Optics: measuring and testing – By light interference – Spectroscopy
Reexamination Certificate
2000-03-29
2003-01-07
Turner, Samuel A. (Department: 2877)
Optics: measuring and testing
By light interference
Spectroscopy
C356S455000
Reexamination Certificate
active
06504613
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical interferometer which is used, for example, in an optical measurement technical field.
2. Description of the Related Art
FIG. 13
is a plan view showing an example of a schematic construction of a small-sized optical interferometer according to an earlier development. In this figure, reference numeral
11
denotes an incident light,
12
denotes a beam splitter,
13
and
14
denote mirrors and
15
denotes a photo-detector.
As shown in
FIG. 13
, the small-sized optical interferometer divides the incident light into two optical paths for a transmitted light and a reflected light, which are perpendicular to each other, by using the beam splitter
12
. Two lights reflected on the mirrors
13
and
14
which are disposed so as to be perpendicular to each optical path are multiplexed by the beam splitter
12
again.
At the same time, a direct acting stage (not shown in the figure), on which one mirror
13
is mounted is moved at a constant speed. The optical path difference between the two lights reflected on the mirrors
13
and
14
is caused. A variety of intensity of interference fringes can be observed.
The variety of intensity of interference fringes is fetched by the photo-detector
15
as an electric signal.
Because the mirror
13
is moved along the optical path as described above, the mirror
13
moves a long distance. It takes longer to move the mirror
13
. The accuracy of the optical interferometer must be obtained according to the length of the movement.
Therefore, there are limits of the downsizing of the optical interferometer and of the shortening of the measurement time. It is desired to improve a control of the accuracy of the optical interferometer.
However, in case of the small-sized optical interferometer shown in
FIG. 13
, if the direct acting stage on which the mirror
13
is mounted is not incorporated into a casing which is provided in order to fix the other optical parts thereto, the mechanical adjustment and the optical adjustment cannot be carried out.
Therefore, in a small-sized optical adjustment according to an earlier development, in order to carry out the mechanical adjustment and the optical adjustment, the casing has a certain size. It is desired to improve the downsizing of the optical interferometer. Further, it is desired to improve the optical interferometer so as to obtain many regions in which the optical path difference is caused.
A moving member, such as a direct acting stage, is a consumable part. Because the moving member is approximately united with the casing like an earlier development, good maintenance of the optical interferometer, such as a repair of the moving member or the exchange thereof, cannot be carried out.
Because the moving member is approximately united with the casing as described above, it is necessary to carry out the optical adjustment in the small casing. It is difficult to improve the accuracy of the ratio of the optical interference.
On the other hand, in the Michelson interferometer, a movable mirror can be moved on the same axis as a reference light.
The wavelength of a light can be measured more precisely by moving the movable mirror straight and a long distance.
However, in an optical interferometer according to an earlier development, there is a following problem.
That is, in case of an optical interferometer like the Michelson interferometer in which a movable mirror is moved on the same axis as a reference light, or like the optical interferometer shown in
FIG. 13
, in which the movable mirror is moved on an axis which is perpendicular to the reference light, in order to move the movable mirror straightly and a long distance, the casing for incorporating each type of optical parts thereinto becomes larger.
SUMMARY OF THE INVENTION
In order to solve the above-described problems, an object of the present invention is to provide an optical interferometer which can carry out the mechanical adjustment and the optical adjustment and can improve the maintenance of the moving member and the accuracy of the ratio of the optical interference and which can be sufficiently small.
Another object of the present invention is to provide an optical interferometer which can improve the accuracy of the measurement for a wavelength of a light by moving the movable mirror straight and a long distance and which can be sufficiently small.
That is, in accordance with one aspect of the present invention, the optical interferometer;
the plurality of optical parts are separated into a fixed optical part which is fixed to a casing and a movable optical part which is movable with respect to the casing, and
the movable optical part is incorporated into a block which is removable from the casing.
For example, as an optical part, a beam splitter or a reflector is used.
According to the present invention, because the movable optical part is incorporated into a block which is removable from the casing, the fixed optical part can be adjusted in the casing mechanically and optically by removing the block into which the movable optical part is incorporated from the casing. Further, the movable optical part which is incorporated into the block removed from the casing can be adjusted mechanically and optically. The maintenance of the movable optical part which is incorporated into the block removed from the casing, such as a repair of the movable optical part or an exchange thereof, can be carried out easily.
Because the movable optical part can be removed from the casing as a block, the fixed optical part and the movable optical part can be separately adjusted mechanically and optically. The maintenance of the movable optical part can be improved. Because the fixed optical part is adjusted optically in the casing by removing the movable optical part with the block from the casing, the accuracy of the ratio of the optical interference can be improved. Further, the casing can be efficiently small.
In accordance with another aspect of the present invention, the optical interferometer in which a reference light and a light to be measured branch into two optical paths for a transmitted light and a reflected light, which are perpendicular to each other, by a beam splitter, and in which after the reflected light and the transmitted light are reflected on a plurality of reflecting members each other in each optical path, the reflected light and the transmitted light are multiplexed by the beam splitter to receive the multiplexed light by a photo-detector, is one wherein
the plurality of reflecting members are separated into a fixed reflecting member which is fixed to a casing and a movable reflecting member which is movable with respect to the casing, and
the movable reflecting member is incorporated into a block which is removable from the casing.
For example, a representative reflecting member is a mirror. Instead of a mirror, for example, a corner cube or a reflector may be used.
The photo-detector is one for fetching a variety of intensity of interference fringes as an electric signal.
According to the present invention, because the movable reflecting member is incorporated into a block which is removable from the casing, the beam splitter and the fixed reflecting member can be adjusted in the casing mechanically and optically by removing the block into which the movable reflecting member is incorporated from the casing. Further, the movable reflecting member which is incorporated into the block removed from the casing can be adjusted mechanically and optically. The maintenance of the movable reflecting member which is incorporated into the block removed from the casing, such as a repair of the movable reflecting member or an exchange thereof, can be carried out easily.
Because the movable reflecting member can be removed from the casing as a block, the beam splitter and the fixed reflecting member can be adjusted mechanically and optically so that the movable reflecting member is adjusted separately from them. The maintenance of the movable refle
Akikuni Fumio
Ichikawa Akio
Sano Eiichi
Ando Electric Co. Ltd.
Turner Samuel A.
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