JP2007127443A - Photodetector and photodetection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent reductions of information on the light intensity of a photosensor having regions unable to detect light and efficiently use light irradiated to the regions unable to detect light of the photosensor. <P>SOLUTION: A photodetector or a photodetection method comprises the photosensor having a photodetection plane having a plurality of photodetection regions and the regions unable to detect light and adjacent to the photodetection regions; a light irradiation part for irradiating light to the photodetection plane; and a displacement action part for displacing the photodetection plane relatively to a position of light irradiation. By displacing the position of light irradiation relatively to the photodetection plane, light irradiated to the regions unable to detect light is irradiated to the photodetection regions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to photodetection using a photosensor having a photodetection surface composed of a plurality of photodetection elements such as a CCD, a photodiode array, and an MCP and an amplification element.

Conventionally, a multi-channel spectrometer separates light for each wavelength from a spectroscopic system consisting of a diffraction grating, etc., and measures the separated light using a surface detection type photosensor such as a fixed CCD or photodiode array, Light intensity information was measured. However, each of the surface detection type photosensors is an assembly of fine photodetection elements. Therefore, when the light having the same size as or smaller than the pixel is irradiated across the pixels, the light non-detectable region between the pixels is also irradiated, and the light intensity is reduced. Are also output in a distributed manner, and the light intensity information is reduced. Furthermore, since the information on the light intensity is output from the two pixels, the resolution is lowered.

(1) An object of the present invention is to suppress a decrease in light intensity information of an optical sensor having a non-detectable region.
(2) Moreover, this invention exists in utilizing effectively the light irradiated to the light undetectable area | region of an optical sensor.
(3) Further, the present invention is to realize a resolution exceeding the resolution determined by the size of the light detection region.

(1) The present invention provides a photosensor having a photodetection surface having a plurality of photodetection regions, a nondetectable region adjacent to the photodetection region, a light irradiation unit for irradiating light on the photodetection surface, A displacement acting portion that displaces the light detection surface relative to the irradiation position of the light, and the light irradiation position is displaced relative to the light detection surface to irradiate the non-detectable region It is in a light detection device that irradiates light detection areas.
(2) Furthermore, the present invention provides a light detection method for detecting light with a light sensor having a plurality of light detection regions and a light detection surface having a light detection non-detectable region adjacent to the light detection region. In the light detection method, the light detection surface is displaced relative to the irradiation position of the light to irradiate the light detection region with the light applied to the non-detectable region.

(Photodetection device)
Photodetectors include photosensors used in spectroscopes, pattern detectors, etc., a light irradiator that irradiates light to the light sensor, a displacement action part that relatively displaces the light detection surface of the photosensor and the light irradiation position, etc. It has. With this configuration, the light detection device can simultaneously detect the light irradiation position and intensity information by measuring the irradiation light in synchronization with the displacement of the light detection surface. Thereby, for example, the light detection device has a sensitivity or resolution that is generated when a light beam having a size equal to or smaller than that of the pixel is applied to a non-detectable region between the pixels on the light detection surface. Can be prevented. Alternatively, the light detection device can accurately measure the boundary position of the pattern even when the boundary of the light pattern irradiated on the light detection surface is in a light undetectable region between the pixels. Alternatively, even if there is a variation in sensitivity for each pixel due to aging of the optical sensor, or there is a defective pixel, it can be corrected using a pixel in the vicinity thereof. Alternatively, the resolution of the apparent number of pixels can be improved.

  The optical sensor is a sensor in which a plurality of photodetecting elements and sensitizing elements such as a CCD, a photodiode array, and an MCP are arranged in a linear or planar shape. The optical sensor includes a light detection surface that can detect light in a linear or planar shape. The light detection surface includes a plurality of light detection areas where light can be detected and a light non-detectable area where light cannot be detected. The light detection region is a region where light can be detected and is a pixel, such as a light detection element such as a CCD or a light receiving diode, or a sensitizing element. The light undetectable region is a region where light between the light detection regions cannot be detected, a light detection region where light detection is disabled, or a light detection region where sensitivity has deteriorated. Examples of the light detection region in which light detection is disabled or the light detection region in which sensitivity has deteriorated include a defective pixel, a defective light detection element, and a defective sensitizer. The CCD of the optical sensor has sensitivity from near ultraviolet to near infrared, and can be used from deep ultraviolet to X-ray region by combining with a fluorescent screen. Alternatively, the sensitivity of the optical sensor can be improved by combining a CCD and an image intensifier such as MCP. The photodiode array is sensitive to visible light from the X-ray region, and includes an optical amplifier and ISPD having a gate function.

