the direction of θ r=θ i usually, and along with the gap of scatteringangle r and incident angle θ i, scattared energy is more and more little.Therefore, to effectively obtain scattered energy and should image-taking device be installed in θ r=θ i direction, but the scattered light in θ r=θ i direction comprises two compositions, Main Ingredients and Appearance reaches the scattered light of few part from coarse particles from the even reflected light on plane, (wave front) phase place unanimity before the even reflecting light, and present erratic variation with rough surface from its Wave-front phase of scattered light of coarse particles, the light of these two kinds of different qualities can interfere with each other the formation conoscope image each other, the correlativity of conoscope image before and after resolving, can obtain light source and the face to be illuminated information that relatively moves, it is modern if face to be illuminated is very coarse, then evenly reflected light will greatly reduce, scattered energy increases, and phase change is quick, unfavorable figure coherence's identification.The present invention is chosen in the direction receiving scattered light of θ r=θ i ± 10 °, can avoid the energy of direct reflection on the one hand, can obtain purer scattered light signal on the one hand, the scattered light that captures this angle is interfered hot spot, can relatively effectively note down three-dimensional object plane feature signal, reach the function of accurate identification and location.

Seeing also Fig. 2 B, is the light path synoptic diagram of aperture position of the present invention and incident field angle relation.As shown in the figure, the same with the embodiment of above-mentioned Fig. 2 A have a light limiting module 12 that comprises imaging len 122 and aperture 121, this aperture 121 can be before or after this imaging len 122, it is example that this figure is seated in this imaging len 122 G point or H point afterwards with this aperture 121, and the relation of aperture position and incident field angle is described.Be seated in this aperture 121 at H point place and this light limiting module 12 that this imaging len 122 is formed, this light limiting module 12 than this aperture 121 that is seated in G point place and this imaging len 122 are formed can stop more from optical axis scattered light far away.By this light path synoptic diagram as can be known, this aperture 121 between this imaging len 122 and this sensor 14, the size of incident field angle can be controlled in the position of this aperture 121, i.e. the capture scope on limiter plane.In this present embodiment, exemplify out when this high same tone light is projeced on this body surface 2 E, F at 2, produce at least one scattered light 102, this at least one scattered light 102 is by this imaging len 122.If this aperture 121 is set when G point place, making this high same tone light be projeced into this at least one scattered light 102 that E, F produced at 2 all can be via this imaging len 122, image in E ', F ' 2 points of this sensor 14, but the luminous flux of F ' point is greater than the luminous flux of E ' point.If this aperture 121 is set in H point place, will make the F point that has only close optical axis can be, and image in the F ' point of this sensor 14 via this imaging len 122, the E point far away from optical axis then can't image on this sensor 14 via this imaging len 122.In the present embodiment, the effect of this aperture is aperture diaphragm (aperturestop), and the effect of this imaging len 122 is field diaphragm (field stop).This light limiting module of present embodiment can realize controlling spot size simultaneously and effectively limit the incident field angle that this at least one scattered light 102 enters this sensor 14 after the size and location of suitably adjusting this aperture, promptly limit the capture scope of object plane.After suitably integrating parameters such as spot size, taking lens focal length, capture angle and capture object plane scope, make and satisfy the relative optical path difference change in hot spot path and measure 4 δ * d*cos ³(θ _AThe value of)/γ then can produce an indeformable hot spot figure less than λ/5 as the plane, wherein λ is the wavelength of high same tone light 100.

Seeing also Fig. 2 C, is the structural representation of another preferred embodiment of the present invention.As shown in the figure, different being with Fig. 2 A embodiment, each light limiting module of present embodiment also comprises an imaging len 122 and an aperture 121, but this imaging len 122 is located at before this aperture 121, promptly this aperture 121 is located between this imaging len 122 and this sensor 14, in order to reach the incident visual angle of effective restriction scattered light, this aperture 121 places after the focus of imaging len 122 usually, before the sensor 14.

