GB2148525A - Compound parabolic reflector - Google Patents

Abstract

By using two reflectors, each a parabolic cylinder, that is curving only in two dimensions, light and other waves can be concentrated to a point focus. Similarly parallel waves, in phase with each other, can be emitted from a point source via the reflector. The waves strike the first reflector, the incoming waves being parallel to it axis. They then strike the second reflector which is mounted orthogonally to the first. The result is a point focus. The precise form of the device depends on the 2 focal lengths chosen and the portion of the parabolas utilized. <IMAGE>

Description

SPECIFICATION Compound parabolic reflector Technical Field The device is relevant to number of fields including; Solar power, telecommunications, radar, lighting, radio astronomy, sound recording and emmission.

Background Art It is intended that the device performs tasks requiring a point focus currently achieved using Paraboloid reflectors. Parabolic cylinder reflectors are also relevant to the solution.

The Problem and the Solution Paraboloid reflectors, having 3-dimensional curvatures, are difficult to construct accurately and with a satisfactory reflective surface and are thus expensive.

The problem is to replicate the performance of a parabolid reflector, i.e; 1) Acheive a point focus from waves travelling in parrallel lines with parrallel wave fronts.

2) Form waves travelling in parrallel lines with parrallel wave fronts from a point source.

3) In the above two cases to keep the waves in phase.

The solution is to use two reflectors, each of which is curved as a parabolic cylinder. The waves strike one reflector which is oriented like a conventional parabolic cylinder reflector where the waves are concentrated to a linear focus along the length of the reflector (see Fig. 1). However, in this device, before the reflected waves reach their theoretical focus they strike the second reflector, whose axis of symmetry is at right angles to both the axis of symmetry and the theoretical focus of the first reflector. The second reflector is positioned such that its theoretical focus lies parrallel to the axis of symmetry of the first, i.e. parrallel to the incoming unreflected waves (see Fig. 2) The combined focussing effects of the two reflectors in two orthogonal dimensions results in a point focus (see Fig. 3).It will thus also work in reverse, a point source producing parrallel outgoing waves.

The Drawings Figure 1 shows the first reflector in relation to the incoming waves, AB is the reflectors theoretical focus ABCD is its axis of symmetry.

Figure 2 shows the second reflector in relation to the incoming waves, the first reflectors axis of symmetry (ABCD), and the first reflectors theoretical focus (AB). EF is the second reflectors theoretical focus. EFGH is its axis of symmetry.

Figure 3 shows the two reflectors together.

Note the precise configuration depends on which focal lengths, AD and EH, are chosen and which portion of the parabolas is utilised.

Note AH = EH.

Example A device based on reflectors simular to those in the drawings could be employed as a solar furnace or cooker. Either the device would 'track' the sun or a heliostat would be used enabling the device and its focus to be fixed whilst plane mirrors following the sun and reflected the light onto the device and thence to the focus.

Other examples could include radio and radio telescope dishes, radar collectors, spotlight reflectors, directional microphones, etc.

Exploitation in Industry As this device uses only parabolic cylinder reflectors i.e. curving in 2 dimensions only, in many applications it would be easier and cheaper to use than a paraboloid reflector.

1. The Compound Parabolic Reflector consists of two reflectors each being part of a parabolic cylinder. Parrallel waves by being reflected off the first reflector onto the second reflector can be concentrated to a point focus.

2. A Compound Parabolic Reflector as described in claim 1 may be used in reverse to produce parrallel waves from a point source, the point source being placed at the reflectors focus.

CLAIMS 1. A means of concentrating parrallel waves of energy, such as solar energy, to a point focus, which consists of two reflectors, each of which is part of a parabolic cylinder, the first reflector facing the energy source and reflecting the waves onto the second reflector which is so positioned that its theoretical focus lies parrallel to the axis of symmetry of the first reflector and parrallel to the the direction of the incoming unreflected waves, that is at right angles to the first reflector.

2. A reflector as described in claim 1 used in reverse to produce parrallel waves from a point source of energy, the point source being placed at the reflectors focus.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Compound parabolic reflector Technical Field The device is relevant to number of fields including; Solar power, telecommunications, radar, lighting, radio astronomy, sound recording and emmission. Background Art It is intended that the device performs tasks requiring a point focus currently achieved using Paraboloid reflectors. Parabolic cylinder reflectors are also relevant to the solution. The Problem and the Solution Paraboloid reflectors, having 3-dimensional curvatures, are difficult to construct accurately and with a satisfactory reflective surface and are thus expensive. The problem is to replicate the performance of a parabolid reflector, i.e; 1) Acheive a point focus from waves travelling in parrallel lines with parrallel wave fronts. 2) Form waves travelling in parrallel lines with parrallel wave fronts from a point source. 3) In the above two cases to keep the waves in phase. The solution is to use two reflectors, each of which is curved as a parabolic cylinder. The waves strike one reflector which is oriented like a conventional parabolic cylinder reflector where the waves are concentrated to a linear focus along the length of the reflector (see Fig. 1). However, in this device, before the reflected waves reach their theoretical focus they strike the second reflector, whose axis of symmetry is at right angles to both the axis of symmetry and the theoretical focus of the first reflector. The second reflector is positioned such that its theoretical focus lies parrallel to the axis of symmetry of the first, i.e. parrallel to the incoming unreflected waves (see Fig. 2) The combined focussing effects of the two reflectors in two orthogonal dimensions results in a point focus (see Fig. 3).It will thus also work in reverse, a point source producing parrallel outgoing waves. The Drawings Figure 1 shows the first reflector in relation to the incoming waves, AB is the reflectors theoretical focus ABCD is its axis of symmetry. Figure 2 shows the second reflector in relation to the incoming waves, the first reflectors axis of symmetry (ABCD), and the first reflectors theoretical focus (AB). EF is the second reflectors theoretical focus. EFGH is its axis of symmetry. Figure 3 shows the two reflectors together. Note the precise configuration depends on which focal lengths, AD and EH, are chosen and which portion of the parabolas is utilised. Note AH = EH. Example A device based on reflectors simular to those in the drawings could be employed as a solar furnace or cooker. Either the device would 'track' the sun or a heliostat would be used enabling the device and its focus to be fixed whilst plane mirrors following the sun and reflected the light onto the device and thence to the focus. Other examples could include radio and radio telescope dishes, radar collectors, spotlight reflectors, directional microphones, etc. Exploitation in Industry As this device uses only parabolic cylinder reflectors i.e. curving in 2 dimensions only, in many applications it would be easier and cheaper to use than a paraboloid reflector. CLAIMS

1. The Compound Parabolic Reflector consists of two reflectors each being part of a parabolic cylinder. Parrallel waves by being reflected off the first reflector onto the second reflector can be concentrated to a point focus.

2. A reflector as described in claim 1 used in reverse to produce parrallel waves from a point source of energy, the point source being placed at the reflectors focus.

2. A Compound Parabolic Reflector as described in claim 1 may be used in reverse to produce parrallel waves from a point source, the point source being placed at the reflectors focus.

CLAIMS 1. A means of concentrating parrallel waves of energy, such as solar energy, to a point focus, which consists of two reflectors, each of which is part of a parabolic cylinder, the first reflector facing the energy source and reflecting the waves onto the second reflector which is so positioned that its theoretical focus lies parrallel to the axis of symmetry of the first reflector and parrallel to the the direction of the incoming unreflected waves, that is at right angles to the first reflector.