JP2008216479A - Wavelength variable filter spectroscopic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength variable filter spectroscopic device which is preferably applied to medical equipment such as an endoscope. <P>SOLUTION: The wavelength variable filter spectroscopic device is equipped with a wavelength variable filter 15 inside an imaging lens system 5 receiving light from a part to be observed 4 and comprising a plurality of lenses, and a spectral image formed by transmitting received light through the wavelength variable filter is formed on a solid state imaging device 6 by the imaging lens system, and successively output from the solid state imaging device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wavelength tunable filter spectroscopic device, and more particularly to a wavelength tunable filter spectroscopic device that is preferably applied to medical equipment such as an endoscope.

  2. Description of the Related Art Conventionally, a medical device such as an endoscope for observing a local part of a human body, as shown in FIG. 4, for example, makes light emitted from a light source 1 incident on a rotating color filter 2 that is being rotated 10 to be R (red). , G (green), and B (blue) are sequentially transmitted, and the emitted light from the observed portion 4 is irradiated to the observed portion 4 through the light guide 3 while the objective lens system 5 Is condensed and led to a solid-state imaging device 6 made of CCD or MOS, and converted into an electrical signal to form image data 13, which is processed by an image processor 8 to be synthesized into a full-color image, and a television monitor (not shown) ) (For example, Patent Documents 1 and 2).

The operation of a motor (not shown) for driving the rotation 10 of the rotary color filter 2 and the reading operation of the image data 13 from the solid-state imaging device 6 are synchronously controlled by control signals 12 and 11 from the controller 7.
The light source 1, the rotating color filter 2, the rear end of the light guide 3, the image processor 8, and the controller 7 are accommodated in a housing-like processing / control unit 23. The distal end portion of the light guide 3, the objective lens system 5, and the solid-state imaging device 6 are disposed near the distal end of an elongated insertion portion 20 that is inserted into the human body cavity. The rear end of the insertion part 20 is connected to the hand operation part 21. The hand operating section 21 and the processing / control section 23 are connected by a detachable connection cord section 22. The light guide 3 and the transmission lines of the image data 13 and the control signal 11 are extended from the insertion unit 20 to the processing / control unit 23 via the hand operation unit 21 and the connection cord unit 22.

  On the other hand, as an example of a wavelength tunable filter, a uniaxial crystal sandwiched between two parallel polarizers is stacked in multiple stages to form a bandpass filter having a specific relatively sharp transmission spectrum. In the filter, an ECB type (electric field control birefringence type using nematic liquid crystal) liquid crystal cell is used instead of the uniaxial crystal, and a voltage source for applying a voltage to the liquid crystal cell is provided to form a liquid crystal rio filter. Furthermore, there is known a modified liquid crystal rio filter (Patent Document 3) in which an ECB cell sandwiched between crossed Nicols (abbreviation of the ECB type liquid crystal cell) is added.

According to this, it is possible to change the transmission wavelength over a wide range by changing the combination of the voltages applied to each of the plurality of liquid crystal cells in the filter.
Further, as a further improvement, the modified liquid crystal rio filter applies the same voltage to the plurality of liquid crystal cells at the same time by limiting the cell thickness ratio of the plurality of liquid crystal cells in the filter. There is known a technique (Patent Document 4) in which the transmission wavelength can be changed over a wide range only by changing one voltage. The modified liquid crystal filter (Patent Document 3) requires a voltage control circuit for each of the plurality of liquid crystal cells. However, in the improved form (Patent Document 4), the same voltage is simultaneously applied to the plurality of liquid crystal cells. There may be only one voltage control circuit to apply variably.
JP-A 61-050546 JP 63-213812 A JP-A-3-282417 JP 2000-267127 A

  In a conventional endoscope, light from a light source is spectrally separated into three primary colors such as R, G, and B using a rotating color filter as described above. Further, as in Patent Document 4, in order to specify the affected area with higher accuracy, a filter that transmits visible light and other wavelengths such as infrared rays is arranged in the rotating color filter, and the combination of filters to be used is changed. It is also known to perform spectroscopy.

