CN207007470U - A kind of mirrors focal length detection means - Google Patents
A kind of mirrors focal length detection means Download PDFInfo
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- CN207007470U CN207007470U CN201720861121.4U CN201720861121U CN207007470U CN 207007470 U CN207007470 U CN 207007470U CN 201720861121 U CN201720861121 U CN 201720861121U CN 207007470 U CN207007470 U CN 207007470U
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Abstract
The utility model discloses a kind of mirrors focal length detection means.The center of standard shows screen (8), image acquisition device (7) is on the same axis and fixed, eyeglass (4) to be measured is installed between conventional display (8) and image acquisition device (7) by mounting bracket, and center is consistent with axis；Controller (9) is connected by cable with standard shows screen (8), image acquisition device (7) and display device (10)；Image acquisition device (7) face eyeglass to be measured (4), pixel position is lighted through eyeglass to be measured (4) observation standard display screen (8)；Controller (9) control image acquisition device (7) carries out the collection of image, the pixel being lit on standard shows screen (8) is projected onto on acquisition chip (12) by eyeglass to be measured (4) and camera lens (11), makes on acquisition chip (12) that there is also point corresponding to one.
Description
Technical field
The present invention relates to field of optical detection, more particularly to a kind of mirrors focal length detection means.
Background technology
In the production and processing field that optical mirror slip, ophthalmic len, various imaging lens are first-class, the focal length of eyeglass is all most important
One of parameter.How to realize that high-precision focometry is extremely important, the detection of current focal length is mainly referred to as using one kind
The measuring instrument of vertometer.
The detection method of vertometer, for its light channel structure referring to accompanying drawing 1, specific method is as follows：
After eyeglass to be measured is placed in the optical path, the illumination that light source is sent is mapped on mobile graticle 2, and the image passes through collimation
Object lens 3, eyeglass 4 to be measured, object lens 5 have been projected on fixed reticle 6, are observed by image acquisition device on fixed reticle 6
Picture；The sensor of real-time measuring reticle position is housed on mobile graticle 2, for detecting 2 real time position.Image is adopted
Whether the image that storage and lens assembly are used to analyze on fixed reticle 6 is clear, makes collection by adjusting mobile graticle 2
Reach most clearly image on device, now show that the image on 6 is the best image of focusing effect, now according to the ginseng of object lens 5
Image distance v is obtained in number and position；Object distance u can be obtained according to the particular location of mobile graticle.
According to focal length formula：1/u+1/v=1/f, try to achieve focal length f.
The shortcomings that making in this way, mainly includes：
(1) precision is low：Determine whether that focusing is accurate by analyzing the image on fixed reticle, due to close to focus
When image definition difference it is smaller, can have certain error in Algorithm Analysis, while limited by sensor accuracy, it is real
The graduation Board position of survey has certain error.Both errors can cause the decline of accuracy of detection.
(2) cylindrical mirror detection error is big：The detection of cylindrical mirror needs to measure axle position and focal length simultaneously, is examined using the equipment
, it is necessary to which extra can be manually rotated servicing unit during survey, detection just can be achieved, but influenceed by analytical error, detection error is substantially big
In common eyeglass.
(3) center of lens detection is inaccurate：Examined principle and observation procedure influence, and the equipment error carries out center of lens
Detection and mark.By taking eyeglass as an example：During optometry and showing on trial, it has been determined that the good eyeglass lens power (inverse of focal length
(unit m) * 100), the eyeglass of actual wear is because the number of degrees are inaccurate, astigmatism axial direction and number of degrees error are big, center of lens is not adjusted
It is whole good, be very easy to cause to wear it is uncomfortable, so as to cause the increase of the human eye number of degrees and continuous worsening.
Therefore, in optical mirror slip detection field, detected with greater need for the detection device of high-precision and high-stability.
The content of the invention
The purpose of the application is：For prior art detection precision is low, cylindrical mirror detection and Spot detection error be big
Problem, the present invention proposes a kind of special purpose device of mirrors focal distance detecting method, by using the device, it is possible to achieve base
In the multipoint mode detection technique of machine vision, the detection based on multiple spot, and the method by asking for average, inspection can be greatly improved
Precision is surveyed, and accurately cylindrical mirror and center of lens are measured, efficiently solves above mentioned problem.
The present invention provides a kind of mirrors focal length detection means, by the center of standard shows screen, image acquisition device
On the same axis and fixed, eyeglass to be measured is installed between standard shows screen and image acquisition device by mounting bracket, and in
The heart is consistent with axis；Controller is connected by cable with standard shows screen, image acquisition device and display device.Image is adopted
Storage face eyeglass to be measured, pixel position is lighted through eyeglass to be measured observation standard display screen；Controller controls image
Collector carries out the collection of image, and the pixel being lit on standard shows screen is projected onto by eyeglass to be measured and camera lens
On acquisition chip, make on acquisition chip that there is also point corresponding to one.
