JP4494580B2 - Optical system of scanning projector / receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical system of a scanning projector / receiver having a function of transmitting light to the outside while scanning the light and collecting and receiving reflected light that is retroreflected and returned.
[0002]
[Prior art]
Conventionally, for example, when measuring the position of an object, a scanning projector / receiver is sometimes used as an optical sensor. This scanning projector / receiver has a function of transmitting the light emitted from the light source to the outside while scanning it using a movable mirror or the like and receiving the reflected return light of the scanned light. As an optical system of such a scanning projector / receiver, a configuration in which reflected return light of light to be scanned is collected using a lens or the like and then received by a photo sensor is common.
[0003]
[Problems to be solved by the invention]
By the way, as one of the configurations of the conventional scanning projector / receiver, there is one that receives the return light reflected in the direction substantially along the optical path of the scanned light, for example, retroreflected by a retroreflecting plate. This applies to cases where light is received. As shown in FIG. 8, the retroreflector reflects incident light in the direction of the light source, the reflected light has a slight spread around the light source, and the light that is closer to the axis connecting the light source and the reflection point is stronger. Has the property of returning. Therefore, in order to receive the light reflected by such a retroreflecting plate by the photosensor of the scanning projector / receiver, the light is condensed using a lens, and the condensing position should be an optical path of the transmitted light. It is desirable to set it close.
[0004]
However, in the conventional scanning projector / receiver optical system, when a lens for condensing the reflected return light is arranged near the optical path of the transmitted light, the condensing lens is positioned within the scanning region of the transmitted light. Therefore, there is a possibility that the transmitted light is bent by the condenser lens and scanned in a direction not depending on the movement of the movable mirror. In addition, there is a problem that part of the transmitted light is reflected by the surface of the condenser lens and the reflected light is received by the photosensor.
[0005]
The present invention has been made paying attention to the above points, and it is inexpensive with a simple configuration capable of scanning and transmitting light to a predetermined area and collecting the reflected light to reliably receive the light. An object of the present invention is to provide an optical system for a simple scanning projector / receiver.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, one aspect of the optical system of the scanning projector / receiver according to the present invention irradiates a movable mirror with light emitted from a light source, and externally scans a predetermined area. A light projecting means for sending, a light collecting means for collecting the reflected light that is returned retroreflected externally from the light projecting means, and a light receiving device that receives the reflected light collected by the light collecting means. And an optical system of the scanning projector / receiver configured to include a Fresnel lens disposed across the optical path of the transmitted light, and corresponding to a scanning region of the transmitted light The light receiving means is positioned between the light projecting means and the light collecting means, and is disposed in the vicinity of the optical path of the transmitted light. Is.
[0007]
In such a configuration, the light emitted from the light source is scanned by the movable mirror, passes through the hole formed in the Fresnel lens , and is sent to the outside. The transmitted light is then retroreflected and returned to the outside, and the reflected return light is collected by a Fresnel lens and then received by a light receiving means disposed in the vicinity of the optical path of the transmitted light. This avoids that a part of the transmitted light is reflected by the Fresnel lens and received by the light receiving means.
[0008]
In addition, the optical system includes a housing that houses the light projecting unit, the light collecting unit, and the light receiving unit by blocking them from outside, and the housing has a side surface that crosses the optical path of the transmitted light. You may make it shape | mold so that it may have an angle with respect to a surface perpendicular | vertical to sending light.
[0009]
According to such a configuration, each element of the optical system is shielded from the outside by the housing, so that there is no fear of contamination of the optical system due to the entry of dust or the like from the outside, and a part of the transmitted light is enclosed by the housing. Even if the light is reflected by the inner surface of the body, the reflected light is not received by the light receiving means.
[0010]
According to another aspect of the optical system of the scanning projector / receiver according to the present invention, the light projecting means for irradiating the movable mirror with the light emitted from the light source and transmitting the light for scanning the preset region to the outside, Condensing means for condensing the reflected light returned from the light reflected from the outside by retroreflecting outside, and a light receiving means for receiving the reflected light collected by the condensing means. In the optical system of the scanning type projector / receiver, the condensing means is a Fresnel lens disposed across the optical path of the transmitted light, and the scanning region of the transmitted light with respect to the side surface on which the transmitted light is incident A transmission light incident portion formed with an incident surface having an angle with respect to a plane perpendicular to the transmission light, and the light receiving means is between the light projecting means and the light collecting means. position and, and is disposed in the vicinity of the optical path of the transmitted light Than is.
