JPH04166790A - Scanning optical system - Google Patents

Abstract

PURPOSE:To receive a reflection light flux from a reflecting object precisely and efficiently by arranging a light casting system and a light receiving system of a scanning optical system on an axis and emitting parallel light flux through a penetration hole toward the reflecting object. CONSTITUTION:An infrared laser beam is reflected in a reflection prism 29 and is introduced in a condenser lens 30. A penetration hole 35 is formed in the condenser lens 30 with the same axis as the optical axis O of the condenser lens 30. The reflection light flux from a corner cube 2 returns to the condenser lens 30 and is reflected by this condenser lens 30, passes through a noise light elimination filter 33 and is focused on a light receiving element 34. The noise light elimination filter 33 lets the light with the same wave length as the infrared laser beam wave length pass. In this case, since the optical axis of a casting light system 10A and a receiving light system 10B are the same, the infrared laser beam reflected by the corner cube 2 is received efficiently and precisely. Also, the incidence of light with other wave length that the infrared laser beam wave length into the light receiving element 34 is prevented.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is an automatic tracking type light wave measurement device that scans a reflecting object in the vertical and horizontal directions and automatically tracks the main body of the light wave ranging device to the reflecting object. The present invention relates to a scanning optical system suitable for use in a distance measuring device.

(Prior Art) Conventionally, scanning optical systems have been known to have a configuration in which a scanning light beam is emitted from a light projection system to scan a reflective object, and the light beam reflected by the reflection object is received by a light receiving system. It is being The light projecting system and light receiving system of this conventional scanning optical system are constructed separately.

(Problem to be Solved by the Invention) However, an automatic tracking type light wave distance measuring device, etc. that scans a corner cube as a reflecting object in the vertical and horizontal directions and automatically tracks the distance measuring device main body to the reflecting object, etc. When equipped with a scanning optical system, if the light emitting system and light receiving system of the scanning optical system are configured separately, the reflected light beam reflected by the object to be reflected will not necessarily return to the light receiving system. However, there is a possibility that the reflected light beam reflected by the object to be reflected may not be efficiently received.

The present invention has been made in view of the above circumstances, and its purpose is to provide a scanning optical system that can reliably and efficiently receive the reflected light beam from the reflecting object. be.

(Means for Solving the Problems) In order to solve the above-mentioned problems, a scanning optical system according to the present invention includes a light projection system that emits a parallel light beam toward a reflection object to scan the reflection object; a light-receiving system that receives the reflected light flux from the reflective object, the light-receiving system is provided with a condensing lens, the condensing lens has a through hole coaxial with its tip axis, and the light-receiving system is provided with a reflecting member for making the optical axis of the light projection system coaxial with the optical axis of the condensing lens,
The parallel light beam is characterized in that it passes through the through hole and is emitted toward the object to be reflected.

(Function) According to the scanning optical system according to the present invention, the parallel light beam emitted from the light projecting system is made coaxial with the optical axis of the condensing lens of the light receiving system by the reflecting member. The light is guided to the object to be reflected through the through hole formed in the condenser lens, and the object to be reflected is scanned. The reflected light beam from the reflecting object is received by the light receiving system.

(Example) Hereinafter, an example in which a scanning optical system according to the present invention is applied to an automatic tracking optical distance measuring device will be described with reference to the drawings.

In FIG. 1, 1 is a surveying table, and 2 is a corner cube as a reflective object installed at the cloudy point.

The surveying platform 1 is installed, for example, on the deck of a ship.

A light wave distance measuring device is installed on this survey table 1.

This light wave distance measuring device 3 has a fixed base 4 and a horizontal rotating section 5. The horizontal rotation part 5 is rotated in the direction of arrow A with respect to the fixed base 4, as shown in FIG. 2, and has a support part 6. The support part 6 is provided with a vertical rotation axis 7, and the vertical rotation axis 7
A distance measuring device main body 8 is provided. Distance measuring device body 8
is rotated in the horizontal direction by the rotation of the horizontal rotation unit 5, and rotated in the vertical direction as shown by arrow B in FIG. 1 by the rotation of the vertical rotation shaft 7.

