JP2021089223A - measuring device - Google Patents

Abstract

To provide a measuring device with which it is possible to facilitate assembling and adjustment without the need for an elaborate adjustment of the fitted position of a light source and the axis alignment of an enlargement lens.SOLUTION: Provided is a measuring device comprising a light source for emitting measurement light, a light receiving unit for receiving reflected light of the measurement light from the object to be measured, the measuring device measuring the distance to the object to be measured, on the basis of the reflected light received by the light receiving unit. The measuring device includes an aperture member for narrowing the beam of measurement light from the light source, the aperture member including a center light permeable part arranged on the optical axis of the light source and a light permeable band part for forming a plurality of light permeable bands arranged in the periphery of the center light permeable part. The emitted beam of measurement light is expanded to a desired angle of aperture by interference due to diffraction at the time measurement light passes through the center light permeable part and the light permeable band part.SELECTED DRAWING: Figure 4

Description

The present invention relates to a measuring device including a diaphragm device for adjusting the measurement light emitted from a light source.

As the above-mentioned measuring device, there is a light wave range finder, which irradiates a measured object with measured light in a modulated predetermined wavelength region, receives reflected light from the measured object, and receives internal reference light and received light. The distance from the measured object to the object to be measured is measured from the phase difference with the measured light (see Patent Document 1 and Patent Document 2).

Patent Document 2 describes the following light wave rangefinders. FIG. 9 is a cross-sectional view showing the configuration of a conventional light wave range finder. FIG. 9 shows a case where a light wave rangefinder 500 is used as a target in a prism mode in which a photoretrospective element is arranged and the distance is measured. The light wave distance meter 500 includes an objective lens 510, a prism 520 having two reflecting surfaces, a light source 530, an emission optical system 540, an emission reflecting mirror 550, a dichroic mirror 560, a collimation optical system 570, and light receiving. It is provided with a secondary light source end 580 such as a fiber.

The objective lens 510 is composed of three lenses arranged on the optical axis Oa. The prism 520 is arranged on the optical axis Oa behind the objective lens 510, and has two parallel reflecting surfaces forming an angle of 45 degrees with respect to the optical axis Oa, that is, an ejection reflecting surface that reflects the measurement light in the emitting direction. It includes a 521 and a light receiving reflecting surface 522 that reflects the incident measurement light toward the light receiving element 580.

The light source 530 generates light in a predetermined wavelength region. The injection optical system 540 is arranged on an optical axis Ob parallel to the optical axis Oa, and includes a collimator 541 that makes the light from the light source 530 parallel light, an optical chopper 542 that intermittently blocks the measurement light, and a throttle member 543. To be equipped with. The reflector 550 is arranged on the optical axis Ob at an angle of 45 degrees, changes the direction of the measurement light from the emission optical system 540 by 90 degrees, and faces the ejection reflection surface 521 of the prism 520 along the optical axis Oct. Reflects the measurement light. The measurement light reflected by the ejection reflecting surface 521 is emitted to the object to be measured through the objective lens 510.

The reflected light from the object to be measured passes through the objective lens 510 and reaches the dichroic mirror 560. The dichroic mirror 560 reflects the measurement light in a predetermined wavelength band from the incident light, transmits the other light, and emits it to the collimation optical system 570. The measurement light reflected by the dichroic mirror 560 is reflected by the light receiving reflecting surface 522 of the prism 520 and is incident on the light receiving element 580.

In such a light wave range finder, the diaphragm member narrows the light from the light source and is selected according to the light distribution characteristics of the light emitted from the light source. That is, it is selected and installed so that the light from the light source is emitted most efficiently. Patent Document 2 describes a slit-shaped diaphragm as a diaphragm. Further, the shape of the opening of the diaphragm member is circular, and other shapes are adopted. (See Patent Document 3)

Japanese Unexamined Patent Publication No. 8-68852 Japanese Unexamined Patent Publication No. 2014-149171 JP-A-2017-6767

However, the aperture shape of the conventional diaphragm member is set according to the light distribution characteristics of the light source. Therefore, if the angular relationship between the light source and the diaphragm member (rotational positional relationship about the optical axis) is not appropriate according to the light distribution characteristics of the light source, the light from the light source will decrease. Therefore, for example, the angular position of the diaphragm member or the light source (the angular position about the optical axis) must be adjusted to be appropriate.

