JPS6149610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an infrared solid-state imaging device constructed from a combination of a charge transfer element and a plurality of infrared detectors.

A large number of infrared detectors are arranged, and this arrangement is combined with a charge transfer element that transfers and outputs the charges generated and accumulated in each detector according to the amount of incident infrared light.
IRCCDs have a scanning function inside the device, and the signal-to-noise ratio can be improved by accumulating a large amount of detector output before outputting it, so if it is used as a light-receiving device in an infrared imaging device, the device will be small and lightweight. It is possible to improve the performance and performance.

FIG. 1 is a diagram showing the configuration of a conventional IRCCD infrared imaging device having a catadioptric light receiving optical system. After the incident infrared light 1 passes through the objective lens 2, it is sequentially reflected by the primary reflecting plane mirror 3 and the secondary reflecting plane mirror 4, and is imaged on the IRCCD 5. Further, the IRCCD output 6 is supplied to the display 8 after being amplified by the amplifier 7, and the driver 9 is
Provides the signals necessary to drive IRCCD5. In the catadioptric optical system shown in Figure 1, the optical path is folded back, so the length of the optical system can be shortened compared to the focal length of the optical system. It is useful as an optical system for an infrared imaging device.

By the way, in an IRCCD in which detectors are arranged in a planar manner, the output of each detector must be connected to a charge transfer element, so linear charges are transferred between multiple detector rows alternately with the detector rows. Transfer elements are often arranged. However, since the charge transfer element cannot convert incident infrared light into an output electrical signal, a dead zone for incident infrared light is generated on the imaging plane. The ratio of the detector area to the imaging plane is also called the filling factor, and in currently manufactured IRCCDs, this value is around 20% at most. Therefore, there is a large gap between the instantaneous fields of view seen by each detector of the IRCCD, and information regarding the shape of the object to be imaged is not only lost, but also may be lost in the case of a small target.

Figure 2 shows IRCCD for a circular target as an example.
FIG. 3 is a diagram showing the instantaneous field of view seen by each detector.
Figure 2 shows a sufficiency rate of about 40%, which corresponds to a higher value than those currently manufactured, but the gap in the instantaneous field of view is large, and information from the target is lost to some extent.

In order to eliminate this drawback, the present invention uses a vibrating mirror as a part of the light receiving optical system of an infrared imaging device, and its contents will be explained in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, in which incident infrared light 1 is reflected by a primary reflecting flat mirror 3 after passing through an objective lens 2. After being reflected by the installed interlace mirror 10, it is imaged on the IRCCD 5. The interlace mirror 10 is driven by a mirror drive motor 1
4, immediately after the IRCCD 5 receives one field of incident infrared light 1 and transfers the accumulated charge from the detector to the charge transfer element, its angle with respect to the optical axis changes slightly, and each IRCCD 5 The optical path is changed so that the detector array sees an instantaneous field of view between the instantaneous fields seen in the previous field.

FIGS. 4a and 4b are diagrams showing the relationship between the instantaneous fields of view seen by each detector row of the IRCCD. FIG. 4a is a diagram when an interlaced mirror is not used as seen in the conventional infrared imaging device shown in FIG. A large portion of the image is not seen by the detector. Figure 4b shows a case where 2:1 interlacing is performed using an interlacing mirror, and the instantaneous field of view 12 seen by each detector row in even fields and the instantaneous field of view 13 seen by each detector row in odd fields are alternate. They are lined up in a row, each supplementing the gaps in the field of view.

Although the above description has been made on the case where the primary mirror and secondary mirror in the catadioptric light receiving optical system are plane mirrors, this invention is also applicable when these reflecting mirrors are not plane mirrors or when the primary mirror is a concave mirror instead of using an objective lens. Needless to say, this is effective when using a mature light-receiving optical system.

As described above, in the infrared imaging device according to the present invention, by changing the optical path of the light receiving optical system for each field by vibrating the secondary mirror, the gap in the instantaneous field of view seen by each detector row of the IRCCD is reduced. Because each instantaneous field of view complements each other, the mask area that occurs in the field of view that is not imaged can be reduced. Furthermore, although the above description has been made regarding the case where 2:1 interlacing is performed, it goes without saying that the interlacing ratio is not limited to 2:1 and can be performed at any desired ratio.

[Brief explanation of the drawing]

Figure 1 shows the configuration of a conventional IRCCD infrared imaging device with a catadioptric light receiving optical system.
FIG. 3 is an embodiment of the present invention, and FIGS. 4a and 4b are diagrams showing the relationship between the instantaneous fields of view seen by each detector row of the IRCCD. In the figure, 2 is an objective lens, 3 is a primary reflection plane mirror, and 5
is an IRCCD, 10 is an interlace mirror, and 14 is a mirror drive motor. It should be noted that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1. A convex lens, a first reflecting mirror having a reflective surface on the convex lens side and having an aperture centered on the optical axis in the center;
a second reflecting mirror having a reflecting surface on the reflecting mirror side and located between the convex lens and the first reflecting mirror;
a light-receiving optical system configured such that the incident light is sequentially reflected by a first reflecting mirror and a second reflecting mirror after passing through the convex lens; and a surface provided on an image-forming surface of the light-receiving optical system. The charge transfer element is composed of an array of a plurality of infrared detectors on a solid-state image sensor, and a charge transfer element that stores charges generated in accordance with the amount of infrared radiation received by the infrared detector array in a predetermined cell, and drives the charge transfer element. In an infrared imaging device that obtains an infrared image by An infrared imaging device comprising a drive device that vibrates the second reflecting mirror so as to tilt an optical path of an optical system.