GB2276718A - Instrument for measuring velocity and direction. - Google Patents

Abstract

An optical instrument for sensing absolute movement v of the instrument, relative only to the aether in which light propagates, comprises a coherent light source 1, which is a laser beam, divide 2 into two parallel rays which fan out as spherical wavefronts and overlap at an observer position to create optical interference fringes. The lateral positions of the fringes are affected by lateral motion through space at velocity v measured in the plane of the parallel ray axes. Displacement of the fringes is detected by a photoresistor 6 placed behind a pinhole in a screen 5. The screen can also be laterally displaced to scan across the fringes. The instrument can be suspended to allow rotation in order to vary its absolute orientation, which is said to be detectable by the fringe displacement. The instrument thus has navigational or educational applications. <IMAGE>

Description

INSTRUMENT FOR MEASURING VELOCITY AND DIRECTION FIELD OF INVENTION This invention relates to apparatus instrumental in detection of motion by optical effects confined to a reference datum seated within the apparatus.

Such apparatus finds application as a scientific educational aid for physics students, where it may sit alongside a modern laser demonstration version of the late 19th century Michelson-Morley experiment, and serve as a teaching aid to contrast their operation.

With adaptation the apparatus may also serve as a navigational aid, particularly as a sensor of a recognized fixed cosmic space direction, just as the gyrostatic compass and the magnetic flux-gate compass assist in navigation by determining, respectively, the directions of the Earth's spin motion axis and that of the local geomagnetic field.

BACKGROUND OF THE INVENTION Although many physicists indoctrinated with the philosophical teachings of the theory of relativity believe that it is impossible to detect linear motion through space by optical interferometry techniques involving enclosed apparatus, they well know that rotation can be detected by such methods.

There is a developing body of scientific opinion which recognises that the detection of linear motion by optical interferometry is elusive when a light ray travelling through space in a forward direction is reflected back on its own path so that its propagation is affected by the energy of the reflected ray. The result in the latter case is the setting up of standing waves which, for a translational linear motion of the apparatus, involves phase locking on mirror surfaces and consequent wave energy transport with the apparatus. In contrast, with rotation, the apparatus can rotate relative to the non-rotating standing wave energy and the rotation can be sensed.

The inventor of the subject invention has earlier proposed in U.K.

Patent 884,830, dating from 1958, that the cosmic speed at which apparatus travels through space can be measured by transmitting a modulated electromagnetic wave in a forward direction and, instead of reflecting that wave back through itself, generating a return wave that propagates by mass displacement and vibration. By matching the low modulation frequency of the high speed electromagnetic wave with the high vibration frequency of the low speed acoustic wave, to achieve comparable wavelength effects, the objectives of the Michelson-Morley experiment can be achieved without the presence of a standing wave condition.

Though the principles underlying that 1958 invention remain valid, the technological implementation has proved difficult and has led the inventor to seek other routes to the objective.

The inventor has been encouraged in this quest by the reports of apparatus built by E. W. Silvertooth, who has routed the forward light ray around a path quite separate from that of the return ray but caused component rays to meet head-on in a specially developed standing wave sensor. Then, by displacing the standing wave sensor so that it tracks along the ray path and senses wave interaction at the surface of a photosensitive window where the rays meet, there is a detection which responds to the space velocity component preserved in the phasing of the separate rays. Silvertooth has detected cosmic motion at a speed of 387 km/s by this apparatus, subject to directional orientation of his apparatus, thereby showing that it is possible to sense a cosmic motion axis by optical interferometry effects in an enclosed laboratory. This Silvertooth experiment does, therefore, achieve the Michelson-Morley objective of detecting motion through an aether.

However, the Silvertooth apparatus involves an intricate interferometry measurement as the detector is displaced in steps through nodes and antinodes spaced according to the very short wavelength of the laser light source used. A separate optical scaling arrangement is required to determine the coincidence of the relevant fringes, whilst very many intervening fringes are discounted. This involves a very sensitive structure and a fringe count which, though first-order, rather than second-order, in the velocity measurement sensitivity (in terms of v/c, the cosmic velocity to speed of light ratio), is inversely proportional to the physical displacement measured.

The subject invention overcomes these problems, whilst affording a first-order v/c test, for which the physical displacement measurement is linearly and directly proportional to the measured velocity v and for which the observation is not obscured by an intervening set of optical fringes which need to be discounted in the observation.

