JPH0464565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a radiation source specifying a wavelength range, dispersing a light beam into component wavelengths along a spectral region, and dispersing an optical beam at a position along said spectral region. The present invention relates to a light conversion device comprising an optical head such that the wavelength of light emitted from the head is reflected onto a position along a spectral region, and a displacement member movable in relation to the spectral region also in the optical path.

BACKGROUND OF THE INVENTION Optical conversion devices are known and typically use a light source receiver, such as that provided at the end of a fiber optic cable, and a device that varies the amount of light falling on the receiver according to its displacement.

The light beam variable device uses a variable mask with a variable shape mirror diameter or a gray optical density filter whose density varies along the direction of displacement. These devices can function satisfactorily provided that the light density impinging on the receiver does not change for other reasons.

PROBLEM SOLVED BY THE INVENTION Modulation of the light beam emitted by a light source, such as that caused by changes in the power supply to the light source,
Causes incorrect displacement decoding.

The effect of such a change in light density is
This can be prevented by modulating the spectral content of the light beam according to the displacement.

However, the problem with this type of conventional conversion device is that it is difficult to output a linear output because the device that causes spectral dispersion is not linear and the wavelength decoder does not always have a linear output response. It is in.

There are other devices in which the light is dispersed into spectral components and a coded mask changes position within the spectrum to transmit different spectra according to the position of the mask.

The light rays passing through the mask are focused onto one end of the fiber optic cable and redistributed at the other end of the fiber optic cable. By measuring the light density of various spectra, it is possible to determine the position of the mask.

However, the problem with such devices is that the image formed is spread across the image plane due to the dispersive nature of the spectrum reflected on the mask, so that all the light rays transmitted through the mask are It is difficult to ensure focusing at the end of the receiving fiber optic cable.

Additionally, there is the problem that under some circumstances it is not possible to use a transparent mask that requires access devices on both sides of the mask.

(Means for Solving the Problems) An object of the present invention is to provide an optical conversion device that overcomes the above-mentioned problems.

According to the invention, the displacement member is optically encoded with a reflective member such that light of different wavelengths is reflected back by the displacement member to the optical head depending on the position of the displacement member; The head emits reflected light according to the wavelength to be imaged at the end of the light guide, and the light guide
It is an object of the present invention to provide an optical conversion device of the type described above, characterized in that it is connected to a detector responsive to different wavelengths of light and is adapted to provide an output depending on the position of the displacement member.

The optical head preferably comprises a diffractive element for dispersing the light beam into its component wavelengths and for emitting the light beam reflected from the reflective element into the light guide. The diffractive member may be a diffraction grating.

The optical head includes a converging reflective surface positioned to direct and reflect the light beam toward the diffractive element to focus the light beam on the end of the reflective member and the light guide.

The conversion device includes a first light guide that delivers light from the light source to an optical head, and a second light guide that delivers light from the optical head to a detector. The first light guide is preferably a single fiber, ie a fiber optic cable. The optical head consists of an optically transparent solid block.

The displacement member is a number display encoder. The encoder has two reflective tracks whose separation varies according to the position of the encoder, and the detector is responsive to the separation between the wavelengths reflected by the two reflective tracks and thereby outputs an output signal. supply.

The displacement element is movable in two mutually perpendicular directions, and the detector is responsive to both the separation between reflected wavelengths and the absolute value of the wavelengths, and provides output in two directions depending on the position of the displacement element.

The displacement member is a rotating disk, one of whose reflective tracks is circular about the axis of the rotating disk, and the other track is spiral.

(Example) Hereinafter, an optical conversion device according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the optical conversion device of the invention comprises a radiation source 1 in the range of wavelengths λ ₁ to λ ₂ provided by a radiation diode or other light source such as a tungsten lamp, and an electric It is equipped with a driver 21. The light beam from the radiation source 1 is delivered to the optical head 3 via a single fiber or fiber optic cable 2, which will be explained in more detail below.

