DE10153104B4 - Light measuring device for the spatially resolved detection of weak light sources - Google Patents

Abstract

Light measuring device (1) for spatially resolved Detection of weak light sources by means of an imaging glass fiber optic (2) with multiple fiber bundles (3), whose light inputs (4) at the individual measuring locations and their light outputs (5) in a central photodetector (6) ending up as a photon counting, Multi-stage multi-channel plate (26) formed with a photocathode (27) is, and an evaluation unit, characterized in that the light inputs (4) the glass fiber bundle (3) in a spatial Arrangement evenly one closed sphere surface (10) with depending from the spatial Detection angles (α) the glass fiber bundle (3) elected intervals are assigned, wherein the totality of all spatial coverage angle α the spherical surface (10) completely covered, and that 32 glass fiber bundles (3) are provided which a detection angle (α) in a Range of 20 ° and those with their light inputs (4) centrally in the flat areas (7, 8) one in the spherical surface (10) inscribed regular polyhedron (9) in the form of a truncated icosahedron of 12 pentagons (7) and 20 hexagons (8) as an auxiliary construction ...

Description

The The invention relates to a light measuring device for spatially resolved detection from weak light sources by means of an imaging glass fiber optic with several fiber bundles, their light inputs at the individual measuring locations and their light outputs in a central photodetector end, and an evaluation unit.

To counting the weak light sources both periodic and stochastic light - changing phenomena in the Space as well as a series of light sources in the depths of the Oceans. This may be in particular bioluminescence or to Cerenkov radiation act. The latter is mainly due to radioactive particles and atmospheric Myons generated in the water. In research is the intensity and the spatial Distribution of occurring weak light sources of particular interest.

On The field of space research is from the essay "Development an underwater neutrino detector "(see" Research topics DESY-Zeuthen "from DESY, Wissenschaftlicher Annual Report 1995, pages 165-167) an underwater neutrino detector is known with which of secondary particles, in a rare reaction of high-energy space neutrinos arise, generated Cerenkov radiation is detectable. The light is doing so in a variety (in planning 4,800, see Wysiwig: // 29 / http: //www.wissenschaft.de/ sixcms / detail.php? id = 7730, page 1, stand 28.03.01) of spatially distributed Photomultipliern registered, which housed in pressure-resistant glass balls and in big Water or ice depth can be arranged. From the arrival times and the amplitudes, the path of the secondary particles (i.a. Myonen) is reconstructed. The signature of secondary particles Neutrino reactions consist of their direction: they traverse The photodetector coming from below, because the sought-after space neutrinos previously have to tunnel through the earth as a filter. Important for neutrino identification is therefore one possible error-free reconstruction of the zenith angle of the secondary muons these are from the much more common muons coming from the atmosphere to be able to distinguish. From a lecture by G. van Aller at the Spring Meeting of the Swiss Physical Society (see G. van Aller et al., Proceedings the Spring Conference Swiss Physical Society, published in Helv. Phys. Acta 59 (1986), pages 1119-1133, Excerpt Chapter 1 and 2) is the structure of the individual optical modules closer known, where the top half the pressure-resistant buoyancy sphere inside with a large-area photocathode is designed. Although this is a particularly high sensitivity reached, but it is also a high dark current or a high registered electronic noise.

In the field of bioluminescence research, a deep-sea photometer (HIDEX-BP - "high intake defined excitation bathyphotometer") from the article "Scales of measurements and methods of calibration" is known (see Workshop Abstracts, EAWidder, http: //lifesci.uscb .edu / ~ biolum / sdworkshop / widderabs.html, as of 12.10.2001). This computer-aided deep-sea photometer is a tubular measuring apparatus (cf. 2 ) in which organisms produce bioluminescence in the incoming flow by hitting a stimulation grid. This is registered by an imaging fiber optic of several fiber optic bundles whose light inputs in optical windows along an axial line of the light-receiving tube ends. Thus, quantitatively bioluminescence in the deep sea can be detected with the known measuring apparatus. A spatial resolution is roughly limited to the location of the measuring apparatus. A spatial resolution of individual light events in space can not be done with this known apparatus.

