CN1563887A - Optical vernier protractor, its measuring range and precision design method - Google Patents

Abstract

The invention belongs to technical area of designing photoelectric sensor. The device contains upper mask plate as optical vernier moving ruler and lower mask plate as optical vernier static ruler. Relative position between the said rulers is fixed and parallel to each other. A piece of lightproof wide dark stripe representing measurement zero point is in center on upper mask plate. Symmetrical periodic dark and light interlaced stripes are distributed on two sides of the said zero point dark stripe. Symmetrical periodic dark and light interlaced stripes are also distributed on lower mask plate, but their periods are different between stripe on upper mask plate and lower mask plate. A piece of optoelectronic converter is setup under the lower mask plate. The invention also discloses method for designing measuring range and precision.

Description

Optical vernier angle-measuring equipment and measurement range thereof and accuracy Design method

Technical field:

Optical vernier angle-measuring equipment and measurement range thereof and accuracy Design method belong to the photoelectric sensor design field.

Background technology:

Present optical angle measuring device and method are a lot, but because the restriction on the principle of work, the general measurement performance requirement that is difficult to realize simultaneously on a large scale with high precision two aspects.By retrieval, do not retrieve and same or analogous optical angle measuring device of the present invention and method in the open source literature both at home and abroad.

Summary of the invention:

The objective of the invention is to, a kind of brand-new optical angle measuring device---optical vernier angle-measuring equipment has been proposed, this device can be measured the angle of incident light, because this invention merges vernier measuring technique and optics angle measurement technique, this device can realize simultaneously optical angle on a large scale with high-precision measurement.The principle that the present invention measures the light incident angle is similar to the long principle of survey of vernier caliper, promptly by the assembly coding of unequal scale of scale cycle and moving chi is realized high-precision measurement.

Optical vernier angle-measuring equipment proposed by the invention is characterised in that: it contains last mask plate and the following mask plate of representing moving chi of optical vernier and optical vernier scale respectively, describedly go up the position relative fixed of mask plate and following mask plate and be parallel to each other, have a representative to measure the wide zero point dark fringe of the shading at zero point in the central authorities of last mask plate, the both sides of described zero point dark fringe symmetry and etc. the light and dark striped of distributing logical light and shading in cycle; Light and dark striped in the distributing logical light and the shading in described following first-class cycle of mask plate; The cycle of the light and shade striped on the described upward mask plate and the cycle of the light and shade striped on the following mask plate are unequal; Below described mask plate down, placing a photoelectric commutator.The described mask plate of going up is fixed by a rigid structure with following mask plate.

The measurement range and the accuracy design of optical vernier angle-measuring equipment proposed by the invention is characterized in that:

Measurement range is determined by following formula:

$W=2\×\arctan \left(\frac{N\×(c+d)}{2h}\right)$

Measuring accuracy is determined by following formula:

$p=\frac{2\·(a+b)\×(c+d)\·W}{(A-B)\·C}$

Wherein W is a measurement range, and N is the total number of cycles of the scale striped of following mask plate, and c is the dark fringe width of scale, and d is the bright fringe width of scale, and h is the distance between the upper and lower mask plate; P is a measuring accuracy, a is a width of going up the dark fringe on the mask plate, b is a width of going up the bright fringe on the mask plate, A is the effective length that goes up the light and shade striped of mask plate, promptly be positioned at the total length that moving chi striped is covered on the mask plate, B is the width of zero point dark fringe on the last mask plate, and C is the effective length of the light and shade striped of following mask plate, the total length that mask plate upper fixed ruler striped is covered under promptly being positioned at.

Proof by experiment, this device can be realized the measurement of angle of incident light, by suitable parameter designing, can realize simultaneously on a large scale and high-precision measurement of angle, has reached the set goal of the present invention.

Description of drawings:

Fig. 1 is a principle structure synoptic diagram of the present invention, and wherein 1 is to go up mask plate, the 2nd, and moving chi mask, the 3rd, scale mask, the 4th, following mask plate, the 5th, photoelectric commutator, the 6th, fixed mount.

Fig. 2 is the moving chi mask pattern synoptic diagram of optical vernier.

Fig. 3 is an optical vernier scale mask pattern synoptic diagram.

Fig. 4 is the optical vernier coding synoptic diagram that tested incident light forms after by optical vernier.

