DD249759A1 - Method for the radiote thermal measurement of light-emitting sources in real time - Google Patents

Method for the radiote thermal measurement of light-emitting sources in real time Download PDF

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Publication number
DD249759A1
DD249759A1 DD29066086A DD29066086A DD249759A1 DD 249759 A1 DD249759 A1 DD 249759A1 DD 29066086 A DD29066086 A DD 29066086A DD 29066086 A DD29066086 A DD 29066086A DD 249759 A1 DD249759 A1 DD 249759A1
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DD
German Democratic Republic
Prior art keywords
light
radiance
emitting sources
lens
measurement
Prior art date
Application number
DD29066086A
Other languages
German (de)
Inventor
Dieter Eberlein
Dieter Hafrang
Dieter Kurth
Gert Leidenberger
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Inst F Nachrichtentechnk
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Publication date
Application filed by Inst F Nachrichtentechnk filed Critical Inst F Nachrichtentechnk
Priority to DD29066086A priority Critical patent/DD249759A1/en
Publication of DD249759A1 publication Critical patent/DD249759A1/en

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Abstract

The aim of the invention is to enable the measurement of the radiance of light-emitting sources of arbitrary geometry and non-rotationally symmetric beam strengths with reasonable mechanical and low optical complexity and high speed. The invention has for its object to provide a method for measuring the radiance of light-emitting sources, the evaluation speed is so great that even dynamic measurements are possible, with a simple optical arrangement is used. According to the invention, the light emitted by the light-emitting source in the far-field plane passes through a traveling-hole stop and is fed to a number of surface-oriented charge-coupled elements which characterize the radiance as a four-dimensional quantity in conjunction with the local dependence of the pinhole by an analog voltage value. This is stored after analog-to-digital conversion in a processor, further processed and displayed. Fig. 1

Description

field of use

The invention relates to a method for measuring the radiance of light-emitting sources of arbitrary geometry and non-rotationally symmetrical radiant intensity, for example of optical waveguide end faces, of laser or of light-emitting diodes in real time, wherein the dependence of the power on both the location and the angle is determined in short 'time intervals.

Characteristic of known technical solutions

Generally known is the two-dimensional snap-in method, which makes it possible to determine the radiance both as a function of the spatial coordinate and as a function of the solid angle coordinate, cf. Olshansky, R., Oaks, S.H., Keck,

DB, "Measurement of different mode attenuation in GRIN optical waveguides", Digest of Topical Meeting on Optical Fiber Trans II, USA, Washington, DC (1977) Paper TuE5. By a sliding aperture and a slidable detector are using a strong micro-lens In this way the radiance is measured as a function of the location and the angle.

This method requires the measurement of a two-dimensional variety of values and is therefore very time consuming. Dynamic measurements are not possible.

A modified arrangement, cf. Stewart, W.J., "Method for Measuring Power Distributions in Graded and Step Index Fibers," Topical Meeting on Optical Fiber Commun., Washington, D.C, (1979) Paper ThG 1, allows much faster measurement of radiance.

By using special optics consisting of two slit diaphragms and spherical and cylindrical lenses and a television chamber, it becomes possible to image the radiance as a function of the spatial and angular coordinates in two mutually perpendicular directions in one and the same plane in which a vidicon is arranged. The image data of the camera arrive at a computer and, after appropriate numerical evaluation, are fed to a monitor which displays the radiance as a function of the area and solid angle element. One slit diaphragm is arranged in the far field plane, the other slit diaphragm in the near field plane. The far field plane is imaged by a cylindrical lens and the near field plane through a spherical lens in the vidiconone plane.

The disadvantage of this method is a high expenditure on equipment, cf. Deserno, U., Schicketanz, D., "Measurement Methods for Future Applications in Fiber Optic Technology," telcom report 6 (1983) Supplement "Nachrichtenübertragung mit Licht," p. 186-192.

Another method allows dynamic measurement in the image plane (near field) by means of the CCD line (charge coupled line), but the values in the focal plane must be set discretely, cf. DD-WP 223 248 A1, G 01 N 21/27. This is done by means of a ring-shaped revolver.

It has already been proposed to replace the annular diaphragm revolver with a dynamic diaphragm, for example by a magnetic fluid, cf. W. Lippmann, DD-WP 278140.4, G 01 N 21/63 "Method for measuring the radiance distribution of radiation sources with central aperture diaphragm." This dynamic diaphragm is mounted during the measuring process, whereby ever larger apertures are detected.

By subtraction one determines by the radiance as a function of the place and the angle. Although the method allows dynamic measurement as a function of location and angle, it becomes increasingly less accurate for larger angles.

In addition, the difference method is only permissible as long as the coherence of the light radiation does not play a role, as otherwise cancellations due to interference occur. In addition, the realization of the dynamic diaphragm by means of a magnetic fluid is technologically difficult to carry out.

So far, no method is known which allows the radiance measurement of light-emitting sources of arbitrary geometry and non-rotationally symmetric radiant intensity in real time.

