JPH09243813A - Filter wheel provided with chromatic aberration compensating lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter wheel capable of covering a wide wavelength region without adjusting a focus. SOLUTION: For example, four optical filters 3 having different wavelength region characteristics and lenses 4 for correcting a focal position constitute an optical system on four optical axes B1-B1,..., B4-B4. An image pickup device 2 is composed of a lens system 5 and a sensor 6 on the optical axis C-C. Four optical systems are arranged on a concentric circle and each of optical axes Bi-Bi is rotated/moved about a mechanical center A-A and it is composed so that any of the optical axes Bi-Bi becomes coaxial with the optical axis C-C. An optical filter 3 having a different transmitting wavelength region shares a wavelength region stepwise and the deviation of focus due to chromatic aberration in a different wavelength region is compensated by the respective lenses 4. The degree of freedom of the design of optical system is increased and the wavelength region is easily widened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter wheel with a chromatic aberration correction lens.

[0002]

2. Description of the Related Art Conventional filter wheels generally have only optical filters. As a conventional technology example related to the present invention and the technical field, Japanese Patent Laid-Open No. 58-8650
The "focus detection device" of No. 4 measures the color temperature and corrects the focus detection error due to chromatic aberration. Also,
In the "automatic focus camera" of Japanese Patent Laid-Open No. 59-208512, the focus is detected by projecting light having a wavelength different from the wavelength mainly contributing to photographing on a subject and receiving the reflected light.

[0003]

However, the conventional filter wheel has only a filter function for limiting the wavelength of light passing therethrough. In an image pickup apparatus that picks up images in a plurality of wavelength regions with this filter wheel, it is necessary to eliminate chromatic aberration of the lens system or provide a correction means as in the above-mentioned publication. Therefore, the design of the lens system of the image pickup device becomes complicated, and it is difficult to perform image pickup over a wide wavelength range with a single image pickup device.

It is an object of the present invention to provide a filter wheel with a chromatic aberration correction lens that can cover a wide wavelength range without adjusting the focus.

[0005]

In order to achieve the above object, a filter wheel with a chromatic aberration correcting lens of the present invention has at least two optical filters having different wavelength region characteristics, and a focus position in combination with each of the optical filters. The present invention is characterized in that the wavelength regions are divided in stages and the focal shift due to the chromatic aberration in different wavelength regions is corrected by each lens.

The optical axes of the at least two optical filters and the lens are arranged concentrically, and the respective optical axes rotate about the concentric axis so that the optical axes can be easily moved to a predetermined axial position. It should be configured so that it can be set.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a filter wheel with a chromatic aberration correcting lens according to the present invention will be described in detail with reference to the accompanying drawings. Referring to FIGS. 1 and 2, there is shown one embodiment of a filter wheel with a chromatic aberration correction lens of the present invention. FIG. 1 is a vertical sectional structural view, and FIG. 2 is a front view.

In FIGS. 1 and 2, the filter wheel with a chromatic aberration correction lens of this embodiment is composed of a filter wheel 1 and an image pickup device 2.

One of the filter wheels 1 has four optical filters 3, ..., 3 and four chromatic aberration correction lenses 4 ,.
And 4. As each of the four optical filters 3, a filter that transmits another wavelength region is generally selected. The chromatic aberration correction lens 4 is a chromatic aberration correction lens that corrects the shift of the focal position of the lens system 5 according to the wavelength region of the front optical filter 3.

The other image pickup device 2 has a lens system 5 and a sensor 6. The lens system 5 is for forming image light on the sensor 6. The sensor 6 is an optical signal / electrical signal conversion sensor. This sensor is installed on the focal plane of the lens system 5, and is, for example, a two-dimensional CCD.
A sensor is used.

One filter wheel 1 has four sets of one optical filter 3 and one chromatic aberration correction lens 4, and four sets of optical axes B1-B1, B2-B2, B3.
-B3, B4-B4 are constructed. The respective optical axes B1 -B1, ..., B4 -B4 are mechanical rotation axes A.
-It is arranged concentrically around A. Therefore, the optical axes B1 to B1, ..., B4 to B4 which rotate about the center A and the axis AA form mutually parallel axes.

The lens system 5 and the sensor 6 of the other image pickup device form an optical axis C-C. The optical axis C-C and the predetermined optical axis Bj-Bj of the filter wheel 1 (where j is any one of 1 to 4) are configured to be coaxial. The setting procedure in which any one of the four optical axes Bj-Bj and the optical axis C-C are coaxial is enabled by rotating the filter wheel 1 about the rotation axis A-A. . Therefore, by constructing the wavelength regions through which the optical filter 3 and the chromatic aberration correction lens 4 transmit in stages, it becomes possible to more accurately correct the focus position due to the wavelength region difference of the lens system 5. .

The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the above embodiment, the number of optical filters on the filter wheel is four, but this may be any integer of 2 or more. In addition, from the subject to the sensor 6
Up to the optical filter 3, chromatic aberration correction lens 4,
Although the lens system 5 and the sensor 6 are arranged in this order, the order may be as follows.

A. Chromatic aberration correction lens 4, optical filter 3, lens system 5, sensor 6 b. Lens system 5, optical filter 3, chromatic aberration correction lens 4, sensor 6 c. Lens system 5, chromatic aberration correction lens 4, optical filter 3, sensor 6

Further, although the sensor 6 is a two-dimensional CCD sensor in the above embodiment, it may be any optical sensor. In particular, a one-dimensional CCD sensor may be used if the positional relationship between the subject and the imaging device changes with time. Further, in all cases, the light that has passed through the optical filter 3 is input to the imaging device 2, but light that does not pass through the optical filter is input to the imaging device 2 by making only a part of the filter wheel into a hole. It may be done.

[0016]

As is apparent from the above description, the filter wheel with a chromatic aberration correction lens of the present invention corrects the focus position by combining at least two optical filters having different wavelength region characteristics with each of these optical filters. And a lens for performing. Therefore, the respective optical filters divide the wavelength region in stages, and the focal shift due to the chromatic aberration in the different wavelength regions can be corrected by the lens combined with the optical filter. Since the chromatic aberration correction lens according to the transmission wavelength region of the optical filter used is on the optical path, it becomes easy to handle the chromatic aberration in the design of the lens system of the imaging device. That degree of freedom can be applied to the correction of other aberrations. A wider wavelength range,
It can be covered by a single imaging device with a filter wheel.

[Brief description of drawings]

FIG. 1 is a sectional structural view showing an embodiment of a filter wheel with a chromatic aberration correction lens of the present invention.

FIG. 2 is a front view of FIG.

[Explanation of symbols]

 1 Filter Wheel 2 Imaging Device 3 Optical Filter 4 Chromatic Aberration Correction Lens 5 Lens System 6 Sensor

Claims (2)

[Claims] 1. An optical filter comprising at least two optical filters having different wavelength region characteristics and a lens for correcting the focal position in combination with each of the optical filters, and the wavelength regions are divided in stages. A filter wheel with a chromatic aberration correction lens, characterized in that a focal shift due to chromatic aberration in different wavelength regions is corrected by the respective lenses. 2. The optical axes of the at least two optical filters and the lens are arranged concentrically, the respective optical axes rotate about the concentric axis, and the optical axes are easily moved to a predetermined axial position. The filter wheel with a chromatic aberration correction lens according to claim 1, wherein the filter wheel can be moved and set.