JP2011180044A - Device for measurement of beam parallelism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam parallelism measuring device, capable of measuring parallelism of a beam emitted from an incoherent light source at a lower measuring frequency. <P>SOLUTION: The beam parallelism measuring device 1 has a lens part 20 for imaging each of light beam components included in the beam 9 at a position separated from an optical axis K in only a distance L corresponding to an incident angle θ to the optical axis K, and a two-dimensional detector 22 for detecting an imaging position P of the beam 9. Also, the beam parallelism measuring device has an analysis device 12 for converting the distance L from the optical axis K to the imaging position P into the incident angle θ and for output of incident angle distribution of the light beam components included in the beam 9. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light flux parallelism measuring apparatus that measures the parallelism of a light flux.

  2. Description of the Related Art Conventionally, a solar simulator device (pseudo-sunlight irradiation device) that emits light having a spectrum equivalent to that of sunlight is known and widely used for evaluating the characteristics of solar cells. When evaluating the characteristics of a solar cell, it is necessary to irradiate light evenly over the entire range of the panel surface of the solar cell. For this reason, the solar simulator device for evaluating solar cell characteristics is configured to irradiate the entire area of the solar cell panel surface by spatially dispersing and collimating the luminous flux of the irradiation light.

By the way, an incoherent light source such as a xenon lamp is usually used as a light source of the solar simulator device instead of a coherent light source such as a laser light source. When the light source is a coherent light source, the parallelism of the light beam can be measured using a well-known interferometer. However, when the parallelism is wide like an incoherent light source, the light beam can be measured with a well-known interferometer. It is difficult to measure the parallelism.
In recent years, therefore, a technique has been proposed for measuring the spread angle of a relatively large luminous flux by measuring the cross-sectional width of the luminous flux at a plurality of points along the optical axis after passing pseudo-sunlight through a bandpass filter and an aperture. ing.
(For example, refer to Patent Document 1).

JP 2008-89526 A

However, the conventional technique has a problem that the measurement takes time because measurement is required at a plurality of locations along the optical axis of the light beam.
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a light beam parallelism measuring device that can measure the parallelism of a light beam emitted from an incoherent light source with a small number of measurements.

  In order to achieve the above object, the present invention provides an imaging optical system that forms an image of each light component contained in a light beam at a position separated from the optical axis by a distance corresponding to an incident angle with respect to the optical axis, and the light beam. And a detector for detecting an imaging position of the light beam, and converting the distance from the optical axis to the imaging position into the incident angle and outputting an incident angle distribution of a light beam component included in the light beam A light beam parallelism measuring device is provided.

  Further, the present invention provides the light beam parallelism measuring apparatus, wherein the detector detects the light intensity at the imaging position, and the analysis means outputs the incident angle distribution by associating the light intensity for each incident angle. It is characterized by doing.

  Further, the present invention provides the beam parallelism measuring apparatus, wherein the imaging optical system forms an image of each of the light components on a predetermined plane away from the optical axis by a distance proportional to an incident angle. It is characterized by.

  Further, the present invention is characterized in that, in the above-mentioned apparatus for measuring the degree of parallelism of light, the imaging optical system makes a principal ray traveling on the predetermined plane parallel to the optical axis.

  According to the present invention, since the distribution of the incident angle with respect to each optical axis of the light beam component contained in the light beam is output, the parallelism of the light beam with respect to the optical axis can be obtained together with the distribution in one measurement. it can.

It is a figure which shows typically the structure of the light beam parallelism measuring apparatus which concerns on embodiment of this invention. It is explanatory drawing of the measurement principle of light beam parallelism. It is a figure which shows the measurement result output screen output to a display apparatus. It is explanatory drawing of the light beam parallelism measurement in the irradiation surface of pseudo sunlight, (A) shows the relationship between an irradiation surface and a measurement location, (B) is the incident angle distribution chart obtained by the measurement in each measurement location. An example is shown. It is explanatory drawing of the application example of the light beam parallelism measuring apparatus which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically illustrating a configuration of a light beam parallelism measuring apparatus 1 according to the present embodiment.
The light beam parallelism measuring device 1 of the present embodiment measures the parallelism of the light beam 9 irradiated from the solar simulator device 3. The solar simulator device 3 includes an incoherent light source 4 such as a xenon lamp that emits light having a wavelength band as wide as sunlight, a parallel light optical system 6 that collimates the light emitted from the light source 4, For example, a homogenizer 8 such as a fly-eye lens is provided to make the spatial intensity distribution of the emitted light uniform, and a light beam 9 having a relatively large cross-sectional area is emitted as pseudo-sunlight. In the figure, a homogenizer 8 is laid out after the collimating optical system 6, but the homogenizer 8 is usually arranged in an array of the collimating optical system 6.