In the field of image projection is from the DE 32 26 015 A1 an arrangement of optical fibers on a spherical sector in the manner of a wide-angle lens for imaging a three-dimensional spatial scene on a two-dimensional plane with the least possible distortion and good resolution known. For this purpose, in a half-shell ball sector, which can be larger if necessary, arranged a plurality of optical fibers evenly distributed, which should capture the scene as completely as possible. The optical fibers are fed out of the downwardly open spherical sector and onto an imaging plane and one of these downstream electronics. A realization of a closed ball with an integration of all components is not possible here for design reasons. Furthermore, no individual light events are counted by means of a central detector, it is only possible to detect an irradiation direction with the aid of an image recording arrangement. In addition, no indication is given of the achievement of uniformly distributed positioning of the optical fibers in the sphere sector, since a highly accurate spatial resolution as in the invention for the spatial registration of individual photons is not required.

A similar built-up device for permanent detection of the radiation density of diffused daylight (pyranometer) is from the DE 197 33 383 A1 known which comprises a spherical cap with surface optical light receivers integrated into the surface, which has glass fibers with a central arranged common photodiode are connected. The ball cap is designed as a half shell and rests on a solid base plate. It is protected from the weather by a protective hood sealed against the base plate. Although the protective hood may only have a minor influence on the incident daylight, it certainly has a negative effect on individual light events due to absorption and distraction. With the pyranometer, however, no individual light events are counted, but the irradiation density of the diffuse daylight is detected by means of a photodiode and a downstream converging lens. In addition, no indication is given of the achievement of the uniformly distributed positioning of the light guides in the sphere sector, since a highly accurate spatial resolution for the spatial registration of individual photons is not required. It is merely stated that the spatial (polar) distance of the light receivers from each other is chosen such that they are arranged statistically evenly distributed over the surface of the spherical cap and thus the incident diffuse light is detected in its sphere density spherical coverage.

In turn in the field of space research is from the article "The multi-channel spectrophotometer MEKASPEK "by K.-H. Mantel, University Observatory Munich, Germany (see http://bigbang.usm.unimuenchen.de:8002/USM/WDST/inst/meka/index german.html, pages 1-21, Stand 09.07.2001) to investigate variable stars in his dimensions already relatively compact multi-channel spectrophotometer known with the local and spectrally resolved Measurements of brightness changes very short time scales with high accuracy are feasible. To this end, four, a variety of individual glass fibers comprehensive Glass fiber bundles, the in the focal plane of a telescope computer-controlled on the measurement object, two comparison objects and the sky background are adjusted, the respective received light signals in a double-prism spectrograph. There, the light is spectrally decomposed and onto the photocathode of a two-dimensional, photon counting Detector shown. The over the Photoelectric resulting electrons are using a cascade reinforced by 5 microchannel plates and directed to a resistance anode. A VME bus computer system is registering and evaluation of the measured data used. To select the objects and for tracking of the telescope during The observation uses a CCD camera with image intensifier. The glass fiber bundles point circular light inputs and rectangular, adapted to the input law of the spectrograph light output on.

at this known light measuring device, of which for the present invention as nearest State of the art is assumed, according to the focal plane only a small solid angle detectable. Only such objects can be detected that were previously accurately located by observation so the four light-trapping glass fiber bundles adjusted accordingly Need to become. While the measurement are constant Adjustments required if the objects to be measured are the respective ones Exit the detection range of the individual fiber optic bundles. A general spatial resolution For free light detection throughout the room is familiar with the Measuring device not possible. The The object underlying the present invention is therefore therein to see, a measuring device of the type mentioned in such a way that a spatial resolution in the complete 4π space is reached. It should also be moving objects continuously be detectable. The measuring device according to the invention should be compact and be insensitive in their construction. A simple production and handling should be guaranteed be.