[0011]
In such a configuration, the light emitted from the light source is scanned by the movable mirror, transmitted through the Fresnel lens via the transmission light incident portion, and transmitted to the outside. At this time, even if a part of the transmitted light is reflected by the incident surface of the transmitted light incident part, the reflected light is not received by the light receiving means. The transmitted light is then retroreflected and returned to the outside, and the reflected return light is collected by a Fresnel lens and then received by a light receiving means disposed in the vicinity of the optical path of the transmitted light.
[0012]
Further, as a specific configuration of each aspect described above, the light receiving unit receives a reflected light collected by the light collecting unit, and the photo sensor is in accordance with a focus of the light collecting unit. A holding member that is held at a position, and the holding member is disposed across the optical path of the transmitted light and has a through hole formed over a range corresponding to the scanning region of the transmitted light. Good. Furthermore, the condensing means may include a Fresnel lens.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an optical system of a scanning projector / receiver according to the first embodiment. FIG. 2 is a side sectional view of the scanning projector / receiver shown in FIG.
[0014]
As shown in FIGS. 1 and 2, the optical system of this scanning type light projecting / receiving device includes, for example, a laser light source 1 and a movable mirror 2 as light projecting means, a photosensor 5 as light receiving means, and a substrate 3 to which the photosensor 5 is attached. And a Fresnel lens 4 as a condensing means, and a case 6 as a housing for housing each of these elements. However, in FIG. 1, the display of the case 6 is omitted so that the internal configuration becomes clear.
[0015]
The laser light source 1 is a general light source that generates laser light having a required wavelength, and is arranged so that the generated laser light is irradiated near the center of the mirror surface 2A of the movable mirror 2.
[0016]
The movable mirror 2 scans the laser light in the horizontal direction in the figure, for example, by totally reflecting the laser light emitted from the laser light source 1 with a oscillating mirror surface 2A. Specific examples of the movable mirror 2 include a resonance mirror and a polygon mirror. In the case of using a resonance type mirror, for example, a semiconductor galvanomirror manufactured using a micromachining technique previously proposed by the present applicant is suitable (Japanese Patent Laid-Open Nos. 7-175005 and 7-218857). No. publication etc.).
[0017]
The substrate 3 is disposed between the movable mirror 2 and the Fresnel lens 4, and a photosensor 5 is attached on a plane facing the Fresnel lens 4. Further, a substrate hole 3 </ b> A penetrating over a range corresponding to the scanning region of the laser beam scanned by the movable mirror 2 is formed near the center of the substrate 3. As this substrate 3, for example, a polychlorinated biphenyl (PCB) substrate or the like can be used.
[0018]
The photosensor 5 receives light collected by the Fresnel lens 4, converts it into an electrical signal, and outputs it to the outside. The arrangement of the photosensor 5 on the substrate surface is set so that the light receiving surface is located at a position corresponding to the focal point of the Fresnel lens 4, and is attached above the substrate hole 3 </ b> A, for example.
[0019]
Although the case where the substrate 3 having a shape that crosses the scanning region of the laser beam is used is shown here, the substrate 3 is a member provided to hold the photosensor 5 at a predetermined position. If a shape that does not cross the scanning region of the laser beam is possible, there is of course no need to provide the substrate hole 3A.
[0020]
The Fresnel lens 4 is a known lens for condensing the reflected light of the transmitted light on the light receiving surface of the photosensor 5. The Fresnel lens 4 is a thin lens made up of many zonal prisms, and collects light rays passing through the center of the zonal zone (hereinafter referred to as the optical center) at one point (see FIG. 2). . Further, a lens hole 4A is formed in the vicinity of the center of the Fresnel lens 4 over a range corresponding to the scanning region of the laser light in the same manner as the substrate 3, and here, for example, a little from the optical center of the Fresnel lens 4 A long hole penetrating the part shifted downward is formed. In the present embodiment, the plastic hole-shaped Fresnel lens 4 is used to facilitate drilling of the lens hole portion 4A. However, the material and shape of the Fresnel lens 4 are not limited to those described above. In FIG. 3, the top view which expanded and showed the uneven | corrugated surface side of the Fresnel lens 4, and the side view are shown.
[0021]
The case 6 is a housing that can accommodate each element of the optical system as described above. In this case 6, it is assumed that the side surface located on the left side in FIG. 2 through which the transmitted light and the reflected light pass is formed using a material that is transparent to the laser light. Specifically, for example, a black visible light cut filter or the like may be used on the side surface to avoid the influence of ambient light. Housing the optical system in the case 6 is important in terms of preventing the optical system from being contaminated. That is, in the first embodiment, since the lens hole 4A is formed in the Fresnel lens 4, if the optical system is housed in the case 6 and is not cut off from the outside, dust and the like enter from the outside and move. This is because the mirror 2, the photosensor 5 and the like may be soiled and hinder the passage of laser light and the reception of reflected light. Here, the light incident / exit surface (the transparent side surface) of the case 6 is provided with an angle so as not to be parallel to a surface perpendicular to the transmitted light. This is a measure for preventing unnecessary light (dotted arrow in FIG. 2) generated by reflection of the laser light from the inner surface of the case 6 from being received toward the photosensor 5.
