CN217637390U

CN217637390U - Optical sensor

Info

Publication number: CN217637390U
Application number: CN202221540067.0U
Authority: CN
Inventors: 不公告发明人
Original assignee: Shenzhen Xhorse Electronics Co Ltd
Current assignee: Shenzhen Xhorse Electronics Co Ltd
Priority date: 2022-06-20
Filing date: 2022-06-20
Publication date: 2022-10-21
Anticipated expiration: 2032-06-20

Abstract

The application provides an optical sensor, relates to the photoelectric technology field, includes: the light emitting component comprises a light emitting end for emitting the detection light beam and a collimation unit coaxially arranged with the light emitting end; the reflector is arranged on a light path of the detection light beam and reflects first reflected light obtained by the detection light beam, and the first reflected light is parallel to the optical axis of the detection light beam; the polarization spectroscope is arranged on the light path of the detection light beam and the first reflected light, the incident angles of the detection light beam and the first reflected light entering the polarization spectroscope are equal to the Brewster angle of the polarization spectroscope, and the normal of the polarization spectroscope and the polarization direction of the detection light beam are in the same plane; the polarization spectroscope reflects the first reflected light to obtain second reflected light; and the light condensing unit is arranged on the light path of the second reflected light and focuses the second reflected light to the photosensitive area of the photoelectric detector. The method and the device can reduce the loss of energy in the detection light path, thereby improving the detection distance and the detection sensitivity.

Description

Optical sensor

Technical Field

The utility model relates to the field of photoelectric technology, especially, relate to an optical sensor.

Background

The existing optical sensor is generally referred to as a retro-reflection type optical sensor, and is an optical sensor composed of a transmitter, a reflector and a receiver, wherein a stable detection optical path is formed among the transmitter, the reflector and the receiver, and the optical sensor can be triggered to be switched on and off when a detection object blocks the detection optical path. The sensitivity of the existing optical sensor depends on the energy of the light beam that can be received by the receiver, and the energy is lower as the distance of light beam propagation in the detection light path is longer, which may cause the energy of the light beam received by the receiver to be too low when the detection distance is too long, resulting in the sensitivity of the optical sensor being reduced. Particularly in an optical sensor using a half mirror, a large amount of energy is lost when a light beam passes through the half mirror. Therefore, the conventional optical sensor cannot further increase the detection distance because of the energy limitation of the detected light beam.

SUMMERY OF THE UTILITY MODEL

For solving the technical problem in the background art, further improve detection distance, the utility model provides an optical sensor, include:

the light emitting component comprises a light emitting end for emitting detection light beams and a collimation unit coaxially arranged with the light emitting end, and the detection light beams are polarized light;

the reflector is arranged on a light path of the detection light beam and reflects first reflected light obtained by the detection light beam, and the first reflected light is parallel to the optical axis of the detection light beam;

the polarization spectroscope is arranged on a light path of the detection light beam and the first reflected light, the incident angles of the detection light beam and the first reflected light entering the polarization spectroscope are equal to the Brewster angle of the polarization spectroscope, and the normal of the polarization spectroscope and the polarization direction of the detection light beam are in the same plane; the polarization spectroscope reflects the first reflected light to obtain second reflected light;

and the light condensing unit is arranged on the light path of the second reflected light and focuses the second reflected light to the photosensitive area of the photoelectric detector.

The beneficial effects of the utility model are that, the utility model discloses in the polarization direction of measuring beam and polarization spectroscope's normal line in the coplanar, the reflectivity when measuring beam is with brewster angle incident polarization spectroscope is close to 0, and the energy that measuring beam passed polarization spectroscope loss is few. The reflector reflects the detection light beam and randomly changes the polarization state of the detection light beam to obtain first reflected light, the first reflected light enters the polarization beam splitter at the Brewster angle, and the part of the first reflected light, which is perpendicular to the normal of the polarization beam splitter, is reflected to obtain second reflected light for detection. Compare in the optical sensor who uses semi-transparent half-reflection lens, the energy of loss still less on optical element in this application, consequently the utility model discloses can reduce the loss of energy in the detection light path, improve detection distance and detectivity.