When solution is in a light measuring device of the type described above, generic type Therefore provided according to the invention, that the light inputs the glass fiber bundle in a spatial Arrangement evenly one closed sphere surface with in dependence from the spatial Detection angles α the glass fiber bundle selected intervals are assigned, wherein the totality of all spatial coverage angle α completely covers the spherical surface.

In the light measuring device according to the invention, the measuring space is transferred to a spherical surface with the unit surface 4π. In order to fully capture the entire measuring space, it is now evenly divided into a number of individual areas of the same size. The size of the individual surfaces depends on the spatial coverage angle α, which has each guided centrally in the individual areas with its light entrance glass fiber bundle. At an already short distance from the surface of the sphere, there is a complete juxtaposition of all detection ranges. The under- or overlapping of the individual detection ranges before and after the optimal distance can be compensated during the measurement evaluation. An overlap of the detection areas leads to a simultaneous detection of a light pulse through two or more fiber optic bundles. This can be used to determine the removal of the light event. Altogether, a number of individual surfaces which are precisely determined as a function of the selected detection angle α is defined, with which the 4π space can be completely detected. Everybody in the Space incident light event is safely captured by a fiber optic bundle and forwarded to the photon measurement. By knowing the positional angle of the respective light-emitting fiber-optic bundle, in addition to a statement about the light intensity, it is also possible to make an immediate statement about the angular occurrence location of the light event that has occurred. Thus, with the light measuring device according to the invention with high sensitivity and spatial resolution light events of weak light sources in the entire 4π space can be detected easily and reliably around the optical fiber optics.

For the assignment the glass fiber bundle to a closed spherical surface as a projection of the complete 4π-space they can for example, integrated directly into the surface of a sphere be. Their mutual distance from the detection angle α is determined. The smaller this is, the closer the fiber optic bundles are to position and the more fiber optic bundles are required. Besides that is the realization of a symmetrical arrangement on a spherical surface extremely difficult. There would be glass fiber bundle with a detection angle α of 2π, however, would be only 6 fiber optic bundles required in the areas a cube are integrated. Such coverage angle α are currently not feasible. An approximate symmetrical distribution of a still relatively small number of glass fiber bundles but can be achieved if according to an embodiment of the light measuring device according to the invention 32 glass fiber bundles are provided, which have a detection angle α in a range of ± 20 ° and those with their light inputs centrally in the flat areas a regular polyhedron inscribed in the projected spherical surface in the form of a Bucky ball made up of 12 pentagons and 20 hexagons. The fullerene chemistry known Bucky Ball as a third manifestation of carbon describes a structure such as, for example also from a football is known. In contrast to this, however, the individual surfaces are flat and not rounded. Nevertheless, with the Bucky Ball at the Light measuring device according to the invention a good approach to a spherical surface achieved because the fiber optic bundles in area centers Drilled so be that they the projected (or real) spherical surface (or. their inner surface) to reach. The distance between the flat surfaces of the Bucky Ball and the thus circumscribing sphere is thus compensated. A detection angle α in one Range of ± 20 °, in particular ± 20,7 °, is a for common Glass fiber bundles more usual Value. A distribution of 32 such fiber bundles in Orientation to the centers of the alternating five- and Hexagons of the Bucky Ball ensures with it in a simple manner in a relatively small distance to the spherical surface already a complete, optimal detection of the 4π-space with a Relatively small number of fiber optic bundles, so that the effort is moderate in the evaluation of the measurement results. By the positioning the light inputs the glass fiber bundle centrally in the individual areas of the Bucky Ball, which serves as an auxiliary construction for fixing the To look at light inputs is, is a largely symmetrical arrangement of the individual fiber optic bundles almost constant distances reached each other. The assembly and maintenance is simplified if according to a next Inventive design of the polyhedra in the shape of a Bucky Ball in two symmetrical halves each with 16 partial surfaces is divided. These can be easily from the inside with the glass fiber bundles equip and then put it together, with only a single data line leading out of the interior got to. The individual surfaces of the Bucky Ball be transparent to allow easy insight into the interior. You can but also opaque be, whereby erroneous measurements are avoided by stray light.

