JPH0550310U - Laser interference displacement meter - Google Patents

Abstract

(57) [Summary] [Purpose] To realize a laser interference displacement meter that can reduce errors during optical axis adjustment and can confirm, quantify, and display cosine errors that occur during measurement. [Structure] A laser light source, and an interferometer section using Michelson's interference optical system on which the output of the laser light source is incident,
In a laser interference displacement meter including a light receiving unit for receiving an interference output obtained from the interferometer unit, and a calculation unit and a display unit for receiving the photoelectric conversion output from the light receiving unit for arithmetic processing and display, A light-receiving element for adjusting the optical axis,
Further, the arithmetic unit is provided with an arithmetic circuit for adjusting the optical axis.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a laser interference displacement meter, and more particularly to a laser interference displacement meter capable of quantifying and displaying the deviation of the optical axis when adjusting the optical axis and also quantifying and displaying the cosine error generated during measurement. Is.

[0002]

[Prior Art]

 In the conventional laser interference displacement type, when the optical axis is adjusted, a movable corner cube (hereinafter simply referred to as CC) is brought close to a polarization beam splitter (hereinafter simply referred to as PBS) as shown in FIG. At this time, a cross-shaped target is placed in front of the light receiving element for adjustment, then the movable CC is moved, and the optical axis is adjusted while visually checking the beam movement on the target accompanying this movement. I was going. Therefore, it was difficult to perform precise optical axis adjustment. A cosine error that occurs during measurement (a cosine error occurs because the laser optical axis is inclined at an angle with respect to the axis passing through the two points to be measured, as shown in FIG. If the true length between two points AB to be measured is L and the length between the laser optical axes AB ′ is L ′, the cosine error ΔL is ΔL = L′−L = (1-1 / cos θ) L) was not confirmed without blocking the laser beam. With the conventional laser interferometric displacement meter, if the laser beam was interrupted during measurement, subsequent measurements would not be possible, so the measurement had to be restarted from the beginning.

[0003]

[Problems to be solved by the device]

 The present invention was made in view of the above-mentioned problems of the prior art.By adding a function to quantify and display the deviation of the optical axis, the error during the optical axis adjustment can be reduced and the cosine generated during measurement can be reduced. -The purpose is to provide a laser interference displacement meter that can confirm, quantify, and display errors.

[0004]

[Means for Solving the Problems]

 The configuration of the present invention for solving the above-mentioned problems is to provide a laser light source, an interferometer section using Michelson's interference optical system on which the output of the laser light source is incident, and an interference output obtained from the interferometer section. In a laser interference displacement meter comprising a light receiving section for receiving light, and a calculation section and a display section for receiving the photoelectric conversion output from the light receiving section for arithmetic processing and displaying, a light receiving element for optical axis adjustment is provided in the light receiving section. Further, it is characterized in that an optical axis adjusting arithmetic circuit is provided in the arithmetic section.

[0005]

[Action]

 According to the present invention, since the degree of optical axis deviation can be displayed numerically, it is possible to perform optical axis alignment with high accuracy and to confirm and quantify cosine errors during measurement.

[0006]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the laser interference displacement meter of the present invention. In FIG. 1, a laser beam of two orthogonal frequencies (polarization directions Es, Ep) emitted from the laser light source 1 is incident on an interferometer section composed of PBS2, fixed CC3 and movable CC4, and is obtained from this interferometer section. The interference output is divided into reflected light and transmitted light by the partial reflection mirror 5. The transmitted light enters the light receiving element 6 for displacement measurement and is photoelectrically converted. This output is processed by the calculation unit 7, and the length measurement value is displayed on the display unit 8. On the other hand, of the light reflected by the partial reflection mirror 5, only the laser light of the polarization Ep is received by the four-division photodiode 10 which is a light receiving element for optical axis adjustment by the polarizing plate 9. The outputs of the upper and lower elements of the elements constituting the 4-divided photodiode 10 are input to a differential amplifier 11 which is an arithmetic circuit for adjusting the optical axis, and the difference is output. The difference between the left and right elements is also output from the differential amplifier 11. Here, if the laser light is incident on the center of the four-divided photodiode 10, the output of each element becomes equal, and the output of the differential amplifier 11 becomes 0 in both the vertical and horizontal directions. Further, when the laser light is incident on the position deviated from the center of the four-divided photodiode 10, a difference occurs in the output of each element, so that the output of the differential amplifier 11 produces an output according to the position of the deviation. To do. The output of the differential amplifier 11 is input to the arithmetic unit 7, and the amount of beam deviation and the cosine error are calculated by arithmetic operation and displayed on the display unit 8.