BRIEF STATEMENT OF INVENTION According to the invention, an optical instrument for measuring velocity and direction of motion comprises a laser light source, means for dividing the laser beam into two parallel rays, each being divergent so as to set up a spherical wavefront, photo sensor means positioned in the ray path and spaced at a set distance from the source points from which the rays are divergent, screening means adjacent the photosensor means positioned in the ray path to intercept most of the light radiation but having a small aperture which admits light to the photosensor over a restricted field of view, means for displacing the screening means in the plane common to the two parallel rays and laterally with respect to the ray path, whereby the displacement position of the screen determines the position of the aperture in relation to optical interference fringes formed by the overlap of the two rays, and electrical measurement means for monitoring the output from the photosensor in relation to the space orientation of the instrument and the displacement position of the screen.

According to a feature of the invention, the means for dividing the laser beam into two parallel rays comprise a translucent plate having surfaces which are partially reflecting, positioned to reflect the beam by producing a first reflected ray at its front reflecting surface and by producing a second reflected ray at its rear surface.

According to further feature of the invention, the means for dividing the laser beam to cause the rays to be divergent further comprise at least one concave lens through which light from the laser passes en route to the photosensor.

According to another feature of the invention, the instrument comprises a rigid frame structure which may be mounted so as to be free to turn about an axis and all components associated with the optical path, including the laser and photosensor are attached to said frame in fixed positions relative to each other, whereby the interference fringes formed by the overlap of the two rays have positions relative to the aperture admitting light to the photosensor with a dependence upon the orientation of the instrument in relation to the applicable optical frame of reference in space that governs the light propagation.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows in schematic form the optical layout of a test apparatus incorporating the invention, in which the fringe patterns set up by a an interferometer are positioned as a function of motion of the apparatus at speed v through space.

Fig. 2 shows how two mutually coherent light sources develop interference fringes in the manner applied by this invention.

DETAILED DESCRIPTION OF THE INVENTION It has been known from the time of Bradley in 1727 that light from stars is subject to aberration. During the transit of light from star to Earth the Earth's motion across the ray path of the incoming starlight has an effect on the apparent position of the star. Even light passage through the observing telescope has a transit time affecting the observation. The telescope has to be inclined as a function of the translational motion of the Earth in order that the ray from the star should be properly focussed in travelling from the objective to the eyepiece.

The aberration or angle of tilt affected is measured by a factor v/c, where v is the speed of motion laterally with respect to the incoming ray, which travels at speed c.

If the star and the Earth were both moving at the same velocity through free space, with light speed referenced on free space, there would be no way of measuring the speed v, because the angle of the telescope would not change with time. It does with Bradley's aberration observations owing primarily to the 30 km/s orbital motion of the Earth around the sun. Such a change follows a one year cycle.

This invention contemplates a way of sensing motion through space when both source and observer are in the Earth laboratory and so move with the same Earth velocity.

The secret of the invention and, indeed, what is a major scientific step forward in science, lies simply in the inventive step of causing the light source, which is a laser beam, to divide into two parallel rays which fan out as spherical wavefronts and overlap at an observer position to create optical interference fringes. The positions of the fringes are affected by motion at velocity v measured in the plane of the parallel ray axes and lateral to the ray direction.

Hitherto, those who subscribe to Einstein's philosophy and do not question the optical principles of the Michelson-Morley experiment, have believed wholeheartedly that v, as a motion of apparatus through space as a light reference frame, could not be sensed in an enclosed laboratory experiment. Experiments using the apparatus of this invention proves that belief to be manifestly illfounded.

This is to the detriment of technological progress, not only in respect of technology relating to navigational aids but also in regard to energy research that is based on probing aether properties. The Einstein school of thought denies the existence of an aether in the real sense and substitutes an imaginary four-dimensional abstract mathematical world which does not guide us to new energy technology.

This invention has therefore an importance that goes beyond navigational applications of the instrumentation and serves to provide laboratory test apparatus essential on a worldwide scale for the reeducation of physicists to get them back on track researching the energy properties of the aether.

The essential features of the invention will be apparent from the following inventor's description of the apparatus shown schematically in Fig. 1 and experimental results obtained in the first tests performed two months prior to the date of this patent application.

The subject of Einstein's theory of relativity is dangerous ground for discussion. It is very emotive and few physicists really understand the subject, whilst engineers and technologists feel unable or dare not challenge those who support it. It concerns transformation factors affecting time and distance, but dependent upon a v/c parameter, v and c representing motion of matter and light respectively. An immediate problem then comes from the question: Motion relative to what? In order to describe this experiment and its manifestly successful result, one has to disregard this awkward question and suppose that a wavefront of light, having left its source, is then on its own in free space.

