Optical information acquisition device and optical information acquisition method

Abstract

To acquire a characteristic related to a wavelength spectrum of incident light from a wide range of an object moving relative to a detection area.SOLUTION: A measurement system 1 comprises: a first line sensor section that has a first pixel section 23a in which a plurality of pixels are arranged, detects measurement light from an object S moving relative to the first pixel section 23a, and outputs a first detection signal; a second line sensor section that has a second pixel section 23b, in which a plurality of pixels are arranged in parallel with the first pixel section 23a, and an LRG filter 31, which is disposed so as to cover the second pixel section 23b and has a characteristic such that transmittance changes monotonically in accordance with wavelength in a predetermined wavelength band, detects the measurement light from the object S moving relative to the second pixel section 23b, and outputs a second detection signal; and a computer 10 that acquires a characteristic value related to a wavelength spectrum of the measurement light on the basis of at least the first detection signal and the second detection signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical information acquisition device and an optical information acquisition method. [Background technology]

[0002] Conventionally, a measuring device capable of detecting the centroid wavelength of incident light has been used (see, for example, Patent Document 1). In this measuring device, an inclined dichroic mirror is used to detect the light transmitted through the inclined dichroic mirror and the light reflected from the inclined dichroic mirror, and the centroid wavelength of the wavelength spectrum of the incident light is calculated based on the light intensity of each light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 161684 Summary of the Invention [Problem to be solved by the invention]

[0004] While the conventional measurement devices described above can acquire characteristics related to the wavelength spectrum of incident light from an object, there is a need for a device that can acquire characteristics related to the wavelength spectrum of incident light from an object that moves relative to a detection area.

[0005] The present disclosure has been made in consideration of such problems, and aims to provide an optical information acquisition device and an optical information acquisition method that can acquire characteristics related to the wavelength spectrum of incident light from a wide range of objects that move relative to the detection area. [Means for solving the problem]

[0006] An optical information acquisition device according to a first aspect of the embodiment includes a first line sensor unit having a first pixel unit in which a plurality of pixels are arranged, which detects measurement light from an object moving relatively to the first pixel unit, and outputs a first detection signal; a second pixel unit having a plurality of pixels arranged in parallel with the first pixel unit; a monotonic function filter arranged to cover the second pixel unit and having a characteristic that transmittance changes monotonically with wavelength in a predetermined wavelength range, which detects measurement light from an object moving relatively to the second pixel unit, and outputs a second detection signal; and a calculation unit that acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal and the second detection signal, and there is a predetermined time difference between the detection timing of the measurement light of the first line sensor unit and the detection timing of the measurement light of the second line sensor unit.

[0007] Alternatively, an optical information acquisition method according to a second aspect of the embodiment includes a first optical detection step of detecting measurement light from an object moving relatively to the first pixel unit using a first pixel unit having a plurality of pixels arranged thereon and outputting a first detection signal; a second optical detection step of detecting measurement light from an object moving relatively to the second pixel unit using a second pixel unit having a plurality of pixels arranged thereon and a monotonic function filter arranged to cover the second pixel unit and having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range and outputting a second detection signal; and a calculation step of acquiring a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal and the second detection signal, wherein there is a predetermined time difference between the detection timing of the measurement light by the first optical detection step and the detection timing of the measurement light by the second optical detection step.

[0008] According to either the first or second aspect, measurement light from an object moving relatively to the first pixel unit is detected by the first pixel unit to output a first detection signal, measurement light from an object moving relatively to the second pixel unit is detected by the second pixel unit after passing through a monotonic function filter to output a second detection signal, and a characteristic value related to the wavelength spectrum of the measurement light is acquired based on the first detection signal and the second detection signal. This makes it possible to acquire a characteristic value related to the wavelength spectrum of measurement light from a wide range of objects moving relatively to the detection region.

[0009] In the first aspect, the first line sensor unit may further include a neutral density filter disposed to cover the first pixel unit and configured to attenuate the measurement light. This reduces the difference in intensity of the measurement light detected by the first pixel unit and the second pixel unit, thereby preventing saturation of the first detection signal. As a result, it is possible to accurately obtain a characteristic value related to the wavelength spectrum of the measurement light.

[0010] In the first aspect, the exposure time for one detection of the measurement light in the first line sensor unit may be set shorter than the exposure time for one detection of the measurement light in the second line sensor unit. This configuration can reduce the difference in intensity of the measurement light detected by the first pixel unit and the second pixel unit, thereby preventing saturation of the first detection signal. As a result, it is possible to accurately acquire a characteristic value related to the wavelength spectrum of the measurement light.

[0011] In the first aspect, the optical element may further include a plate member that is arranged to cover the second pixel unit and transmits the measurement light, and the monotonic function filter is arranged on a surface of the plate member that faces the second pixel unit. According to the above configuration, the measurement light from the object that has transmitted through the monotonic function filter can be stably detected by the second pixel unit with a simple configuration.

[0012] In the first aspect, the optical fiber optical system may further include a third line sensor unit including a third pixel unit having a plurality of pixels arranged in parallel with the first pixel unit and the second pixel unit, and a first curve function filter arranged to cover the third pixel unit and having a transmittance that changes curvedly with wavelength in a predetermined wavelength range, the third line sensor unit detecting measurement light from an object moving relative to the third pixel unit and outputting a third detection signal, wherein the calculation unit acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, and the third detection signal. In the second aspect, the optical fiber optical system may further include a third light detection step of detecting measurement light from an object moving relative to the third pixel unit using the third pixel unit having a plurality of pixels arranged in parallel with the first pixel unit and the first curve function filter arranged to cover the third pixel unit and having a transmittance that changes curvedly with wavelength in a predetermined wavelength range, and outputting a third detection signal, wherein the calculation step acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, and the third detection signal. With this configuration, it is possible to acquire a plurality of types of characteristics relating to the wavelength spectrum of measurement light from a wide range of an object that moves relatively to the detection region.

[0013] In the first aspect, the first curved line function filter may be a filter formed by stacking two monotonic function filters each having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range. With this configuration, the first curved line function filter can be realized with a simple configuration.

