JP-2026074627-A - Distance measurement system

JP2026074627AJP 2026074627 AJP2026074627 AJP 2026074627AJP-2026074627-A

Abstract

[Problem] To provide a distance measurement system that can suppress misalignment of the optical axis of the projected light and suppress changes in the spot diameter of the projected light. [Solution] The distance measuring system 1A comprises a light source 110 that emits light, a collimator lens 120A, and a base member 130 that contacts the collimator lens 120A. The coefficient of linear expansion of the collimator lens 120A and the coefficient of linear expansion of the base member 130 are different, and at least one of the portion of the base member 130 that contacts the collimator lens 120A and the portion of the collimator lens 120A that contacts the base member 130 has an inclined surface that is inclined with respect to the optical axis Ax of the light source 110. [Selection Diagram] Figure 9

Inventors

水越文也
上野博隆
松村一幸
菊池文孝

Assignees

パナソニックＩＰマネジメント株式会社

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (16)

A light source that emits light, Collimator lens and A base member that contacts the collimator lens, The system includes a retaining member for holding down the collimator lens, The linear expansion coefficient of the collimator lens and the linear expansion coefficient of the base member are different. At least one of the portion of the base member that contacts the collimator lens and the portion of the collimator lens that contacts the base member has an inclined surface that is inclined with respect to the optical axis of the light source. Distance measurement system.
In a cylindrical coordinate system where the light emission point of the light source is the origin, the optical axis is the z-axis, the direction in which the collimator lens is positioned relative to the light emission point is the positive direction, and the radial direction of the optical axis is the r-axis, the inclination of the inclined surface is positive. The distance measuring system according to claim 1.
In the cross-section of the distance measuring device when cut by a plane passing through the optical axis, if the inclined surface is defined as z = a 1 × r + b 1 , then b 1 ≈ 0. The distance measuring system according to claim 2.
The base member has a first inclined surface as the inclined surface formed in the portion that contacts the collimator lens. The distance measuring system according to claim 1.
The collimator lens has a second inclined surface as the inclined surface formed in the portion that contacts the base member. The distance measuring system according to claim 1.
The base member has a first inclined surface formed in the portion that contacts the collimator lens, The collimator lens has a second inclined surface formed as the inclined surface in the portion that contacts the base member, The first inclined surface and the second inclined surface are in surface contact. The distance measuring system according to claim 1.
A light source that emits light, Collimator lens and A holding member for holding the collimator lens, A base member in contact with the aforementioned holding member, The system includes a retaining member for holding down the collimator lens, The coefficient of linear expansion of the base member and the coefficient of linear expansion of the holding member are different. At least one of the portion of the base member that contacts the holding member and the portion of the holding member that contacts the base member has an inclined surface that is inclined with respect to the optical axis of the light source. Distance measurement system.
If the linear expansion coefficient of the collimator lens is α L , the linear expansion coefficient of the base member is α B , and the linear expansion coefficient of the holding member is α H , then the relationship is α B < α L , α H , or α B > α L , α H. In a cylindrical coordinate system where the light emission point of the light source is the origin, the optical axis is the z-axis, the direction in which the collimator lens is positioned relative to the light emission point is the positive direction, and the radial direction of the optical axis is the r-axis, the inclination of the inclined surface is positive. The distance measuring system according to claim 7.
In the cross-section of the distance measuring device when cut by a plane passing through the optical axis, if the focal length of the collimator lens is f₀ and the inclined surface is z = a₁ × r + b₁ , then the relationship b₁ × (α₁ B₁ - α₂ H₁ ) ≈ f₀ × (α₁ L₁ - α₂ H₁ ) is satisfied. The distance measuring system according to claim 8.
The base member has a first inclined surface as the inclined surface formed in the portion that contacts the holding member. The distance measuring system according to claim 7.
The holding member has a second inclined surface formed on the portion that contacts the base member. The distance measuring system according to claim 7.
The base member has a first inclined surface formed on the portion that contacts the holding member, The holding member has a second inclined surface formed as the inclined surface in the portion that contacts the base member, The first inclined surface and the second inclined surface are in surface contact. The distance measuring system according to claim 7.
The coefficient of linear expansion of the collimator lens and the coefficient of linear expansion of the retaining member are different. At least one of the portion of the collimator lens that contacts the retaining member and the portion of the retaining member that contacts the collimator lens has another inclined surface that is inclined with respect to the optical axis of the light source. A distance measuring system according to any one of claims 7 to 12.
In a cylindrical coordinate system where the light emission point of the light source is the origin, the optical axis is the z-axis, the direction in which the collimator lens is positioned relative to the light emission point is the positive direction, and the radial direction of the optical axis is the r-axis, the inclination of the other inclined surface is negative. The distance measuring system according to claim 13.
Let the coefficient of thermal expansion of the retaining member be αH2 , the outer diameter of the collimator lens be 2R, the coefficient of thermal expansion of the collimator lens be αL , the coefficient of thermal expansion of the base member be αB , the coefficient of thermal expansion of the holding member be αH , the focal length of the collimator lens be f0 , and in the cross-section of the distance measuring device when cut by a plane passing through the optical axis, if the other inclined surface is z = a² × r + b² , then the relationship f0 × ( αB - αL ) ≈ -a² × R( αL - αH2 ) is satisfied. The distance measuring system according to claim 14.
The retaining member is fixed to the base member by a joining member, screwing, or press-fitting. A distance measuring system according to any one of claims 1 to 12.