Further, let us regard this wavefront as being a small conic sector of a spherical wave transmitted in all directions from a point source, and centred on its original point in space. Then, if the motion is at rightangles to the path, source to observer, this small conic sector, this wavefront, which reaches the observer must be travelling along the path, source to observer, not normal to its direction, but obliquely at an angle.

It is this small angle of obliquity of a wavefront that is detected in the present experiment. The exact centre of such a wavefront is not affected, but all other parts of a wavefront arrive at the observer early or late compared to the centre, the earliness or lateness being dependent on a lateral distance from the centre and on the motion, v.

Referring to Fig. 2, suppose that a coherent source of light can be divided to form two sources of light side by side, preserving the phase coherence, as is possible using laser and beam splitting technology.

Two wavefronts travelling from sources S1 and S2 developing into spherical waves propagating from the respective sources are shown to overlap at a surface where they form interference fringes F1, F2, etc.

Note that the fringes have their brightest positions where the distances to the two sources differ by zero or an integral number of wavelengths at the light frequency.

Those familiar with optics will well understand how such fringes are formed with their intervening dark areas where the waves overlap destructively instead of constructively.

However, what is overlooked in the teachings of optics is the fact that the light waves actually travel through an aether medium and, though leaving the two sources with coherence, if those two sources are moving at velocity v relative to that aether, that pattern of fringes depicted in Fig. 2 is a pattern of light energy that moves with velocity v but the physics governing its formation is referenced on the aether itself.

By this it is meant that the construction of the wave interference has to allow for lateral displacement of the apparatus through that aether during the transit time of light from the source to the fringe detection position.

If v changes, the positions of the fringes should change as well.

Otherwise, since a laser source can be sufficiently stable and the optical geometry of the apparatus can be fixed, the fringes should be relatively insensitive to ambient disturbances.

Here one must note that, as with Bradley's 1727 aberration measurements, the factor being measured is v/c, where v is small in relation to c. This is much easier than trying to measure (v/c)2, which is the factor that was the subject of the test in the Michelson-Morley experiment. Accordingly, the experiment and apparatus now to be described does not suffer from the high sensitivity to noise and vibration and general enivironmental disturbances which beset the pioneer experiments in this field.

The inventor's apparatus to detect the v-dependent fringe displacement was assembled as shown in Fig. 1 and operated as follows: A helium-neon laser 1 provided a convenient split beam in a very simple manner. The laser with its beam directed upwards at an angle was mounted on a framework (not shown). Its beam was reflected vertically downwards from a piece of plain glass 2, the surfaces of which are partially reflecting. Two interfering parallel beams are produced, one from the front surface of the glass and one from the back surface. The narrow (circa lmm diameter) beam was expanded slightly with a concave lens 3, just before the glass plate, and expanded, again with a concave lens 4, after the glass plate 2. The expanded split beam produced an interference pattern of light and dark bands where the two beams overlap on a flat screen 5 which also forms the base of the supporting framework.

In the overlapping area the extremities (extreme edges) of the wavefronts of one beam interfere with wavefronts of a part of the other beam closer to its centre, somewhat as shown in Fig. 2. In terms of an assumed motion through the aether, a small lateral shift of the interference bands was thus expected when the whole assembly was rotated on a vertical axis (as described later) thereby reversing the angle of obliquity. By very rough approximation, calculation showed that such a shift could not be greater than about 0.1 or 0.2 mm, and therefore impossible to see unaided in the low light values projected on the screen, for although the narrow laser beam is intensely bright, when it is expanded over a large area in the manner described, the interference bands are only visible in a dark-room.

In order to detect this lateral shift of the interference bands, a photo-resistor 6 was mounted close to the fulcrum of a lever which could be moved horizontally, allowing the photo-resistor to be moved very precisely across one or two interference bands. This lever system is not shown in the drawings because, functionally, the action is only to displace the position of the screen on which the fringe pattern forms.

The double headed arrow indicates the axis of such position adjustment.

A suitable vernier leadscrew displacement device or any equivalent precision mechanical adjustment technique could serve the same objective.

The photo-resistor 6 was obscured by thin sheet metal (the screen 5) except for a pin-hole about 0.15 mm diameter. With the lever and fulcrum position adjustment, moving the lever in the inventor's test apparatus gave a sixteen to one reduction over the movement of the pinhole, so that the pin-hole could be positioned exactly in the centre of a transition area between a light and dark band. The slightest lateral movement of the interference bands would thus cause a change in the value of the photo-resistor. Conversely, a measured movement of the lever, giving the same change in resistance gave a fairly accurate measurement of the movement of the interference bands and was useful for calibration purposes.

The lever operation is not shown but the reader can visualize the screen 5 having a pivot point (or fulcrum) close to the aperture but positioned in a vertical axis offset slightly from the plane of the diagram.