  The displacement action part relatively displaces the light detection surface of the photosensor and the light irradiation position on the light detection surface. Displacement refers to a change in position such as movement and vibration, and any method may be used. For example, a piezo element can be used as the displacement action unit, and fine vibrations can be applied to the object. The displacement acting unit may give displacement to the optical sensor, or may give displacement to the light irradiation unit on the light irradiation side.

  FIG. 1 shows an example of a photodetection device used as a multichannel spectrometer (polychromator). A multi-channel spectrometer is a spectrometer that measures light of a plurality of wavelengths simultaneously. The light from the light source 1 passes through the entrance slit 12, is narrowed down, and enters the diffraction grating 13. The light is separated for each wavelength by the diffraction grating 13. The separated light beams 14 having different wavelengths are incident on different positions of the light detection surface 21 of the photosensor 20. The light detection surface 21 of the light sensor 20 has a large number of light detection regions 22 and a light undetectable region 23 between the light detection regions 22. The light irradiation unit 10 includes a light source 11, an entrance slit 12, a diffraction grating 13, and the like.

  The position and intensity signals of the light beams 14, 14,... Received by the light detection surface 21 are amplified by the amplifier 41 and processed by the computer 40. Thereby, the irradiation position and intensity | strength of the light of a different wavelength can be memorize | stored in the memory | storage device of the computer 40. FIG.

  The displacement acting unit 30 acts a displacement such as vibration on the optical sensor 20. The displacement amount of the optical sensor 20 is measured by the position detection unit 31. The displacement action unit 30 and the position detection unit 31 only need to be able to apply the displacement of the light detection surface 21 and detect the amount of displacement, and may be configured integrally. The displacement acting unit 30 and the position detection unit 31 measure the relative displacement between the light detection surface 21 and the irradiation position of the light beam 14 with respect to the light detection surface 21 at a certain time point, and transmit the position information to the computer 40. The displacement acting unit 30 and the position detecting unit 31 may measure the position by giving displacement to the optical sensor planarly or three-dimensionally using not only one axis but also two or three axes. The term “planar” or “three-dimensional” may include not only parallel movement but also movement including rotational movement. For example, the light detection surface 21 may vibrate in a seesaw shape with its center portion as a fulcrum, or may rotate with the center portion as a fulcrum, or a combined motion of seesaw-like vibration and rotation motion.

  The light detection device irradiates the light detection surface with the separated light beams 14, 14,... The light detection apparatus measures the irradiation position and intensity of the light beam by the light detection surface 21 at a certain time, and measures the displacement position of the light detection surface by the position measurement unit 31. Similarly, the photodetection device measures the irradiation position and intensity of light at another time and measures the displacement position of the photodetection surface. By processing these measured values by the computer 40, the light beam that has been irradiated to the non-detectable region at one time point is irradiated to the light detection region at another time point, and the undetectable light beam is also detected. It can be detected reliably. Thereby, the photodetection device can accurately measure the irradiation position and intensity of the dispersed light, and can increase the resolution.

  FIG. 2 shows an example of a light detection device that detects the shape of the light pattern 17. The light from the light source 11 passes through an optical system 15 such as a lens and becomes, for example, innumerable light rays parallel to the optical axis and enters the photomask 16. The photomask 16 has a light transmission region 161 and a non-transmission region 162. The parallel light rays pass through the transmission region 161 of the photomask 16 and irradiate the light detection surface 21 of the photosensor 20. The light detection surface 21 is irradiated with the light pattern 17 having the same shape as the transmission region 161 of the photomask 16. The light irradiation unit 10 includes a light source 11, an optical system 15, a photomask 16, and the like.

  The image signal of the light pattern 17 received by the light detection surface 21 is amplified by the amplifier 41 and processed by the computer 40. Thereby, the irradiation position signal and the intensity signal of the light pattern 17 are stored in the storage device of the computer 40 or the like. The displacement action unit 30 and the position detection unit 31 measure the displacement position of the light detection surface 21 and transmit the position information to the computer 40. The displacement acting unit 30 and the position detecting unit 31 may measure the position by displacing the optical sensor using not only one axis but also two or three axes, similarly to the photodetecting device of FIG. good.