Further, the elongated slit used as the diaphragm member by the technique according to Patent Document 2 has a wide measurement range with a prism in the horizontal direction, and the distance measurement light is diffracted and spread in the vertical direction, so that the spread in the horizontal direction is narrow. .. For this reason, the wraparound of light due to the diffraction action is biased in the vertical and horizontal directions, causing blurring of the diaphragm. Furthermore, the light distribution characteristics of the light source may differ from individual to individual, and the light distribution characteristics of the light source may be grasped in advance for each individual to select the aperture shape of the aperture member or set the mounting angle of the light source or aperture member. There is a problem that it has to be troublesome.

Further, in the technique according to Patent Document 3, the shape of the opening of the diaphragm member is circular, but the opening angle of the light (luminous flux) passing through the aperture diaphragm member may not be a desired angle due to diffraction by the aperture of the diaphragm. is there. If you try to increase this angle, the aperture will become smaller and the amount of light will decrease. Therefore, in order to set the spread of the luminous flux to a desired value, it is necessary to arrange a magnifying lens system (concave lens) 590 (shown by a broken line in FIG. 9) that widens the opening angle of the luminous flux passing through the diaphragm member.

However, in order to arrange such a magnifying lens system, it is necessary to secure a space for it, and it is necessary to strictly adjust the arrangement position and optical axis of the lens system, which is troublesome and costly for assembly and adjustment. Will take.

The present invention has been made in view of the above-mentioned problems, and is a lens for eliminating the influence of blurring due to a diffraction phenomenon, adjusting the mounting state of a light source according to the light distribution characteristics of the light source, and expanding the luminous flux. It is an object of the present invention to provide a measuring device capable of imparting a desired opening angle to a light flux passing through a diaphragm member without the need to install a system or set an optical axis adjustment.

In order to solve the above problem, the invention according to claim 1 includes a light source that emits measurement light and a light receiving portion that receives reflected light from the object to be measured, and the reflection received by the light receiving portion. In a measuring device that measures the distance to the object to be measured based on light, a throttle member for narrowing the light beam of the measurement light from the light source is provided, and the throttle member is centered on the optical axis of the light source. When a light-transmitting portion and a light-shielding band portion forming a plurality of light-transmitting band portions arranged around the central translucent portion are provided, and the measurement light passes through the central translucent portion and the translucent band portion. It is a measuring device characterized in that the light beam of the light to be emitted is expanded to a desired opening angle by interference due to the diffraction of the light.

Similarly, according to the second aspect of the present invention, in the measuring device according to the first aspect, the light-shielding band portion of the aperture member is arranged around the central translucent portion and is concentric with the central translucent portion. It is characterized in that it is a plurality of torus bands arranged at predetermined intervals.

Similarly, according to the third aspect of the present invention, in the measuring device according to the first aspect, the translucent band portion of the aperture member is arranged around the central translucent portion and is concentric with the central translucent portion. It is characterized in that it is a plurality of arcuate bands arranged at predetermined intervals.

Similarly, the invention according to claim 4 is characterized in that, in the measuring device according to claim 1, the shape of the central translucent portion is circular.

Similarly, the invention according to claim 5 is the measuring device according to claim 3, wherein the diaphragm member is divided into a plurality of fan-shaped regions concentric with the center of the central translucent portion, and at least in each fan-shaped region. It is characterized in that the arrangement intervals of the transmissive band portions are different in the two fan-shaped regions.

Similarly, the invention according to claim 6 is characterized in that the measuring device according to claim 3 includes a driving means for rotating the diaphragm member about an optical axis.

Similarly, according to the seventh aspect of the present invention, in the measuring apparatus according to the first aspect, the diaphragm member is composed of a translucent element capable of changing the pattern of light shielding and transmission by external control, and the central translucent portion and the central translucent portion. It is characterized in that the shapes of the light-shielding band portion and the translucent band portion are changed.

According to the optical wave distance meter according to the present invention, the influence of blurring due to the diffraction phenomenon can be eliminated, the mounting state of the light source can be adjusted according to the light distribution characteristics of the light source, and a lens system for expanding the luminous flux can be installed. It is not necessary to set the optical axis adjustment, and a desired opening angle can be imparted to the light flux passing through the diaphragm member.