[0022]
In the scanning type projector / receiver provided with the optical system as described above, the laser beam emitted from the laser light source 1 is reflected by the movable mirror 2 to be scanned in a required region. The scanned laser light sequentially passes through the substrate hole 3A, the lens hole 4A, and the transparent side surface of the case 6 and is transmitted to the outside. Then, when the light transmitted to the outside reaches, for example, a retroreflecting plate as described with reference to FIG. 8 described above, the light is retroreflected and returned to the scanning projector / receiver. As shown in FIG. 2, the reflected return light enters the scanning projector / receiver as a parallel light beam having a certain extent, passes through the transparent side surface of the case 6, and then enters the Fresnel lens 4. Is condensed on the light receiving surface of the photosensor 5. In the photosensor 5, the collected reflected light is converted into an electric signal and output to the outside as a light reception signal.
[0023]
As described above, according to the first embodiment, the Fresnel lens 4 is arranged near the optical path of the transmitted light in order to efficiently receive the light that is returned after being retroreflected. Even so, by performing a simple process of forming the lens hole 4A according to the scanning region of the transmitted light, the transmitted light is bent by the Fresnel lens 4 and scanned in a direction not depending on the movement of the movable mirror 2. At the same time, it is possible to easily avoid a problem that a part of the transmitted light is reflected by the surface of the Fresnel lens 4 and received by the photosensor 5. Further, with respect to each element of the optical system configured by using the Fresnel lens 4 or the like in which the lens hole portion 4A is formed, by accommodating it in the case 6, there is no fear of contamination due to the entry of dust or the like from the outside. Since the light emission surface of the case 6 is inclined with respect to the optical axis, unnecessary light reflected by the inner surface of the case 6 is hardly received by the photosensor 5, and the light retroreflected outside. Can be reliably received. A scanning projector / receiver using such an optical system can be used as an optical sensor of various devices that measure, for example, the position of an object existing in a scanning region of a laser beam.
[0024]
Next, a second embodiment will be described.
FIG. 4 is a perspective view showing an optical system of a scanning projector / receiver according to the second embodiment. FIG. 5 is a cross-sectional view showing the structure of a Fresnel lens used in the optical system of FIG.
[0025]
As shown in FIGS. 4 and 5, the portion of the optical system in the second embodiment different from that in the first embodiment is provided with a Fresnel lens 7 instead of the Fresnel lens 4 in which the lens hole 4A is formed. Part. The configuration of other parts other than that is the same as in the case of the first embodiment, and thus the description thereof is omitted here.
[0026]
The Fresnel lens 7 has a transmission light incident portion 7A formed in the vicinity of the central portion of the plane on the side facing the substrate 3 over a range corresponding to the laser light scanning region. As shown in the cross-sectional view of FIG. 5, the outgoing light incident portion 7A is inclined such that the incident surface on which outgoing light is incident has an angle with respect to a plane perpendicular to the outgoing light, that is, downward in the drawing. This is provided in order to prevent unnecessary light generated by reflecting a part of the transmitted light from the surface of the Fresnel lens 7 from being directed toward the photosensor 5.
[0027]
As described above, the same effect as that of the first embodiment can be obtained even if the outgoing light incident portion 7A is formed instead of providing the through hole through which the outgoing light passes, for the Fresnel lens. . In addition, because the Fresnel lens 7 that does not have a penetrating hole part cuts off the configuration of the optical system such as the photosensor 5 and the movable mirror 2 from the outside, the case 6 as shown in FIG. Thus, the portion located outside the Fresnel lens (left side in FIG. 2) is not required, and the scanning type light projector / receiver can be miniaturized.
[0028]
In the first and second embodiments described above, the case of using a Fresnel lens of a type that condenses parallel rays incident on the uneven surface side at one point has been described, but the present invention is not limited thereto, You may use the type of Fresnel lens which condenses the collimated light ray which injects into the plane on the opposite side to an uneven surface to one point. Specifically, in the case of the first embodiment, the Fresnel lens 4 ′ in which the lens hole portion 4A ′ is formed as shown in the cross-sectional view of FIG. 6 is arranged so that the uneven surface faces the substrate 3 side. do it. Further, in the case of the second embodiment, as shown in the cross-sectional view of FIG. 7, the Fresnel lens 7 ′ having the transmission light incident portion 7 </ b> A ′ is disposed so that the uneven surface faces the substrate 3 side. do it.