The beam parallelism measuring device 1 includes a sensing head 10, an analysis device 12, and a display device 14. The sensing head 10 is arranged at the set position of the irradiation target of the pseudo-sunlight (wavelength 300 nm to 2000 nm) of the solar simulator device 3, and detects light, and includes a filter unit 16, an aperture stop ring 18, a lens unit 20, and A two-dimensional detector 22 is provided.
The filter unit 16 is configured by overlapping an ND filter and a color tone correction filter. The ND filter is a neutral density filter and prevents saturation of the detection intensity in the two-dimensional detector 22. The color tone correction filter corrects the spectral distribution of the light beam 9 according to the wavelength sensitivity characteristic of the two-dimensional detector 22 to prevent detection variations for each wavelength.
The aperture stop ring 18 adjusts the amount of light incident on the two-dimensional detector 22 and defines the range in the cross section of the light beam 9 incident on the two-dimensional detector 22. That is, the aperture resolution ring 18 defines the spatial resolution (minimum measurable area) of the beam parallelism measuring device 1. In the present embodiment, the viewing angle of the sensing head 10 is configured to be a circular viewing angle of ± 5 degrees around the optical axis K of the lens unit 20 described later.

The lens unit 20 is an imaging optical system that forms an image at a position corresponding to the incident angle θ of the incident light beam 24. More specifically, as shown in FIG. 2, the lens unit 20 has a relationship between the incident angle θ of the incident light beam 24 with respect to the optical axis K of the lens unit 20 and the distance L from the optical axis K of the imaging position P. Satisfies the relationship defined by the predetermined function f (θ), and the image forming position P does not depend on the incident position of the incident light beam 24 on the lens unit 20 at least within the range of the circular viewing angle. The optical design is made in consideration of the distortion characteristic of the lens unit 20 as determined only by θ. Thus, the incident angle θ is obtained from the imaging position P by calculation based on the inverse function of the predetermined function f (θ).
In the present embodiment, the lens unit 20 is optically designed so as to satisfy the relationship of function f (θ) = aθ (where a is a proportional constant), and as a result, the incident angle θ increases as the incident angle θ increases. The imaging position P is configured to have a distance L from the optical axis K that is directly proportional to the angle θ.
The lens unit 20 is configured as an isotropic optical system, and forms an image at an imaging position P separated from the optical axis K by L = f (θ) in a direction corresponding to the incident direction of the incident light beam 24. That is, based on the XY coordinate value of the imaging position P with respect to the origin O (K axis) on the detection surface Q, the traveling direction of the incident light beam 24 can be detected together with the incident angle θ.

  The lens unit 20 is configured as a so-called image-side telecentric optical system that makes the principal ray 25 on the imaging side parallel to the optical axis K. As a result, even if the focus of the lens unit 20 changes due to a temperature rise due to irradiation of the light beam to be measured, the center of gravity position of the imaging position P does not change only by increasing the area (image) of the imaging position P. . That is, by measuring the barycentric position (the point at which the light intensity is maximum) of the imaging position P as the imaging position P, the parallelism of the light beam 9 is measured while always maintaining a certain accuracy with respect to the temperature rise of the lens unit 20. it can.

  The two-dimensional detector 22 includes, for example, a CCD image sensor, and outputs the light intensity at each position (pixel) in the rectangular planar detection surface Q (FIG. 2) of the CCD image sensor to the analysis device 12. As shown in FIG. 1, the two-dimensional detector 22 includes a case body 28 having a flat surface 26 on the bottom surface, and the detection surface Q of the CCD image sensor is provided in parallel to the flat surface 26. Further, the lens unit 20 is provided so that the optical axis K is perpendicular to the detection surface Q. With these configurations, the case body 28 is irradiated with the irradiation surface (or the irradiation target) of the pseudo-sunlight irradiation target. The optical axis K of the lens unit 20 is positioned vertically with respect to the irradiation surface, and the parallelism of the light beam 9 with respect to the mounting surface is accurately measured.