Preferably, wherein eyeglass to be measured is placed on standard shows screen front end, image acquisition device is placed on eyeglass to be measured
Rear end, the distance between image acquisition device and eyeglass to be measured are 0.5mm-50000mm, and image acquisition device gathers against eyeglass to be measured
Image on standard shows screen.
Beneficial effect：Using the mirrors focal length detection means of the present invention, can be achieved to utilize focal length calculation formula, with reference to
The mode of machine vision, independent quantization is carried out to multiple spot and detected, obtain the focal length distribution of tested lens surface, and then by asking
The modes such as average are taken to determine eyeglass focal length, center and axial method, it is possible to achieve compared to the detection of prior art higher precision.
Brief description of the drawings
Fig. 1 is prior art vertometer detection method light channel structure figure.
Fig. 2 is mirrors focal length structure of the detecting device figure of the present invention.
Fig. 3 is the IMAQ device assembly enlarged diagram of mirrors focal length detection means of the present invention.
Fig. 4 is that mirrors focal distance detecting method screen of the present invention lights coordinate graph.
Fig. 5 lights coordinate graph for mirrors focal distance detecting method acquisition chip of the present invention.
Accompanying drawing identifies：1 it is light source, 2 be mobile graticle, 3 be collimator objective, 4 be eyeglass to be measured, 5 be object lens, 6 is solid
Determine graticle, 7 be image acquisition device, 8 be standard shows screen, 9 be controller, 10 be display device, 11 be camera lens, 12 be
Acquisition chip.
Embodiment
For make present invention solves the technical problem that, the technical scheme that uses and the technique effect that reaches it is clearer, below
The present invention is described in further detail in conjunction with the accompanying drawings and embodiments.It is understood that specific implementation described herein
Example is used only for explaining the present invention, rather than limitation of the invention.It also should be noted that for the ease of description, accompanying drawing
In illustrate only part related to the present invention rather than full content.
The mirrors focal length structure of the detecting device of the present invention, as shown in Fig. 2 including standard shows screen 8, IMAQ
Device 7, controller 9 and display device 10.
Standard shows screen 8, the center of image acquisition device 7 are on the same axis and fixed, and eyeglass 4 to be measured is by common
Mounting bracket is installed to shown position, and between standard shows screen 8 and image acquisition device 7, and center is consistent with axis.
Controller 9 is connected by cable with standard shows screen 8, image acquisition device 7 and display device 10.
Because position is fixed between standard shows screen 8, eyeglass to be measured 4, image acquisition device 7, therefore standard shows screen 8
Spacing d1 with eyeglass 4 to be measured is, it is known that known to the eyeglass to be measured 4 and centre distance d2 of camera lens 11 of image acquisition device 7.
According to the hardware parameter of standard shows screen 8, it may be determined that the resolution ratio of standard shows screen 8 is laterally
Screenres1, longitudinal direction is screenres2, while determines pixel away from for screenpixel.
Eyeglass 4 to be measured is amplified with image acquisition device 7, reference picture 3, image acquisition device 7 can be divided into camera lens 11 and collection core
Piece 12.It is observed on eyeglass 4 to be measured and is a little projected by camera lens 11 on acquisition chip 12.
According to the component parameter of image acquisition device 7, it may be determined that the focal length dfocus of camera lens 11, point of acquisition chip 12
Resolution transverse direction ccdres1, longitudinal ccdres2, pixel is away from ccdpixel.
Next in a manner of point by point scanning, main flow of the present invention in real work is illustrated：
1st, control standard shows screen 8 to be lighted point by point by controller 9, using light current screen coordinate as
Exemplified by (Xscreen, Yscreen), with reference to figure 4：
Due to known standard shows screen 8 resolution ratio and pixel away from, the pixel that is lit (Xscreen,
Yscreen rise dscreen) can be determined by formula：
Dscreen=sqrt ((Xscreen-screenres1/2) * (Xscreen-screenres1/2)-
(Yscreen-screenres2/2)*(Yscreen-screenres2/2))*screenpixel；
2nd, the face of image acquisition device 7 eyeglass 4 to be measured, the point bright pixel observed through eyeglass 4 to be measured on standard display screen 8
Point position.Controller 9 controls the collection of the progress image of image acquisition device 7, and the pixel being lit on standard shows screen 8 leads to
Cross eyeglass 4 and camera lens 11 to be measured to be projected onto on acquisition chip 12, there is also point corresponding to one, its coordinate ginseng on acquisition chip 12
Examine as (Xccd, Yccd), as shown in Figure 5.