Fig. 5 is the structural drawing of the optical vernier angle-measuring equipment of the invention process example.Wherein 1 is to go up mask plate, the 2nd, and moving chi mask, the 3rd, scale mask, the 4th, following mask plate, the 5th, photoelectric commutator, the 7th, circuit board, the 8th, fixed mount pressing plate, the 9th, fixed mount main body.

Embodiment:

Principle structure synoptic diagram of the present invention as shown in Figure 1, pass through micromachining technology, design and produce two blocks of optical figuring transmissive mask plates up and down, the carrier that upper and lower mask plate is assembled in a rigid structure respectively is on the fixed mount, the relative position of last mask plate and following mask plate is fixed, be parallel to each other, constitute the moving chi of optics and the optics scale of optical vernier structure respectively, the distance between the mask plate is h up and down.Moving chi of optics of the present invention and optics scale constitute the sensing unit that incident angle of light is measured.Because moving chi (as Fig. 2) and scale (as Fig. 3) are respectively by having periodic distribution, and the special mask pattern structure that the cycle size not exclusively equates constitutes, variation with the incident light incident angle, the moving projection of chi on the optics scale of optics changes, thereby makes the optical vernier coding that tangible light and shade striped code change (as Fig. 4) take place.Similar with the measurement of vernier caliper, each light angle has and has only an optical vernier coding corresponding with it.The variation of optical vernier coding by certain transformational relation, just can draw high-precision incident angle of light information by follow-up line array CCD or similarly photoelectric commutator reception and detection.

The moving chi mask pattern of optics in the optical vernier structure is made of " the logical light " of symmetrical distribution and cycle variation and the light and shade stripe of " shading " as shown in Figure 2.Optics scale mask pattern in the optical vernier structure is made of " the logical light " of cycle variation and the light and shade stripe of " shading " as shown in Figure 3.The width and the cycle of the light and shade stripe of " logical light " and " shading " on moving chi of optics and the scale, optical interval between the mask plate of moving chi of optics and scale, and the structural parameters such as size of moving chi and scale mask plate all are the keys of design, and these parameters will determines whole measuring accuracy and the measurement range that can realize of installing.

The moving chi structure of optical vernier as shown in Figure 2, width is that the dark fringe of B is the zero point of vernier, moving chi is symcenter with " zero point " and is made of the light and shade striated structure with periodic characteristic.If the length of the moving chi one-period of optical vernier is T ₁=a+b, a wherein and b are respectively moving chi " shading " dark fringe width and " logical light " the bright fringe width that produces through microtechnology processing back.The moving chi of optical vernier adopts the asymmetric encoding structure, and the total number of cycles of the moving monolateral striped of chi of optical vernier is M.The width that optical vernier moves chi " zero point " striped is B.The effective length of the moving chi of optical vernier is A, promptly is positioned at the total length that moving chi striated pattern is covered on the mask plate.

Optical vernier scale structure as shown in Figure 3, scale is made of the light and shade striated structure with periodic characteristic.If the length of optical vernier scale one-period is T ₂=c+d.C wherein and d are respectively scale " shading " dark fringe width and " logical light " the bright fringe width that produces through microtechnology processing back.The total number of cycles of optical vernier scale striped is N.The effective length of optical vernier scale is C, the total length that mask plate upper fixed ruler striated pattern is covered under promptly being positioned at.

The moving chi mask of optical vernier and the cycle of the light and shade striped on scale mask size are approaching but unequal, i.e. T ₁≠ T ₂After the tested light incident, moving chi has carried out primary modulation to light, produces and the corresponding light and dark primary modulation image of moving chi striped, and this modulation image is dynamically projected to the variation of incident angle of light on the diverse location of scale.The primary modulation image that scale then produces moving chi carries out the modulation second time, thereby has produced the optical vernier coded image (light and shade striped coding) of significant change, as shown in Figure 4.By the design of scale and moving chi, can guarantee that each angle of incident light correspondence unique light and shade striped coding, i.e. the optical vernier coding.This optical vernier coded image can be at an easy rate by follow-up line array CCD or similarly photoelectric commutator reception and detection, by certain transformational relation, just can draw high-precision incident angle of light information, measuring accuracy depends primarily on that optical vernier is moving, the structural parameters of scale.If the length that scale is enough then can draw incident ray in theory near the angle change information in the incident scope of 180 ° (180 ° of ultimate values that are generally considered to be the angle measuring instrument measurement range).The present invention that Here it is can realize on a large scale the reason with high-acruracy survey simultaneously, and measurement range and measuring accuracy depend on the design of optical vernier structural parameters fully.