[0014] In the first aspect, the optical element further includes a fourth line sensor unit that has a fourth pixel unit in which a plurality of pixels are arranged in parallel with the first pixel unit, the second pixel unit, and the third pixel unit, and a second curve function filter that is arranged to cover the fourth pixel unit and has a characteristic that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and that detects measurement light from an object that moves relative to the fourth pixel unit and outputs a fourth detection signal, and the calculation unit may acquire a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, and the fourth detection signal. In the second aspect, the method may further include a fourth light detection step of detecting measurement light from an object moving relatively to the fourth pixel unit using a fourth pixel unit having an array of multiple pixels and a second curve function filter arranged to cover the fourth pixel unit and having a characteristic that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and outputting a fourth detection signal, and the calculation step may acquire a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, and the fourth detection signal. In this case, it is possible to acquire more types of characteristics related to the wavelength spectrum of the measurement light from a wide range of the object moving relatively to the detection area.

[0015] In the first aspect, the second curved line function filter may be a filter formed by stacking three monotonic function filters each having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range. With this configuration, the second curved line function filter can be realized with a simple configuration.

[0016] In the first aspect, the optical element further includes a fifth line sensor unit having a fifth pixel unit in which a plurality of pixels are arranged in parallel with the first pixel unit, the second pixel unit, the third pixel unit, and the fourth pixel unit, and a third curve function filter arranged to cover the fifth pixel unit and having a characteristic in which transmittance changes curvedly depending on wavelength in a predetermined wavelength range, the fifth line sensor unit detecting measurement light from an object moving relative to the fifth pixel unit and outputting a fifth detection signal, and the calculation unit may acquire a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, the fourth detection signal, and the fifth detection signal. In the second aspect, the method further includes a fifth light detection step of detecting measurement light from an object moving relatively to the fifth pixel unit using a fifth pixel unit having an array of multiple pixels and a third curve function filter arranged to cover the fifth pixel unit and having a property that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and outputting a fifth detection signal, and the calculation step may acquire a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, the fourth detection signal, and the fifth detection signal. With this configuration, it is possible to acquire even more types of characteristics related to the wavelength spectrum of the measurement light from a wide range of the object moving relatively to the detection area.

[0017] In the first aspect, the third curved line function filter may be a filter formed by stacking four monotonic function filters each having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range. With this configuration, the third curved line function filter can be realized with a simple configuration.

[0018] The optical information acquisition device of the embodiment includes: [1] a first line sensor unit having a first pixel unit in which a plurality of pixels are arranged, which detects measurement light from an object moving relatively to the first pixel unit, and outputs a first detection signal; a second line sensor unit including a second pixel unit having a plurality of pixels arranged in parallel with the first pixel unit, and a monotonic function filter disposed to cover the second pixel unit and having a characteristic that transmittance changes monotonically according to wavelength in a predetermined wavelength range, the second line sensor unit detecting measurement light from an object moving relatively to the second pixel unit and outputting a second detection signal; a calculation unit that acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal and the second detection signal, a predetermined time difference exists between the detection timing of the measurement light of the first line sensor unit and the detection timing of the measurement light of the second line sensor unit; Optical information acquisition device.

[0019] In the optical information acquisition device of the embodiment, [2] "the first line sensor unit further includes a neutral density filter that is arranged to cover the first pixel unit and that attenuates the measurement light, The optical information acquisition device may be the one described in [1] above.

[0020] The optical information acquisition device of the embodiment is, [3] "an exposure time for one detection of the measurement light in the first line sensor unit is set shorter than an exposure time for one detection of the measurement light in the second line sensor unit, The optical information acquisition device may be the one described in [1] or [2] above.

[0021] The optical information acquisition device of the embodiment further includes: [4] "a plate member arranged to cover the second pixel unit and transmitting the measurement light; The optical information acquisition device according to any one of [1] to [3] above may be configured such that the monotonic function filter is disposed on a surface of the plate member that faces the second pixel unit.

[0022] The optical information acquisition device of the embodiment further includes a third line sensor unit that includes: [5] "a third pixel unit in which a plurality of pixels are arranged in parallel with the first pixel unit and the second pixel unit; and a first curve function filter that is arranged to cover the third pixel unit and has a characteristic in which transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range; detects measurement light from an object that moves relatively to the third pixel unit; and outputs a third detection signal; The calculation unit may be an optical information acquisition device according to any one of [1] to [4] above, which acquires a characteristic value relating to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, and the third detection signal.

[0023] The optical information acquisition device of the embodiment may be [6] "the optical information acquisition device described in [5] above, wherein the first curve function filter is a filter made by stacking two monotonic function filters having a characteristic that the transmittance changes monotonically depending on the wavelength in a predetermined wavelength range."

[0024] The optical information acquisition device of the embodiment further includes: [7] "a fourth pixel unit including a plurality of pixels arranged in parallel with the first pixel unit, the second pixel unit, and the third pixel unit; and a second curve function filter arranged to cover the fourth pixel unit and having a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range; and a fourth line sensor unit that detects measurement light from an object moving relatively to the fourth pixel unit and outputs a fourth detection signal; The calculation unit may be an optical information acquisition device described in [5] above, which acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, and the fourth detection signal.

[0025] The optical information acquisition device of the embodiment may be [8] "the optical information acquisition device described in [7] above, wherein the second curve function filter is a filter made by stacking three monotonic function filters having a characteristic that the transmittance changes monotonically depending on the wavelength in a predetermined wavelength range."

[0026] The optical information acquisition device of the embodiment further includes: [9] "a fifth pixel unit including a plurality of pixels arranged in parallel with the first pixel unit, the second pixel unit, the third pixel unit, and the fourth pixel unit; and a third curve function filter arranged to cover the fifth pixel unit and having a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range; and a fifth line sensor unit that detects measurement light from an object moving relatively to the fifth pixel unit and outputs a fifth detection signal; The calculation unit may be an optical information acquisition device described in [8] above, which acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, the fourth detection signal, and the fifth detection signal.

