CN1632462A - Triangle method range error compensation method based on angular measurement - Google Patents

Abstract

This invention discloses a triangulation distance measurement compensation method based on angle measurement, which belongs to error compensation technique of triangulation distance measurement. The method adopts vertical incidence triangulation distance measurement that divides the incidence light into two beams, wherein, one part comes to the object surface vertically and its reflection angel is measured by the threshold angle measurement device; the other part adopts vertical incidence triangulation distance measurement and its result minus the measurement error caused by the object inclination angle changes. The identification of the compensation is the following: when the rotation angle is zero, there is only the error of displacement change; when the object surface rotation angle according to the excursion distance lambada equals to measurement value gamma, there is only angle change displacement as zero; when there is displacement and angel changes , then the linear from the computation of gamma measurement doesn't equal to lambada; then to get pure line displacement x according to measurement value Sigma after computation.

Description

Triangle method range error compensation method based on measurement of angle

Technical field

The present invention relates to a kind of triangle method range error compensation method, belong to the error compensating method of triangle measurement method based on measurement of angle.

Background technology

At present, microdisplacement measurement method commonly used mainly contains laser interferance method, laser triangulation, light probe method etc., and triangulation since have noncontact, simple in structure, measuring distance is big, anti-interference, measurement point is little, accuracy of measurement is high, can be used for fast characteristics such as measurement of real-time online, in the geometric measurement field, be widely used.In the method, the error that the corner variation of testee is introduced under the common accuracy requirement can be ignored.But when Measurement Uncertainty is had relatively high expectations,, the testee corner must compensate because changing the error component of introducing.Given this, on laser triangulation range measurement principle basis, utilize angle measurement method to measure inclination angle, testee surface in real time and change, change the measuring error of introducing with offset angle, thereby improve the precision of displacement measurement.

Summary of the invention

The object of the present invention is to provide a kind of triangle method range error compensation method based on measurement of angle, this method utilizes angle measurement method to measure the inclination angle variation of testee surface in real time, change the measuring error of introducing with offset angle, thereby improve the precision of displacement measurement.

The objective of the invention is to be achieved through the following technical solutions: adopt triangle method range error compensation device based on measurement of angle, this device comprises the catoptron of collimated light source, convex lens, testee surface or body surface in the vertical incidence triangle measurement method device, and the catoptron of convex lens back, photelectric receiver, quarter wave plate, polarisation spectroscope, spectroscope, two critical angle prisms, two photodiodes, realize triangle method range error compensation method based on measurement of angle.It is characterized in that incident light is divided into two bundles, a part of vertical incidence testee surface, its catoptrical deflection angle detects through the critical angle angle measurement unit; A branch of gloss is with vertical incidence light triangle measurement method.Then, in the range finding result, deduct because inclination angle, testee surface changes the measuring error of introducing.Described error compensation amount is as follows:

1. when having only change in displacement

When having only change in displacement, incident angle θ _iConstant, reflected light is parallel to the chief ray reflection, and reflection angle is also constant, i.e. θ among the figure ₁=θ ₂=θ converges on chief ray and the focal plane focus through behind the lens, shown in figure (1).As can be seen from Figure: tg θ=d/f, wherein d be incident light to the lens center distance, f is the focal length of lens.

When tested surface have upwards/during bottom offset x, the offset distance Δ of reflected light on lens is:

Δ＝±2xtgθ (1)

Try to achieve displacement x by Δ.

2. when having only angle to change

When tested surface does not have change in displacement and is initial point when doing the one dimension small angle variation with the O point just, incidence point O is constant, so reflected light can see and make the scattered light that is sent by focus O, penetrates through becoming directional light behind the lens.Shown in figure (2).When the left-handed γ of tested surface angle, make γ ₁=γ ₂=γ, the reflection ray 2 γ angles of turning left, so the offset distance Λ of reflected light on lens is:

Λ ₁＝f[tgθ-tg(θ-2γ)] (2)

When tested surface dextrorotation β angle, the reflection ray 2 β angles of turning right, so the offset distance of reflected light on lens is:

Λ ₂＝f[tg(θ+2γ)-tgθ] (3)

Measure angular displacement γ by angle measurement unit.