Because the resolution ratio and pixel of known acquisition chip 12 are away from the rise for the pixel (Xccd, Yccd) being lit
Dccd can be determined by formula：
Dccd=sqrt ((Xccd-ccdres1/2) * (Xccd-ccdres1/2)-(Yccd-ccdres2/2) *
(Yscreen-ccdres2/2))*ccdpixel；
3rd, according to similar triangles relation, by rise dccd, to be measured eyeglass 4 and image acquisition device 7 of the light on CCD
The centre distance d2 of camera lens 11 and the focal length dfocus of camera lens 11 can obtain rise dlens of the light on eyeglass 4 to be measured.
Dlens=(d2/dfocus) * dccd；
4th, shown according to rise dscreen of the light on standard shows screen 8, the rise dlens on eyeglass 11 and standard
The spacing d1 of display screen curtain 8 and eyeglass 4 to be measured, calculate object space position of intersecting point u：
U=d1*dlens/ (dlens-dscreen).
5th, because object space intersection point distance v is the center of eyeglass 4 to be measured to optical center distance d2, i.e.,：
V=d2；
6th, according to focal length formula 1/u+1/v=1/focus, the real focal length of the point can be calculated：
Focus=u*v/ (u+v)；
7th, to calculate a bit in scanning process more than, each point is scanned successively in this mode, with common 1,300,000 pixel
Exemplified by, even if effectively shooting area is only 10%, its points also can reach at 130,000 points, and mirror to be measured can be drawn according to scanning element
The focal length distribution on the surface of piece 4.
8th, according to institute's number of scan points, mean value computation is carried out, can obtain the true focal length of eyeglass 4 to be measured, because actual measurement is counted
It is more, it is very high to calculate focal length precision.
9th, the principle of radiation direction is not changed according to center of lens, in the focal length that the central area of eyeglass 4 to be measured calculates
Abnormal situation about being worth greatly occurs, therefore extracts the position coordinates of higher value focal length in the focal length matrix that scanning obtains, you can
To the accurate center of eyeglass 4 to be measured.
10th, measured for the axle position of cylindrical mirror, because the focal length for having obtained the surface of eyeglass 4 to be measured is distributed, and cylindrical mirror is in axle position
The focal length of direction and vertical direction is significantly different, passes through the analysis of focal length size in a rotational direction, you can obtain degree of precision
Axle position direction.
11st, display result is output on display device 10 by controller.
The features of the present invention：Control display screen curtain, image acquisition device and controller, tested eyeglass is placed on screen and figure
As collector medium position, image acquisition device observes the image of display screen against tested eyeglass, and screen is controlled by controller
Display, IMAQ, and calculate focal length and result output.
Display screen of the present invention, not only it is contained in liquid crystal display, flat panel TV, LED lamp bead display screen, projection screen
Deng should also contain the arbitrary device acted on display, display pattern with special characteristic etc., these patterns can be with more
Kind form is shown, is placed in specific display structure (mainly for avoiding using the situation of some pictures or show canvas not
By the patent protection) display methods includes but is not limited to that lamp bead is shown, there is certain characteristic image to show in transverse and longitudinal direction, striped
Display etc..
Controller of the present invention can be single-chip microcomputer, industrial computer or other there is the electronic equipment of computing function, comprising
But it is not limited to 1.
Image of the structure of the present invention for image acquisition device against tested eyeglass observation display screen, including diagram are straight
Connect face mode, should also include tiltedly to, reflected by some speculums after the positive indirect implementation of equity.
In computational methods of the present invention, point by point scanning is to illustrate the easy realization side of one kind easily enumerated
Formula, the present invention should also include other as being scanned using certain given shape image or stripe pattern, rise calculated by multiple spot
And then the method for calculating focal length.
Embodiment 1
Using display screen resolution as 1024*768 in embodiment, Diagonal Dimension is 12 inches i.e. 30.48mm, it may be determined that
Hardware parameter is as follows：
Screenres1=1024
Screenres2=768
Due to screen size ratio position 4:3, determine that lateral dimension is cornerwise 0.8 times according to Pythagorean theorem, i.e.,
30.48*0.8=20.384mm, the Pixel Dimensions of screen are calculated accordingly：
Screenpixel=20.384/1024=0.238mm
The spacing of established standardses display screen 8 and eyeglass 4 to be measured：D1=200mm
The optical center spacing of eyeglass 4 to be measured and image acquisition device 7：D2=150mm
So that 1,300,000 pixel, 1/2 cun of CMOS chip is beaten in 16mm focal length lenses as an example, hardware parameter may be determined as follows：
Dfocus=16mm
Ccdres1=1280
Ccdres2=1024
Ccdpixel=0.0052mm
Continue so that the controller control pixel of upper left first is lighted as an example：
Xscreen=1
Yscreen=1
The pixel causes (800,600) on collector to be lit：
Xccd=800
Yccd=600
With image acquisition device center, treat that center of lens, standard shows screen center are conllinear and are set as Z axis, Z axle zero points
It is that just the XY directions of coordinate system refer to screen pixel map to screen orientation for optical center.