[0027] The optical information acquisition device of the embodiment may be

[10] "the optical information acquisition device described in [9] above, wherein the third curve function filter is a filter made by stacking four monotonic function filters having a characteristic that the transmittance changes monotonically depending on the wavelength in a predetermined wavelength range."

[0028] The optical information acquisition method of the embodiment includes:

[11] "a first optical detection step of detecting measurement light from an object moving relatively to a first pixel unit in which a plurality of pixels are arranged, and outputting a first detection signal; a second light detection step of detecting measurement light from an object moving relatively to the second pixel unit using a second pixel unit having an array of multiple pixels and a monotonic function filter that is arranged to cover the second pixel unit and has a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range, and outputting a second detection signal; a calculation step of acquiring a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal and the second detection signal, a predetermined time difference exists between the detection timing of the measurement light in the first light detection step and the detection timing of the measurement light in the second light detection step; The optical information acquisition method may be an optical information acquisition method.

[0029] The optical information acquisition method of the embodiment further includes a third optical detection step of detecting measurement light from an object moving relatively to the third pixel unit using a third pixel unit having an array of a plurality of pixels and a first curve function filter that is arranged to cover the third pixel unit and has a characteristic that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and outputting a third detection signal; In the calculation step, a characteristic value related to the wavelength spectrum of the measurement light is acquired based on at least the first detection signal, the second detection signal, and the third detection signal. The optical information acquisition method described in

[11] above may also be used.

[0030] The optical information acquisition method of the embodiment further includes a fourth optical detection step of detecting measurement light from an object moving relatively to the fourth pixel unit using a fourth pixel unit having an array of a plurality of pixels and a second curve function filter that is arranged to cover the fourth pixel unit and has a characteristic that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and outputting a fourth detection signal; In the calculation step, a characteristic value related to the wavelength spectrum of the measurement light is acquired based on at least the first detection signal, the second detection signal, the third detection signal, and the fourth detection signal. The optical information acquisition method described in

[12] above may also be used.

[0031] The optical information acquisition method of the embodiment further includes a fifth optical detection step of detecting measurement light from an object moving relatively to the fifth pixel unit using a fifth pixel unit having an array of a plurality of pixels and a third curve function filter that is arranged to cover the fifth pixel unit and has a characteristic that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and outputting a fifth detection signal; In the calculation step, a characteristic value related to the wavelength spectrum of the measurement light is acquired based on at least the first detection signal, the second detection signal, the third detection signal, the fourth detection signal, and the fifth detection signal. The optical information acquisition method described in

[13] above may also be used. [Effects of the Invention]

[0032] According to any aspect of the present embodiment, it is possible to obtain characteristics related to the width of the wavelength spectrum of incident light. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a schematic diagram of a measurement system 1 that is an optical information acquisition device according to the first embodiment. [Figure 2] FIG. 2(a) is a plan view of the imaging device 5 as seen from a direction perpendicular to the light receiving surface, and FIG. 2(b) is a side view of the imaging device 5 as seen from a direction along the light receiving surface. [Figure 3] FIG. 3 is a block diagram showing the hardware configuration of the computer 10 of FIG. [Figure 4] FIG. 4(a) is a diagram showing an imaging range of the object S, and FIGS. 4(b) to 4(d) are timing charts showing imaging timings of the first pixel portion 23a and the second pixel portion 23b. [Figure 5] FIG. 5 is a diagram showing the incidence state of incident light I0 and transmitted light I1 that are the subject of calculation by the image generating unit 7 in FIG. [Figure 6] FIG. 6(a) is a plan view of the imaging device 5A as seen from a direction perpendicular to the light receiving surface, and FIG. 6(b) is a side view of the imaging device 5A as seen from a direction along the light receiving surface. [Figure 7] FIG. 7 is a diagram showing the incidence states of incident light I0, transmitted light I1, and transmitted light I2 that are the objects of calculation by the image generating unit 7. In FIG. [Figure 8] FIG. 8(a) is a plan view of the imaging device 5B as seen from a direction perpendicular to the light receiving surface, and FIG. 8(b) is a side view of the imaging device 5B as seen from a direction along the light receiving surface. [Figure 9]FIG. 9 is a diagram showing the incidence states of incident light I0, transmitted light I1, transmitted light I2, and transmitted light I3 that are the objects of calculation by the image generating unit 7. In FIG. [Figure 10] FIG. 10(a) is a plan view of the imaging device 5C as seen from a direction perpendicular to the light receiving surface, and FIG. 10(b) is a side view of the imaging device 5C as seen from a direction along the light receiving surface. [Figure 11] FIG. 11 is a diagram showing the incidence states of incident light I0, transmitted light I1, transmitted light I2, transmitted light I3, and transmitted light I4 that are the objects of calculation by the image generating unit 7. In FIG. [Figure 12] FIG. 12 is a side view of an imaging device 5D according to a modified example, as viewed in a direction along the light receiving surface. [Figure 13] FIG. 13 is a timing chart showing the imaging timing of the first pixel portion 23a and the second pixel portion 23b in the modified example. [Figure 14] FIG. 14 is a diagram showing an example of the transmission characteristics of an LRG filter according to a modified example. [Figure 15] FIG. 15 is a diagram showing an example of the transmission characteristics of an LRG filter according to another modified example. [Figure 16] FIG. 16 is a diagram showing the configuration of a transport section 2A according to a modified example. [Figure 17] FIG. 17 is a diagram showing the structure of the imaging device 5B. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted. [First embodiment]

[0035] FIG. 1 is a schematic diagram of a measurement system 1, which is an optical information acquisition device according to a first embodiment of the present disclosure. The measurement system 1 shown in FIG. 1 is configured as a device that acquires characteristic values ​​related to the wavelength spectrum of measurement light incident from an object S by irradiating the object with light La. As will be described later, the measurement system 1 uses an optical element having transmission characteristics in which the transmittance changes monotonically with wavelength in a predetermined wavelength range. The measurement system 1 receives, of the measurement light Lb from the object S generated by the light La, light that has passed through the optical element and light that has not passed through the optical element and is incident. Then, image data related to the distribution of centroid wavelengths in the object S is generated based on brightness data based on the respective detection signals obtained as a result of receiving the two light beams. Note that the "centroid wavelength" in this embodiment may also be referred to as the "center wavelength."