The light detection device applies displacement to the light detection surface 21 while irradiating the light detection surface 21 with the light pattern 17. The light detection device measures the shape and intensity of the light pattern by the light detection surface 21 at a certain time, and measures the position of the light detection surface 21 by the position measurement unit 31. The shape and intensity are measured, and the position of the light detection surface 21 is measured. By processing these measured values by the computer 40, the light that has been applied to the non-detectable region 23 at one point in time will be irradiated to the photo-detecting region at another point in time. It is also possible to reliably detect the contour of.

(Light detection method)
FIG. 3 shows the intensity distribution of the light beam and the position of the light detection surface of the photosensor. FIG. 3A shows a state in which the light detection surface is in a certain position and light is irradiated on the light detection surface. The intensity distribution extends over a plurality of light detection regions 22a, 22b, and 22c. For this reason, in the light intensity distribution, the light applied to the non-detectable regions 23b and 23c is not detected by the optical sensor. In addition, when the periphery (R, L) of the light ray is in the light undetectable region, the position around the light ray becomes ambiguous. As a result, the optical sensor cannot detect the amount of light of the entire light beam, and cannot accurately measure the irradiation position.

FIG. 3B shows a state in which the light detection surface 21 is displaced while measuring the position of the light detection surface 21 while measuring the light beam 14 on the light detection surface 21. The position of the optical sensor 20 is changed to 20a, 20b, and 20c with respect to the light beam 14. Therefore, the position of the light detection surface 21 for measuring the light beam 14 is different. It is assumed that the intensity distribution of the light beam 14 does not vary within the time of displacement of the optical sensor 20. In that case, the irradiation position and intensity of the same light beam 14 are measured for each displacement position of the optical sensor 20. As a result, the light irradiated to the non-detectable regions 23b and 23c at the position of the photosensor 20a is irradiated to the photodetection regions 22b and 22c at the position of the photosensor 20b. Is measured. In this way, by displacing the light detection surface 21, it is possible to measure the light irradiation position and intensity that could not be measured at a certain position, so that it is possible to prevent the light irradiation position and intensity information from being lowered. In particular, it is possible to theoretically reduce the decrease in light intensity information that occurs when light having a width less than one pixel is irradiated over two pixels. Furthermore, even if there is a defective pixel in the optical sensor 20, by taking the magnitude of displacement of the light detection surface 21 to be larger than the width of the pixel, it is possible to irradiate the adjacent excellent pixel with the light irradiated to the defective pixel, Variations in the pixels of the optical sensor 20 can be corrected. By giving the vibration displacement, it is possible to increase the number of times of measurement of the optical sensor and increase the measurement accuracy. Alternatively, by making the amplitude (displacement width) of the optical sensor by the displacement acting part large, for example, by setting it to a width over a plurality of light detection areas, it is possible to measure the same light in a large number of light detection areas. Measurement accuracy can be increased. For example, when a certain pixel is a defective pixel such as poor sensitivity and an adjacent pixel is a normal pixel with good sensitivity, the light irradiated to the defective pixel is irradiated to the normal pixel due to the displacement of the light detection surface 21. Accurate light quantity and position can be measured. In addition, when there is a variation in sensitivity for each pixel, the same light is irradiated to a plurality of pixels due to the displacement of the light detection surface 21, so that the measurement values of the plurality of pixels are averaged for the same light. By doing so, pixel variations can be corrected. Processing such as light amount comparison processing and average processing of each pixel can be performed by the computer 40.

  FIG. 4 shows the intensity distribution of the light pattern 16 and the position of the light detection surface 21 of the light sensor 20. FIG. 4A illustrates a state in which the light detection surface 21 is irradiated with the light pattern 16 in a state where the light detection surface 21 is at a certain position. The intensity distribution extends over a plurality of light detection regions 22a, 22b, 22c, and 22d. For this reason, in the light intensity distribution, the light applied to the non-detectable regions 23b, 23c, and 23d is not detected by the optical sensor 20. Further, if the periphery R, L of the light pattern 16 is in the light undetectable region 23, the position around the light pattern 16 becomes ambiguous. As a result, the shape and intensity distribution of the light pattern 61 cannot be measured accurately.