Next rise of the corresponding bright spot on standard shows screen, on eyeglass to be measured, on acquisition chip is calculated respectively：
Rise calculates on standard shows screen：
Because display center is XY centers, current location of pixels (Xscreen, Yscreen) of lighting is (1,1), can
Calculating current location is ((Xscreen-screenres1/2) * screenpixel ,-(Yscreen-screenres2/2) *
Screenpixel/2), i.e.,：
((1-1024/2) * 0.238 ,-(1-768/2) * 0.238)=(- 121.86,91.39)
It is h_screen=sqrt ((- 121.86) * (- 121.86)+91.39* to calculate corresponding rise according to Pythagorean theorem
91.39)=152.32mm
Same method can calculate the rise on acquisition chip：
((Xccd-ccdres1/2) * ccdpixel ,-(Yccd-ccdres12/2) * ccdpixel/2), i.e.,：
((800-1280/2) * 0.0052,-(600-1024/2) * 0.0052/2)=(0.832, -0.458)
H_ccd=sqrt (0.832*0.832+ (- 0.458) * (- 0.458))=0.950mm
According to similar triangle theory, can obtain：
D2/dfocus=h_lens/h_ccd
Calculate the rise on eyeglass：
H_lens=d2/dfocus*h_ccd=150/16*0.95=8.91mm
In this structure, image distance v is eyeglass to optical center distance, i.e. v=d2；
Object distance u forms according to the spacing d1 of screen rise h_screen, eyeglass rise h_lens and screen and eyeglass to be measured
Similar triangles can be calculated：
U/d1=h_lens/ (h_screen-h_lens)
U=h_lens/ (h_screen-h_lens) * d1
=8.91/ (152.32-8.91) * 200
=12.42mm
Due to rise h_screen>H_lens, object space intersection point is on the right side of eyeglass, therefore object distance is negative value, i.e. u=-
12.42mm, according to focal length formula：
1/u+1/v=1/f
Calculate：
F=u*v/ (u+v)
=-12.42*150/ (- 12.42+150)
=-13.54mm
Negative value shows that the eyeglass is concavees lens.
Focal length matrix is established, size is suitable with screen pixels, i.e. Focus [1024] [768], negative value
Focus [1] [1]=- 13.54mm
The like can according to said method continue to improve the matrix, finally draw a focal length matrix comprising 780,000 points,
This matrix, which is averaged, can obtain pinpointed focus, and cylindrical mirror and center of lens can easily be drawn according to matrix distribution.
Finally it should be noted that：Various embodiments above is merely illustrative of the technical solution of the present invention, rather than its limitations；To the greatest extent
The present invention is described in detail with reference to foregoing embodiments for pipe, it will be understood by those within the art that：Its is right
Technical scheme described in foregoing embodiments is modified, and either which part or all technical characteristic are equally replaced
Change, the essence of appropriate technical solution is departed from the scope of various embodiments of the present invention technical scheme.
Claims (2)
1. a kind of mirrors focal length detection means, it is characterised in that by standard shows screen (8), image acquisition device (7)
The heart is on the same axis and fixed, and eyeglass (4) to be measured is installed to standard shows screen (8) and image acquisition device by mounting bracket
(7) between, and center is consistent with axis；Controller (9) passes through cable and standard shows screen (8), image acquisition device (7)
And display device (10) connection；Image acquisition device (7) face eyeglass to be measured (4), conventional display is observed through eyeglass to be measured (4)
Curtain (8) lights pixel position；Controller (9) control image acquisition device (7) carries out the collection of image, in standard shows screen
(8) pixel being lit on is projected onto on acquisition chip (12) by eyeglass to be measured (4) and camera lens (11), makes acquisition chip
(12) there is also point corresponding to one on.
2. mirrors focal length detection means according to claim 1, it is characterised in that eyeglass (4) wherein to be measured is placed
In standard shows screen (8) front end, image acquisition device (7) is placed on the rear end of eyeglass to be measured (4), and image acquisition device (7) is with treating
It is 0.5mm-50000mm to survey the distance between eyeglass (4), and image acquisition device (7) gathers conventional display against eyeglass to be measured (4)
Image on curtain (8).
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