[0036] The measurement light Lb is light from the object S, such as light emission, fluorescence, output light, reflected light, or transmitted light from the object S. The object S may be a semiconductor device, a semiconductor wafer, an optical integrated circuit, a light-emitting element, food, a resin material, waste, or a biological sample.

[0037] As shown in FIG. 1, the measurement system 1 includes a transport unit 2, a light source unit 3, an imaging device 5, and a computer (arithmetic unit) 10. The transport unit 2 transports the object S in a predetermined direction. The transport unit 2 is configured, for example, by a belt conveyor. The transport unit 2 transports the object S in the horizontal direction at a constant speed v toward the irradiation position of light La from the light source unit 3. This causes the object S to be scanned toward the irradiation position of light La.

[0038] The light source unit 3 is a part that outputs light La toward the target S. In this embodiment, the light source unit 3 is composed of light source devices 3a and 3b that can output light La toward the target S from two directions, the upstream and downstream sides in the conveyance direction. The light La is, for example, a directional light beam. Examples of the light source devices 3a and 3b that output such light include a multi-band LED bar illumination device. The illumination device incorporates, for example, an LED bar with a central wavelength of 1200 nm, an LED bar with a central wavelength of 1300 nm, an LED bar with a central wavelength of 1450 nm, an LED bar with a central wavelength of 1550 nm, and an LED bar with a central wavelength of 1650 nm. The configuration including the two light source devices 3a and 3b can reduce the difference in intensity of the incident measurement light due to differences in the light receiving position or height between the first pixel unit 23a and the second pixel unit 23b (described later).

[0039] 2 shows the configuration of the imaging device 5, where (a) is a plan view seen from a direction perpendicular to the light-receiving surface, and (b) is a side view seen from a direction along the light-receiving surface. The imaging device 5 includes a substrate 21, a first pixel portion 23a, a second pixel portion 23b, a window portion (plate member) 25, an LRG (Linear Reflectance Gradient on the wavelength axis) filter (monotonous function filter) 31, and AR (Anti-Reflection) coatings 27 and 29.

[0040] The first pixel section 23a is made up of a plurality of pixels 22 linearly arranged on the substrate 21. The second pixel section 23b is made up of a plurality of pixels 22 linearly arranged on the substrate 21 parallel to the first pixel section 23a. The pixel spacing between the first pixel section 23a and the second pixel section on the substrate 21, in other words, the arrangement pitch of the pixels 22 between the first pixel section 23a and the second pixel section, is set to d. The window section 25 is a plate-shaped transparent member made of a material that transmits the measurement light Lb, such as glass, and is arranged so as to entirely cover the first pixel section 23a and the second pixel section 23b on the substrate 21, with a gap therebetween. An LRG filter 31 is formed on the surface of the window section 25 facing the first pixel section 23a and the second pixel section 23b only in the area covering the second pixel section 23b, and an AR coating 29, which is an anti-reflection film that prevents reflected light, is formed only in the area covering the first pixel section 23a. In addition, an AR coating 27 is formed on the surface of the window portion 25 opposite to the surface facing the first pixel portion 23a and the second pixel portion 23b, in an area that covers the entire first pixel portion 23a and the second pixel portion 23b.

[0041] The imaging device 5 having the above configuration is disposed so that the light-receiving side of the substrate 21 faces the object S transported on the transport unit 2, and the arrangement direction of the pixels 22 of the first pixel unit 23a and the second pixel unit 23b is perpendicular to the transport direction. The first pixel unit 23a detects incident light I0, which is measurement light Lb, from the object S moving relative to the first pixel unit 23a, and constitutes a first line sensor unit that outputs a first detection signal. Meanwhile, the second pixel unit 23b and the LRG filter 31 detect transmitted light I1, which is incident light I0 from the object S moving relative to the second pixel unit 23b and transmitted through the LRG filter 31, and constitutes a second line sensor unit that outputs a second detection signal. The imaging device 5 may include a lens.

[0042] The LRG filter 31 provided in the imaging device 5 is a filter member made of a special optical material, and has the property that the light transmittance in a predetermined wavelength range changes depending on the wavelength, specifically, the light transmittance in a predetermined wavelength range changes linearly with the wavelength. In other words, the LRG filter 31 has the property that the light transmittance in a predetermined wavelength range changes monotonically with changes in wavelength (for example, the transmittance in a predetermined wavelength range increases or decreases monotonically), and has the light transmittance T1 characteristic expressed by the following formula (1), where λ is the wavelength of incident light. T1(λ)=s1λ+t1…(1) In the above formula (1), s1 and t1 are known constants determined by the transmittance characteristics. The above-mentioned predetermined wavelength range is a wavelength range that overlaps with the wavelength range of the incident light I0 to be measured, for example, a wavelength range of 400 nm to 800 nm.

[0043] The computer 10 has a function of controlling the operation of the light source unit 3 and the imaging device 5, and a function of acquiring characteristic values ​​related to the wavelength spectrum of the incident light I0 based on a detection signal output from the imaging device 5. FIG. 3 is a block diagram showing the hardware configuration of the computer 10. As shown in FIG. 3, the computer 10 is physically a computer or the like including a processor such as a CPU (Central Processing Unit) 131 and a GPU (Graphic Processing Unit) 135, a storage medium such as a RAM (Random Access Memory) 132 and a ROM (Read Only Memory) 133, a communication module 134, and an input / output module 136, all of which are electrically connected. The computer 10 may include input / output devices such as a display, a keyboard, a mouse, a touch panel display, or a data storage device such as a hard disk drive or semiconductor memory. The computer 10 may also be configured using a microcomputer or FPGA. The computer 10 may also be configured using multiple computers, or may be integrated with the imaging device 5.

[0044] First, the control function of the computer 10 for the light source unit 3 and the imaging device 5 will be described.

[0045] When measurement of the object S is started, the computer 10 controls the light source unit 3 to output light La of a temporally uniform light intensity toward the object S. The computer 10 may also control the light source unit 3 to turn on intermittently in synchronization with the imaging timing of the first pixel unit 23a and the second pixel unit 23b described below.