Drawings

Fig. 1 is a schematic structural diagram of an optical sensor in embodiment 1 of the present invention;

fig. 2 is a detection light path diagram when the detection object is located in the detection area in embodiment 1 of the present invention;

fig. 3 is a diagram of a detection optical path of a polarization state when there is no detection object in embodiment 2 of the present invention;

fig. 4 is a polarization detection light path diagram when the mirror surface object is located in the detection area in embodiment 2 of the present invention.

Wherein, 1: a light emitting component; 2: a collimating unit; 3: a reflector; 4: a polarizing beam splitter; 5: a light condensing unit; 6: a photodetector; 7: an analyzer; 8: a light-tight housing; 9: an optical filter; 10: a light barrier; 11: a light source; 12: a polarizer; 13: detecting an object; 14: a mirror surface object; a: detecting the light beam; b: a first reflected light; c: the second reflected light.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without any creative effort belong to the protection scope of the present invention.

It should be noted that all the directional indicators in the embodiments of the present invention (such as upper, lower, left, right, front, and rear … …) are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is also changed accordingly, and the connection may be a direct connection or an indirect connection.

In addition, descriptions in the present application as to "first", "second", and the like are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

Example 1

The present embodiment provides an optical sensor, as shown in fig. 1, which is a schematic structural diagram of the optical sensor, and the optical sensor includes:

the light emitting assembly 1 comprises a light emitting end for emitting a detection light beam a, and a collimation unit 2 coaxially arranged with the light emitting end, wherein the detection light beam a is polarized light. The light emitting end comprises a light source 11 and a polarizer 12, the normal line of the polarizer 12 is the same as the polarization direction of the detection light beam a, and the light beam emitted by the light source 11 becomes linearly polarized light after passing through the polarizer 12. Wherein the light source 11 is preferably an LED light source 11, the emitted light is natural light, the polarization direction of which is randomly distributed in all directions in a plane perpendicular to the propagation direction, and thus does not show polarization. For convenience of description, the propagation direction of the detection light beam a is the Z direction, linearly polarized light with the polarization direction parallel to the Y axis is denoted as p-polarized light, linearly polarized light with the polarization direction parallel to the X axis is denoted as s-polarized light, and the polarization direction is denoted by a thick double-headed arrow in the drawings of the present application. The polarizer 12 is a linear polarizer whose polarization direction is parallel to the Y-axis direction, and a light vector perpendicular to the polarization direction is suppressed by the linear polarizer and cannot pass through the linear polarizer, so that the natural light emitted from the light source 11 passes through the polarizer 12 and becomes linearly polarized light whose polarization direction is the Y-axis direction. And polarizer 12 can prevent other stray light generated by light source 11 from entering the inside of the optical sensor.

The polarization direction of the polarized light is the vibration direction of the light vector and is perpendicular to the propagation direction of the light. The collimating unit 2 is used to shape the detection beam a into parallel light, preferably a positive lens. The collimating unit 2 is further preferably an aspheric lens, which reduces aberrations introduced by the spherical lens and improves the parallelism of the light beams. The parallelism of the detection light beam a is improved, and the energy loss caused by the diffusion of the detection light beam a in the propagation process can be reduced.

And the reflector 3 is arranged on the optical path of the detection light beam a and reflects a first reflected light b obtained by the detection light beam a, wherein the first reflected light b is parallel to the optical axis of the detection light beam a. The reflector 3 may be any total reflection reflector capable of changing the polarization state of the reflected light. The reflector 3 may also be a cube corner prism. The cube corner prism is also called as a retroreflection mirror and consists of three perpendicular right-angle surfaces, incident light forms total reflection on the three right-angle surfaces, and the incident light returns in the original path. The reflector 3 changes the polarization direction of the first reflected light b by the total reflection structure, and makes the obtained first reflected light b parallel to the optical axis of the detection beam a, and the polarization state of the first reflected light b is changed, and the polarization is not displayed.

The polarization beam splitter 4 is arranged on the light paths of the detection light beam a and the first reflected light b, the incident angles of the detection light beam a and the first reflected light b entering the polarization beam splitter 4 are both equal to the Brewster angle theta of the polarization beam splitter 4, and the normal of the polarization beam splitter 4 and the polarization direction of the detection light beam a are in the same plane; the polarizing beam splitter 4 reflects the first reflected light b to obtain a second reflected light c.