That is, according to the measuring device according to claim 1, the diaphragm member for squeezing is a central translucent portion arranged on the optical axis of the light source and a plurality of translucent band portions arranged around the central translucent portion. The light beam of the measurement light emitted is expanded to a desired opening angle by interference due to diffraction when the measurement light passes through the central light transmission portion and the light transmission band portion.

Therefore, according to the present invention, the luminous flux passing through the diaphragm member can be set to a desired opening angle without particularly arranging the lens system on the downstream side of the diaphragm portion. Therefore, in assembling and adjusting the measuring device, it is not necessary to strictly set the mounting position and mounting angle of the light source and the diaphragm member, and the assembly and adjustment can be easily performed, and the production and adjustment costs can be reduced. Moreover, since the lens system is not required, the cost of the lens system and the trouble of mounting and adjusting can be eliminated, and the cost can be reduced.

Further, according to the measuring device according to claim 2, the light-shielding band portion of the diaphragm member is arranged around the central translucent portion, is concentric with the central translucent portion, and is arranged at a predetermined interval. Multiple toruses. For this reason, the diaphragm member is a plurality of torus bands arranged around the central translucent portion and the central transmissive portion, which are concentric with the central transmissive portion and are arranged at predetermined intervals. The translucent band portions are formed at predetermined intervals.

Therefore, the light that has passed through the plurality of ring-shaped translucent band portions separated from the central transmissive portion by a predetermined distance is diffracted and interferes with each other, and the emitted light from the diaphragm member becomes a luminous flux distributed with a predetermined spread. Therefore, by setting the shape and dimensions of the central translucent portion and the translucent band portion, it is possible to emit a light beam having a desired amount of light and spread from the diaphragm portion. At this time, the emitted luminous flux has a regular distribution of strength and weakness in the radial direction. However, this distribution is averaged by the fluctuation of air at the time of measurement and the vibration of the device and does not affect the measurement.

Further, according to the measuring device according to claim 3, the translucent band portion of the diaphragm member is arranged around the central translucent portion, is concentric with the central translucent portion, and is arranged at a predetermined interval. There are multiple arcuate bands. For this reason, the diaphragm member is a transparent band that is arranged around the central translucent portion and the central transmissive portion, and is concentric with the central transmissive portion and arranged at predetermined intervals. Light bands are formed at predetermined intervals.

Therefore, the light that has passed through the plurality of arc-shaped translucent band portions separated from the central transmissive portion by a predetermined distance is diffracted and interferes with each other, and the emitted light from the diaphragm member becomes a luminous flux distributed with a predetermined spread. Therefore, by setting the shape and dimensions of the central translucent portion and the translucent band portion, it is possible to emit a light beam having a desired amount of light and spread from the diaphragm portion. At this time, the emitted luminous flux has a regular distribution of strength and weakness in the radial direction. However, this distribution is averaged by the fluctuation of air at the time of measurement and the vibration of the device and does not affect the measurement.

That is, according to the measuring device according to claim 4, since the shape of the central translucent portion is circular, the emitted light flux is distributed symmetrically around the optical axis. Therefore, the distribution of light transmitted through the central translucent portion is rotationally symmetric about the optical axis, and also interferes with diffraction and light from the surrounding translucent band portion to have a predetermined spread and rotationally symmetric luminous flux. Can be ejected.

Further, according to the measuring device according to claim 5, the diaphragm member is divided into a plurality of fan-shaped regions concentric with the center of the central light-transmitting portion, and in each fan-shaped region, the light-transmitting region is formed in at least two fan-shaped regions. The arrangement interval of the band is different. Therefore, in each fan-shaped region, light having a different intensity distribution due to different interference states is emitted. Therefore, the luminous flux emitted from the diaphragm member overlaps the luminous fluxes having different intensity distributions, the intensity distribution in the radial direction is averaged, and the influence of the intensity distribution due to interference can be reduced.

Further, according to the measuring device according to claim 6, the driving means is a diaphragm member having a plurality of arcuate band diaphragm members arranged with the light-shielding band portion around the central light-transmitting portion and concentrically arranged with the central light-transmitting portion. Is rotated around the optical axis. Therefore, the interference state of the emitted light changes with the passage of time. Therefore, the distribution of the intensity of the emitted luminous flux can be averaged.