However, in the spectroscopic method using a rotating color filter, (1) it is difficult to reduce the size because it requires a driving means such as a motor, (2) unpleasant noise is generated from the driving means such as the motor, 3) The problem that the color filter is likely to deteriorate due to heat from the light source remains as a problem to be solved.
An object of the present invention is to solve the above-mentioned problems and to provide a wavelength tunable filter spectroscopic device that is preferably applied to a medical device such as an endoscope.

The present invention made to solve the above problems is as follows.
1. An imaging lens system comprising a plurality of lenses that receive light from the observation portion includes a wavelength tunable filter, and a spectral image obtained by transmitting the received light through the wavelength tunable filter is the imaging lens. A wavelength tunable filter spectroscopic device characterized in that an image is formed on a solid-state image sensor by a system and is sequentially output from the solid-state image sensor.

2. 2. The wavelength tunable filter spectroscopic device according to item 1, wherein the imaging lens system is a combination of a meniscus lens and a double Gauss lens.
3. 3. The wavelength tunable filter spectroscopic device according to item 1 or 2, wherein the wavelength tunable filter is a modified liquid crystal rio filter.

  According to the present invention, it is possible to realize a wavelength tunable filter device in which a medical device such as an endoscope can be easily downsized, no unpleasant sound is generated, and transmission performance is not deteriorated by heat.

  FIG. 1 is a schematic view showing an example of the present invention applied to an endoscope. The same or corresponding members as those in FIG. Reference numeral 9 denotes an optical system portion of the wavelength tunable filter device of the present invention, and the optical system portion 9 of the wavelength tunable filter device includes a wavelength tunable filter 15 in the imaging lens system 5. Reference numeral 14 denotes a control signal for electrically changing the transmission wavelength of the wavelength tunable filter 15.

  The imaging lens system (objective lens system) 5 includes a plurality of lenses, and receives light from the observed portion 4 (light emitted from the light guide 3 and irradiated on the observed portion 4). When this received light is transmitted through the wavelength tunable filter 15, it is converted into light having the same wavelength as the transmission wavelength of the wavelength tunable filter 15 that is electrically changed in the order of R, G, B, for example, in accordance with the control signal 14 from the controller 7. The spectral image is formed, and the spectral image is imaged on the solid-state imaging device 6 by the imaging lens system 5.

The formed spectral image is converted into an electrical signal by the solid-state imaging device 6 to become image data 13, and sequentially from the solid-state imaging device 6 by the control signal 11 (synchronized with the control signal 14) from the controller 7. 8 and synthesized by the image processor 8.
As is clear from comparison between FIG. 1 and FIG. 4, in the present invention, there is no large member such as the rotating color filter 2 between the light source 1 and the light guide 3, so that the endoscope can be easily downsized. Further, since the transmission wavelength of the wavelength tunable filter 15 is changed (switched) electrically, not mechanically, no unpleasant noise is generated, and the wavelength tunable filter 15 is hardly affected by the heat from the light source 1. Since it is incorporated in the vicinity of the distal end of the insertion portion 20, there is no deterioration due to the thermal effect.

The imaging lens system 5 is preferably a combination of a meniscus lens and a double Gaussian lens from the viewpoint of ease of focusing and zooming. An example is shown in FIG. This around the pair of double Gauss-type lens 5 _3, 5 _4, first on the incident side, a second meniscus lens 5 _1, 5 _2, the back focus adjustment lens 5 ₅ on the exit side, common to these This is an example of the imaging lens system 5 arranged on the optical axis 5A. Between the pair of double Gauss lenses 5 ₃ and 5 ₄ , an iris diaphragm 16 is disposed as a device for mechanically changing the effective diameter of the optical system.

The wavelength tunable filter 15 is not particularly limited as long as it is provided inside the imaging lens system 5, but is preferably disposed near the opening of the iris diaphragm 16. At the opening of the iris diaphragm 16, the light beam diameter of the light sequentially passing through the incident side lens groups (first and second meniscus lenses 5 ₁ , 5 ₂ , double Gauss lens 5 ₃ ) is minimized. Therefore, by arranging the wavelength tunable filter 15 in the vicinity of the opening of the iris diaphragm 16, the size of the wavelength tunable filter 15 can be minimized (the light receiving area is minimized).