3. existing displacement has angle to change again

Because the displacement moving direction does not influence the measurement of angle, nor influences the calculating of angle in the displacement measurement system, might as well suppose that sense of displacement is downward.

(1) tested surface has displacement and when anticlockwise γ angle, and angle changes makes displacement and the change in displacement caused offset vector of reflected light on lens superimposed, as scheming shown in (3).Have by the triangle relation among the figure:

x＝x′+x′tgθtgγ (4)

Position relation by incident ray and emergent ray can draw:

Δ＝x′[tgθ+tg(θ-2γ)] (5)

Angle changes the introducing displacement and is provided by formula (2), and comprehensive above three formulas can draw left-handed displacement ∑ total formula:

$\mathrm{\Σ}=\mathrm{\Δ}+\mathrm{\Λ}=\frac{x}{1+\mathrm{tg\θtg\γ}}[\mathrm{tg\θ}+\mathrm{tg}(\mathrm{\θ}-2\mathrm{\γ})]+f[\mathrm{tg\θ}-\mathrm{tg}(\mathrm{\θ}-2\mathrm{\γ})]---\left(6\right)$

After measuring angular displacement γ by angle measurement unit, try to achieve real offset by formula (6).

(2) tested surface has displacement and when right rotation γ angle, and angle changes makes displacement and the change in displacement caused offset vector of reflected light on lens superimposed.At this moment:

x＝x′-x′tgθtgγ (7)

Position relation by incident ray and emergent ray can draw:

Δ′＝x′[tgθ+tg(θ+2γ)] (8)

Angle changes the introducing displacement and is provided by formula (3), and comprehensive three formulas can draw the dextral displacement total formula:

$\mathrm{\Σ}={\mathrm{\Δ}}^{\′}+\mathrm{\Λ}=\frac{x}{1-\mathrm{tg\θtg\γ}}[\mathrm{tg\θ}+\mathrm{tg}(\mathrm{\θ}+2\mathrm{\γ})]+f[\mathrm{tg}(\mathrm{\θ}-2\mathrm{\γ})-\mathrm{tg\θ}]---\left(9\right)$

After measuring angular displacement γ by angle measurement unit, try to achieve real offset by formula (9).

The invention has the advantages that utilizing angle measurement method to measure inclination angle, testee surface in real time changes, and changes the measuring error of introducing with offset angle, thereby improves the precision of displacement measurement.

Description of drawings

Fig. 1 is for having only change in displacement calculation of error synoptic diagram.

Fig. 2 changes the calculation of error synoptic diagram for having only angle.

Fig. 3 changes the calculation of error synoptic diagram for existing displacement has angle again.

Embodiment

When utilizing preceding method to carry out Measurement and analysis, at first detect the direction of corner variable quantity γ and corner variation thereof by the critical angle angle measurement unit; γ=0 a no corner of identification changes, and try to achieve object plane displacement of the lines amount x according to measured value Δ and formula (1) this moment.

When corner changes, according to the judgement of corner direction, bring this corner variable quantity into formula (2) or (3), the displacement of the lines amount that obtains after as calculated assert that then this moment, object plane had only corner to change γ if equal Λ.

When existing displacement has corner to change again, according to the judgement of corner direction, bring this corner variable quantity into formula (2) or (3), the displacement of the lines amount that obtains after as calculated is not equal to Λ, then bring this corner variable quantity into formula (6) or (9), try to achieve pure displacement of the lines x according to the measured value ∑.

In this programme: d=40mm, f=60mm, then tg θ=0.333.When tested surface has x=100 μ m actual displacement, if γ=0 o'clock, the offset distance of reflected light on convex lens is 66.667 μ m; If γ=300arcsec, x/x '=1.0005 μ m then, x ' as a result=99.95 μ m that record during uncompensation even, measuring error is 0.05 μ m, relative error is 0.05%; If γ=600arcsec is x/x '=1.001 μ m then, x ' as a result=99.90 μ m that record during uncompensation even, measuring error is 0.10 μ m, the relative error of measurement can reach 0.1%.