Object of the invention

The aim of the invention is to reduce the effort required for the radiance measurement, to shorten the measurement time and to improve the quality of the measurement by increasing the dynamic range.

Explanation of the essence of the invention

The invention has for its object to provide a dynamic method for measuring the radiance of light-emitting sources of arbitrary geometry and non-rotationally symmetric beam strength, with which the beam density in response to four variables in a large optical intensity range can be determined, stored and displayed in low measurement time with high evaluation speed.

According to the invention, this object is achieved in that the light emitted by a radiation source to be measured in the far field plane passes an orthogonal to the optical axis arranged Wanderlochblende, which is realized by a rotating spiral aperture and a rotating slit, and by means of a lens system of a certain number areal oriented charge coupled Elements are supplied, which are controlled by a clock circuit such that the spiral and the slit diaphragm, driven synchronized by two independent motors, rotate and the clock frequency is a multiple of the angular frequency of the spiral shutter and the angular frequency of the spiral shutter is a multiple of the angular frequency of the slit and in that the output signal of the areally coupled charge-coupled elements is detected, digitally converted, stored and stored for a wide distance by means of a processor in dependence on the location in the far-field and image plane ere evaluation is provided. By changing the clock frequency and synchronized by the clock frequency angular frequencies of the spiral and slit diaphragm variable sensitivity is realized, so that the optical Intensitätsmeßberiech is extended without optical attenuators.

Thus, by influencing the light emitted by a radiation source to be measured with the help of the rotating spiral aperture and the rotating slit aperture both a radiance measurement of light sources of arbitrary geometry or non-rotationally symmetric radiant intensity in real time allows, and extends the optical Intensitätsmeßbereich without optical attenuators. To implement the method, a light-emitting source to be measured is arranged in the front focal plane of a first lens. In the rear focal plane of the first lens, which is identical to the front focal plane of the second lens, there is a Wanderlochblende. The Wanderlochblende is formed by two closely spaced apertures in the form of a spiral aperture and a slit, which rotate about a gmeinsame axis mit.unterschiedlichen speeds. Arranged in the rear focal plane of the second lens is an optical receiver formed by areally coupled charge-coupled elements, which is connected to a clock circuit and an analog-to-digital converter. To the clock circuit and the analog-to-digital converter, a process is connected, which is connected to a display device. The clock circuit is over there hi na us each connected to a motor which is coupled to the spiral or with the slit. This device enables the radiance measurement of light-emitting sources with rotationally symmetric and non-rotationally symmetric radiant intensity in real time, that is a dynamic radiance measurement.

embodiment

Reference to an embodiment shown in drawings, the essence of the invention will be explained in more detail. Show it:

1 shows an arrangement for carrying out the method,

2 shows the principle of scanning a radiance,

Fig. 3: an idialisierten Raddichteverlauf for a Gradientenlichtwellenleiter.

1, a first lens 2, a spiral shutter 3, a slit diaphragm 4, and a second lens 5 are disposed between a light-emitting source 1 to be measured and an optical receiver 6 formed by two-dimensionally oriented charge-coupled elements. To the optical receiver 6, a clock circuit 7 and an analog-to-digital converter 12 are connected. The clock circuit 7 and the analog-to-digital converter 12 are connected to a processor 8, to which a Anzeigevorrichtng 9 is connected. The clock circuit 7 is connected to a motor 10 and 11, which is coupled to the spiral shutter 3 and the slit 4, respectively. The end face of the light-emitting source 1 to be measured is arranged in the front focal plane of the first lens 2. In the rear focal plane of the first lens 2, which is identical to the front focal plane of the second lens 5, are closely behind the spiral shutter 3 and the slit 4, which form a Wanderlochblende by rotation about a common axis and of the motors 10 and 11th are driven. The length of a slit of the slit 4 and the swept over during rotation of the spiral shutter 3 area are greater than the extent of the far field. The end face of the light-emitting source 1 to be measured is magnified on the first lens 2 and the second lens 5 on the optical receiver 6. The angular frequency of the rotating spiral shutter 3 is a multiple of the angular frequency of the rotating slit 4. From the speed at which the slit 4 rotates and the number of slits arranged on a disk, the repetition frequency of the measurement results. The linearity between the rotation angle of the spiral shutter 3 and the displacement of the traveling hole aperture is realized by a modified Archimedean spiral of the spiral shutter 3. This ensures that at constant angular frequency of the spiral shutter 3, the far field area to be selected is traversed at a constant speed. Likewise, the local area in the image plane is swept line by line at a constant rate, which is ensured by a constant clock frequency at which the CCD matrix or the optical receiver 6 formed by the charge-coupled elements is read.