The optical head 3 disperses the light beam into a component spectrum and directs this component spectrum to an encoder plate 4 which rotates about an axis 5 due to changes in the input variables. Thus, for example, an input variable is derived from a pressure or temperature sensor which is coupled to rotate the shaft 6 of the encoder plate 4 .

The encoder plate 4 reflects different spectra back to the optical head 3 depending on its position. This reflected light beam is collected by the optical head 3 and fed to one end of a single fiber or return fiber optic cable 7. The other end of the return fiber optic cable 7 is connected to a wavelength decoder 8 which separates the light beam returned by the cable 7 into component wavelengths.

The wavelength decoder 8 is equipped with a conventional dispersive device such as a grating or a prism.
is focused into a photodiode or similar linear array 9 that supplies the .

Since the emitted photodiode is always spread over several photodiodes rather than just one, a signal processor 11 is used to equalize the peak distribution. The output from the signal processor 11 is fed to a display 12 which provides a visual depiction of the position of the encoder plate 4 which is calibrated to directly indicate the variable being observed, e.g. pressure or temperature. The output is fed to other devices, for example to provide control over the measured variables.

When using white light of sufficient intensity, some of the modified light is dispersed and used to illuminate a point on the control panel.

Such devices display variable status easily and directly. For example, at one end of the visible spectrum is red, which indicates dangerously high pressure, while green indicates safe pressure.

The optical head 3 will be explained in detail with reference to FIG.

The optical head 3 is a solid glass block formed of several glass elements bonded together. However, other optically transparent materials can also be used. The main part of the optical head 3 consists of a conventional collimating block 31 with a converging spherical surface 32 provided with a reflective coating layer 33.

The opposing surface 34 of the collimating block 31 is flat and supports the other components of the optical head 3. These include prism members 35 and 36 mounted at the upper end of the plane 34 and into which the light rays enter and emanate from the optical head 3.

The input member 35 has a flat surface 37 adjoining the flat surface 34 of the collimating block 31 and an inclined surface that reflects the incident light rays onto the collimating block 31 and passes the rays exiting from the collimating block to the radiating member 36. It has 38.

The radiation member 36 is a parallelepiped, and one surface 39 thereof is in contact with the inclined surface 38 of the input member 35 . The opposing surface 40 is coated with a reflective material to direct the light beam back to the fiber optic cable 7.
reflect to.

A diffractive member 141 is joined to the plane 34 below the input member 35 and the emitting member 36 . The diffraction member 141 is a glass block having a flat surface 142 that joins the light collimating block 31 and an inclined surface 43 coated with a reflective diffraction grating layer 44.

At the lower end of the plane 34 of the light collimating block 31,
Reflective coated and collimating block 3
A prism member 45 having an inclined surface 46 that reflects light rays exiting downward from the encoder plate 4 is attached.

Similarly, the light beam reflected by the encoder plate 4 is
The light is reflected onto the collimating block 31 by the inclined surface 46 .

Following the optical path through the optical head 3, the light beam from the optical fiber cable 2 enters the optical head 3 perpendicularly and downwardly and is dispersed. The inclined surface 38 reflects the light beam horizontally to the right toward the focusing spherical surface 32, as shown in FIG.

Focusing sphere 32 is arranged to produce a horizontally reflected beam that is directed to the left through collimating block 31 and onto diffraction grating 44 .

Diffraction grating 44 disperses the incident light beam into a component spectrum to create a reflected beam spread between the solid and dashed lines, as shown in FIG. This dispersed light beam is directed towards a focusing sphere 32 which focuses the incident light beam and further to the left, i.e. to the prism member 4.
Directed to 5.

Further, this light beam is transmitted to the inclined surface 4 of the prism member 45.
6 and is reflected downward and focused on the surface of the encoder plate 4. This ray therefore has a spectrum 6 formed along the radial area of the encoder plate 4.
It is dispersed into 0 component wavelengths.