According to the measuring device according to claim 7, a translucent element capable of changing the shapes of the central translucent portion, the light-shielding band portion, and the translucent band portion is used as the diaphragm member. Therefore, by changing the shapes of the light-shielding band portion and the translucent band portion with time, it is possible to average the distribution of the intensity of the emitted light beam. As the translucent element, a piezoelectric element such as a PLZT element can be used in addition to the liquid crystal panel.

It is a front view which shows the light wave range finder which concerns on embodiment of this invention. It is sectional drawing which shows the light wave range finder. The optical system of the light wave rangefinder is shown, (a) is a schematic diagram showing a state of measurement light emission, and (b) is a schematic diagram showing a state of internal reference light emission. The diaphragm arrangement member configuration of the light wave range finder is shown, (a) is an overall perspective view of the light wave range finder, and (b) is an enlarged view of the diaphragm member. The pattern of the diaphragm member of the light wave range finder is shown, and (a), (b), and (c) are schematic views showing different patterns. The diffraction phenomenon is shown, (a) is an enlarged view of a slit portion, and (b) is a graph showing an amplitude intensity distribution of emitted light. For the purpose of explaining Young's interference experiment, (a) is a schematic diagram showing an experimental device, and (b) is a schematic diagram showing a state of emitted light. It is a graph which shows the amplitude intensity distribution of the emission light in the diaphragm member which concerns on embodiment. It is sectional drawing which shows the structure of the conventional light wave range finder.

A measuring device according to a mode for carrying out the present invention will be described.

<First Embodiment>
FIG. 1 is a front view showing a light wave rangefinder according to a first embodiment of the measuring device according to the present invention. As shown in FIG. 1, in the light wave rangefinder 100 according to the first embodiment, a pedestal 102 is provided on a base portion 101 attached to a tripod (not shown), and the pedestal 102 includes a telescope unit including an optical system. 103 is supported. The base portion 101 has a leveling screw 104, and can be leveled so that the base 102 is horizontal. The gantry 102 is rotatable about the vertical axis, and the telescope unit 103 is rotatable about the horizontal axis. Further, the gantry 102 is provided with an operation input unit 107 having a display unit 106, and the display unit 106 displays a measured value of the distance to the object to be measured.

Next, the optical system of the light wave rangefinder 100 will be described. FIG. 2 is a cross-sectional view showing the light wave range finder, FIG. 3 shows the optical system of the light wave range finder, (a) is a schematic view showing a state of measurement light emission, and (b) is an internal reference light emission. It is a schematic diagram which shows the state of.

In the light wave rangefinder 100, a lens barrel 120 and a base portion 130 are formed in the housing 110. Further, as shown in FIG. 2, the light wave distance meter 100 has an objective lens system 210 which is a light receiving optical system, an injection optical system 220 which emits measurement light to irradiate a measurement object, and an objective lens as an optical system 200. It includes an injection reflection optical system 240 that guides the measurement light from the system 210 to the optical fiber 260. Further, the optical system 200 includes a light receiving and reflecting optical system 250 and a collimation optical system 270. The optical fiber 260 guides the measurement light to the optical sensor 261 (see FIG. 3) which is a light receiving unit. The collimation optical system 270 is used to make the image of the object to be measured from the objective lens system 210 visible, and to determine or correct the direction of the light wave rangefinder 100.

The objective lens system 210 is arranged in the lens barrel 120, includes a first optical axis O1 directed to the prism 280, which is the object to be measured, and collects light from the object to be measured. The objective lens system 210 includes three lenses, and various aberrations are corrected to provide positive power as a whole. The emission optical system 220 is arranged on the base portion 130, includes a second optical axis O2 parallel to the first optical axis O1, and emits light from an ideal point light source 230 as measurement light which is parallel light. The point light source 230 is, for example, a laser diode that generates infrared rays.

The emission optical system 220 is controlled by a collimator lens 221, a chopper 226 equipped with a trapezoidal prism 225 that intermittently blocks the emission light and extracts the emission light as internal reference light acquired from the light source, and a microcomputer or the like. It includes a circular 222 that adjusts the amount of light flux, a density filter 310 that adjusts the amount of light of internal reference light by manually setting a rotation position, and a throttle arrangement member 224. The density filter 310 is a disk-shaped member having a density gradient on its circumference. Further, the circular 222 is a disk-shaped member provided with a density filter having a density gradient on the circumference for adjusting the amount of light emitted from the measured light, and is rotationally driven by the circular drive motor 223.