If the optical range in the optical vernier structure between moving chi of optical vernier and the optical vernier scale is h (as Fig. 1).Then the relation of the measurement range of each parameter and incident angle of light to be measured and measuring accuracy is as follows:

The measurement range of incident angle of light to be measured is determined:

The measurement range of incident angle of light to be measured is determined fairly simple.According to geometric optical theory, the measurement range W of incident angle of light to be measured depends on the resulting structure size C of optical vernier scale and the optical range h between moving chi of optical vernier and the optical vernier scale.As Fig. 1 and Fig. 3, it is as follows to get parameters relationship:

$W=2\×\arctan \left(\frac{C/2}{h}\right)---\left(1\right)$

The resulting structure size C of optical vernier scale depends on the length T of scale fringe period sum N and scale one-period ₂As Fig. 3, it is as follows to get parameters relationship:

C＝N×T ₂ (2)

T ₂＝c+d (3)

Can get by (1), (2), (3):

$W=2\×\arctan \left(\frac{N\×(c+d)}{2h}\right)---\left(4\right)$

Determining of the measuring accuracy of incident angle of light to be measured:

Definite more complicated of the measuring accuracy of incident angle of light to be measured also is a key of the present invention.After the measurement range W of incident angle of light to be measured determined, the measuring accuracy of incident angle of light to be measured (being designated as p) depended on the multiple n of optical vernier structure to the incident angle of light segmentation.Its relation is as follows:

$p=\frac{W}{n}---\left(5\right)$

According to the vernier measuring principle, segmentation multiple (being designated as n) with the pass of the monolateral fringe period sum M of moving chi, scale fringe period sum N is:

n＝M×N (6)

As Fig. 2, the moving monolateral fringe period sum M of chi and its physical dimension A, B and T ₁Relation as follows:

$M=\frac{A-\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="A20041003078800092.png"\; state="\{\{state\}\}">B</figure-callout>}}{2\&CenterDot;T_1}---\left(7\right)$

T ₁＝a+b (8)

Can get by (2):

$N=\frac{C}{T_2}---\left(9\right)$

Can get by (3), (6), (7), (8), (9):

$n=\frac{(A-B)\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20041003078800092.png"\; state="\{\{state\}\}">C</figure-callout>}}{2\&CenterDot;(a+b)\&times;(c+d)}---\left(10\right)$

The measuring accuracy that can be got incident angle of light to be measured by (4), (10) is:

$p=\frac{2\&CenterDot;(a+b)\&times;(c+d)\&CenterDot;W}{(A-B)\&CenterDot;C}---\left(11\right)$

More than various in: a+b ≠ c+d, B＞a, B＞c.

Proof by experiment, this device can be realized the measurement of angle of incident light, by suitable parameter designing, can realize simultaneously on a large scale and high-precision measurement of angle, has reached the set goal of the present invention.

Reason and advantage that the moving chi of optical vernier is designed to symmetrical structure are: (1) is convenient to the identification at zero point.As shown in Figure 2,, therefore on line array CCD or similar photoelectric commutator, can cover bigger zone, produce tangible null position information, make things convenient for the identification of null position because the width B at zero point is bigger than the dark fringe width a in moving chi cycle of vernier.(2) produce redundancy encoding, improve the precision and the reliability of optical vernier code identification.Zero point, the right and left can constitute a relatively independent optical vernier respectively, and these two symmetrical optical verniers are measured (sensitivity) unidirectional optical vernier blurring simultaneously, but the direction that relatively moves of vernier image, scale is just opposite, and consequently the result of both sides vernier measurement should be complementary.She Ji target and obvious advantage are like this: the coding of measurement result is complementary redundant, the measurement result of left and right sides vernier verification mutually (being equivalent to digital parity checking), lower the possibility of vernier reading software erroneous judgement greatly, improve the reliability of measurement result and the accuracy of software interpretation with a kind of simple and efficient method.(3) pass through about complementary method, all do not exist about optical vernier and measure the blind area.In the bigger measurement range of incident angle of light, by vernier on one side measure less than angle information can measure by the vernier of another side, under the equivalent constructions size, enlarged measurement range.