For the possible fulfillment of special requirements for the light measuring device according to the invention in the measuring operation and in the measurement evaluation, it is advantageous if it is provided according to a Invention continuation, that in the optical fiber optics between the light outputs of the fiber optic bundle and the central photodetector an additional optical component is provided. This can according to a further embodiment, in particular a single convex lens or two convex lenses having an interposed angeord Neten filter wheel. In the case of a single convex lens; which serves the light beam focusing, this must each have a distance equal to their double focal length to the light output of the glass fiber bundle and the photocathode of the detector. If, as in the second case, two convex lenses are used with an intermediate filter wheel, only the simple focal distance is required in each case. The filter wheel can serve interference measurements. In particular, according to a next embodiment of the invention it is advantageous if the filter wheel has a transmission filter with a transmission τ = 1, a blocking filter with a transmission τ = 0, a neutral attenuation filter, for example with a transmission τ = 0.001, a red filter and a blue filter. Thus, different measurement conditions can be established by simple rotation of the filter wheel. In this case, the filter wheel can be controlled via the same feed line as the measuring arrangement. The pass filter or a position in the filter wheel without filter realizes a simple measuring setup with two convex lenses. The attenuation filter, which transmits, for example, only 1/1000 of the incident light radiation, is used to protect the sensitive photodetector when relatively bright events - as interference or as Mes events - to be expected. Blue and red light filters are used when light events with a center of gravity in the respective spectral range are to be expected or detected. When storing and transporting the light measuring device according to the invention to its place of use in the environment of weak light sources, it is also useful to completely shade the sensitive photodetector through the notch filter, that is, to close to avoid destruction.

The sensitive photodetector can be an electronic camera, for example a CCD camera (charge coupled device). Although this has a two-dimensional image field on which a certain spectrum width can be imaged. However, such cameras do not register individual photons, but integrate incident photons before they are detected. Therefore, it is advantageous according to a next continuation of the light measuring device according to the invention, when the central photodetector is designed as a photon counting, multistage multi-channel plate with a photocathode and the round light inputs of the glass fiber bundles are converted into rectangular light outputs, either with a reproduction ratio of 1: 1 on the photocathode imaged or closely adjacent as rows or columns are positioned directly on the photocathode. In the 1: 1 image on the photocathode corresponds to the glass fiber array formed by the rectangular light outputs then the grid of the channel plate detector. For the signal detection, in particular a photodetector with a two-stage microchannel plate can be used. An incident on the photocathode quantum of light releases an electron via the external photoelectric effect, which is accelerated in the applied high voltage field and triggers an avalanche effect in the associated channel of the microchannel plate. Depending on the size of the electric field 10 ³ to 10 ⁶ electrons are released per photon event. These meet an anode array for detection of the electron cloud. The measuring electronics are then connected to the terminals of the anode array. Although the photocathode has a maximum quantum efficiency of 20% as a function of the wavelength, that is to say that a charge cloud is only generated by every fifth impinging photon, with such a sensitive photon detector individual photons which often occur in weak light sources are nevertheless present , quite registrable. The conversion of the round light inputs into rectangular light outputs of the fiber optic bundles provides a particularly simple and fast assignment of the measured values to the measuring locations.