The polarization beam splitter 4, also called a polarization beam splitting plate, has a high transmittance of more than 95% for linearly polarized light with the polarization direction in the same plane as the normal line thereof, and has a high reflectance of more than 99.5% for linearly polarized light with the polarization direction perpendicular to the normal line thereof. Thus, when light is incident at Brewster's angle θ, almost all of the p-polarized light is transmitted through the polarizing beamsplitter 4 and almost all of the s-polarized light is reflected by the polarizing beamsplitter 4.

And a light condensing unit 5 disposed on an optical path of the second reflected light c to focus the second reflected light c onto a photosensitive area of the photodetector 6. Wherein the light-condensing unit 5 does not change the polarization state of the second reflected light c. The second reflected light c is parallel light, and the energy of the second reflected light c can be collected by focusing the second reflected light c by the light condensing unit 5, so that the light spot focused on the photodetector 6 is minimum, the illuminance is maximum, and the detection accuracy of the optical sensor is improved.

In this embodiment, the polarization direction of the detection beam a is in the same plane as the normal of the polarization beam splitter 4, the reflectivity of the detection beam a when entering the polarization beam splitter 4 at the brewster angle θ is close to 0, and the energy lost when the detection beam a passes through the polarization beam splitter 4 is very small. The reflector 3 reflects the detection light beam a and randomly changes the polarization state of the detection light beam a to obtain a first reflected light b, the first reflected light b enters the polarization beam splitter 4 at the brewster angle θ, and a portion of the first reflected light b perpendicular to the normal of the polarization beam splitter 4 is reflected to obtain a second reflected light c for detection. Compare in the optical sensor who uses semi-transparent half-reflection lens, the energy of loss still less on optical element in this application, consequently the utility model discloses can reduce the loss of energy in the detection light path, improve detection distance and detectivity.

As shown in fig. 2, a detection optical path diagram when the detection object is located in the detection area. The detection area in this embodiment is the area between the optical sensor and the reflector 3. When the detection object 13 is located in the detection area and blocks the detection light beam a emitted by the optical sensor, the detection light beam a cannot be reflected back to the optical sensor, so that the photodetector 6 cannot detect light energy, and the optical sensor triggers to send out a signal for detecting the detection object 13.

Example 2

This embodiment is a further optimized solution according to embodiment 1, and the optical sensor provided in this embodiment further includes an analyzer 7, where the analyzer 7 is disposed on the optical path of the second reflected light c, and the polarization direction of the analyzer 7 is perpendicular to the polarization direction of the detection light beam a. The light condensing unit 5 is an off-axis parabolic reflector, the light sensing area of the photoelectric detector 6 is arranged at the focus of the off-axis parabolic reflector, and the analyzer 7 is arranged between the photoelectric detector 6 and the off-axis parabolic reflector. The analyzer 7 is a linear polarizer having a polarization direction parallel to the X-axis direction, and allows only s-polarized light to pass therethrough.

As shown in fig. 3, the detection optical path diagram is a polarization state diagram when there is no detection object. When the detection light path is not blocked by the detection object 13, the divergent light beam emitted by the light source 11 passes through the polarizer 12 and is collimated by the positive lens, and the formed detection light beam a is p-polarized light with good collimation. The p-polarized light is directed to the polarization beam splitter 4 and almost completely transmitted, and reaches the reflector 3 to form a first reflected light b, and then is reflected to the optical sensor. The first reflected light b is partially reflected when passing through the polarization beam splitter 4 to obtain second reflected light c, most of the second reflected light c is s-polarized light, the second reflected light c is emitted to the light condensing unit 5 and then focused, the second reflected light c passes through the analyzer 7, the analyzer 7 only allows the s-polarized light to pass through, finally the s-polarized light forms a focused light spot in a photosensitive area on the photoelectric detector 6, light energy is detected on the photoelectric detector 6, the optical sensor is closed, and no electric signal or a signal that the detection object 13 is not detected is emitted.

Fig. 4 is a diagram of a polarization detection path when a specular object is located in the detection area. After being reflected by the specular reflection object, the detection light beam a emitted from the optical sensor is still p-polarized light without changing the polarization state, and the light polarization direction of the detection light beam a is in the same plane as the normal of the polarization beam splitter 4, so that almost all the detection light beam is transmitted when passing through the polarization beam splitter 4, the energy of the obtained second reflected light c is very low, and the second reflected light c is also p-polarized light at this time, when the second reflected light c passes through the analyzer 7, the p-polarized light is blocked, and the second reflected light c cannot be detected by the photodetector 6, so that the optical sensor can be triggered to emit a signal for detecting the detection object 13.