Other consults Fig. 2 D, is the structural representation of another preferred embodiment of the present invention.As shown in the figure, different being of embodiment with Fig. 2 A, this light limiting module 12 is micro lens 123, and this micro lens 123 around a light barrier 124 is set, the effect that has the aperture 121 of this Fig. 2 A because of this light barrier 124, make this at least one scattered light 102 produce diffraction effect, and then generation diffraction light, and with the irradiated area acting in conjunction of this body surface 2 to limit the incident field angle that this at least one scattered light 102 enters this sensor 14, and, and on this sensor 14, produce this indeformable hot spot figure by this set micro lens 123 of its center.

Seeing also Fig. 3, is the structural representation of another preferred embodiment of the present invention.As shown in the figure, different being with Fig. 2 A embodiment, this light limiting module 12 of present embodiment comprises an imaging len 122, one first aperture 125 and one second aperture 126, and this imaging len 122 is located at after this first aperture 125 and this second aperture 126, promptly this imaging len 122 is located between this second aperture 126 and this sensor 14, and be to place this first aperture 125 earlier by this light limiting module 12 to the arrangement of 14 of this sensors, then place this second aperture 126, place this imaging len 122 again, place this sensor 14 at last.When this optical transmitting set 10 these high same tone light 100 of emission to this body surface 2 produces this at least one scattered light 102, at least one scattered light 102 of this of these first aperture, 125 stop portions, limit this at least one scattered light 102 and enter this sensor 14, when part should be at least one after scattered light 102 passes through this first aperture 125, utilize this second aperture 126 once again this at least one scattered light 102 of restricted part enter this sensor 14.The diameter of this first aperture 125 and this aperture 126 and distance have between the two determined the incident field angle that this at least one scattered light 102 partly enters this sensor 14, promptly limited the capture scope of object plane, and then make this at least one scattered light 102 in the incident field angle produce diffraction light, this diffraction light images on this sensor 14 by this imaging len 122, forms an indeformable hot spot figure.The arrangement of above-mentioned this imaging len 122, this first aperture 125 and this second aperture 126, also this imaging len 122 can be located at before this first aperture 125 and this second aperture 126, promptly this first aperture 125 and this second aperture 126 are located between this imaging len 122 and this sensor 14.This imaging len 122 also can be arranged between this first aperture 125 and this second aperture 126 in addition.

Seeing also Fig. 4 A, is the synoptic diagram that the present invention produces rescattering light.As shown in the figure, with different being of embodiment of Fig. 2 B, each light limiting module comprises imaging len 122 and aperture 121, and adds a sleeve 141 on this sensor 14, because of this sensor 14 has this sleeve 141.This body surface 2 is not in the incident field angle, that is the I in non-signal zone is ordered this at least one scattered light 102 that is produced and is projected on the I ' point of these sleeve 141 inboards, I ' names a person for a particular job and produces a rescattering light 104, this rescattering light 104 can be by being located at this aperture 121 on the H point I of this sensor 14 of directive " on the point; this rescattering light 104 can't reach the indeformable effect of hot spot image if can't effectively remove.Because of the phase change of rescattering light can't effectively be controlled in a jumble, so when rescattering light 104 overlaps on the picture plane with primary scattering signal light 102, synthetic hot spot image flicker is come and go, can't reach the purpose of the indeformable light-spot view-finding of the present invention.