Further, the chopper 226 is rotationally driven by the chopper drive motor 227, and is driven so as to appear and disappear on the front side of the collimator lens 221 on the second optical axis O2 at a predetermined timing. Here, the chopper 226 is formed with a plate portion 226a that covers the collimator lens 221. Further, the trapezoidal prism 225 includes two reflecting surfaces 225a and 225b as shown in FIG. 3B, and guides the internal reference light to the optical sensor 261.

When the measurement light is emitted, as shown in FIG. 3A, the chopper 226 deviates from the emission port of the collimator lens 221 and the light from the point light source 230 is intermittently blocked by the circular 222 and is blocked by the reflector 241. Directed and ejected. In FIG. 3A, the optical axis of the internal reference light is indicated by a long-dashed line, and the optical path of the measurement light is indicated by a solid line with an arrow. 3 (a) In the state shown, no internal reference light is generated.

At the time of emitting the internal reference light, as shown in FIG. 3B, the chopper 226 is in a state where the reflecting surface 225a of the trapezoidal prism 225 is arranged at the emitting port of the collimator lens 221. In this state, the light from the point light source 230 passes through the collimator lens 221, is reflected by the reflecting surfaces 225a and 225b of the trapezoidal prism 225, and is emitted toward the density filter 310. The internal reference light whose density is adjusted by the density filter 310 is incident on the optical fiber 263. At this time, since the aperture of the collimator lens 221 is completely covered by the plate portion 226a, no light is incident on the objective lens system 210 side. The optical fiber 263 merges with the optical fiber 260, and the internal reference light from the optical fiber 263 and the measurement light from the optical fiber 260 are detected by the same optical sensor 261. In FIG. 3B, the optical path of the internal reference light is indicated by a solid line with an arrow, and the optical axis of the measurement light is indicated by a dashed line. In the state shown in 3 (b), no measurement light is generated.

The emission reflection optical system 240 includes a reflecting mirror 241 having a reflecting surface obliquely formed on the second optical axis O2, and a light transmitting reflecting prism which is a second reflecting means arranged on the incident side (outside) of the objective lens system 210. 242 and the like. The light transmitting / reflecting prism 242 includes a reflecting surface 242a inclined on the first optical axis O1. In this example, a cover glass 281 which is a parallel flat glass is arranged on the outside of the objective lens system 210, and the light transmitting / reflecting prism 242 is arranged so as to be adhered to the inside of the cover glass 281.

The light-receiving reflection optical system 250 is composed of a dichroic mirror 251 and a light-receiving reflection prism 252 which is a light-receiving / reflecting member that reflects light from the dichroic mirror 251 in a perpendicular direction. The dichroic mirror 251 is arranged in the lens barrel 120 and reflects the measurement light, which is the light in a predetermined wavelength band, among the light incident from the objective lens system 210 along the first optical axis O1. Light in other bands is transmitted and incident on the collimation optical system 270 arranged in the lens barrel 120. The operator of the light wave rangefinder 100 can perform collimation using the collimation optical system 270. The light receiving / reflecting prism 252 has a reflecting surface 252a formed at an angle of 45 degrees on the first optical axis O1 and reflects the light from the dichroic mirror 251 toward the optical fiber 260.

In such a light wave rangefinder 100, the distance to the prism 280, which is the object to be measured, is determined based on the measurement light from the prism 280, which is the object to be measured, detected by the optical sensor 261 and the internal reference light from the optical fiber 263. Calculate.

Next, the diaphragm member 400 according to the present embodiment will be described. The diaphragm member 400 is attached to the diaphragm arrangement member 224. FIG. 4 shows a diaphragm arrangement member configuration of the light wave range finder, (a) is an overall perspective view of the light wave range finder, and (b) is an enlarged view of the diaphragm member. The diaphragm arrangement member 224 is composed of a light-shielding thin plate, and the diaphragm member 400 is arranged at the position of the optical axis of the diaphragm arrangement member 224.