The separated and numbered 32 on the light entry side glass fiber bundle are through brass sleeves mechanically stabilized and arbitrarily alignable in the room. On the Light exit side of the fiber optics is the arrangement of the individual Glass fibers such that each bundle is converted into a rectangle and the sum of the juxtaposed rectangles an array results, in which the rectangles are found in the same numbering. The individual rectangles are mechanical due to thin sheets or foils separated. Instead, the entire array is in for stabilization a rectangular recess of a brass cylinder and cast additionally stabilized by a shrink tube. The shape and size of the array match in the reproduction scale 1: 1 of the arrangement of anodes behind the two-stage channel plate. The channel plate and the photocathode immediately in front of it are not structured. The small distances between photocathode, Channel plate and anodes largely avoid scattering of the released Electrons and leave a clear association between the place on the photocathode, where the photoelectron is generated, and the respective anode.

A first possible protection of the highly sensitive light measuring device according to the invention has been described in the form of the additional filter wheel. Further protection against destruction is given if, according to a next embodiment of the invention, the glass fiber optic with the light outputs of the glass fiber bundles is surrounded by an opaque rubber grommet. With a simple rubber grommet, the sensitive optics can be protected from both light and water, especially spray and condensation water. In addition, the entire measuring device can be effectively protected from underwater measurements of weak light sources against water, if according to another Invention continuation, the ball surface is formed by a untersertauglichen glass ball in the form of a pressure-resistant, equatorial divided buoyancy ball, at its north pole an underwater plug for connecting a supply and data exchange cable and a ventilation valve. The buoyancy sphere then houses the optical and electronic components for the light measurement. By way of a single conductor cable which can be connected to the underwater plug (the shield is the second conductor), the buoyancy sphere is connected, for example, to a research vessel as an overwater unit as a supply and data transmission line. There, in particular, there is a computer unit with whose software the setting tasks, the evaluation and presentation of the measured data take place. The buoyancy ball, which can have a compressive strength for water depths up to 6000 m, consists of two hemispheres with ground edges. Borosilicate with a refractive index of n = 1.48 (n of water = 1.33) is used as the glass. To close the ball halves, the glass cuts are carefully made of grease and Dust cleaned and pressed the two half-shells with low pressure by evacuation via the air valve. In the measurements in the deep sea, the water pressure then ensures a stronger cohesion of the two halves. Dismantling takes place after previous ventilation via the valve.

To the easy insertion and removal of in the manner described a buoyancy ball protected Light measuring device on site under relatively harsh operating conditions it is particularly advantageous if, according to a next embodiment of the invention the buoyancy ball over two mutually braced retaining rings in the amount of the tropics in one Holding rack is stored, the over a wire rope is lowered. The retaining rings reinforce the Cohesion of the two hemispheres and provide a secure connection to a sturdy rack This ensures safe protection of the light measuring device both under water as well as during storage Water, especially on board a research vessel. Further constructive Details can be found in the special description section.

exemplary Embodiments of the light measuring device according to the invention will be below with reference to the schematic figures and diagrams for further understanding closer to the invention explained. It shows

1 an arrangement of the glass fiber bundles in a Bucky ball in the partial view,

2 a diagram of the spatial coverage angle α of a glass fiber bundle,

3 a diagram of detected light pulses,

4 a fiber optic with an additional convex lens,

5 a fiber optic with a filter wheel,

6 half a Bucky ball with photodetector,

7 the rectangular bundled glass fiber bundles in a strong magnification view from below,

8th several in a brass cylinder combined fiber bundles in perspective and

9 a complete light measuring device according to the invention with holding frame in the view.

In the 1 is a light measuring device 1 according to the invention for the spatially resolved detection of weak light sources shown in the view. In detail, an imaging glass fiber optics 2 with several, consisting of a plurality of individual glass fibers glass fiber bundles 3 shown. The light inputs 4 the glass fiber bundle 3 end in the individual measuring locations, the light outputs 5 the glass fiber bundle 3 end in a central photodetector 6 , The single glass fiber bundles 3 captured light pulses are from the photodetector 6 registered and one in the 1 Not shown further evaluation unit supplied (arrow). In the illustrated embodiment, the light inputs 4 the glass fiber bundle 3 centrally in the pentagonal areas 7 and the hexagonal surfaces 8th a polyhedron 9 spatially arranged in the form of a Bucky Ball. The Bucky Ball presents with its total 32 Individual surfaces ( 12 pentagons 7 . 20 hexagons 8th ) a good approximation to a closed spherical surface 10 This results in a largely uniform distribution of the individual surfaces 7 . 8th centrally assigned 32 light inputs 4 in the entire 4π space. Furthermore, each light entrance 4 the glass fiber bundle 3 a spatial detection angle α in a range of ± 20 ° (see. 2 ), so that the sum of all detection angles α results in a largely closed detection surface. This can be done with the light measuring device 1 According to the invention, each occurring in the room nearby light event reliably from one light entrance 4 be detected.