Seeing also Fig. 4 B, is the light path synoptic diagram of another preferred embodiment of the present invention.As shown in the figure, be with the different of Fig. 4 A, because being projected to this rescattering light that these sleeve 141 inboards are produced, this at least one scattered light 102 enters this sensor 14 in order to stop, and cause the flicker of hot spot image to come and go, therefore one prime light limiting piece 16 is set before this light limiting module 12, and this prime light limiting piece 16 is a prime aperture 161 at present embodiment, because of this prime light limiting piece 16 is to be located between this body surface 2 and this light limiting module 12, this light limiting module 12 comprises this imaging len 122 and this aperture 121, so 122 of this body surface 2 and this imaging lens are provided with this prime aperture 161, this aperture 121 is set between this imaging len 122 and this sensor 14, be projected to the F point and the I point of this body surface 2 when this high same tone light, the F that falls within the signal zone is ordered this at least one scattered light 102 that is produced and can be passed through this prime aperture 161, the imaging of this imaging len 122 and this aperture 121 directly into being incident upon sensor 14, the I that falls within non-signal zone is ordered this at least one scattered light 102 of being produced and is limited by this prime aperture 161 and stop, and all the other are by this at least one scattered light 103 of this prime aperture 161, be projected to this rescattering light that this sleeve 14 produced and also can't enter this sensor 14, so can effectively reduce background information light, improve the signal to noise ratio of this sensor 14 and obtain the indeformable effect of hot spot image.Present embodiment is set up this prime light limiting piece 16 before being illustrated in this light limiting module 12, thereby can stop effectively that this at least one scattered light 103 that this body surface 2 through this high same tone light projection is produced is projected to this rescattering light that another body surface produces, avoid this rescattering light to enter this sensor 14, effectively reduce the background information of this sensor 14, and then reach the indeformable purpose of hot spot.

Seeing also Fig. 4 C, is the structural representation of another preferred embodiment of the present invention.As shown in the figure, different being of embodiment with Fig. 2 C, each light limiting module comprises imaging len 122 and aperture 121, and before this imaging len 122, and this prime aperture 161 of 2 addings of this body surface, this prime aperture 161 can effectively stop, this rescattering light that this at least one scattered light 102 that this body surface 2 is produced is produced, avoid this rescattering light to enter this sensor 14, effectively reduce the background information of this sensor 14, and then reach the indeformable purpose of hot spot.

Above-mentioned Fig. 2 A to Fig. 4 C is all the preferred embodiment of indeformable light-spot view-finding device of the present invention, this indeformable light-spot view-finding device mainly has an optical transmitting set, a light limiting module and a sensor, and this light limiting module can effectively limit the incident field angle that this at least one scattered light 102 enters this sensor 14, has promptly limited the capture scope of object plane.Suitably integrating parameters such as spot size, taking lens focal length, capture angle and capture object plane scope, satisfy the relative optical path difference change in hot spot path and measure 4 δ * d*cos ³(θ _AThe value of)/γ is less than 1/5th high same tone optical wavelength, then can obtain producing an indeformable hot spot figure as the plane, and then can be applicable to computer mouse, finger navigator, smart card, three-dimensional fingerprint identity identification device, machine-tool or mechanical arm Precision Position Location System etc.Laser facula photoelectricity read head by Fig. 4 C-structure of the present invention institute output, the hot spot image of measuring, as shown in Figure 5, the object plane of this experiment is a rigidity mouse plate, and every image moves 60 μ m with translation stage, is moved continuously by left-to-right, a series of hot spot images can be confirmed from front and back, the hot spot image is from appearing on the sensor to shifting out sensor, and the hot spot image has only translation can not be out of shape, and really obtains indeformable light-spot view-finding effect.

Therefore, indeformable light-spot view-finding device of the present invention and method can be applicable in the laser mouse 300, as shown in Figure 6A, light source 10 and sensor 14 all are installed in the housing 310 of laser mouse 300.Light source 10 presents a parallel beam and is incident on the surface 2 via a collector lens 11, and generation scattered light 102, this at least one scattered light 102 is by light limiting module 12, imaging len 122 in the module is adjusted through suitable in advance with aperture 121, the interference light spot size that this at least one scattered light 102 is produced on sensor 14 is required size, and limited the incident field angle that scattered light 102 enters sensor 14 simultaneously, received by sensor 14 at last.So, before housing 310 moves, the sensor 14 records first hot spot figure, after housing 310 apparent surfaces 2 move, the sensor 14 records second hot spot figure, via the relation of the image identifying first hot spot figure and the second hot spot figure, judged the moving direction and the displacement size of housing 310, and moving as computer mouse.