[0046] Moreover, the computer 10 controls the imaging timing of the first pixel unit 23a and the second pixel unit 23b by outputting a control pulse to each of the first pixel unit 23a and the second pixel unit 23b. Fig. 4 is a diagram for explaining the control of the imaging timing by the computer 10, Fig. 4(a) is a diagram showing the imaging range of the object S, and Figs. 4(b) and 4(c) are timing charts showing the imaging timing of the first pixel unit 23a and the second pixel unit 23b.

[0047] As shown in FIG. 4(a), while the object S is being transported by the transport unit 2 so as to move at a speed v relative to the first pixel unit 23a and the second pixel unit 23b, the computer 10 controls the imaging timing, thereby capturing images for each range (e.g., four ranges indicated by "1" to "4") divided in the transport direction by the first pixel unit 23a and the second pixel unit 23b. In the control shown in FIG. 4(b), the computer 10 controls the first pixel unit 23a and the second pixel unit 23b to repeatedly detect the measurement light Lb at a period determined by the width of the divided range of the object S and the speed v. At this time, the computer 10 controls the detection start timing of each detection by the second pixel unit 23b arranged downstream of the transport so that the detection start timing of each detection by the first pixel unit 23a arranged upstream of the transport is delayed by a time difference (predetermined time difference) ΔT=d / v determined by the transport speed v and the arrangement pitch d. As a result, immediately after the first pixel unit 23a captures each of the ranges "1" to "4," the second pixel unit 23b captures each of the ranges "1" to "4." When the transport direction is reversed, the computer 10 may control the timing of each detection start by the first pixel unit 23a, which is arranged downstream of the transport, to be delayed by a time difference (predetermined time difference) ΔT=d / v determined by the transport speed v and the array pitch d relative to the timing of each detection start by the second pixel unit 23b, which is arranged upstream of the transport. In other words, the computer 10 may control the timing of each detection start by the first pixel unit 23a and the timing of each detection start by the second pixel unit 23b to have a time difference (predetermined time difference) ΔT=d / v determined by the transport speed v and the array pitch d.

[0048] Here, the computer 10 may set the imaging timing of the first pixel unit 23a and the second pixel unit 23b to the timing shown in Figures 4(c) and 4(d). That is, the computer 10 controls the imaging period of the first pixel unit 23a and the second pixel unit 23b to a period ΔT = (1 / n) · d / v determined by the transport speed v, the array pitch d, and the integer n, i.e., to set the imaging rate to n · v / d. Figure 4(c) shows a control example when n = 1, and Figure 4(d) shows a control example when n = 2. As a result, the first pixel unit 23a simultaneously captures the range "1" to "4" and the second pixel unit 23b simultaneously captures the range "1" to "4," resulting in a time difference of n × ΔT between the imaging timing of the same range between the first pixel unit 23a and the second pixel unit 23b. In other words, the computer 10 may control the timing at which the first pixel section 23a starts detection each time and the timing at which the second pixel section 23b starts detection each time so that there is a time difference (predetermined time difference) n·ΔT=n·d / v determined by the transport speed v and the array pitch d.

[0049] Next, we will explain the function of acquiring characteristic values ​​related to the wavelength spectrum of the incident light I0 by the computer 10. As shown in Fig. 1, the computer 10 includes a signal acquisition unit 6, an image generation unit 7, and a display unit 8 as functional components.

[0050] The signal acquiring unit 6 acquires a first detection signal output from the pixel row of the first pixel unit 23a at each imaging timing, and generates first image data indicating the intensity distribution of incident light I0 incident from the entire object S. The signal acquiring unit 6 also acquires a second detection signal output from the pixel row of the second pixel unit 23b at each imaging timing, and generates second image data indicating the intensity distribution of transmitted light I1 incident from the entire object S. At this time, the signal acquiring unit 6 may acquire the first detection signal from the first pixel unit 23a via a delay circuit and memory (not shown) inside the imaging device 5, thereby synchronizing the output timing of the first detection signal that detects the range of the object S from the first pixel unit 23a with the output timing of the second detection signal that detects the same range of the object S from the second pixel unit 23b.

[0051] The image generating unit 7 has a function of calculating a characteristic value relating to the wavelength spectrum of the incident light I0 for each pixel based on the first image data and the second image data. In the following description, the light intensity of the incident light I0 is represented by the symbol I0, and the light intensity of the transmitted light I1 is represented by the symbol I1 or I T0 5 shows the incidence states of incident light I0 and transmitted light I1 that are the subject of calculation by the image generation unit 7. As such, incident light I0 is light that enters the imaging device 5 without passing through the LRG filter 31, and transmitted light I1 is light that passes through the LRG filter 31 and enters the imaging device 5.

[0052] In detail, the image generating unit 7 calculates a centroid wavelength λ , which is a first moment in the wavelength spectrum of the incident light I0, for each pixel. G0 That is, the image generating unit 7 calculates the first moment of the wavelength spectrum of the incident light I0 based on the light intensity I0 indicated by the pixel value of the first image data and the light intensity I1 indicated by the pixel value of the second image data, and obtains the centroid wavelength λ in the wavelength spectrum of the incident light I0. G0 The principle of this function is as follows: Assuming that the wavelength spectrum of incident light I0 has a distribution of the function i0(λ) = I0 × f0(λ) and the wavelength spectrum of transmitted light I1 has a distribution of the function i1(λ), ​​the following equation is established.

number

[0053] According to the above principle, the image generating unit 7 calculates the light intensities I0 and I1 indicated by the first image data and the second image data in accordance with the following formula (2):

number

[0054] The display unit 8 outputs the output image data generated by the image generation unit 7. The output destination may be a display, which is an input / output device, or a data recording device such as a hard disk drive or semiconductor memory.

[0055] Next, the procedure of the measurement process of the measurement light from the object S by the measurement system 1 will be described, and the light information acquisition method of this embodiment will be described in detail.