The light beam reflected by the encoder plate 4 follows the same optical path through the optical head 3 and back to the diffraction grating 44. The light beam reflected from the encoder plate 4 to the diffraction grating 44 is deflected at an angle corresponding to the wavelength of the light beam. The rays reach the inclined surface 38 of the input element 35 after being reflected by the focusing spherical surface 32 .

Since the inclined surface 38 of the input element 35 and the surface 39 of the radiating element 36 both act like a beam dispersion surface,
The light beam reflected from the encoder plate 4 is transmitted by the surfaces 38 and 39 to the reflective surface 40 and radiated to the return fiber optic cable 7.

The diffraction grating 44 images all the rays reflected by the encoder plate 4 to the same point on the return fiber optic cable 7 end.

By using the optical head 3, the light beam is dispersed and those wavelengths reflected by the reflective track of the encoder plate 4 are recombined by the diffraction grating 44 before being imaged onto the encoder plate 4. Ru.

In this way, a small diameter objective image formed at the end of the fiber optic cable 2 is created along the spectrum 60 on the encoder plate 4, and its reflected rays are retro-reflected to the end of the return fiber optic cable 7. are combined and focused as a small-diameter objective image.

The image focused on the end of the return fiber optic cable 7 is the same size as the image on the end of the fiber optic cable 2. Therefore, when the diameter of the return fiber optic cable 7 is the same as the diameter of the fiber optic cable 2, the efficiency is highest.

The same type of optical head is used to disperse and combine the light beams by using a reflective encoder plate. Therefore, there is no need to provide a separate coupler which increases cost and volume.

The use of a reflective encoder plate also eliminates the need for an access device after the encoder plate. This allows encoding symbols to be attached to opaque members such as flywheels.

a focusing spherical surface 32, a diffraction grating 44 and a reflecting surface 38,
Since 45 and 40 are all mounted on solid blocks, there is little risk of mutual contact between the surfaces due to vibration.

It is possible to use the same fiber optic cable to supply and receive the light beam. However, when a fiber optic cable is provided with a connector, there is a risk that reflections will occur at the connector or that a portion of the incident light beam will be delivered to the decoder, where it will be difficult to distinguish it from the reflected light beam.

One type of encoder plate 4 is shown in FIG.

This encoder plate has tracks 71 and 72.
There is a non-reflective background and a reflective member such as.

The outer track 71 is circular, centered on the axis 5 of the encoder plate. The inner track 72 is
The distance between the two tracks 71, 72 is spiral-shaped so that the encoder plate 4 rotates and changes.
The spectrum formed on the encoder plate 4 has a region 60 extending radially across both tracks.
It is indicated by.

As the encoder plate 4 rotates, the various components of the spectrum are reflected back from the helical track 72 to the optical head 3.

If both tracks are concentric, circular track 71 will retroreflect rays of the same component of the spectrum. However, in the present invention, by measuring the separation distance between two tracks, the transducer
You will no longer notice concentricity errors on the encoder board.

The encoder plate can be digitally encoded, such as using a Gray encoding system.

The encoder plate does not need to be a rotary plate type as described above, and may be any plate that can move in the length direction of the plate. An example of this plate 70 is shown in FIG.
It has two reflective tracks 71 and 72. Each track 71, 72 is inclined towards each other in the width direction of the plate 70 such that the track separation varies depending on the length of the plate.

For such a board, at right angles to its width,
and it is possible to measure the displacement of the plate in the direction of its length.

FIG. 4A shows the image spectrum 60 shown in FIG.
The output response of the photodiode array 9 to the plate 70 at the position .

As plate 70 is displaced to the left, the separation between tracks 71 and 72 on which spectrum 60 is imaged decreases, and the power peaks of the response move closer together, as shown in FIG. 4B. However, if the plate 70 is displaced in the width direction without any displacement in the length direction, the separation between the peaks in the response will not change, but the relative positions will change as shown in FIG. 4C.