  Of the sensing head 10, the filter unit 16, the aperture stop ring 18, and the lens unit 20 are configured as an optical unit 29 that is integrally provided in a cylindrical case body so as to have the same optical axis, and is formed of optical components. The end of the lens unit 20 is screwed into the case body 28 of the two-dimensional detector 22 and is detachably provided. The total flux (W, lm) can be easily measured by removing the two-dimensional detector 22 from the optical unit 29 and attaching a power meter instead. Further, for example, a power meter calibrated in accordance with NIST (National Institute of Standards and Technology) is attached to the sensing head 10 and measured by the beam parallelism measuring device 1, and the output value of the two-dimensional detector 22 and the power meter are measured. Thereafter, the total flux can be obtained only with the output value of the two-dimensional detector 22 and output as the light intensity on the measurement result output screen 40 (FIG. 3) described later. .

  The analysis device 12 is connected to the sensing head 10 via a signal cable, and generates an incident angle distribution chart C (see FIG. 3) of the light flux 9 based on an output signal output from the two-dimensional detector 22 of the sensing head 10. For example, the data is output to the display device 14 which is an example of an output device. The analysis device 12 is configured by causing a computer device having a general configuration to execute a program for generating the incident angle distribution chart C.

FIG. 3 is a diagram showing a measurement result output screen 40 of the display device 14.
As shown in this figure, the incident angle distribution chart C and the color scale bar 41 are displayed on the measurement result output screen 40.
The incident angle distribution chart C is obtained by mapping the incident angle distribution of each light beam component having a different incident angle θ included in the measured light beam 9. In the incident angle distribution chart C, the relative light intensity for each incident angle θ is displayed by a change in color tone, and the color tone and the light intensity are indicated by the color scale bar 41.

For details of the incident angle distribution chart C, as described with reference to FIG. 2, when the light beam 9 is incident on the lens unit 20 of the sensing head 10 at the incident angle θ, each light beam component included in the light beam 9 is On the detection surface Q, an image is formed at an imaging position P that is separated from the optical axis K in a direction corresponding to the incident direction by a distance L proportional to the incident angle θ. Based on the light intensity at the imaging position P, the light intensity is determined for each incident angle θ. Such calculation is performed by the analysis device 12.
In the incident angle distribution chart C, the origin is set at an incident angle θ = 0 (optical axis K) in order to show the distribution of the incident angle θ obtained in this way together with the traveling direction of the light ray component at the incident angle θ. It is displayed as dimensional orthogonal coordinates, and the distribution of the incident angle is displayed by color tone for each light intensity.
Thus, the incident angle distribution chart C includes not only the magnitude of the incident angle θ of the light component contained in the light beam 9 (that is, the parallelism with respect to the optical axis K) but also the traveling direction of the light component (deviation from the optical axis K). Direction) along with the intensity of the light component.

Note that the pixel arrangement direction of the detection surface Q of the sensing head 10 and the coordinate axis direction in the incident angle distribution chart C are fixed, and when the detection surface Q is turned upside down and placed on the irradiation surface, the incident direction is changed. Similarly, the angle distribution chart C is a chart that is inverted upside down. In other words, the traveling direction of the light component appearing in the incident angle distribution chart C differs depending on how the sensing head 10 is placed. Therefore, in order to always place the detection surface Q in the same direction with respect to the irradiation surface, the sensing head 10 is provided with a mark indicating the upward direction (for example, the Y axis positive direction), and when measuring a plurality of locations on the irradiation surface By placing the sensing head 10 on the irradiation surface so that this mark is always directed in the same direction, the traveling direction of the light component in the measurement result at each measurement point can be aligned and compared with each other.
In addition, although the shift direction of the imaging position P on the detection surface Q with respect to the traveling direction of the light component corresponds to the one-to-one relationship, the shifting direction of the imaging position P does not indicate the traveling direction of the light component. . That is, depending on the orientation of the lens unit 20 or the like, the traveling direction of the light beam component, the shift direction of the imaging position P on the detection surface Q, and the opposite direction with respect to the optical axis K, for example, may be indicated. May be corrected so that they are aligned in the same direction, and the incident angle distribution chart C may be generated.