The 2 shows a diagram for the angle-dependent measurement at a light input of a glass fiber bundle. Plotted are the measured pulses of a point light source above the detection angle α. It can clearly be seen that within a detection angle α of approximately ± 20 °, most of the light pulses are detected. The exact value of the spatial detection angle α can be determined by calculation. The surface of a sphere of radius R is calculated as 4πR ² (I). This is split at 32 glass fiber bundles in 32 individual areas: 4πR ^2/32 (II). The area of a circular single surface with the radius r is calculated to πr ² (III). The quotient r / R describes on the sphere the sine of the desired detection angle α. It must be valid (II) = (III). From this, an exact value of ± 20.7 ° can be calculated for the detection angle α, independently of the values of the radii R and r. This proves that with 32 glass fiber bundles, each with a detection angle α of ± 20.7 °, the 4π space can be completely detected. At other detection angles α correspondingly different numbers of individual fiber optic bundles are required, resulting in another polyedri The auxiliary structure as the results in the form of a Bucky ball.

The 3 shows a measurement diagram, as it can arise, for example, on an Antarctic expedition. The measurements refer to a cloudless sky at sunrise and an ice-covered water surface. Light pulses are taken in a depth of 500 m under the ice in dim light. The individual curves, which represent a plot of the measured light pulses over time, relate to different measurement series. When the sun is high daylight can be measured with clear ocean water to a depth of about 1000 m. The measurement sensitivity extends to the resolution of individual photons.

In the 4 and 5 are different optical additional components 20 in glass fiber optics 2 shown. In 4 this is a single convex lens 21 for 1: 1 mapping of the light exit of the glass fiber bundle 3 on the photocathode 27 , In the 5 are two convex lenses 22 shown, between which a filter wheel 23 is arranged. The single convex lens 21 in 4 is in the beam path between the combined glass fiber bundles 3 and the central photodetector 6 in a housing 24 between fortifications 25 arranged. At the central photodetector 6 is it in the illustrated embodiment is a multi-channel plate 26 with a round photocathode window 31 , The glass fiber bundles 3 are with a shrink tube 28 summarized and ends in rectangular light outputs 5 that are grouped together in the area exactly the area of the anode array 32 correspond. The convex lens 21 is now at a distance of twice the lens focal length f between the light outputs 5 and the photocathode 27 arranged. In the 5 is in each case a convex lens 22 at a distance of the simple lens focal length f, which may be 40 mm, for example, to the combined light outputs 5 and the photocathode 27 arranged. Between the convex lenses 22 is the filter wheel 23 with different filter inserts 29 , These can be pass, lock, attenuate and color filters. Depending on the application, one of the filter cartridges 29 rotated by control via the evaluation unit in the beam path. A blocking filter 30 serves to protect the highly sensitive photodetector 6 from harmful light, especially during transport. For this purpose and to protect against water, the glass fiber optics may be surrounded in this area with an opaque rubber grommet, but this is not shown here.