Description

This disclosure relates to a distance measurement system. Distance measuring devices that measure the distance to an object using the Time of Flight (TOF) method are known. TOF distance measuring devices project a laser beam towards the object and receive the reflected laser beam. By detecting the delay time between the projection of the laser beam and its reception, the distance from the distance measuring device to the object can be calculated. The distance measuring device comprises a light-emitting unit that emits light and a light-receiving unit that receives the light reflected from the object to be measured. The light-emitting unit includes a light source that emits laser light, a collimator lens for making the laser light emitted from the light source into parallel light, a holding member for holding the collimator lens, and a base member (housing) on which the light source and collimator lens are arranged. In such distance measuring devices, the position of the collimator lens may shift from its predetermined position when the ambient temperature changes. Specifically, when the ambient temperature changes, various components such as the collimator lens, retaining member, and base member expand or contract due to heat, resulting in the collimator lens shifting from its predetermined position. Therefore, in conventional light-emitting units having a semiconductor laser and a collimator lens, techniques have been proposed to suppress the positional displacement of the collimator lens. For example, Patent Document 1 discloses a lens support mechanism as such a light-emitting unit, comprising a semiconductor laser element, a housing to which the semiconductor laser element is fixed, a collimator lens to which light emitted from the semiconductor laser element is incident, a first cylindrical member to which the collimator lens is fixed, and a second cylindrical member fitted to the first cylindrical member and fixed to the housing. In the lens support mechanism disclosed in Patent Document 1, the positional displacement between the light-emitting point of the light source and the collimator lens caused by thermal expansion and contraction is absorbed by making the linear expansion coefficient of the second cylindrical member and the linear expansion coefficient of the housing approximately the same. International Publication No. 2003/102940 Figure 1 shows a distance measuring device and an object to be measured according to Embodiment 1.Figure 2 is a cross-sectional view showing the configuration of a distance measuring device according to Embodiment 1.Figure 3 is a cross-sectional view showing the configuration of the light-emitting section in the distance measuring device according to Embodiment 1.Figure 4 shows the configuration of the light-emitting section in the distance measuring device of the comparative example.Figure 5 is a diagram illustrating the operation of the distance measuring device according to Embodiment 1.Figure 6 is a semi-cross-sectional view of the light-emitting section in the distance measuring device according to Embodiment 1.Figure 7 shows the change in the focal length of the collimator lens and the change in the distance between the collimator lens and the light source when the ambient temperature changes.Figure 8 is a cross-sectional view showing the configuration of the light-emitting section in the distance measuring device according to Embodiment 2.Figure 9 is a diagram illustrating the operation of the distance measuring device according to Embodiment 2.Figure 10 is a cross-sectional view showing the configuration of the light-emitting section in a distance measuring device according to Modification 1.Figure 11 is a cross-sectional view showing the configuration of the light-emitting section in a distance measuring device according to Modification 2. The embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are all specific examples of this disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples and are not intended to limit this disclosure. Accordingly, components in the following embodiments that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as optional components. Please note that each figure is a schematic diagram and not necessarily a strictly accurate representation. Therefore, the scale and other aspects may not necessarily be consistent across all figures. Furthermore, the same reference numerals are used for substantially identical components in each figure, and redundant explanations are omitted or simplified. Also, in this specification, the terms "up" and "down" do not necessarily refer to the absolute upward (vertically upward) and downward (vertically downward) directions in spatial pe