JPH0474934A - Measuring apparatus of characteristics of beam - Google Patents

Abstract

PURPOSE:To detect characteristics precisely irrespective of a difference in transmittivity or reflectivity between polarized components by a method wherein both of beam splitters or reflecting members having the same angle of incidence and planes of incidence intersecting perpendicularly each other and being equal in the characteristic of polarization are made to conduct reflection or transmission. CONSTITUTION:Quartz flat plates 2 and 3 are so disposed as to have the same angle of incidence and planes of incidence intersecting perpendicularly each other. Thereby a difference between two components P and S of a reflected light generated by the quartz flat plate 2 is compensated by the surface reflection of the quartz flat plate 3, so as to keep the property of polarization of a laser beam, and the light is made to enter a linear sensor 4. The width of the flux of an incident light is detected by the linear sensor 4. The quartz flat plate 2 and the quartz flat plate 8 are so disposed as to have the same angle of incidence and planes of incidence intersecting perpendicularly each other. The difference between the two components P and S of a light transmitted through the quartz flat plate 2 is compensated by transmitting the light through the quartz flat plate 8, and thereby the property of polarization of the laser beam is kept. A light of surface reflection by the quartz flat plate 8 enters an energy detector 9 and thereby the intensity of the incident light is detected. By this method, characteristics such as the shape of the beam can be measured without being affected by polarization.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a device for measuring beam characteristics.

[Conventional technology] A conventional configuration is shown in FIG.

1 is a laser oscillator, 2, 5, and 8 are quartz flat plates or half mirrors, 4 and 7 are linear sensors, 9 is an energy detector, 12 is a power detector, 13 is a polarization degree indicator, 14
1 is a power indicator, and 15 is a beam shape indicator.

Conventionally, when measuring laser beam characteristics (beam shape, polarization component, power, etc.), a quartz flat plate (or half mirror) was placed on the optical axis of the laser beam, as shown in Figure 2.
2, 5, and 8 are provided in this order to split the laser beam, and guide it to the linear sensors (or area sensors) 4, 7, the energy detector 9, and the power detector 12, respectively, for measurement.

[Problems to be Solved by the Invention] However, when measuring a laser beam with polarized components, in the conventional example described above, the laser beam after surface reflection on the quartz flat plates 2, 5, and 8 has both horizontal and vertical components. Due to the difference in reflectance, the laser beam does not preserve the polarization state immediately after being emitted from the laser oscillator when it enters the linear sensors 4 and 7. For this reason, the linear sensors 4 and 7 cannot accurately measure the beam shape.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a beam characteristic measuring device capable of accurately detecting characteristics regardless of differences in transmission or reflectance of polarized light components.

[Means and effects for solving the problem] In order to achieve the above object, according to the present invention, both beams are reflected or transmitted through a beam splitter or reflecting member having the same incident angle and having the same polarization characteristics and whose incident planes are orthogonal to each other. This makes it possible to measure in real time the characteristics of a laser beam, etc., which has polarization characteristics and whose polarization characteristics vary, such as the beam shape.

The plane of incidence here refers to a plane that includes (the center line of) the incident beam and the normal to the plane onto which the beam is incident.

Embodiment FIG. 1 is a drawing showing the configuration of an embodiment of the present invention. 1
is a laser oscillator; 2, 3, 5, 6, 8, and 10 are beam splitters such as quartz flat plates or half mirrors; 4 and 7 are linear sensors; 9 and 11 are energy detectors; 13 is a quartz flat plate; Energy power and polarization degree indicators; 15 indicates a beam shape indicator; Quartz flat plate 2
and 3 are arranged so that the incident angles are the same and the incident planes are orthogonal. As a result, P and S of the reflected light generated on the quartz flat plate 2
The difference between the two components is compensated for by surface reflection of the quartz flat plate 3, and the laser beam enters the linear sensor 4 while preserving its polarization. A linear sensor 4 detects the width of the incident light beam.

The quartz plane plates 2 and 8 are arranged so that the incident angles are the same and the incident planes are perpendicular to each other. p of the transmitted light generated by the quartz flat plate 2
. The light reflected from the surface of the quartz flat plate 8 enters an energy detector 9, which detects the intensity of the incident light. The above quartz flat plates 2, 3,
8. A detection system having the same configuration as the detection system consisting of the linear sensor 4 and the energy detector 9 (i.e., quartz flat plates 5, 6,
10, a detection system consisting of a linear sensor 7 and an energy detector 11) is placed at a position rotated 90 degrees around the optical axis (in Figure 1, the direction of 7 is reversed, but the effect is the same)
The beam shape rotated by 90 degrees, that is, the width in the direction perpendicular to the direction in which the width is detected by the linear sensor 4, and the quartz flat plate 10.
Detects the intensity of surface reflected light. The energy, power and polarization degree indicator 13 is connected to the energy detectors 9 and 1.
1 output enters, the energy of the laser beam, the degree of polarization,
Power can be calculated. A beam shape display 15 displays the outputs of the linear sensors 4 and 7.