Here, the incident angle distribution chart C shown in FIG. 3 shows a case where a fly-eye lens is used for the homogenizer 8 provided in the solar simulator device 3. For this reason, the light from the light source 4 is spatially discretized by passing through the fly-eye lens, and the deviation (that is, parallelism) of the discretized light components from the optical axis K is incident angle distribution chart C. Appear in
That is, although it is desirable that the irradiation light of the solar simulator device 3 is parallel light, normally, when the light beam passes through the homogenizer 8, spatial discretization is performed, so that all the light components contained in the light beam 9 are included. It does not become a parallel light beam, but includes a light ray component having an angle with respect to the parallel light. For this reason, in the solar simulator device 3, the parallelism of the irradiation light should be evaluated based on the amount and angle of the light beam of the light component having an angle other than that of the parallel light beam. Then, according to the light beam parallelism measuring apparatus 1 of the present embodiment, as shown in the incident angle distribution chart C of FIG. 3, the respective angles and relative intensities of the light ray components having different angles included in the light beam 9 are distributed as distribution diagrams. Since it is the structure shown, the parallelism of the irradiation light of the solar simulator apparatus 3 can be evaluated easily and correctly.
In the measurement result output screen 40 of the present embodiment, an allowable range that can be regarded as a substantially parallel light beam as the light beam 9 of the solar simulator device 3 is indicated by a line 42 in the incident angle distribution chart C. The degree of success can be evaluated at a glance.

  In addition, in the incident angle distribution chart C, since the incident angle distribution is indicated by two-dimensional coordinates on a linear scale, the magnitude of the incident angle θ of each light component can be intuitively grasped. At this time, as described above, the lens unit 20 forms an image of each of the light components contained in the light flux 9 at an image forming position P on the detection surface Q away from the optical axis K by a distance L proportional to the incident angle θ. Therefore, it is possible to reduce the amount of calculation performed by the analysis device 12 in order to represent the incident angle distribution on the two-dimensional coordinates of the linear scale.

FIG. 4 is an explanatory diagram of the measurement of the light beam parallelism in the irradiation surface of the pseudo sunlight, FIG. 4 (A) shows the relationship between the irradiation surface 50 and the measurement location, and FIG. 4 (B) is the measurement at each measurement location. It is a figure which shows an example of the incident angle distribution chart C obtained by these. In the figure, in order to prevent complication of the drawing, the illustration of the light intensity scale display is omitted.
When the simulated solar light irradiation surface 50 of the solar simulator device 3 is relatively wide, the light beam parallelism measurement is performed by discretely measuring a plurality of locations on the irradiation surface 50. As shown in FIG. 4 (A), the measurement location includes a point T1 intersecting with the optical axis center R of the emitted light of the solar simulator device 3, and four surrounding points T2 to T5 centering on the point T1. To be determined.

  Here, when the optical axis K of the sensing head 10 and the traveling direction of the principal ray 52 incident on the sensing head 10 at the measurement points T1 to T5 substantially coincide with each other, the incidence at the measurement point T1 in FIG. As shown in the angle distribution chart C, the center of the distribution of light ray components having different incident angles θ is located at the origin of the incident angle distribution chart C. On the other hand, when the traveling direction of the principal ray 52 incident on the sensing head 10 is deviated from the optical axis K, the optical axis in the traveling direction of the principal ray 52 is at each incident angle θ of the ray component of the principal ray 52. Since a deviation angle β from K is added, for example, as shown in each incident angle distribution chart C at measurement points T2 to T5 in FIG. 4B, the center S of the distribution of the light component is entirely the origin (optical axis). K) deviates in a direction corresponding to the traveling direction of the light component.

As described above, the deviation angle β from the optical axis K in the traveling direction of the principal ray 52 incident on the sensing head 10 is detected as a deviation from the origin of the entire distribution in the incident angle distribution chart C. By measuring parallelism at each of the measurement points T1 to T5, in each case, in addition to the distribution of the incident angle θ of the light beam component contained in the light beam 9, the deviation angle β in the traveling direction of the light beam 9 (principal light beam 52). Can be grasped.
Elements that cause the shift angle β in the principal ray 52 include variations in flatness of the irradiation surface 50 (mounting surface), and positions of the light source 4, the collimating optical system 6, and the homogenizer 8 provided in the solar simulator device 3. Misalignment etc. are mentioned. By adjusting these elements based on the deviation angle β obtained from the incident angle distribution chart C, pseudo-sunlight with high parallelism can be obtained over the entire irradiation surface 50.