Claims (1)

1. triangle method range error compensation method based on measurement of angle, this method adopts the triangle method range error compensation device based on measurement of angle, this device comprises the collimated light source in the vertical incidence triangle measurement method device, convex lens, the catoptron of testee surface or body surface, and the catoptron of convex lens back, photelectric receiver, quarter wave plate, the polarisation spectroscope, spectroscope, two critical angle prisms, two photodiodes, it is characterized in that incident light is divided into two bundles, part vertical incidence testee surface, its catoptrical deflection angle detects through the critical angle angle measurement unit; A branch of gloss then, deducts in the range finding result because inclination angle, testee surface changes the measuring error of introducing with vertical incidence light triangle measurement method, and described error compensation amount is as follows:

1). when having only change in displacement

When having only change in displacement, incident angle θ _iConstant, reflected light is parallel to the chief ray reflection, and reflection angle is also constant, i.e. θ among the figure ₁=θ ₂=θ through converging on chief ray and the focal plane focus behind the lens, obtains: tg θ=d/f, wherein d be incident light to the lens center distance, f is the focal length of lens, makes progress when tested surface has/during bottom offset x, the offset distance Δ of reflected light on lens is:

Δ＝±2xtgθ (1)

Try to achieve displacement x by Δ;

2). when having only angle to change

When tested surface does not have change in displacement and is initial point when doing the one dimension small angle variation with the O point just, incidence point O is constant, so reflected light can see and make the scattered light that is sent by focus O, penetrates through becoming directional light behind the lens, when the left-handed γ of tested surface angle, makes γ ₁=γ ₂=γ, the reflection ray 2 γ angles of turning left, so the offset distance of reflected light on lens is:

Λ ₁＝f[tgθ-tg(θ-2γ)] (2)

When tested surface dextrorotation β angle, the reflection ray 2 β angles of turning right, so the offset distance of reflected light on lens is:

Λ ₂＝f[tg(θ+2γ)-tgθ] (3)

Measure angular displacement γ by angle measurement unit;

3). existing displacement has angle to change again

Because the displacement moving direction does not influence the measurement of angle, nor influences the calculating of angle in the displacement measurement system, might as well suppose that sense of displacement is downward,

(1) tested surface has displacement and when anticlockwise γ angle, and angle changes makes displacement and the change in displacement caused offset vector of reflected light on lens superimposed, and its relational expression is:

x＝x′+x′tgθtgγ (4)

Position relation by incident ray and emergent ray can draw:

Δ＝x′[tgθ+tg(θ-2γ)] (5)

The angle variation is provided by formula (2), and comprehensive above three formulas obtain left-handed displacement ∑ total formula:

$\mathrm{\Σ}=\mathrm{\Δ}+\mathrm{\Λ}=\frac{x}{1+\mathrm{tg\θtg\γ}}[\mathrm{tg\θ}+\mathrm{tg}(\mathrm{\θ}-2\mathrm{\γ})]+f[\mathrm{tg\θ}-\mathrm{tg}(\mathrm{\θ}-2\mathrm{\γ})]---\left(6\right)$

After measuring angular displacement γ by angle measurement unit, try to achieve real offset x by formula (6);

(2) tested surface has displacement and when right rotation γ angle, and angle changes makes displacement and the change in displacement caused offset vector of reflected light on lens superimposed, at this moment:

x＝x′-x′tgθtgγ (7)

Position relation by incident ray and emergent ray can draw:

Δ′＝x′[tgθ+tg(θ+2γ)] (8)

The angle variation is provided by formula (3), and comprehensive three formulas can draw the dextral displacement total formula:

$\mathrm{\Σ}={\mathrm{\Δ}}^{\′}+\mathrm{\Λ}=\frac{x}{1-\mathrm{tg\θtg\γ}}[\mathrm{tg\θ}+\mathrm{tg}(\mathrm{\θ}+2\mathrm{\γ})]+f[\mathrm{tg}(\mathrm{\θ}-2\mathrm{\γ})-\mathrm{tg\θ}]---\left(9\right)$

After measuring angular displacement γ by angle measurement unit, try to achieve real offset x by formula (9).