To find the degree of polarization P from the output of the energy detector 9.11, calculate the following equation. Let the intensity of the laser beam be , and the intensities in the horizontal and vertical directions be 8, .
Let the horizontal and vertical polarization intensities of the incident light of energy detector 9.11 be IH', ■'7. IH', I
v′ The transmittance of both P and S components in each half mirror is “rp
, T, , where the reflectance is Rs, the incident light intensity I' of the energy detector 9 is T' - IH
'+L'=IN(TSX RP)"IV(TP
X R5)...■ The intensity I'' of the incident light on the energy detector 11 is I' = I
H'+TV''-IN (TS X Tp X Tp
X R, )+ Iv(Tp X 7.x Tsx Rp
)...■ By solving the above simultaneous equations ① and ②, IH and EW can be found from 1' and I''. By substituting these into the formula for calculating the degree of polarization, the degree of polarization can be calculated.

To find the energy or power I from the output of the energy detector 9.11, use the process found from the simultaneous equations above.
It is obtained by substituting and Iv into the following equation.

I=I H+1, FIG. 3 shows another embodiment. By arranging an area sensor 16.17 in place of the energy detector 9.11 in FIG. 1, the polarization distribution within the laser beam can be calculated.

Furthermore, the degree of polarization can be calculated by integrating the outputs of each pixel of the area sensors 16 and 17. The shape of the beam may be detected by placing an area sensor at the position of either linear sensor instead of the linear sensor 4.7. In this case, one sensor can detect the shape of the entire beam. Further, when the area sensor is placed at the position of the linear sensor 4, the quartz flat plate 2.3 may be replaced with a simple mirror if there is no need to detect other characteristics. In this case as well, the two mirrors are arranged so as to compensate for the difference between the p and s components of the reflected light, as described above.

The beam characteristics detected at the position of the linear sensor 4.7 may be other than the beam shape, such as illuminance distribution.

[Effects of the Invention] As explained above, in a measuring device for measuring beam characteristics, reflective members or beam splitters with equal polarization characteristics are arranged so that the incident angles are equal and the incident surfaces are orthogonal, and both reflect or transmit. By arranging the beam so that it can be detected by a detector, characteristics such as beam shape can be measured without being affected by polarization.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a laser beam measuring device according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional laser beam measuring device, and FIG. 3 is a block diagram of another embodiment of the present invention. 1: Laser oscillator, 2.3.5.6.8.10: Quartz flat plate or half mirror 4, 7: Linear sensor, 9.11: Energy detector, 13: Energy, power and polarization degree indicator, beam Shape display, 16.17・Area sensor.

Claims (5)

[Claims] (1) A device for detecting beam characteristics by receiving a beam to be inspected by a detector, which includes a first reflecting member in the optical path, having the same polarization reflecting characteristics as the first reflecting member, and having the same polarization reflecting characteristics as the first reflecting member; and a second reflecting member oriented such that the incident angle of the beam is the same and the incident plane of the beam is orthogonal to each other, and the beam to be inspected is directed to the first reflecting member and the second reflecting member. A beam characteristic measuring device characterized in that the beam characteristics are arranged so as to be incident on the detector after being reflected together. (2) In a device that detects beam characteristics by receiving a beam to be inspected by first and second detectors, the first beam splitter has the same polarization reflection characteristics as the first beam splitter; a first reflecting member disposed in the optical path of the reflected beam from the first beam splitter and oriented so that the incident angle of the beam is the same as that of the first beam splitter and the incident plane of the beam is perpendicular; The optical path of the transmitted beam from the first beam splitter is such that the beam splitter has the same polarization transmission characteristics as the first beam splitter, and the incident angle of the beam is the same as that of the first beam splitter, and the beam incidence plane is orthogonal to the first beam splitter. a second beam splitter disposed within the beam splitter, a second reflective member disposed in the optical path of the transmitted beam from the second beam splitter, and a second reflective member having the same polarization reflection characteristics as the second reflective member; and a second reflecting member disposed in the optical path of the reflected beam from the second reflecting member so that the incident angle of the beam is the same as that of the second reflecting member and the beam incidence plane is perpendicular to the second reflecting member. A part of the beam to be inspected is reflected by the first beam splitter and the first reflecting member and then enters the first detector, and another part of the beam to be inspected is reflected by the first beam splitter and the first reflecting member. and a second beam splitter and are reflected by the second and third reflecting members, and then incident on the second detector. (3) Further, the second beam splitter or the second reflecting member receives the beam separated from the beam to be inspected detected by the first or second detector, and measures other characteristics of the beam. 3. The beam characteristic measuring device according to claim 2, further comprising a detector for detecting the beam characteristics. (4) A device for detecting beam characteristics by receiving a beam to be inspected by a detector, which includes a first beam splitter in the optical path, and has the same polarized light transmission or reflection characteristics as the first beam splitter, and The first beam splitter and a second beam splitter are oriented such that the incident angle of the beams is the same and the plane of incidence of the beams is orthogonal to each other, and the beam to be inspected passes through both the first and second beam splitters. Alternatively, a beam characteristic measuring device is arranged such that the beam is reflected and then enters the detector. (5) The beam characteristic measuring device according to claim 1, 2, or 4, wherein the beam characteristic is a beam shape.