4B, while measuring the light pattern 16 on the light detection surface 21, the light detection surface 21 is displaced, and the position of the light detection surface 21 is measured. The relative position of the optical sensor 20 with respect to the optical pattern 16 is changed to 20a, 20b, and 20c. It is assumed that the intensity distribution of the light pattern 16 does not vary within the time of displacement of the optical sensor 20. In that case, the shape and intensity of the same light pattern 16 can be measured for each position of the optical sensor 20. Therefore, in the photosensor 20 at the position 20a, the light irradiated to the light non-detectable areas 23b, 23c, and 23d is irradiated to the light detection areas 22b, 22c, and 22d at another position 20b, where light The irradiation position and intensity can be measured. The light sensor at the position 20b cannot measure the light near the right end R of the light pattern 20 because it irradiates the light undetectable region 23b. However, the light sensor 20 at the position 20a or 20c does not measure the light. It can be measured in the detection areas 22a and 22b. Similarly, the light near the left end L of the light pattern 20 is irradiated to the non-detectable region 23e in the light pattern 20 at the position 20c and cannot be measured, but the light sensor 20 at the positions 20a and 20b has the same light. It can be measured in the detection region 22d. In this way, since light that cannot be measured can be measured, the apparent number of pixels and resolution can be improved.

(Lock-in amplifier, time-resolved amplification)
When vibration is used as the displacement of the optical sensor 20, the output signal of the optical sensor 20 is periodically modulated. Therefore, a lock-in amplifier or time-resolved amplification is used as the amplifier 41. For example, the output signal of the optical sensor 20 is locked-in amplified. By locking-in amplification of the output signal of the optical sensor 20 in accordance with the vibration of the optical sensor 20, noise such as shot noise included in the output signal of the optical sensor 20 can be reduced, and the output signal of the optical sensor 20 can be reduced. The S / N ratio can be improved.

(Pixel slit)
The pixel slit is disposed on the light detection surface of the photosensor to make the sensitivity of each pixel in the light detection surface uniform. The pixel slit has a light transmission window corresponding to each pixel. The transmission window transmits light that irradiates the central portion of the pixel with uniform sensitivity and blocks light that irradiates the peripheral portion of the pixel with non-uniform sensitivity. Thereby, the sensitivity characteristic of each pixel can be sharpened and the sensitivity of each pixel can be made uniform.

Explanatory drawing of photodetection device used as polychromator Explanatory drawing of a light detection device for detecting a light pattern Explanatory drawing to detect the light beam by applying displacement to the optical sensor Explanatory drawing to detect the light pattern by applying displacement to the optical sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light irradiation part 11 ... Light source 12 ... Incident slit 13 ... Diffraction grating 14 ... Light beam 15 ... Optical system 16 ... Photomask 17 ... Optical pattern 20 ... -Optical sensor 21-Photodetection surface 22-Photodetection region 23-Non-detectable region 30-Displacement action unit 31-Position measurement unit 40-Computer 41-Amplifier

Claims (9)

A photosensor having a plurality of photodetection regions and a photodetection surface having a non-detectable region adjacent to the photodetection region;
A light irradiation unit for irradiating light to the light detection surface;
A displacement acting part that displaces the light detection surface relative to the light irradiation position,
A light detection device that irradiates a light detection region with light irradiated on a light non-detectable region by displacing the light irradiation position relative to the light detection surface.
The photodetection device according to claim 1,
The displacement action unit is a light detection device that vibrates the light detection surface with respect to the light irradiation position.
The light detection device according to claim 2,
An amplifier that amplifies the electrical signal from the optical sensor
The amplifier is a light detection device that performs time-resolved amplification or lock-in amplification in accordance with the vibration of the light irradiation position.
The photodetection device according to claim 1,
The light irradiation unit is a light detection device that simultaneously irradiates a light detection surface with light beams having a plurality of wavelengths.
The photodetection device according to claim 1,
The light irradiation unit is a light detection device that irradiates a light detection surface with a light pattern.
The photodetection device according to claim 1,
A photodetecting device comprising a pixel slit disposed to face the photodetecting surface.
In a light detection method for detecting light with a plurality of light detection regions and a light sensor having a light detection surface having a light detection impossible region adjacent to the light detection region,
A light detection method in which a light detection surface is displaced relative to a light irradiation position to irradiate a light detection region with light irradiated on a light non-detectable region.
The light detection method according to claim 7.
A light detection method in which a light detection surface is vibrated with respect to a light irradiation position and time-resolved amplification or lock-in amplification is performed in accordance with the vibration.
The light detection method according to claim 7.
The light detection method, wherein a displacement amount for relatively displacing the light detection surface with respect to the light irradiation position is a width across at least a plurality of light detection regions.

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