In the 6 is a half 40 a polyhedron 9 presented in the shape of a bucky ball in the view. 16 glass fiber bundles 3 with round light inputs 4 (Brass sleeves) end with rectangular light outputs 5 in front of a photodetector 6 in the form of a multi-channel plate 26 , The summary of the individual fiber optic bundles 3 to a rectangle 50 is the 7 refer to. Between the individual, numbered glass fiber bundles 3 are located for separation thin metal sheets or plastic films (not shown). In the 7 the rectangularly bundled glass fiber bundles are shown from below, with light being fed into each second light entrance for better discrimination. By positioning all 32 rectangular glass fiber bundle 3 previously used for stabilization in the shrink tube 28 were summarized, in a round, a corresponding rectangular section 51 in the front side having brass cylinder 52 next to each other, a glass fiber array is created 53 (see. 8th ), which in its dimensions exactly the anode array 32 the multi-channel plate 26 (see. 6 , only occupancy share shown) corresponds. The light signals are via a Bildbildgsoptik 59 in the form of an optical additive component according to 4 and 5 on the anode array 32 1: 1 shown. The imaging optics 59 can also do this directly in front of the photocathode 54 be positioned. Thus, the structure described is a simple but complete transformation of the information from the individual fiber optic bundles 3 on the multi-channel plate 26 guaranteed. In this case, the assignment to the individual measuring locations is to be regarded as one-dimensional, since each column characterizes only one measuring location, whereby a particularly fast and effective measured value evaluation is ensured. The dimensions of the components involved are very moderate. At a length of about 40 cm, the fiber optic bundles 3 a cross section of about 2.1 mm. Each rectangular glass fiber bundle has the dimensions of 6 mm × 0.5 mm, so that the entire glass fiber array 53 at 32 glass fiber bundles 3 Dimensions of 6 mm × 16 mm. In the 6 is a two-stage multi-channel plate 26 shown at the bottom of the photocathode 54 two amplifier layers 55 and 32 Single anodes 56 arranged the anode array 32 are. To evaluation unit 57 then lead overall 32 data lines 58 ,

The 9 shows a light measuring device 1 according to the invention with a 32-area, regular polyhedron 9 as an auxiliary construction for the even distribution and fixation of 32 glass fiber bundles in 4π space. In the illustrated embodiment, deep-sea measurements are to be performed. The light measuring device 1 is therefore in an equatorial split buoyancy ball for protection 60 encapsulated. In the buoyancy sphere 60 it may be, for example, a commercial Vitrovex ball of the company Jenaer Glaswerke GmbH. This one has egg diameter of 432 mm and weighs about 17.3 kg. It is suitable for diving depths up to 6,700 m. In the area of the division, the buoyancy ball has a narrow tape ring on its surface 61 on. This is in the illustrated embodiment, a layer winding tape and about a layer of insulating tape, since the winding tape has a sticky surface. The tape ring 61 only serves to protect the dividing seam. The seal is made exclusively on the glass surfaces of the hemispheres. Furthermore, the buoyancy ball is at the north pole 60 an underwater plug 62 for connecting a supply and data exchange cable 63 intended. Next to it is a ventilation valve 64 for easy installation of the two hemispherical shells. At the height of the tropics is the buoyancy sphere 60 in two retaining rings 65 stored. These are in turn with a holding frame 66 firmly connected. A tension of the two retaining rings 65 in the holding frame 66 still supports the cohesion of the two half-shells in the measuring mode and in particular also during storage, when the buoyancy ball 60 not compressed by the water pressure. Neither the equatorial tape ring 61 still the two retaining rings 65 hamper the spatially resolved Lichtpulsmes solution. In the holding frame 66 is the buoyancy ball 60 Protected from destruction and can easily over a wire rope 67 be removed and returned. A storage on board in the support frame 66 also serves to protect the light meter 1 ,