[0029]
Et al is, has been adapted to deliver by scanning the laser beam, the light source in the present invention is not limited to a laser.
[0030]
【The invention's effect】
As described above, the present invention can efficiently collect the light transmitted to the outside after being retroreflected and returned by the light collecting means using the Fresnel lens and receive the light by the light receiving means. Even if the configuration of the optical system is such that the Fresnel lens is arranged near the optical path of the transmitted light, by providing a hole or a transmitted light incident portion penetrating the Fresnel lens according to the scanning region of the transmitted light. The transmitted light can be prevented from being bent by the Fresnel lens and scanned in a direction not depending on the movement of the movable mirror. At the same time, a part of the transmitted light is reflected by the Fresnel lens and received by the light receiving means. Can be easily avoided.
[0031]
Further, each element of the optical system configured by using the light collecting means in which the through-hole is formed is accommodated in the casing, and the side surface of the casing crossing the optical path of the transmitted light is set to a surface perpendicular to the transmitted light. By tilting the optical system with respect to the optical system, it is possible to prevent the optical system from being contaminated due to the entry of dust or the like from the outside, and to prevent the light reflected by the inner surface of the housing from being received by the light receiving means.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical system of a scanning projector / receiver according to a first embodiment of the present invention.
2 is a side sectional view of the scanning projector / receiver shown in FIG. 1. FIG.
FIGS. 3A and 3B are a plan view and an enlarged side view showing an uneven surface side of a Fresnel lens according to the first embodiment. FIGS.
FIG. 4 is a perspective view showing an optical system of a scanning projector / receiver according to a second embodiment of the present invention.
5 is a cross-sectional view showing the structure of a Fresnel lens used in the optical system of FIG.
FIG. 6 is a cross-sectional view showing the structure of another Fresnel lens related to the first embodiment.
FIG. 7 is a cross-sectional view showing the structure of another Fresnel lens related to the second embodiment.
FIG. 8 is a diagram for explaining optical characteristics of a general retroreflector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laser light source 2 ... Movable mirror 2A ... Mirror surface 3 ... Substrate 3A ... Substrate hole part 4, 4 ', 7, 7' ... Fresnel lens 4A, 4A '... Lens hole part 7A, 7A' ... Sending light incident part 6 ... Case

Claims (4)

A light projecting means for irradiating a movable mirror with light emitted from a light source and transmitting light that scans a preset area to the outside, and a reflection in which light transmitted from the light projecting means is retroreflected and returned to the outside. In an optical system of a scanning projector / receiver configured to include a light collecting means for collecting light and a light receiving means for receiving reflected light collected by the light collecting means,
The condensing means is a Fresnel lens disposed across the optical path of the transmitted light, and has a through hole formed over a range corresponding to the scanning region of the transmitted light,
An optical system of a scanning type light projecting and receiving device, wherein the light receiving means is located between the light projecting means and the light collecting means and disposed in the vicinity of an optical path of the transmitted light.   A housing for blocking and accommodating the light projecting means, the light collecting means, and the light receiving means from the outside; The optical system of the scanning projector / receiver according to claim 1, wherein the optical system is shaped to have an angle. The light emitted from the light source is irradiated onto the movable mirror, and the light projecting means for transmitting the light for scanning the preset region to the outside, and the light transmitted from the light projecting means is retroreflected outside and returned. In the optical system of the scanning projector / receiver configured to include a condensing unit that collects the reflected light and a light receiving unit that receives the reflected light collected by the condensing unit,
The condensing means is a Fresnel lens disposed across the optical path of the outgoing light, and the side surface on which the outgoing light is incident is perpendicular to the outgoing light over a range corresponding to the scanning area of the outgoing light. A transmission light incident portion formed with an incident surface having an angle with respect to a plane;
An optical system of a scanning type light projecting and receiving device, wherein the light receiving means is located between the light projecting means and the light collecting means and disposed in the vicinity of an optical path of the transmitted light. The light receiving means includes a photosensor that receives reflected light collected by the light collecting means, and a holding member that holds the photosensor at a position corresponding to the focal point of the light collecting means,
4. The holding member according to claim 1, further comprising a through-hole portion that is disposed across an optical path of the transmitted light and is formed over a range corresponding to a scanning region of the transmitted light. The optical system of the scanning projector / receiver described in 1.

Images