Shown in Fig. 6 B, light source 10 and sensor 14 all are installed in the housing 310 of laser mouse 300.Light source 10 presents a parallel beam and is incident on the surface 2 via a collector lens 11, and produces scattered light 102, and the rescattering light of this scattered light 102 after by prime aperture 161 can be blocked and can't enter sensor 14.This at least one scattered light 102 by prime aperture 161 passes through light limiting module 12, imaging len 122 in the module is adjusted through suitable in advance with aperture 121, the interference light spot size that this at least one scattered light 102 is produced on sensor 14 is required size, and limited the capture scope of object plane simultaneously, received by sensor 14 at last.So, before housing 310 moves, the sensor 14 records first hot spot figure, after housing 310 apparent surfaces 2 move, the sensor 14 records second hot spot figure, via the relation of the image identifying first hot spot figure and the second hot spot figure, judged the moving direction and the displacement size of housing 310, and moving as computer mouse.

In above framework explanation, we can learn indeformable light-spot view-finding method of the present invention, see also Fig. 7 A, at first launch a branch of high same tone light (step 500), this high same tone light incident one surface, and then scattering produces scattered light (step 511), after the imaging len focus, before the sensor, one aperture is set, this aperture and this imaging len are combined into light limiting module (step 522), when scattered light passes through this light limiting module, the incident field angle that this scattered light enters sensor can be limited by light limiting module, and because of the aperture diffraction of this aperture of this light limiting module produces diffraction light (step 531), this diffraction light interferes with each other, and generation hot spot (step 540), writing down this hot spot at last again becomes an image (step 550), and carries out figure comparison with the moving of this hot spot of identification at this image, and relatively move (step 560) of interpretation image-taking device and body surface.

See also Fig. 7 B, at first launch a branch of high same tone light (step 500), this high same tone light incident one surface, and then scattering produces a scattered light (step 511), this scattered light is by first aperture (step 521), this scattered light is again by second aperture and imaging len, this first aperture, this second aperture and this imaging len are formed a light limiting module, in order to limit the incident field angle that scattered light enters sensor, and make this scattered light that the diffraction phenomenon take place when this light limiting module, and producing a diffraction light (step 530), this diffraction light interferes with each other, and produces hot spot (step 540), write down this hot spot at last again and become an image (step 550), and carry out the figure comparison at this image, with moving of this hot spot of identification, and relatively move (step 560) of interpretation image-taking device and body surface.

See also Fig. 7 C, at first launch a branch of high same tone light (step 500), this high same tone light incident one surface, and then scattering produces a scattered light (step 511), one aperture is set as prime light limiting piece (step 512) between body surface and imaging len, this scattered light is by behind this prime light limiting piece, can be blocked and can't enter sensor (step 513) via the rescattering light of sleeve, one less aperture is set between imaging len and sensor, this aperture and this imaging len are combined into a light limiting module (step 522), when scattered light passes through this light limiting module, the incident field angle that this scattered light enters sensor can be limited by this light limiting module, and because of the aperture diffraction of this aperture of this light limiting module produces diffraction light (step 531), this diffraction light interferes with each other, and produce a hot spot (step 540), write down this hot spot at last again and become an image (step 550), and carry out the figure comparison at this image, with moving of identification hot spot, and relatively move (step 560) of interpretation image-taking device and body surface.

So the present invention proposes a kind of image-taking device and method of indeformable hot spot, before sensor, install light limiting module additional, suitably integrating parameters such as spot size, taking lens focal length, capture angle and capture object plane scope, satisfy the relative optical path difference change in hot spot path and measure 4 δ * d*cos ³(θ _AThe value of)/γ then can produce an indeformable hot spot figure less than 1/5th optical source wavelengths as the plane, the spot pattern that moves front and back is had only move can not be out of shape, and therefore is easy to obtain precision positioning and identification.Therefore, indeformable light-spot view-finding device of the present invention and method can be applicable to computer mouse, finger navigator, smart card, three-dimensional fingerprint identity identification device, machine-tool or mechanical arm Precision Position Location System etc.

By the above detailed description of preferred embodiments, be to wish to know more to describe feature of the present invention and spirit, and be not to come category of the present invention is limited with above-mentioned disclosed preferred embodiment.On the contrary, its objective is that hope can contain in the category of claim of being arranged in of various changes and tool equality institute of the present invention desire application.Therefore, the category of the claim that the present invention applied for should be done the broadest explanation according to above-mentioned explanation, contains the arrangement of all possible change and tool equality to cause it.