As the wavelength tunable filter that can electrically change the transmission wavelength, the above-described modified liquid crystal filter (“wavelength tunable optical bandpass filter” described in the claims of Patent Document 3) is preferably used. sell. More preferably, it is an improved form thereof ("wavelength variable color filter using liquid crystal" described in claims of Patent Document 4). One example is shown in FIG. In this example, as shown in FIG. 6 of Patent Document 3, liquid crystal (P, LC) in which an ECB cell (P, LC ₃ , P) sandwiched between crossed Nicols is sandwiched between two sets of parallel polarizers. ₁ , P, LC ₂ ), that is, one ECB cell sandwiched between crossed Nicols is arranged on the output side.

ECB cell _{LC 1,} LC 2, applied voltages _V 1 individual to LC _3, V 2, _{V 3} is sent placed on the applied voltage signal _{14 1,} 14 2, 14 ₃ from the controller 7. If the combination of voltages to be applied to each cell (V ₁ , V ₂ , V ₃ ) is changed, the peak wavelength of the transmitted light changes, and an arbitrary spectrum within the visible range or outside the visible range (infrared range or ultraviolet range). An image can be obtained.

In this example, the ratio of the cell thicknesses of the _three ECB cells LC ₁ , LC ₂ , LC ₃ is set to 1: 2: 1.5, so that one embodiment of the improved embodiment (see FIG. 4). 1) is realized. That is, the applied voltage can be set to one voltage V (V = V ₁ = V ₂ = V ₃ ) common to each cell (that is, the voltage control circuit can be integrated into one), and this voltage V can be changed. By doing so, an arbitrary spectral image in the visible range or outside the visible range can be obtained similarly.

In addition, as light having a transmission peak wavelength that generates a spectral image corresponding to the three primary colors, three primary colors other than R, G, and B (for example, cyan, magenta, and yellow) may be employed.
The wavelength tunable filter used in the present invention is not limited to the one that can switch the transmission wavelength electrically as described above. For example, the wavelength tunable filter is received by a micromachine (for example, MEMUS) that is small enough to ignore sound generated during operation. The transmission wavelength may be mechanically switched, such as a color filter that changes the transmission wavelength by changing the angle of the surface.

  In the above example, the case where the present invention is applied to an endoscope has been described. However, the present invention can also be applied to medical devices other than endoscopes, for example, medical devices for dental caries diagnosis.

It is the schematic which shows one example of this invention applied to the endoscope. It is the schematic which shows an example of the wavelength tunable filter spectroscopy apparatus of this invention. It is the schematic which shows an example of the correction | amendment type liquid crystal lyo filter which is one of the wavelength tunable filters preferably applied to this invention. It is the schematic which shows an example of the conventional endoscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Rotation color filter 3 Light guide 4 Observation part (human body part)
5 Objective lens system (imaging lens system)
DESCRIPTION OF SYMBOLS 5 ₁ 1st meniscus lens 5 ₂ 2nd meniscus lens 5 ₃ , 5 ₄ Double Gauss type lens 5 ₅ Lens for back focus adjustment 5A Optical axis 6 Solid-state image sensor 7 Controller 8 Image processor 9 Optical system of wavelength variable filter apparatus Part 10 Rotation 11 Control signal 12 Control signal 13 Image data 14 Control signal 14 ₁ , 14 ₂ , 14 ₃ Applied voltage signal 15 Wavelength variable filter 16 Iris diaphragm 20 Insertion unit 21 Hand operation unit 22 Connection code unit 23 Processing / control unit LC ₁ , LC ₂ , LC ₃ ECB cell P Polarizer V ₁ , V ₂ , V ₃ applied voltage

Claims (3)

  An imaging lens system comprising a plurality of lenses that receive light from the observation portion includes a wavelength tunable filter, and a spectral image obtained by transmitting the received light through the wavelength tunable filter is the imaging lens. A wavelength tunable filter spectroscopic apparatus characterized in that an image is formed on a solid-state image sensor by a system and is sequentially output from the solid-state image sensor.   2. The wavelength tunable filter spectroscopic device according to claim 1, wherein the imaging lens system is a combination of a meniscus lens and a double Gauss lens.   The wavelength tunable filter spectroscopic apparatus according to claim 1, wherein the wavelength tunable filter is a modified liquid crystal rio filter.

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