[0056] First, when the transport unit 2 starts transporting the object S, light La is output toward the object S under the control of the computer 10. At the same time, the computer 10 outputs a control pulse to each of the first pixel unit 23a and the second pixel unit 23b in the imaging device 5, and the imaging timing of each of the first pixel unit 23a and the second pixel unit 23b is controlled so that the image is captured at a timing determined by the transport speed v of the object S and the arrangement pitch d.

[0057] In response to imaging control by the computer 10, first detection signals are sequentially output from the first pixel unit 23a to the computer 10, and first image data is generated by the computer 10 based on the first detection signals output for each pixel column. Concurrently, second detection signals are sequentially output from the second pixel unit 23b to the computer 10, and second image data is generated by the computer 10 based on the second detection signals output for each pixel column. Next, in the computer 10, a characteristic value related to the wavelength spectrum of the incident light I0 for each pixel is obtained based on the first image data and the second image data, and output image data indicating the distribution of the characteristic value related to the wavelength spectrum of the incident light I0 for each pixel is generated and output.

[0058] According to the measurement system 1 of the first embodiment described above, the first pixel unit 23a detects the incident light I0 from the object S moving relatively to the first pixel unit 23a, thereby outputting a first detection signal, and the second pixel unit 23b detects the incident light I0 from the object S moving relatively to the second pixel unit 23b after passing through the LRG filter 31, thereby outputting a second detection signal, and the distribution of characteristic values ​​related to the wavelength spectrum of the incident light I0 is obtained based on the first detection signal and the second detection signal. This makes it possible to obtain characteristic values ​​related to the wavelength spectrum of the incident light I0 from a wide range of the object S moving relatively to the detection region.

[0059] In the first embodiment, a window portion 25 that is arranged to cover the second pixel portion 23b and transmits the incident light I0 may be further provided, and the LRG filter 31 may be arranged on a surface of the window portion 25 that faces the second pixel portion 23b. According to the above-described simple configuration, the transmitted light I1 from the object S that has passed through the LRG filter 31 can be stably detected by the second pixel portion 23b. [Second embodiment]

[0060] The configuration of a measurement system according to the second embodiment will be described. The measurement system according to the second embodiment differs from the first embodiment in the configuration of the imaging device 5 and the functions of the computer 10. Only the differences between the first embodiment and the second embodiment will be described below.

[0061] 6 shows the configuration of an imaging device 5A according to a second embodiment, with (a) being a plan view seen from a direction perpendicular to the light-receiving surface and (b) being a side view seen from a direction along the light-receiving surface. The imaging device 5A further includes a third pixel section 23c consisting of a plurality of pixels 22 linearly arranged in parallel with the first pixel section 23a and the second pixel section 23b on the substrate 21. The third pixel section 23c is provided adjacent to the second pixel section 23b, but the arrangement order of the first pixel section 23a, the second pixel section 23b, and the third pixel section 23c may be changed to any order.

[0062] The window portion 25 is disposed so as to entirely cover the first pixel portion 23 a, the second pixel portion 23 b, and the third pixel portion 23 c on the substrate 21, with a gap therebetween. A quadratic function filter (first curve function filter) 33 is formed on the surface of the window portion 25 facing the first pixel portion 23 a, the second pixel portion 23 b, and the third pixel portion 23 c, only in the area covering the third pixel portion 23 c. An AR coating 27 is formed on the surface of the window portion 25 opposite to the surface facing the first pixel portion 23 a, the second pixel portion 23 b, and the third pixel portion 23 c, in an area entirely covering the first pixel portion 23 a, the second pixel portion 23 b, and the third pixel portion 23 c.

[0063] The imaging device 5A having the above configuration is disposed so that the light receiving side of the substrate 21 faces the object S transported on the transport unit 2, and the arrangement direction of the pixels 22 in the first pixel unit 23a, the second pixel unit 23b, and the third pixel unit 23c is perpendicular to the transport direction. The third pixel unit 23c and the quadratic function filter 33 constitute a third line sensor unit that detects transmitted light I2 that is transmitted through the quadratic function filter 33 from incident light I0 from the object S that moves relative to the third pixel unit 23c, and outputs a third detection signal.

[0064] The quadratic function filter 33 included in the imaging device 5A is a filter member made of a special optical material, and has a characteristic that the transmittance of light in a predetermined wavelength range changes depending on the wavelength, specifically, the transmittance of light in a predetermined wavelength range changes in a curved manner depending on the wavelength. More specifically, the quadratic function filter 33 has a characteristic of light transmittance T2 expressed by the following equation (3), where λ is the wavelength of incident light. T2(λ)=r2λ 2 +s2λ+t2…(3) In the above formula (3), r2, s2, and t2 are known constants determined by the transmittance characteristics. The quadratic function filter 33 having the above characteristics can be realized by stacking two LRG filters. Alternatively, the quadratic function filter 33 may be realized by a single filter.

[0065] Similar to the first embodiment, the computer 10 according to the second embodiment controls the imaging timing of the first pixel unit 23a, the second pixel unit 23b, and the third pixel unit 23c by outputting control pulses to each of the first pixel unit 23a, the second pixel unit 23b, and the third pixel unit 23c. That is, the computer 10 controls the timing of each detection start of the first pixel unit 23a, the second pixel unit 23b, and the third pixel unit 23c so that they are spaced apart by a time difference (a predetermined time difference) determined by the transport speed v and the array pitch d. The signal acquisition unit 6 of the computer 10 acquires a third detection signal output from the pixel row of the third pixel unit 23c at each imaging timing and generates third image data indicating the intensity distribution of transmitted light I2 incident from the entire target S.

[0066] The image generating unit 7 of the computer 10 has a function of calculating a characteristic value relating to the wavelength spectrum of the incident light I0 for each pixel based on the first image data, the second image data, and the third image data. In the following description, the light intensity of the transmitted light I2 will be referred to as I2 or I T17 shows the incidence states of incident light I0, transmitted light I1, and transmitted light I2 that are the objects of calculation by the image generation unit 7. As described above, incident light I0 is light that enters the image capture device 5A without passing through the LRG filter 31 and the quadratic function filter 33, transmitted light I1 is light that passes through the LRG filter 31 and enters the image capture device 5A, and transmitted light I2 is light that passes through the quadratic function filter 33 and enters the image capture device 5A.