Key of the present invention is the optical figuring on upper and lower two mask plates and the design of size thereof, converts the variation that is radiated at the light incident angle of light on the optical vernier member to optical vernier code change easy to identify.Characteristics of the present invention are the structural parameters of the measurement range and the optical vernier structure that measuring accuracy depends on particular design fully of incident light incident angle, and irrelevant with the line array CCD or the similar photoelectric commutator (additional device) of reception and detection optical vernier code change.Therefore, the invention has the advantages that and to use relatively low line array CCD of resolution or similar cheap photoelectric commutator in king-sized measurement range, the omnidistance high-acruracy survey that realizes that angle of incidence of light changes.

Concrete embodiment of the present invention: require in 128 ° angle of incidence of light measurement range, to realize omnidistance 0.01 ° high-acruracy survey.Concrete technical application is as follows:

The optical vernier structure of the invention process example as shown in Figure 5, with the carrier of optical glass as the optical vernier mask, the optical vernier mask processes on optical glass.The aluminum fixed rack structure is used for assembling two blocks of glass, guarantees the accurate location between two blocks of glass.The aluminum fixed rack structure is made up of main body and pressing plate two parts, and two parts are aluminum.Main body is used for placing two blocks of glass up and down, guarantee two blocks of glass apart from the requirement of size peace row degree.The main effect of pressing plate then is at upper surface glass to be fixed, and also can play the effect of blocking parasitic light simultaneously.Photoelectric commutator is welded on the circuit board, and mask plate down is close on the surface.Placing the electronic devices and components that are used to carry out data processing on the circuit board simultaneously.Based on principle of work of the present invention, specific implementation Design of device parameter value is got: T ₁=98um, M=50, a=42um, b=56um, A=9.958mm, B=158um, N=264, T ₂=100um, c=42um, d=58um, C=26.4mm, h=6.3mm.

The check of measurement range and measuring accuracy is as follows:

With above parameter substitution formula (4), obtain measurement range W and be:

With above parameter substitution formula (11), can obtain measuring accuracy p and be:

The experimental result of embodiment shows that experimental result conforms to theoretical analysis.

Claims (3)

1, optical vernier angle-measuring equipment, it is characterized in that, it contains last mask plate and the following mask plate of representing moving chi of optical vernier and optical vernier scale respectively, describedly go up the position relative fixed of mask plate and following mask plate and be parallel to each other, have a representative to measure the wide zero point dark fringe of the shading at zero point in the central authorities of last mask plate, the both sides of described zero point dark fringe symmetry and etc. the light and dark striped of distributing logical light and shading in cycle; Light and dark striped in the distributing logical light and the shading in described following first-class cycle of mask plate; The cycle of the light and shade striped on the described upward mask plate and the cycle of the light and shade striped on the following mask plate are unequal; Below described mask plate down, placing a photoelectric commutator.

2, optical vernier angle-measuring equipment as claimed in claim 1 is characterized in that: the described mask plate of going up is fixed by a rigid carrier with following mask plate.

3, the measurement range of optical vernier angle-measuring equipment as claimed in claim 1 and accuracy design is characterized in that: measurement range is determined with following formula:

$W=2\&times;\arctan \left(\frac{N\&times;(c+d)}{2h}\right)$

Measuring accuracy is determined with following formula:

$p=\frac{2\&CenterDot;(a+b)\&times;(c+d)\&CenterDot;W}{(A-B)\&CenterDot;C}$

Wherein W is a measurement range, and N is the total number of cycles of the scale striped of following mask plate, and c is the dark fringe width of scale, and d is the bright fringe width of scale, and h is the distance between the upper and lower mask plate; P is a measuring accuracy, a is a width of going up the dark fringe on the mask plate, b is a width of going up the bright fringe on the mask plate, A is the effective length that goes up the light and shade striped of mask plate, promptly be positioned at the total length that moving chi striped is covered on the mask plate, B is the width of zero point dark fringe on the last mask plate, and C is the effective length of the light and shade striped of following mask plate, the total length that mask plate upper fixed ruler striped is covered under promptly being positioned at.

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