With such a configuration, the operation of adjusting the optical axis and the operation of confirming / quantifying the cosine error will be described with reference to FIG. (Optical axis adjustment: However, rough adjustment has been completed) The display unit 8 is set to the adjustment mode. The movable CC4 is closest to the PBS2. The 4-division photodiode 10 is reset, and the 4-division photodiode 10 is moved so that the output of the differential amplifier 11 becomes zero. The movable CC4 is moved to the farthest point from the PBS2. The display unit 8 displays the output of the differential amplifier 11 as the optical axis shift amount on an arbitrary scale. If the amount of deviation at this time is not 0, after adjusting the laser optical axis, return to the section and repeat the adjustment. If the shift amount is 0, the optical axis adjustment is completed. (Confirmation / quantification of cosine error) The display unit 8 is set to the cosine error mode. The movable CC 4 is fixed at an arbitrary position, and the position of the laser light on the 4-division photodiode 10 is detected. At this time, the detected coordinate is set to P ₁ . The movable CC 4 is moved by a distance L (arbitrary), and the position of the laser light on the 4-division photodiode 10 is detected. At this time, the detected coordinate is P ₂ . The beam deviation angle Δθ is calculated by the calculation unit 7. Δθ = sin ⁻¹ (| P ₁ −P ₂ | / L) The computing unit 7 calculates the cosine error ΔL. ΔL = (1-1 / cosΔθ) L Displayed on the display unit 8.

The four-division photodiode used as the light receiving element for optical axis adjustment in the above embodiment may be replaced with another position sensor such as a photodiode array, and the same effect can be expected.

As described above, the laser interference displacement meter of the present invention has the function of quantitatively displaying the deviation of the optical axis, which can reduce the error at the time of adjusting the optical axis and confirm the cosine error generated at the time of measurement.・ Quantitative display is possible.

[0010]

[Effect of the device]

 As described above in detail with reference to the embodiments, according to the present invention, by adding the light receiving element for optical axis adjustment to the light receiving element, it is possible to display the degree of the optical axis deviation numerically. It is possible to realize a laser interference displacement meter that can perform accurate optical axis alignment, check and quantify cosine errors during measurement.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a laser interference displacement meter of the present invention.

FIG. 2 is a diagram showing optical axis adjustment of a conventional laser interference displacement meter.

FIG. 3 is a diagram for explaining a cosine error.

[Explanation of symbols]

 1 Laser Light Source 2 Polarization Beam Splitter 3 Fixed Corner Cube 4 Movable Corner Cube 5 Partial Reflecting Mirror 6 Photoreceptor 7 Computing Unit 8 Display 9 Polarizing Plate 10 4-Division Photodiode (Optical Axis Adjustment Photoreceptor) 11 Differential Amplifier (Optical) Arithmetic circuit for axis adjustment)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shunji Hayashi Yokogawa Electric Co., Ltd. 2-9-32 Nakamachi, Musashino-shi, Tokyo

Claims (1)

[Scope of utility model registration request] 1. A laser light source, an interferometer section using Michelson's interference optical system on which the output of this laser light source is incident, a light receiving section for receiving the interference output obtained from this interferometer section, and this light receiving section. In a laser interference displacement meter including a calculation unit and a display unit for receiving and processing the photoelectric conversion output from the unit, a light receiving element for optical axis adjustment is provided in the light receiving unit, and an optical axis adjustment is provided in the calculation unit. A laser interference displacement meter characterized by having an arithmetic circuit for use therein.