The distance measuring device body 8 includes a distance measuring optical system 9 and a scanning optical system 1.
0 is provided. The distance measuring optical system 9 has a light projecting system 11 and a light receiving system 12, as schematically shown in FIG. The light projection system 11 has a laser light source 13. The light receiving system 12 has a light receiving element 14 .

The laser light source 13 emits infrared laser light waves.

The infrared laser light wave is reflected by the dichroic mirror 16 of the beam splitter 15 toward the objective lens 17, and is emitted as a plane wave from the distance measuring device main body 8 via the cover glass 18.

The infrared laser light wave is reflected by the corner cube 2, returns to the objective lens 17 via the cover glass 18, is reflected by the dichroic mirror 19 of the beam splitter 15, and is focused on the light receiving element 14. The light-receiving probe 1
The received light output of 4 is input to a known measuring circuit (not shown), and the distance to the corner cube 2 is measured. This distance measuring optical system 9 has an imaging lens 20 and a reticle plate 21, and visible light passes through an objective lens 17 and a dichroic mirror 16, 19, reaches the imaging lens 20, and is converged on the reticle plate 21. The measurement person can visually recognize the measurement point location including the corner cube 2 through the eyepiece lens 22.

As shown in FIG. 4, the scanning optical system 10 includes a laser diode 23, a collimator lens 24, and a horizontal deflection element 25.
, vertical deflection element 26, reflection prism 27.28.2
9. Condensing lens 30. Cover glass 31, reflective prism 32, noise light removal filter 33, light receiving element 34
has. laser diode 23, collimator lens 24, horizontal deflection element 25, vertical deflection element 26,
The reflecting prisms 27, 28, and 29 roughly constitute the projection system 10A. In addition, a condensing lens 30 and a reflecting prism 32
, the noise light removal filter 33, and the light receiving element 34 generally constitute the light receiving system 10E. The horizontal deflection element 25 and the vertical deflection element 26 are composed of, for example, an acousto-optic element.

The laser diode 23 emits an infrared laser beam having a wavelength different from that of the distance measuring light wave of the distance measuring optical system 9.

The infrared laser beam is made into a parallel beam by a collimator lens 24 and guided to a horizontal deflection element 25 . This horizontal deflection element 25 has a function of deflecting the infrared laser beam in the horizontal direction H, as shown in FIG. The vertical deflection element 26 has a function of deflecting the infrared laser beam in the vertical direction (2).

The infrared laser beam is deflected in the horizontal direction H1 and the vertical direction V by the horizontal deflection element 25 and the vertical deflection element 26, guided to the reflection prism 27, reflected by the reflection prism 27, and passed through the reflection prism 28. It is guided to a reflecting prism 29.

The reflective prism 29 functions as a reflective member to make the optical axis of the light projection system 10A coaxial with the optical axis of the condensing lens 30,
The infrared laser beam is reflected by the reflecting prism 29 and guided to the condenser lens 30.

The condensing lens 30 has a through hole 35 formed coaxially with the optical axis ○ of the condensing lens 3o.The infrared laser beam P reflected by the 0 reflection prism 29 passes through the through hole 35 to the distance measuring device. The light is emitted to the outside of the main body 8, and the corner cube 2 is scanned.

The scanning of the corner cube 2 is performed by first scanning in the horizontal direction H as shown in FIG. 6, and then scanning in the horizontal direction H while deflecting the corner cube 2 in the vertical direction. In FIG. 6, reference numeral 36 indicates a beam spot of the infrared laser beam P within a plane including the corner cube 2. In FIG. This beam spot 36 has a Gaussian intensity distribution I (36) as shown in FIG. If the beam spot 36 is located at The vertical deflection element 26 is controlled in this manner.