By monitoring the relative positions of these peaks, the displacement of the plate in the two coordinate directions can be monitored.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conversion device according to the invention. FIG. 2 is a side view of the optical head of the conversion device according to the invention. FIG. 3 is a plan view of a displacement encoder element used with a transducer according to the invention. FIG. 4 is a plan view of another encoder member. 4A, 4B and 4C show the output response at various positions of the encoder member of FIG. 4. FIG. 1... Radiation source, 2... Optical fiber cable, 3
...Optical head, 4...Encoder plate encoder, 5...Rotary shaft, 6...Input shaft, 7...
Return optical fiber cable, 8...detector decoder, 9...detector linear array, 1
0... Line, 11... Detector signal processor, 12... Display device, 21... Electric driver, 31... Light collimating block, 32... Focusing reflective spherical surface, 33... Reflective coating layer, 34,
42...Plane, 35...Incidence member, 36...Radiation member, 37, 38, 39, 40, 43, 46...
Reflection surface, 141... Diffraction member, 44... Diffraction grating, 45... Prism member, 60... Spectral region, 70... Interplate encoder member, 71,7
2...Reflex track.

Claims (1)

[Scope of Claims] 1. An optical radiation source specifying a range of wavelengths, dispersing the light beam into component wavelengths along a spectral range across the radiation path, and emitting light from an optical head at a position along the spectral range. an optical head adapted to image a light beam wavelength onto a position along a spectral range that traverses the radiation path; and a displacement member movable in relation to the spectral range that also traverses the radiation path in the optical path. The displacement member 4, 70 is an optical conversion device comprising a reflective member such that light beams of various wavelengths are reflected back to the optical head 3 by the displacement member according to the lateral position of the displacement member. The optical head 3 consists of a light collimating block 31 of optically transparent material containing on its surface a diffraction grating 44 which disperses the radiation according to the component wavelengths and a converging reflective sphere 32 on another surface. The converging reflection spherical surface 32 is configured to direct the reflected light beam toward the diffraction grating 44 and condense the emitted light beam onto the reflection members 41, 42, 71, 72, and the reflection member 4.
1, 42, 71, 72 is arranged so that the reflected light rays are focused on one end of a return fiber optic cable 7, said return fiber optic cable being connected to a detector 8, which is responsive to light of different wavelengths.
9 and 11, and is adapted to supply an output according to the position of the displacement member. 2. The optical conversion device according to claim 1, wherein the diffraction member is a diffraction grating 44. 3. It is characterized by comprising an optical fiber cable 2 for supplying the light beam from the radiation source 1 to the optical head 3, and a return optical fiber cable 7 for supplying the light beam from the optical head 3 to the detectors 8, 9, 11. An optical conversion device according to claim 1 or 2. 4. Optical conversion device according to claim 3, characterized in that the first light guide is a single fiber or optical fiber cable 2. 5. The displacement members are number display encoders 4, 70, and the encoder 4 has two reflective tracks 41, 70.
42, the other encoder 70 has two reflective tracks 71, 72 whose separation distance varies according to the position of the encoder, and detectors 8, 9, 11 detect the wavelengths reflected by the two tracks. 5. An optical conversion device according to any one of claims 1 to 4, adapted to be responsive to and thereby provide an output. 6. The displacement member 70 is movable in two mutually perpendicular directions, and the detectors 8, 9, 11 are responsive to both the separation between the reflected wavelengths and the absolute value of the wavelengths, and are responsive to the position of the displacement member along both directions. 6. An optical conversion device according to claim 5, characterized in that the optical conversion device provides an output by. 7. A patent claim characterized in that the displacement member is the rotary plate 4, one reflective track 71 is circular and centered on the rotation axis of the rotary plate 4, and the other reflective track 72 is spiral-shaped. The optical conversion device according to item 5.