FIG. 5 is a schematic view showing a pattern of a diaphragm member of the light wave rangefinder. In the present embodiment, as shown in FIGS. 4B and 5A, the diaphragm member 400 is placed around the central translucent portion 401 arranged on the optical axis of the light source and around the central translucent portion 401. A light-shielding band portion 402 arranged between the light-transmitting band portions 403, which are a plurality of arranged ring bands, is provided. With this configuration, the luminous flux of the emitted measurement light is expanded to a desired opening angle and the amount of light is determined by the interference of the diffracted light when the rainfall measurement light passes through the central translucent portion 401 and the translucent band portion 403. The value of. In this example, the central translucent portion 401 has a circular shape as shown in FIG. 5 (a).

In the example shown in FIG. 5A, the central translucent portions 401 concentrically with the central translucent portion 401 having a diameter d1 are arranged at a plurality of locations (4 locations in FIG. 5A) with a predetermined interval d2. There is. Here, the light-shielding band portion 402 has a width dimension of the interval d1 of the light-transmitting band portion 403. Then, a plurality of light-transmitting band portions 403 (three locations in the figure) are arranged between the central light-transmitting portion 401 and the light-shielding band portion 402 and between the adjacent light-shielding band portions 402. The diameter dimension of the central translucent portion 401 and the width dimension of the central translucent portion 401 and the light-shielding band portion 402 can be appropriately set and changed according to the required amount of light and the opening angle.

Next, the operation of the diaphragm member 400 will be briefly described together with the principle that the diffracted light interferes to spread the luminous flux as desired.

For the sake of simplicity, the light transmitted through the linear slit will be described. First, in the case of one slit (single slit), as shown in FIG. 6A, the wavelength of the incident light is λ, the width of the single slit for diffraction is a, and the process proceeds without diffraction after passing through the slit. Assuming that the amplitude of the signal light is A (0) and the amplitude of the signal light diffracted by θ is A (θ), the following equation holds.

式２を、絶対値を含まない形にするため、両辺を２乗しその式をｆ(θ)とすると、

In order to make Equation 2 not include absolute values, if both sides are squared and the equation is f (θ),

のときであり、

の角度となる。
以下順次その隣の角度で振幅が“０”になるのは、

のときとなる。 Then, as shown in FIG. 6B, the interference angle at which the first amplitude becomes “0” from θ = 0 in Equation 3 is

At that time

It becomes the angle of.
Below, the amplitude becomes "0" at the angle next to it in sequence.

It will be the time of.

となる。 For example, with a (laser) light source with λ = 840 nm and a slit width of 0.2 mm, the primary interference point is

Will be.

This spread angle is sufficient for normal measurement using a prism (reflector). By utilizing this effect, it is possible to easily widen the luminous flux emitted without using a normal lens system.

However, with the above settings, there will always be a point on the surrender image where the signal strength is zero or weak. If there is a target in this part, the signal strength will be unmeasurable even if the signal strength is sufficient at the center position. Of course, if the slit width (actually the circular pinhole diameter) is reduced, the amount of diffraction increases and the primary interference point angle widens (in the case of a circle, the angle from the center to the radial direction), but the center is correspondingly large. The light beam cannot be transmitted, and as a result, the amount of signal light may decrease to an unacceptable amount.

Therefore, in the present invention, a plurality of translucent band portions 403 are arranged around the central translucent portion 401. Hereinafter, the interference of light waves will be briefly described.

The above explanation is the result of considering the diffraction intensity regarding the width of a single slit, but from a different viewpoint, the interference of light when slits having a similar slit width a are arranged at the center spacing d of the slit width will be explained. To do. This is basically the same phenomenon as Young's interference experiment shown in FIG. 7 (a).

Take the interference caused by two slits as an example. 7A and 7B are for explaining Young's interference experiment, FIG. 7A is a schematic diagram showing an experimental apparatus, and FIG. 7B is a schematic diagram showing a state of emitted light. As shown in FIG. 7B, when the slit spacing is d, the optical path difference between the luminous flux 1 and the luminous flux 2 is d · sin θ, considering the interference of the luminous flux at the angle θ, so that the phase delay is corresponding to that. appear. Therefore, the equations of the light wave φ1 of the luminous flux 1 and the light wave 2 of the luminous flux 2 are as follows.

但し、ｆ：光波の周波数を示す。

However, f: indicates the frequency of the light wave.

ここで三角関数sinの和積の公式

式６の第１項は時間のパラメータｔを含んでいないので、関数φの振幅を表す項となり、角度θの位置での振幅強度を示す。 Here, the combined wave φ is
φ = φ1 + φ2
And

Here is the formula of the sum product of trigonometric functions sin

Since the first term of Equation 6 does not include the time parameter t, it is a term representing the amplitude of the function φ and shows the amplitude intensity at the position of the angle θ.