[0067] The image generating unit 7 of the computer 10 also has a function of acquiring the standard deviation σ0, which is the second moment of the wavelength spectrum of the incident light I0. That is, the image generating unit 7 calculates the second moment of the wavelength spectrum of the incident light I0 based on the light intensity I0 indicated by the pixel values ​​of the first image data, the light intensity I1 indicated by the pixel values ​​of the second image data, and the light intensity I2 indicated by the pixel values ​​of the third image data, and acquires the standard deviation σ0 or variance σ0 in the wavelength spectrum of the incident light I0. 2 The principle of this function is as follows: If we assume that the wavelength spectrum of the transmitted light I2 has a distribution of the function i2(λ)=I2×f2(λ), the following equation is established:

number

number

[0068] According to the above principle, the image generating unit 7 calculates the light intensities I0 and I2 using the following formula (4):

number

[0069] According to the measurement system of the second embodiment described above, it is possible to obtain multiple types of distributions of characteristic values ​​related to the wavelength spectrum of incident light I0 from a wide range of an object S that moves relative to the detection area, including a standard deviation σ0. [Third embodiment]

[0070] The configuration of a measurement system according to the third embodiment will be described. The measurement system according to the third embodiment differs from the second embodiment in the configuration of the imaging device 5A and the functions of the computer 10. Only the differences between the second embodiment and the third embodiment will be described below.

[0071] 8 shows the configuration of an imaging device 5B according to a third embodiment, with (a) being a plan view seen from a direction perpendicular to the light-receiving surface and (b) being a side view seen from a direction along the light-receiving surface. The imaging device 5B further includes a fourth pixel section 23d consisting of a plurality of pixels 22 linearly arranged in parallel with the first pixel section 23a, the second pixel section 23b, and the third pixel section 23c on the substrate 21. The fourth pixel section 23d is provided adjacent to the third pixel section 23c, but the arrangement order of the first pixel section 23a, the second pixel section 23b, the third pixel section 23c, and the fourth pixel section 23d may be changed to any order.

[0072] The window portion 25 is disposed so as to entirely cover the first pixel portion 23 a, the second pixel portion 23 b, the third pixel portion 23 c, and the fourth pixel portion 23 d on the substrate 21, with a gap therebetween. A cubic function filter (second curve function filter) 35 is formed on the surface of the window portion 25 facing the first pixel portion 23 a, the second pixel portion 23 b, the third pixel portion 23 c, and the fourth pixel portion 23 d, only in the area covering the fourth pixel portion 23 d. An AR coating 27 is formed on the surface of the window portion 25 opposite the surface facing the first pixel portion 23 a, the second pixel portion 23 b, the third pixel portion 23 c, and the fourth pixel portion 23 d, in the area entirely covering the first pixel portion 23 a, the second pixel portion 23 b, the third pixel portion 23 c, and the fourth pixel portion 23 d.

[0073] The imaging device 5B having the above configuration is disposed so that the light receiving side of the substrate 21 faces the object S transported on the transport unit 2, and the arrangement direction of the pixels 22 in the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, and the fourth pixel unit 23d is perpendicular to the transport direction. The fourth pixel unit 23d and the cubic function filter 35 constitute a fourth line sensor unit that detects transmitted light I3 that is transmitted through the cubic function filter 35 from incident light I0 from the object S that moves relative to the fourth pixel unit 23d, and outputs a fourth detection signal.

[0074] The cubic function filter 35 included in the imaging device 5B is a filter member made of a special optical material, and has a characteristic that the transmittance of light in a predetermined wavelength range changes depending on the wavelength, specifically, the transmittance of light in a predetermined wavelength range changes in a curved manner depending on the wavelength. More specifically, the cubic function filter 35 has a characteristic of light transmittance T3 expressed by the following equation (5), where λ is the wavelength of incident light. T3(λ)=q3λ 3 +r3λ 2 +s3λ+t3…(5) In the above formula (5), q3, r3, s3, and t3 are known constants determined by the transmittance characteristics. The cubic function filter 35 having the above characteristics can be realized by overlapping three LRG filters. The cubic function filter 35 may also be realized by a single filter, or by overlapping an LRG filter and a quadratic function filter.

[0075] The computer 10 according to the third embodiment controls the imaging timing of the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, and the fourth pixel unit 23d by outputting control pulses to each of the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, and the fourth pixel unit 23d, as in the second embodiment. That is, the computer 10 may control the timing of each detection start of the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, and the fourth pixel unit 23d so that they are spaced apart by a time difference (predetermined time difference) determined by the transport speed v and the array pitch d. The signal acquisition unit 6 of the computer 10 acquires a fourth detection signal output from the pixel row of the fourth pixel unit 23d at each imaging timing and generates fourth image data representing the intensity distribution of transmitted light I3 incident from the entire target S.

[0076] The image generating unit 7 of the computer 10 has a function of calculating a characteristic value relating to the wavelength spectrum of the incident light I0 for each pixel based on the first image data, the second image data, the third image data, and the fourth image data. In the following description, the light intensity of the transmitted light I3 will be referred to as I3 or I T2 9 shows the incidence states of incident light I0, transmitted light I1, transmitted light I2, and transmitted light I3 that are the objects of calculation by the image generation unit 7. As described above, incident light I0 is light that enters the image capture device 5B without passing through the LRG filter 31, the quadratic function filter 33, or the cubic function filter 35, transmitted light I1 is light that passes through the LRG filter 31 and enters the image capture device 5B, transmitted light I2 is light that passes through the quadratic function filter 33 and enters the image capture device 5B, and transmitted light I3 is light that passes through the cubic function filter 35 and enters the image capture device 5B.