Claims (20)

1. the image-taking device of an indeformable hot spot is characterized in that, comprises:

One light source, it launches a high same tone light, and this high same tone rayed one surface, and then scattering produces a plurality of scattered lights;

One light limiting module limits the incident field angle of these a plurality of scattered lights, makes these a plurality of scattered lights produce a plurality of diffraction light, and these a plurality of diffraction light interfere with each other and produce a plurality of hot spots;

One sensor, accept this a plurality of hot spots, and then produce one first hot spot figure, when this light limiting module and this sensor when should the surface moving, then produce one second hot spot figure, via comparison this first hot spot figure and this second hot spot figure, judged moving direction and displacement that this sensor relatively should the surface; And

One prime light limiting piece is arranged between this light limiting module and this surface, stops the rescattering light of this scattered light to enter sensor by this light limiting module.

2. the image-taking device of indeformable hot spot as claimed in claim 1 is characterized in that, this prime light limiting piece is an aperture.

3. the image-taking device of indeformable hot spot as claimed in claim 1, wherein, this light limiting module comprises an imaging len and an aperture, this aperture reaches before this sensor after being arranged at this imaging len focus, this imaging len and this aperture when imaging in this sensor of these a plurality of scattered lights by this light limiting module is because of the effect of this light limiting module has limited the incident field angle that these a plurality of scattered lights enter this sensor.

4. the image-taking device of indeformable hot spot as claimed in claim 1 is characterized in that, also comprises a collector lens, places this light source front end, makes this high same tone light become a directional light and shine this surface.

5. the image-taking device of indeformable hot spot as claimed in claim 1, it is characterized in that, the optical axis of this light limiting module is set in θ r 〉=θ i+10 ° direction, and wherein θ r is that optical axis and this surperficial angle, the θ i of this light limiting module are incident light and this surperficial angle.

6. the image-taking device of indeformable hot spot as claimed in claim 1, it is characterized in that, the optical axis of this light limiting module is set in θ r≤θ i-10 ° direction, and wherein θ r is that optical axis and this surperficial angle, the θ i of this light limiting module are incident directional light and this surperficial angle.

7. the image-taking device of indeformable hot spot as claimed in claim 1 is characterized in that, 4 δ * d*cos are measured in the change that arrives the relative optical path difference of this hot spot ³(θ _AThe value of)/γ is less than λ/5, and wherein this δ is mean radius, the θ of hot spot _AFolded capture angle, d is the diameter of surperficial capture scope and is equivalent to maximum moving distance, the γ of this image when indeformable and is this high same tone light wavelength for this imaging len to this Surface Vertical distance, λ between the optical axis for this surface and this light limiting module.

8. the image-taking device of indeformable hot spot as claimed in claim 1, it is characterized in that, this light limiting module comprises an aperture and an imaging len, this aperture is arranged at before this imaging len, this aperture and this imaging len when imaging in this sensor of these a plurality of scattered lights by this light limiting module is because of the effect of this light limiting module has limited the incident field angle that these a plurality of scattered lights enter this sensor.

9. the image-taking device of indeformable hot spot as claimed in claim 8, it is characterized in that, also comprise second aperture, be provided with near this body surface, this aperture and this second aperture limit the incident field angle that these a plurality of scattered lights enter this sensor, make the change of the relative optical path difference that arrives this hot spot measure 4 δ * d*cos ³(θ _AThe value of)/γ is less than λ/5, and wherein this δ is mean radius, the θ of hot spot _AFolded capture angle, d is the diameter of surperficial capture scope and is equivalent to maximum moving distance, the γ of this image when indeformable and is this high same tone light wavelength for this imaging len to this Surface Vertical distance, λ between the optical axis for this surface and this light limiting module.

10. the image-taking device of indeformable hot spot as claimed in claim 1 is characterized in that, this light limiting module is to be a micro lens.