With nine volts applied across the photo-resistor the changes in current were too small to be measured with available instruments.

Therefore a D. C. differential amplifier 7 was designed using an I. C. 741 op-amp. This gave an output comfortably within the range 0-50 analogue microammeter 8 available. The circuit of the amplifier 7 is not shown, because D. C. amplifiers of the design adopted are well known in the electronic art.

Everything here described, except the microammeter, was supported on the same framework, which was suspended, balanced and vertical, by a single slender synthetic fibre cord. This structure, by which the apparatus of Fig. 1 was mounted on a wooden frame or carriage, is not shown in the drawings and the following description therefore serves primarily to show that even a relatively crude test assembly can function without suffering the sensitivity problems which confront the Michelson-Morley method. The mains cable to the laser for its power supply and twin flex for the microammeter were slackly suspended more or less parallel with the supension cord. The whole assembly could thus be gently turned on a vertical axis through a full turn in any direction without any alteration of its centre of gravity, or any change in stress in the framework. As it transpired, the physical action of turning the assembly gently, or not so gently, made no detectable difference to the readings obtained, which were very definite and repeatable.

In operation the following procedure was carried out. The laser was switched on an hour or two before commencing, in order that it would have timw to stabilize. The pin-hole was covered, i.e. the photoresistor was put in complete darkness, and the amplifier was adjusted to read zero microamperes. Making sure that the room was completely dark except for a very small light on the dial of the microammeter, the interference bands were then visible on the screen. The lever was moved, carrying the pin-hole from a light band to a dark band (or vice versa). The meter indicated 40 microamps in a light band and 5 microamps in a dark band. If the lever was moved, placing the pin-hole in a transition area between light and dark bands, the meter reading was an intermediate value.

While watching the meter the whole assembly was rotated. Between two orientations 1800 apart, the meter moved down to a minimum and up to a maximum reading. During the day, the difference between minimum and maximum varied between 11 and 25 microamperes movement, the smaller difference occurring around noon and the greater difference occurring around midnight. These observations were made during January and early February 1993.

During the orientation of the assembly, these maximum and minimum readings were observed when a line at right-angles to the interference bands was aligned approximately N-S or NNW-SSE, this also varying during the day.

Moving the lever, i.e. moving the pin-hole, a measured distance giving equivalent results, showed that the interference bands had moved approximately 0.2 mm minimum and 0.4 mm maximum during the orientations.

To conclude this description, it is apt to quote the last paragraph from the first specification of the inventors original U.K. Patent No.

884,830 dating from 1958: 'The measurement of true or absolute velocity and direction has many important applications for the astronomer. Another application for the apparatus is in navigation. The direction of the Earth's motion through space tabulated as an angle with the surface of the Earth, together with position and Greenwich time, will be a useful addition to the magnetic compass and make the navigator independent of the position of sun and stars in conditions when cloud obscures the sky.'

Claims (4)

1. CLAIMS 1. An optical instrument for measuring velocity and direction of motion comprises a laser light source, means for dividing the laser beam into two parallel rays, each being divergent so as to set up a spherical wavefront, photosensor means positioned in the ray path and spaced at a set distance from the source points from which the rays are divergent, screening means adjacent the photosensor means positioned in the ray path to intercept the light radiation but having a small aperture which admits light to the photosensor over a restricted field of view, means for displacing the screening means in the plane common to the two parallel rays and laterally with respect to the ray path, whereby the displacement position of the screen determines the position of the aperture in relation to optical interference fringes formed by the overlap of the two rays, and electrical measurement means for monitoring the output from the photosensor in relation to the space orientation of the instrument and the displacement position of the screen.
2. 2. An instrument according to claim 1, wherein the means for dividing the laser beam into two parallel rays comprise a translucent plate having surfaces which are partially reflecting, positioned to reflect the beam by producing a first reflected ray at its front reflecting surface and by producing a second reflected ray at its rear surface.
3. 3. An instrument according to claim 2, wherein the means for dividing the laser beam to cause the rays to be divergent further comprise at least one concave lens through which light from the laser passes en route to the photosensor.
4. 4. An instrument according to claims 1, 2 or 3, which comprises a rigid frame structure which may be mounted so as to be free to turn about an axis and all components associated with the optical path, including the laser and photosensor are attached to said frame in fixed positions relative to each other, whereby the interference fringes formed by the overlap of the two rays have positions relative to the aperture admitting light to the photosensor with a dependence upon the orientation of the instrument in relation to the applicable optical frame of reference in the space medium that governs the light propagation.