If the analyzer 7 is not installed, a small amount of the second reflected light c is detected by the photodetector 6, which may cause the optical sensor to be not triggered and to emit an error signal. This problem can be prevented by adjusting the threshold of the photodetector 6 high, but the sensitivity of the optical sensor is reduced.

In this embodiment, the analyzer 7 further filters p-polarized light and other stray light emitted to the photodetector 6, so as to improve the accuracy of the optical sensor and ensure the sensitivity of the optical sensor.

Example 3

In this embodiment, according to a further optimized scheme of embodiment 2, the optical sensor provided in this embodiment further includes an opaque housing 8, the light emitting assembly 1, the polarizing beam splitter 4, the light condensing unit 5, and the photodetector 6 are all disposed inside the opaque housing 8, and an emission window is disposed on the opaque housing 8 and is disposed on a light path of the detection light beam a and the first reflected light b. The emission window is provided with a filter 9. The filter 9 is a single-pass filter 9, and the passing center wavelength of the filter is the same as the wavelength of the light source 11, so that the effects of inhibiting background light and eliminating stray light are achieved.

The light-tight shell 8 is coated with black light-absorbing material to reduce stray light generated by diffuse reflection inside the optical sensor. A light barrier 10 is provided inside the light-tight housing 8, separating the light emitting assembly 1 and the photodetector 6, so as to eliminate the influence of stray light on the photodetector 6 due to diffuse reflection inside the optical sensor.

The above only is the preferred embodiment of the present invention, not limiting the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings, or directly or indirectly applied to other related technical fields, are included in the same way in the protection scope of the present invention.

Claims

1. An optical sensor, comprising:

the light emitting component (1) comprises a light emitting end and a collimating unit (2), wherein the light emitting end emits detection light beams (a), and the collimating unit (2) is coaxially arranged with the light emitting end;

the reflector (3) is arranged on the optical path of the detection light beam (a) and reflects first reflected light (b) obtained by the detection light beam (a), and the first reflected light (b) is parallel to the optical axis of the detection light beam (a);

a polarization beam splitter (4) arranged on the light path of the detection light beam (a) and the first reflection light (b), wherein the incident angles of the detection light beam (a) and the first reflection light (b) entering the polarization beam splitter (4) are both equal to the Brewster angle of the polarization beam splitter (4), and the normal of the polarization beam splitter (4) and the polarization direction of the detection light beam (a) are in the same plane; the polarization spectroscope (4) reflects the first reflected light (b) to obtain a second reflected light (c);

and the light condensing unit (5) is arranged on the light path of the second reflected light (c) and focuses the second reflected light (c) to the photosensitive area of the photoelectric detector (6).

2. An optical sensor according to claim 1, further comprising an analyzer (7), the analyzer (7) being arranged in the optical path of the second reflected light (c), the polarization direction of the analyzer (7) being perpendicular to the polarization direction of the detection light beam (a).

3. An optical sensor according to claim 2, characterized in that the light concentrating unit (5) is an off-axis parabolic mirror, the light sensitive area of the photodetector (6) is arranged at the focus of the off-axis parabolic mirror, and the analyzer (7) is arranged between the photodetector (6) and the off-axis parabolic mirror.

4. The optical sensor according to claim 1, further comprising a light-tight housing (8), wherein the light-emitting assembly (1), the polarizing beam splitter (4), the light-focusing unit (5) and the photodetector (6) are all disposed inside the light-tight housing (8), and an emission window is disposed on the light-tight housing (8), and the emission window is disposed on the optical path of the detection light beam (a) and the first reflected light (b).

5. An optical sensor as claimed in claim 4, characterized in that the emission window has a filter (9) mounted thereon.

6. The optical sensor according to claim 4, characterized in that a light barrier (10) separating the light emitting assembly (1) and the photodetector (6) is provided inside the light-tight housing (8).

7. An optical sensor as claimed in claim 4, characterized in that the light-tight housing (8) is internally coated with a black light-absorbing material.

8. The optical sensor according to claim 1, characterized in that the light emitting end comprises a light source (11) and a polarizer (12), the normal of the polarizer (12) being the same as the polarization direction of the detection light beam (a).

9. An optical sensor according to claim 1, characterized in that the reflector (3) is a cube-corner prism.