Optical: systems and elements – Deflection using a moving element
Reexamination Certificate
2000-03-31
2001-08-28
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
C359S208100, C359S212100, C359S214100, C359S221200, C359S223100, C359S226200
Reexamination Certificate
active
06282008
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to scanning optical systems and, more particularly, to a compact scanning optical system comprising a combination of a deflecting mirror and a reflecting optical system, which is suitable for various uses, e.g. information reading, information recording, and measurement.
Japanese Patent Application Unexamined Publication (KOKAI) No. 11-84291, which was proposed by the present applicant, discloses a scanning optical system comprising a combination of a reflecting optical system having a reflecting surface formed from a rotationally asymmetric surface having only one plane of symmetry, e.g. a free-form surface, and a deflecting mirror, e.g. a polygon mirror.
Japanese Patent Application Unexamined Publication (KOKAI) No. 10-123449, which was also proposed by the present applicant, discloses a compact scanning optical system of the type described above, which uses a deflecting mirror arranged in the form of a micro-mirror device by using semiconductor manufacturing technology.
Incidentally, it is desirable from the viewpoint of obtaining a compact scanning optical system, particularly a thin scanning optical system, to arrange the optical system so that the central beam of the incident light beam and the central beam of the scanning light beam are approximately on a straight line or approximately parallel to each other. However, such an arrangement has not yet been proposed in conventional scanning optical systems using a deflecting mirror, e.g. a galvanometer mirror or a polygon mirror.
SUMMARY OF THE INVENTION
In view of the above-described circumstances of the prior art, an object of the present invention is to provide a compact scanning optical system formed by combining a deflecting mirror and a reflecting optical system so that the central beam of the incident light beam and the central beam of the scanning light beam are approximately on a straight line or approximately parallel to each other.
To attain the above-described object, the present invention provides a scanning optical system including an entrance-side reflecting optical system on which a light beam from a light source is incident. The scanning optical system further includes a deflecting mirror for reflecting and deflecting the light beam exiting from the entrance-side reflecting optical system, and an exit-side reflecting optical system on which the light beam reflected from the deflecting mirror is incident. When an axial principal ray is defined by a light ray emanating from the light source and passing through the center of the deflecting mirror that constitutes a stop of the optical system, the axis of rotation of the deflecting mirror is set approximately parallel to the axial principal ray entering the entrance-side reflecting optical system from the light source.
In this case, it is desirable to arrange the optical system so that the axial principal ray entering the entrance-side reflecting optical system from the light source and the axial principal ray exiting from the exit-side reflecting optical system are approximately parallel to each other at some position in the range of rotation of the deflecting mirror.
It is also desirable to arrange the optical system so that the deflected light beam exiting from the exit-side reflecting optical system converges on a surface to be scanned.
In the present invention, the axis of rotation of the deflecting mirror is set approximately parallel to the axial principal ray entering the entrance-side reflecting optical system from the light source. Therefore, the scanning optical system can be constructed in a compact form. The scanning optical system can be constructed in an even more compact form by arranging the scanning optical system so that the axial principal ray entering the entrance-side reflecting optical system from the light source and the axial principal ray exiting from the exit-side reflecting optical system are approximately parallel to each other.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention be indicated in the claims.
REFERENCES:
patent: 3604932 (1971-09-01), Beach
patent: 5365049 (1994-11-01), Peng
patent: 11-84291 (1999-03-01), None
Olympus Optical Co,. Ltd.
Phan James
Pillsbury & Winthrop LLP
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