  As described above, according to the present embodiment, since the distribution of the incident angle θ with respect to each optical axis K of the light component contained in the light beam 9 is output, the parallelism of the light beam 9 with respect to the optical axis K is It can be obtained together with its distribution in a single measurement.

  In addition, according to the present embodiment, since the distribution of the incident angle θ is output by associating the light intensity for each incident angle θ, the light intensity of the light component having a large incident angle θ is used for the intensity of the light component. The parallelism of the light beam 9 can be evaluated. Further, in the incident angle distribution chart C, the presence of stray light can be grasped by determining whether or not a light ray component having a strong light intensity is included at a position where the incident angle θ is shifted from the optical axis K.

  Further, according to the present embodiment, since each of the light ray components is imaged at the imaging position P that is separated from the optical axis K on the detection surface Q by a distance L proportional to the incident angle θ, each light ray component is The distribution map of the linear scale that can intuitively grasp the magnitude of the incident angle θ is obtained by simple calculation.

  Further, according to the present embodiment, the lens unit 20 is configured as a so-called image side telecentric optical system in which the principal ray 25 toward the detection surface Q is parallel to the optical axis K. With this configuration, even if the lens unit 20 is out of focus at the imaging position P due to a temperature rise, the center of gravity position does not change only by increasing the area of the imaging position P. As a result, the parallelism of the light beam 9 can be measured while maintaining a constant accuracy with respect to the temperature rise of the lens unit 20.

The above-described embodiment is merely an example of the present invention, and can be arbitrarily modified and applied without departing from the spirit of the present invention.
For example, when a large wavelength dependency occurs in the parallelism of the light beam 9 by the collimating optical system 6 or the homogenizer 8 included in the solar simulator device 3, a sensing head is used as a bandpass filter for monochromating the light beam 9. The parallelism may be measured for each monochromatic light.

Further, for example, according to the light beam parallelism measuring apparatus 1 according to the present embodiment, the intensity distribution of the incident angle θ with respect to the optical axis K of each light component included in the light beam 9 incident on the sensing head 10 can be obtained. It can be applied to the evaluation of the diffusion degree of the diffusion plate.
That is, a diffusion plate to be evaluated is arranged on the incident side of the sensing head 10, and a light beam with high parallelism is made incident on the sensing head 10 through this diffusion plate and measured, and an incident angle distribution chart C is generated. As shown in FIG. 5, in the incident angle distribution chart C, the higher the diffusivity, the more the incident angle θ is distributed, and the diffuser plate can be evaluated from this distribution range.

DESCRIPTION OF SYMBOLS 1 Light flux parallelism measuring device 3 Solar simulator device 9 Light flux 10 Sensing head 12 Analysis device (analysis means)
14 Display device 16 Filter unit 18 Aperture stop ring 20 Lens unit (imaging optical system)
22 Two-dimensional detector 24 Incident light 29 Optical unit 40 Measurement result output screen 41 Color scale bar 50 Irradiation surface 52 Principal light C Incident angle distribution chart K Optical axis L Distance P Imaging position Q Detection surface

Claims (4)

An imaging optical system that forms an image at a position away from the optical axis by a distance corresponding to an incident angle with respect to the optical axis for each of the light beam components contained in the light beam;
A detector for detecting an imaging position of the luminous flux,
An apparatus for measuring a parallelism of a light beam, comprising: an analyzing unit that converts a distance from the optical axis to the imaging position into the incident angle and outputs an incident angle distribution of a light ray component included in the light beam. The detector detects the light intensity at the imaging position;
2. The beam parallelism measuring apparatus according to claim 1, wherein the analyzing unit outputs the incident angle distribution in association with light intensity for each incident angle.   3. The light beam according to claim 1, wherein the image forming optical system forms an image of each of the light beam components at a position separated from the optical axis on a predetermined plane by a distance proportional to an incident angle. Parallelism measuring device.   4. The apparatus according to claim 1, wherein the imaging optical system makes a principal ray traveling on the predetermined plane parallel to the optical axis. 5.