1

Light measuring device

2

Fiber optic

3

glass fiber bundle

4

light input

5

light output

6

photodetector

7

pentagonal area

8th

hexagonal area

9

polyhedron

10

spherical surface

20

optical additional component

21

convex lens

22

convex lens

23

filter wheel

24

casing

25

attachment

26

Multi-channel plate

27

photocathode

28

shrinkable tubing

29

filter cartridge

30

cut filter

31

Photocathodes window

32

anode array

40

Half of one polyhedron

50

Rectangular cross-section

51

rectangular neckline

52

brass cylinder

53

fiber optic array

54

photocathode

55

promoting layer

56

single anode

57

evaluation unit

58

data line

59

imaging optics

60

drift ball

61

tape ring

62

Underwater plug

63

supply and data exchange cable

64

loading and bleed valve

65

retaining ring

66

holding frame

67

Wire rope

Claims (9)

Light measuring device ( 1 ) for the spatially resolved detection of weak light sources by means of an imaging glass fiber optic ( 2 ) with several glass fiber bundles ( 3 ) whose light inputs ( 4 ) at the individual measuring locations and their light outputs ( 5 ) in a central photodetector ( 6 ), which serves as a photon counting, multistage multichannel plate ( 26 ) with a photocathode ( 27 ), and an evaluation unit, characterized in that the light inputs ( 4 ) of the glass fiber bundles ( 3 ) in a spatial arrangement uniformly a closed spherical surface ( 10 ) depending on the spatial detection angles (α) of the glass fiber bundles ( 3 ) are selected, wherein the totality of all spatial coverage angle α the spherical surface ( 10 ) completely covered, and that 32 glass fiber bundles ( 3 ) are provided, which have a detection angle (α) in a range of 20 ° and with their light inputs ( 4 ) centrally in the flat areas ( 7 . 8th ) one into the spherical surface ( 10 ) regular polyhedron ( 9 ) in the form of a truncated icosahedron of 12 pentagons ( 7 ) and 20 hexagons ( 8th ) are performed as an auxiliary construction for fixing and largely symmetrical arrangement, wherein the spherical surface ( 10 ) is formed by a glass sphere into which the entire light measuring device ( 1 ) is encapsulated, on whose inner surface the guided glass fiber bundles ( 3 ) and from which only one supply and data transmission line is led out. Measuring device according to claim 1, characterized in that the polyhedron ( 9 ) in the form of a truncated icosahedron in two symmetrical halves ( 40 ) is divided with 16 faces each. Light measuring device according to claim 1 or 2, characterized in that in the optical fiber optics ( 2 ) between the light outputs ( 4 ) of the glass fiber bundles ( 3 ) and the central photodetector ( 6 ) one additional optical component ( 20 ) is provided. Light measuring device according to claim 3, characterized in that the additional optical component ( 20 ) a single convex lens ( 21 ) or two convex lenses ( 22 ) with an interposed filter wheel ( 23 ) having. Light measuring device according to claim 4, characterized in that the filter wheel ( 23 ) has a transmission filter with a transmission τ = 1, a blocking filter ( 30 ) with a transmission τ = 0, a neutral attenuation filter, for example with a transmission τ = 0.001, a red filter and a blue filter ( 29 ) having. Light measuring device according to one of claims 1 to 5, characterized in that the round light inputs ( 4 ) of the glass fiber bundles ( 3 ) in rectangular light outputs ( 5 ), either with a reproduction ratio of 1: 1 on the photocathode ( 27 ) or closely adjacent rows or columns directly to the photocathode ( 27 ) are positioned. Light measuring device according to one of claims 1 to 6, characterized in that the glass fiber optics with the light outputs of glass fiber bundle from an opaque rubber grommet is surrounded. Light measuring device according to one of claims 1 to 7, characterized in that the glass ball of a unterassertauglichen glass ball in the form of a pressure-resistant, equatorial divided buoyancy ball ( 60 ), which at its north pole is an underwater plug ( 62 ) for connecting a supply and data exchange cable ( 63 ) and a ventilation valve ( 64 ) having. Light measuring device according to claim 8, characterized in that the buoyancy ball ( 60 ) via two mutually braced retaining rings ( 65 ) at the level of the tropics in a support frame ( 66 ), which is connected via a wire rope ( 67 ) is lowered.