11. the image-taking device of indeformable hot spot as claimed in claim 10 is characterized in that, also comprises a light barrier, be connected in this micro lens around, in order to stop this scattered light of not taking.

12. a laser mouse is characterized in that, comprises:

One light source, it launches a high same tone light, and this high same tone rayed one surface, and then scattering produces a plurality of scattered lights;

One light limiting module limits the incident field angle of these a plurality of scattered lights, makes these a plurality of scattered lights produce a plurality of diffraction light, and these a plurality of diffraction light interfere with each other and produce a plurality of hot spots;

One sensor is accepted this a plurality of hot spots, and then produces one first hot spot figure, when this light limiting module and this sensor when should the surface moving, then produce one second hot spot figure;

One prime light limiting piece is arranged between this light limiting module and this surface, makes the rescattering light of these a plurality of scattered lights enter sensor by this light limiting module; And

One processing unit in order to accepting this first hot spot figure and this second hot spot figure, and is compared this first hot spot figure and this second hot spot figure, with moving direction and the displacement of judging that this sensor relatively should the surface.

13. laser mouse as claimed in claim 12, it is characterized in that, this light limiting module comprises an aperture and an imaging len, this aperture reaches before this sensor after being arranged at this imaging len focus, this imaging len and this aperture when imaging in this sensor of these a plurality of scattered lights by this light limiting module is because of the effect of this light limiting module has limited the incident field angle that these a plurality of scattered lights enter this sensor.

14. laser mouse as claimed in claim 12 is characterized in that, this light limiting module makes the change of the relative optical path difference that arrives this hot spot measure 4 δ * d*cos ³(θ _AThe value of)/γ is less than λ/5, and wherein this δ is mean radius, the θ of hot spot _AFolded capture angle, d is the diameter of surperficial capture scope and is equivalent to maximum moving distance, the γ of this image when indeformable and is this high same tone light wavelength for this imaging len to this Surface Vertical distance, λ between the optical axis for this surface and this light limiting module.

15. laser mouse as claimed in claim 12 is characterized in that, this light limiting module comprises an aperture and imaging picture thoroughly, and this aperture is arranged at before this imaging len.

16. laser mouse as claimed in claim 12 is characterized in that, this light limiting module is for connecting the combination of a micro lens of a light barrier on every side.

17. the view finding method of an indeformable hot spot is characterized in that, comprises:

Launch a high same tone light;

This high same tone light incident one surface, and then scattering produces a plurality of scattered lights;

These a plurality of scattered lights make the rescattering light of these a plurality of scattered lights be blocked by a prime light limiting piece;

This a plurality of scattered lights and then by a light limiting module, this light limiting module has limited the visual angle, incident field of these a plurality of scattered lights, and makes this a plurality of scattered light generation diffraction, and produces a plurality of diffraction light;

These a plurality of diffraction light interfere with each other, and produce a plurality of hot spots; And

Write down these a plurality of hot spots and become an image.

18. the view finding method of indeformable hot spot as claimed in claim 17 is characterized in that,, also comprises at this image and carries out the figure comparison and monitor moving of this hot spot after this hot spot becomes the step of an image in record, the step that moves with respect to the surface with interpretation.

19. the view finding method of indeformable hot spot as claimed in claim 17, it is characterized in that, this light limiting module comprises an aperture and an imaging len, this aperture reaches before this sensor after being arranged at this imaging len focus, this imaging len and this aperture when imaging in a sensor of these a plurality of scattered lights by this light limiting module is because of the effect of this light limiting module has limited the incident field angle that these a plurality of scattered lights enter this sensor.

20. the view finding method of indeformable hot spot as claimed in claim 17 is characterized in that, this light limiting module makes the change of the relative optical path difference that arrives this hot spot measure 4 δ * d*cos ³(θ _AThe value of)/γ is less than λ/5, and wherein this δ is mean radius, the θ of hot spot _AFolded capture angle, d is the diameter of surperficial capture scope and is equivalent to maximum moving distance, the γ of this image when indeformable and is this high same tone light wavelength for this imaging len to this Surface Vertical distance, λ between the optical axis for this surface and this light limiting module.

Images