式７の絶対値記号を2乗することで外すことを考える。

Consider removing the absolute value symbol of Equation 7 by squared.

式１０で得られる振幅強度の分布状態を図８に示す。 Therefore, to summarize Equation 8,

The distribution state of the amplitude intensity obtained by Equation 10 is shown in FIG.

Equation 10 above is the result of amplitude analysis of two parallel slits. The same is true by providing transmission tracks (bands) concentrically as slits and causing the slits to interfere with the equivalent light and the light of the central luminous flux. It is also possible to exert an effect. In the present invention, it is discussed as a slit on concentric circles.

The diffraction phenomenon of only pinholes has the above-mentioned problems, and it is necessary to make the pinhole diameter extremely small in order to widen the range in which the intensity of the diffracted light becomes the zero point. Then, the required amount of light cannot be secured because the passing luminous flux is reduced. In the present invention, the diffraction phenomenon of a pinhole and the translucent band portion are provided by providing a translucent band portion concentrically with the central transmissive portion (pinhole) by utilizing the diffraction and the interference phenomenon while securing the required amount of light. Due to the interference between the transmitted lights of the above, the distribution state of the amplitude intensity can be shown in FIG.

From this, the influence of the intensity distribution is reduced while obtaining the required amount of light, and the spreading angle of the luminous flux is substantially realized in the lens system.

の間隔で発生する。 Specifically, if the diameter d1 of the central translucent portion 401 corresponding to the slit width a is 0.4 mm and the interval d2 of the translucent band portion 403 is 2.5 mm, the first-order zero point of the amplitude intensity in diffraction is

Occurs at intervals of.

の間隔で振幅強弱が発生する。 Also, since the slit spacing is 2.5 mm, the internal amplitude intensity primary zero point is

Amplitude strength and weakness occur at intervals of.

However, as shown in FIG. 8, in addition to the large zero points, higher-order zero points are periodically generated in the distribution of the amount of light. However, in an actual light wave rangefinder, the amplitude intensity at a certain place cannot be maintained because the light signal luminous flux fluctuates positionally due to fluctuations in the atmosphere or the like. Therefore, even if there is a small amplitude fluctuation as described above, it is averaged due to the influence of atmospheric fluctuations, so that the small intensity change can be virtually ignored.

Therefore, the amplitude fluctuation function shown in Equation 10 can control the setting of the amplitude intensity with respect to θ, and the wide angle of the luminous flux can be set to a desired value with a simple configuration without using a special lens system for expanding the luminous flux. You can see that it can be set to.

ここで、cos²(πd・sinθ/λ)の項は、d*sinθ=λよりcos^２ (π)=1である。このため、式１０より、I(θ)/I(0) =0.919×1.0=0.919 が正確な表現となる。 In the above example, when the phase difference dsinθ = λ, the center intensity f (0) has a relationship of a = d / 6.25 from 0.4 mm = 2.5 mm / 6.25.

Here, the term of cos ² (πd · sinθ / λ) is cos ² (π) = 1 from d * sinθ = λ. Therefore, from Equation 10, I (θ) / I (0) = 0.919 × 1.0 = 0.919 is an accurate expression.

<Second Embodiment>
In the first embodiment, the light transmitting band portion is provided concentrically of 401 as the aperture member 400. The diaphragm member of the light wave rangefinder according to the second embodiment is divided into a plurality of fan-shaped regions concentric with the center of the central transmissive portion, and in each fan-shaped region, the transmissive band portions are arranged in at least two fan-shaped regions. Is changing.

That is, the diaphragm member 410 shown in FIG. 5B is divided into two fan-shaped regions 410A and 410B with a diameter separated from each other. Then, in the fan-shaped regions 410A and 410B, the light-transmitting band portions 413A and 413B are separated from the light-shielding band portions 412A and 412B forming an arc-shaped band having a predetermined interval (d3), and the phases of the light-transmitting band portions 413A and 413B are different in the fan-shaped regions 410A and 410B. It is arranged at the arrangement interval.

Then, in the present embodiment, the diaphragm member 410 is rotated about the optical axis by a driving means such as a motor. As a result, the angular position of the amplitude strength changes with time, a mixing effect can be obtained, and further averaging can be performed.

