JPH0736263Y2 - Pyroelectric detector and power monitor device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a pyroelectric detector and a power monitor device that applies the pyroelectric detector to detect the power of laser light and perform feedback control.

(B) Conventional technology In a laser generator, the power of the laser light may fluctuate with time. Therefore, conventionally, a power monitor device was provided to detect the power of the laser light and feed back this detection output to a computer. Then, the power of the laser light is kept constant, or the abnormality of the laser generator is detected to improve the reliability of the laser generator.

Such power monitoring device B is conventionally, as shown in FIG. 3, the emission light path L ₀ of the laser beam from the laser generator 1 ₀
A beam splitter 2 ₀ disposed above the beam splitter 2 filter 4 ₀ on the reflection optical path L ₁ of _0, sequentially provided lens 6 ₀ and pyroelectric detector 8 ₀ for condensing further pyroelectric detector configuration connected an amplifier 10 ₀ for amplifying the detection output 8 ₀ is adopted.

Pyroelectric detector 8 ₀ prior used in the device B, as shown in FIG. 4, a frame 12 ₀ metallic which holes 11 ₀ is formed in the upper and the frame 12 ₀ Bottom cap 14
₀ is attached, the wiring board 16 on the bottom cap 14 _{0 0}
Is provided, the semiconductor chip 18 ₀ is stationary arranged made of pyroelectric material on the wiring board 16 _0. Further, each electrode of the semiconductor chip 18 ₀ are respectively connected to the pair of external lead terminals 22 ₀ via a lead 20 _0. Then, above the semiconductor chip 18 _0, the light receiving window plate 24 ₀ is provided. The light receiving window plate 24 ₀ is fixed to the frame ₁₂₀ .

Pyroelectric detector 8 ₀ of the above configuration, other less wavelength dependence as compared with the light detector such as a photodiode, although there is an advantage to be able to be applied to a laser light in a wide wavelength range, current commercial products is compact in overall, relatively small light receiving area of the semiconductor chip 18 ₀ consisting of pyroelectric material is compared to the beam diameter of the laser beam reflected by the beam splitter 2 _0.
Laser light generally has a radial intensity distribution, and
Since the intensity distribution is also slightly change over time, its just that the light received by the pyroelectric detector 8 ₀ part, the detection output is constantly varies, it is difficult to perform accurate feedback control. Therefore, conventionally, have focused laser beam in the following receiving the width of the semiconductor chip 18 ₀ lens 6 _0. In this case, lens 6
Since use of ₀ when the detection output of the pyroelectric detector 8 _0. energy density of the laser beam becomes higher may be saturated, reducing the laser beam uniformly place the filter 4 ₀ in front of the pre-lens 6 ₀ I try to shine.

(C) Problems invention is to solve Meanwhile, in the power monitoring device B of the conventional configuration shown in FIG. 3, the relationship in which a lens 6 _0, the laser beam is focused on the position of the pyroelectric detector 8 ₀ An adjustment mechanism (not shown) such as optical axis alignment is indispensable so that the whole apparatus becomes complicated.
Moreover, it takes time and effort to adjust the optical system.

To improve this, the semiconductor chip 18 ₀ pyroelectric detector 8 ₀
However, if the light receiving area is simply increased, the following problem occurs. That is, when laser oscillation is performed, discharge excitation or the like is performed, so that electromagnetic noise or the like is generated. Therefore, when receiving the laser light, a pyroelectric detector 8 ₀ The electromagnetic noise at the same time
Will be detected in. Since the noise component is also amplified by the amplifier 10 _0, it can damage the elements of the subsequent signal processing circuit.

The present invention has been made in view of the above circumstances, and provides a pyroelectric detector having excellent noise resistance, and simplifies the configuration of the light receiving unit of the power monitor device to reduce the size of the entire device. The purpose is to make it easy to maintain.

(D) Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a semiconductor chip made of a pyroelectric material in a conductive frame, and a light-receiving window plate above the semiconductor chip. In the pyroelectric detector provided with, the upper part of the light receiving window plate is covered with a conductive mesh, and the mesh is electrically connected to the frame.

In addition, in the power monitor device that includes a beam splitter that reflects a part of the laser light from the laser generator and outputs a detection signal according to the amount of received light of the laser light reflected by the beam splitter, The electron detector is arranged on the reflection optical path of the beam splitter, and the light receiving width of the semiconductor chip of the pyroelectric detector is set to be larger than the beam cross-sectional shape of the laser light reflected by the beam splitter.

(E) Action In the pyroelectric detector having the above configuration, since electromagnetic noise is shielded by the mesh, only laser light can be selectively detected.