If the clock frequency at which the optical receiver 6 is omitted, a multiple of the angular frequency of the spiral aperture 3 and this in turn a multiple of the angular frequency of the slit 4 and thus a multiple of the repetition of the Wanderlochblende, it can be assumed in good approximation that in a differential small period of time the Wanderlochblende is fixed while the image area is scanned once. The measured values then represent the radiance as a function of the area elements for a specific space angle element. In fact, however, change the selected by the Wanderlochblende solid angle elements during a different small period of time to a particular solid angle element, so that again reading out the CCD matrix again the radiance is measured in dependence on eienm certain surface element, but now element for a solid angle

changed angle. The charge-coupled elements thus characterize by stress values the radiation density as a four-dimensional quantity in connection with the location dependence of the traveling-hole diaphragm.

In Fig. 2, the principle of scanning a beam density is shown. In this case, in each case an area A 0 is scanned for a specific solid angle element, which area is determined by the extent of the CCD matrix or the charge-coupled elements or the optical receiver 6 and the imaging scale of the arrangement. The sum of the solid angle elements forms a solid angle O 0 , which is given by the numerical aperture of the lenses and the dimensions of the Wanderlochblende.

The area bounded by the area A 0 and the solid angle Ω ο is traversed, for example, from bottom left to top right. The measured values determined are stored and provided for further evaluation. As a result, an azimuthal averaging in the near field and the far field is possible, so that the beam density in the phase space diagram can be represented as a function of a normalized radius R and a normalized aperture U.

Fig. 3 shows an idealistic radiance profile for a gradient of occasional titer. Different beam densities can be represented by different gray values or colors. A pseudo-spatial representation is also possible.

From Fig. 2 it can be seen that the number of distinguishable solid angle elements results from the frequency ratio of the repetition frequencies. From this, the aperture size of the Wanderlochblende can be estimated, which is so dimenisoniert that it averages over a solid angle element.

It should be noted that the resolution is limited in principle by diffraction phenomena. The consequence of the Rayleigh diffraction criterion is that the number of the smallest resolvable phase space elements in the phase space diagram is limited, that is to say that a finer sampling in the location or aperture range does not bring about any increase in information. Consequently, the number of measured solid angle elements and the matrix elements used should not be too large.

As a result, the effort for the evaluation is reduced and a higher processing and evaluation speed possible.

Claims (1)

  1. A method for radiance measurement of light-emitting sources in real time for light emitting sources of arbitrary geometry and non-rotationally symmetric radiant intensity with a Wanderlochblende, a lens system and formed by areal oriented charge coupled elements optical receiver, characterized in that the light emitted from a radiation source to be measured in the Fernfeldebene orthogonal to the optical Axial arranged Wanderlochblende happens, by a rotating spiral shutter (3) and a. is realized by means of a lens system of a number of surface-oriented charge coupled elements of an optical receiver (6) and detected by a processor (8) depending on the location in the far field and image plane, digitally converted, stored and as a radiance is provided for an evaluation.
    For this 1 page drawings
DD29066086A 1986-05-28 1986-05-28 Method for the radiote thermal measurement of light-emitting sources in real time DD249759A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DD29066086A DD249759A1 (en) 1986-05-28 1986-05-28 Method for the radiote thermal measurement of light-emitting sources in real time

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DD29066086A DD249759A1 (en) 1986-05-28 1986-05-28 Method for the radiote thermal measurement of light-emitting sources in real time

Publications (1)

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DD249759A1 true DD249759A1 (en) 1987-09-16

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005048685A1 (en) * 2005-10-11 2007-04-26 Schuh & Co. Gmbh Measuring arrangement and method for measuring the far field of a light source
WO2011061706A1 (en) 2009-11-19 2011-05-26 Bystronic Laser Ag Method and device for determining a characteristic of a beam, by means of a rotating disc, in particular in a laser processing machine
DE102010053323B3 (en) * 2010-12-02 2012-05-24 Xtreme Technologies Gmbh Method for the spatially resolved measurement of parameters in a cross section of a beam of high-energy, high-intensity radiation

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005048685A1 (en) * 2005-10-11 2007-04-26 Schuh & Co. Gmbh Measuring arrangement and method for measuring the far field of a light source
WO2011061706A1 (en) 2009-11-19 2011-05-26 Bystronic Laser Ag Method and device for determining a characteristic of a beam, by means of a rotating disc, in particular in a laser processing machine
DE102010053323B3 (en) * 2010-12-02 2012-05-24 Xtreme Technologies Gmbh Method for the spatially resolved measurement of parameters in a cross section of a beam of high-energy, high-intensity radiation
JP2012118061A (en) * 2010-12-02 2012-06-21 Xtreme Technologies Gmbh Method for measuring spatial decomposition of parameter on beam cross section of high-energy radiation light of high intensity
NL2007739C2 (en) * 2010-12-02 2013-11-18 Xtreme Tech Gmbh Method for the spatially resolved measurement of parameters in a cross section of a beam bundle of high-energy radiation of high intensity.
US8686372B2 (en) 2010-12-02 2014-04-01 Ushio Denki Kabushiki Kaisha Method for the spatially resolved measurement of parameters in a cross section of a beam bundle of high-energy radiation of high intensity

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Expiry date: 20060529