In the example shown in FIG. 5C, the diaphragm member 420 is divided into four fan-shaped regions 420A, 420B, 420C, and 420D with two orthogonal diameters separated from each other. The light-shielding band portions 422A, 422B, 422C, 422D, and the translucent band portions 423A, 423B, 423C, and 423D can be arranged in the fan-shaped regions 420A, 420B, 420C, and 420D.

<Third Embodiment>
In the third embodiment, the diaphragm member is composed of a liquid crystal panel as a translucent element capable of changing the pattern of light shielding and transmission by external control. As the translucent element, a piezoelectric element such as a PLZT element can be used in addition to the liquid crystal panel. Then, the shapes of the central translucent portion, the light-shielding band portion, and the translucent band portion are changed. For example, the patterns of the fan-shaped regions 410A, 420B, 420C, and 420D of the pattern shown in FIG. 5 (c), in which the patterns of the fan-shaped regions 410A and 410B of the pattern shown in FIG. Can be displayed as if it was rotated by 90 degrees.

As a result, the mixing effect can be exerted by changing the angular position of the amplitude strength of the emitted light with time without using a rotation driving means or the like that generates vibration or the like, and the measured light can be averaged.

100: Light wave distance meter 101: Base 102: Base 103: Telescope 104: Leveling screw 106: Display 107: Operation input 110: Housing 120: Lens tube 130: Base 200: Optical system 210: Objective Lens system 220: Injection optical system 221: Collimeter lens 222: Circular 223: Circular drive motor 224: Aperture arrangement member 225: Trapezoidal prism 225a: Reflective surface 225b: Reflective surface 226: Chopper 226a: Plate part 227: Chopper drive motor 230: Ideal point light source 240: Ejection reflection optical system 241: Reflector 242: Light transmission reflection prism 242a: Reflection surface 250: Light reception reflection optical system 251: Dicroic mirror 252: Light reception reflection prism 252a: Reflection surface 260: Optical fiber 261: Optical sensor 263: Optical fiber 270: Collimation optical system 280: Prism 281: Cover glass 310: Density filter 400: Filter member 401: Central light-transmitting part 402: Light-shielding band part 403: Light-transmitting band part 410: Filter member 410A, 410B: Fan-shaped area 412A, 412B: Light-shielding band part 413A, 413B: Light-transmitting band part 420: Filter members 420A, 420B, 420C, 420D: Fan-shaped area 422A, 422B, 422C, 422D: Light-shielding band part 423A, 423B, 423C, 423D: Translucent band

Claims (7)

A measuring device including a light source that emits measurement light and a light receiving unit that receives reflected light from the object to be measured, and measures the distance to the object to be measured based on the reflected light received by the light receiving unit. In
A diaphragm member for narrowing the luminous flux of the measurement light from the light source is provided.
The aperture member includes a central translucent portion arranged on the optical axis of the light source and a light-shielding band portion forming a plurality of translucent band portions arranged around the central transmissive portion, and the measurement light is measured. A measuring device characterized in that the luminous flux of the measured light emitted is expanded to a desired opening angle by interference due to diffraction when the light is transmitted through the central translucent portion and the translucent band portion. The light-shielding band portion of the diaphragm member is a plurality of torus bands arranged around the central translucent portion, concentric with the central translucent portion, and arranged at predetermined intervals. The measuring device according to claim 1. The translucent band portion of the diaphragm member is a plurality of arc-shaped bands arranged around the central translucent portion, concentric with the central translucent portion, and arranged at predetermined intervals. The measuring device according to claim 1. The measuring device according to claim 1, wherein the central translucent portion has a circular shape. The diaphragm member is divided into a plurality of fan-shaped regions concentric with the center of the central translucent portion, and each fan-shaped region is characterized in that the arrangement intervals of the translucent band portions are different in at least two fan-shaped regions. The measuring device according to claim 3. The measuring device according to claim 3, further comprising a driving means for rotating the diaphragm member about an optical axis. The claim is characterized in that the diaphragm member is composed of a light-transmitting element whose light shielding and transmission patterns can be changed by external control, and the shapes of the central light-transmitting portion, the light-shielding band portion, and the light-transmitting band portion are changed. Item 1. The measuring device according to item 1.

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