Further, in the power monitor device using the pyroelectric detector,
Since all the laser light reflected by the beam splitter is applied to the semiconductor chip of the pyroelectric detector, a lens for condensing the laser light and a mechanism for adjusting its optical axis are unnecessary. Moreover, since the pyroelectric detector has excellent noise resistance, it is possible to prevent damage to the elements of the signal processing circuit in the subsequent stage.

(F) Embodiment FIG. 1 is a block diagram of a power monitor device according to an embodiment of the present invention. In the figure, reference numeral 1 is a laser generator,
A is a power monitor device. This power monitor device A
Is a beam splitter 2 as a semi-permeable film element on the laser light emitting optical path L ₀ of the laser generator 1 with respect to the optical path L ₀ .
This beam splitter 2 is placed at an angle of
The pyroelectric detector 8 is provided on the reflection optical path L _{1 according} to, and the amplifier 10 is connected to the pyroelectric detector 8.

As shown in FIG. 2, the pyroelectric detector 8 is provided with a metallic frame 12 having a U-shaped cross section, which is open at the top, and a semiconductor chip 18 made of a pyroelectric material is provided at the bottom of the frame 12. It is fixedly placed. This semiconductor chip 18 is, for example,
Electrodes formed by depositing platinum or the like are formed on the upper and lower opposite surfaces of the LiTaO ₃ crystal plate, and each electrode is connected to a pair of external lead terminals 22 via a lead wire 20.
A light-receiving window plate 24 formed by forming an antireflection film on the upper surface of the quartz plate is provided above the semiconductor chip 18, and the light-receiving window plate 24 is fixed to the frame 12 with an adhesive or the like. The upper portion of the light receiving window plate 24 is covered with a mesh 26 made of a conductive material such as Ni, and the mesh 26 is electrically connected to the frame 12 by soldering or the like. Further, in the pyroelectric detector 8, the light receiving width w of the semiconductor chip 18
Is set to be sufficiently larger than the beam diameter of the laser light reflected by the beam splitter 2.

In the above configuration, the laser light from the laser generator 1 is transmitted to the outside through the beam splitter 2, and a part of the laser light is reflected in the orthogonal direction. The reflected laser light enters the pyroelectric detector 8. In this case, the electromagnetic noise emitted from the laser generator 1 is the pyroelectric detector 8
Only the laser light passes through the mesh 26 and is selectively irradiated onto the semiconductor chip 18 because it is shielded by the mesh 26 provided in the. In addition, the mesh 26 also has a dimming function. Further, the light receiving width w of the semiconductor chip 18 of the pyroelectric detector 8
Is larger than the beam diameter of the laser light, so that the laser light reflected by the beam splitter 2 is entirely irradiated onto the semiconductor chip 18. Therefore, a lens for condensing the laser light and an adjusting mechanism for adjusting the optical axis thereof are not required. Moreover, since the pyroelectric detector 8 has excellent noise resistance, damage to the elements of the signal processing circuit in the subsequent stage connected to the amplifier 10 can be prevented.

(G) Effect According to the present invention, a pyroelectric detector excellent in noise resistance can be obtained and the structure of the light receiving portion of the power monitor device is simplified, so that the entire device can be downsized. Moreover, excellent effects such as easy maintenance can be achieved.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a configuration diagram of a power monitor device, and FIG. 2 is a vertical sectional view of a pyroelectric detector applied to the device. 3 and 4 show a conventional example, FIG. 3 is a configuration diagram of a power monitor device, and FIG. 4 is a vertical sectional view of a pyroelectric detector applied to the device. A ... Power monitor device, 1 ... Laser generator, 2 ...
... Beam splitter, 8 ... Pyroelectric detector, 18 ... Semiconductor chip, 24 ... Transparent window plate, 26 ... Mesh.

Claims (2)

[Scope of utility model registration request] 1. A pyroelectric detector in which a semiconductor chip made of a pyroelectric material is arranged in a conductive frame, and a light receiving window plate is provided above the semiconductor chip. A pyroelectric detector characterized by being covered with a conductive mesh and electrically connecting the mesh to the frame. 2. A power monitor device comprising a beam splitter for reflecting a part of laser light from a laser generator and outputting a detection signal according to the amount of received laser light reflected by the beam splitter. The pyroelectric detector according to Item 1 is arranged on the reflection optical path of the beam splitter, and the light receiving width of the semiconductor chip of the pyroelectric detector is larger than the beam cross-sectional shape of the laser light reflected by the beam splitter. A power monitor device characterized by being set.