Now, as shown in FIG. 7, if the diameter of the beam spot 36 is 2ω and the interval between scanning lines in the vertical direction V (vertical scanning step) is S, then the intensity I due to the beam spot 36 (38L) The intensity I (37L) of the overlapping part 38 of the beam spot 36 and the beam spot 37 is I (36)=I@EXP (-2ρ2/ω2), respectively.
I (37) -It+EXP (-2(ρ-8)2/
ω2) I (38) = IsEXP (-82/2ω2)
It is expressed as

Note that Ill is the peak intensity of the beam spot.

Therefore, by setting the intensity I (38) to 1, for example, using a coefficient K having the meaning described later, intensity I (38) 5 intensity (1/K)
When designing the scanning step S to satisfy Is, IsE X P (S 2/2ω2)≧(1/K)
By natural logarithm transformation of the inequality of XIe, ln[: I s EXP(-82/2 ω2)]≧
Calculate ln[(1/K)XI@].

Transforming this formula, 1nIs+(S2/ 2 (132)≧in (1/
K) +lr+4 s Therefore, S2/2ω2≦1nK Therefore, (S−ωX (21nK)−”2)(S+ ωX (2
1nK)-172)≦0From this equation, S≦ωX (21
nK) -172 is obtained, and the scanning step S can be determined. Note that the coefficient is a constant for determining the peak intensity of the overlapping portion 38 with respect to the peak intensity (2) 0, and it is sufficient if K≦3. As a result, the intensity (38) of the overlapping portion 38 between the beam spot 36 and the beam spot 37 can be ensured to be 1/3 or more of the peak intensity IO.

The reflected light flux from the corner cube 2 is passed through the condenser lens 30
, is converged by the condenser lens 30, reflected by the reflection prism 32, and passed through the noise light removal filter 3.
3 and is imaged on the light receiving element 34. The noise light removal filter 33 has a function of transmitting light having the same wavelength as the infrared laser light.

According to this scanning optical system 10, the light projecting system 10A and the light receiving system 1
Since the optical axis with 0B is coaxial, there is an advantage that the infrared laser beam reflected by the corner cube 2 can be efficiently and reliably received. Further, since the noise light removal filter 33 is provided, it is possible to prevent light having a wavelength other than the wavelength of the infrared laser light from entering the light receiving element 34.

(Effects of the Invention) As explained above, in the scanning optical system according to the present invention, since the light projecting system and the light receiving system of the scanning optical system are formed coaxially, the reflected light beam from the object to be reflected can be reliably and This has the effect of efficiently receiving light.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a schematic configuration of an automatic tracking type light wave distance measuring device to which a scanning optical system according to the present invention is applied, and FIG. 2 is a side view showing a schematic configuration of an automatic tracking type light wave ranging device to which a scanning optical system according to the present invention is applied. FIG. 3 is an optical diagram showing the schematic configuration of the distance measuring optical system shown in FIG. 1, FIG. 4 is a detailed configuration diagram of the scanning optical system shown in FIG. 1, and FIG. Figure 4 is an explanatory diagram for schematically explaining the deflection by the scanning optical system, Figure 6 is a schematic diagram showing an example of scanning by the scanning optical system according to the present invention, and Figure 7 is a diagram showing the vertical direction of the beam spot. FIG. 8 is a schematic diagram for explaining overlapping. FIG. 8 is an explanatory diagram when scanning is performed by overlapping beam spots in the vertical direction. 2... Corner cube (reflecting object) 10... Scanning optical system, IOA... Light projecting system 10B... Light receiving system, 2
9...Reflection prism (reflection member) 30...Condenser lens, 35...Through hole 0...Optical axis, P...Infrared laser beam (parallel beam) mirror

Claims (1)

[Claims] The light receiving system includes a light projecting system that emits a parallel light beam toward a reflective object to scan the reflective object, and a light receiving system that receives the reflected light beam from the reflective object, and the light receiving system includes a condenser lens. a through hole coaxial with the optical axis of the condensing lens is formed, and a reflecting member is provided in the light receiving system for making the optical axis of the light projecting system coaxial with the optical axis of the condensing lens. A scanning optical system, wherein the parallel light beam is emitted toward the reflection target through the through hole.