Radiant energy – Radiation controlling means
Patent
1995-11-16
1997-11-18
Anderson, Bruce
Radiant energy
Radiation controlling means
378149, G02B 500, G21K 100
Patent
active
056891180
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a slit pattern, to be referred to as grid, and a method for the manufacture thereof.
The present grids which are the object of this invention are intended in particular for observing electromagnetic radiation, in particular X-radiation and gamma-radiation, using satellites. A detection device for observing such radiation generally comprises two so-called arrays, each comprising a plurality of grids, and a detection surface made up of radiation detectors. Each grid has a surface area in the range of from 50 mm by 50 mm to 200 mm by 200 mm. An array comprises, for instance, 32 grids, each grid having a different slit width and/or slit direction. The two arrays are identical and are arranged in spaced parallel relationship perpendicularly above each other. A suitable distance between the two arrays is, for instance, 6 m. The radiation is incident on the first array and is transmitted or absorbed depending on the angle of incidence. The transmitted part of the radiation is incident on the second array and there, too, is transmitted or absorbed depending on the angle of incidence. Behind the second array a detection surface with radiation detectors is arranged. The radiation incident on the detection surface provides, upon detection and subsequent signal processing, an image of the source of radiation.
The slit width of the grids in an array should vary from about 4 mm to about 50 .mu.m. For a grid of a slit width of about 50 .mu.m, the distance between the centers of two adjacent slits, to be referred to as pitch, is about 100 .mu.m and the deviation of the slit width should not exceed a few microns. The resolution of the detection device is determined by the grid having the smallest slit width and by the relative distance of the arrays.
In itself it is no problem to manufacture a slit pattern of a slit width of 50 .mu.m and a pitch of 100 .mu.m in thin material. This is simple to realize by means of etching techniques.
However, the problem is that the present grids must have a thickness of at least about 3 mm. The ratio between the height and the width of a slit is therefore at least 60:1. Such a pattern can no longer be manufactured by means of etching technique.
Moreover, the grids must be resistant to the vibrations that occur upon the launching of the satellite in which the grids are disposed and to the large temperature fluctuations that occur when the satellite moves from the sunlight into the shade or vice versa.
A further problem which occurs with the manufacture of grids is that when the thickness of the spacers deviates from the nominal thickness, the desired pitch between the slits is not achieved. However, the spacers can be manufactured in such a manner that the deviation in the thickness of the spacers is very slight. On the other hand, by stacking the spacers, each very slight deviation is successively added to the preceding deviation. Thus, stacking a large number of spacers which themselves are manufactured with an accurate thickness still leads to an unacceptable positional deviation through cumulation of the deviations in the thickness of the spacers.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a grid which satisfies the above stated requirements and with which the problems of the prior art are solved.
A grid thus built up offers the advantage that the separate parts thereof, such as the laminations and the spacers, can be manufactured in a highly accurate manner at relatively slight cost and that after assembly, which in essence does not amount to more than stacking the separate spacers onto each other with interposition of the separate laminations, a grid is obtained which satisfies the stated requirements. The presence of the guides provides the advantage that the laminations are distanced by spacers at several points along their length, so that the chances of the laminations bending relative to each other, which would disturb the slit pattern, are reduced to a minimum.
Because of the guides with the
REFERENCES:
patent: 3749911 (1973-07-01), Hoover et al.
patent: 4288696 (1981-09-01), Albert
patent: 4419585 (1983-12-01), Strauss et al.
patent: 4460832 (1984-07-01), Bigham
patent: 4465540 (1984-08-01), Albert
patent: 4951305 (1990-08-01), Moore et al.
patent: 5099134 (1992-03-01), Hase et al.
Anderson Bruce
Michaelson Peter L.
Technische Universiteit Delft
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