[0077] The image generation unit 7 of the computer 10 also has a function of acquiring the skewness S0, which is the third moment of the wavelength spectrum of the incident light I0. That is, the image generation unit 7 calculates the third moment of the wavelength spectrum of the incident light I0 based on the light intensity I0 indicated by the pixel values ​​of the first image data, the light intensity I1 indicated by the pixel values ​​of the second image data, the light intensity I2 indicated by the pixel values ​​of the third image data, and the light intensity I3 indicated by the pixel values ​​of the fourth image data, to acquire the skewness S0 of the wavelength spectrum of the incident light I0. The principle of this function is as follows. Here, assuming that the wavelength spectrum of the transmitted light I3 has a distribution of the function i3(λ) = I3 × f3(λ), the following equation holds:

number

number

[0078] According to the above principle, the image generating unit 7 calculates the light intensities I0 and I3 using the following formula (6):

number

[0079] According to the measurement system of the third embodiment described above, it is possible to obtain many types of distributions of characteristic values ​​related to the wavelength spectrum of incident light I0 from a wide range of an object S that moves relative to the detection area, including standard deviation σ0 and skewness S0. [Fourth embodiment]

[0080] The configuration of a measurement system according to the fourth embodiment will be described. The measurement system according to the fourth embodiment differs from the third embodiment in the configuration of the imaging device 5B and the function of the computer 10. Only the differences between the fourth embodiment and the third embodiment will be described below.

[0081] 10 shows the configuration of an imaging device 5C according to a fourth embodiment, with (a) being a plan view seen from a direction perpendicular to the light-receiving surface and (b) being a side view seen from a direction along the light-receiving surface. The imaging device 5C further includes a fifth pixel section 23e consisting of a plurality of pixels 22 linearly arranged in parallel with the first pixel section 23a, the second pixel section 23b, the third pixel section 23c, and the fourth pixel section 23d on the substrate 21. The fifth pixel section 23e is provided adjacent to the fourth pixel section 23d, but the arrangement order of the first pixel section 23a, the second pixel section 23b, the third pixel section 23c, the fourth pixel section 23d, and the fifth pixel section 23e may be changed to any order.

[0082] The window portion 25 is disposed so as to entirely cover, with a gap therebetween, the first pixel portion 23 a, the second pixel portion 23 b, the third pixel portion 23 c, the fourth pixel portion 23 d, and the fifth pixel portion 23 e on the substrate 21. A quartic function filter (third curve function filter) 37 is formed on the surface of the window portion 25 facing the first pixel portion 23 a, the second pixel portion 23 b, the third pixel portion 23 c, the fourth pixel portion 23 d, and the fifth pixel portion 23 e, only in the range covering the fifth pixel portion 23 e. An AR coating 27 is formed on the surface of the window portion 25 opposite to the surface facing the first pixel portion 23a, the second pixel portion 23b, the third pixel portion 23c, the fourth pixel portion 23d, and the fifth pixel portion 23e, in an area that entirely covers the first pixel portion 23a, the second pixel portion 23b, the third pixel portion 23c, the fourth pixel portion 23d, and the fifth pixel portion 23e.

[0083] The imaging device 5C having the above configuration is arranged so that the light-receiving side of the substrate 21 faces the object S transported on the transport unit 2, and the arrangement direction of the pixels 22 in the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, the fourth pixel unit 23d, and the fifth pixel unit 23e is perpendicular to the transport direction. The fifth pixel unit 23e and the quartic function filter 37 constitute a fifth line sensor unit that detects transmitted light I4 that is transmitted through the quartic function filter 37 from incident light I0 from the object S that moves relative to the fifth pixel unit 23e, and outputs a fifth detection signal.

[0084] The quartic filter 37 included in the imaging device 5C is a filter member made of a special optical material, and has a characteristic that the transmittance of light in a predetermined wavelength range changes depending on the wavelength, specifically, the transmittance of light in a predetermined wavelength range changes in a curved manner depending on the wavelength. More specifically, the quartic filter 37 has a characteristic of light transmittance T4 expressed by the following equation (7), where λ is the wavelength of incident light. T4(λ)=p4λ 4 +q4λ 3 +r4λ 2 +s4λ+t4…(7) In the above formula (7), p4, q4, r4, s4, and t4 are known constants determined by the transmittance characteristics. The quartic function filter 37 having the above characteristics can be realized by overlapping four LRG filters. Furthermore, the quartic function filter 37 may be realized by a single filter, by overlapping an LRG filter and a cubic function filter, or by overlapping two quadratic function filters.

[0085] The computer 10 according to the fourth embodiment controls the imaging timing of the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, the fourth pixel unit 23d, and the fifth pixel unit 23e by outputting control pulses to each of the first pixel unit 23a, the second pixel unit 23b, the third pixel unit 23c, the fourth pixel unit 23d, and the fifth pixel unit 23e, in the same manner as in the third embodiment. That is, the computer 10 may control the timing of each detection start by the first pixel unit 23a, the timing of each detection start by the second pixel unit 23b, the timing of each detection start by the third pixel unit 23c, the timing of each detection start by the fourth pixel unit 23d, and the timing of each detection start by the fifth pixel unit 23e so that there is a time difference (a predetermined time difference) between them that is determined by the transport speed v and the arrangement pitch d. The signal acquisition unit 6 of the computer 10 acquires a fifth detection signal output from the pixel row of the fifth pixel unit 23e at each imaging timing, and generates fifth image data indicating the intensity distribution of the transmitted light I4 incident from the entire object S.

[0086] The image generating unit 7 of the computer 10 has a function of calculating a characteristic value relating to the wavelength spectrum of the incident light I0 for each pixel based on the first image data, the second image data, the third image data, the fourth image data, and the fifth image data. In the following description, the light intensity of the transmitted light I4 will be referred to as I4 or I T3 11 shows the incidence states of incident light I0, transmitted light I1, transmitted light I2, transmitted light I3, and transmitted light I4, which are the objects of calculation by the image generation unit 7. As described above, incident light I0 is light that enters the image capture device 5C without passing through the LRG filter 31, the quadratic function filter 33, the cubic function filter 35, or the quartic function filter 37, transmitted light I1 is light that passes through the LRG filter 31 and enters the image capture device 5C, transmitted light I2 is light that passes through the quadratic function filter 33 and enters the image capture device 5C, transmitted light I3 is light that passes through the cubic function filter 35 and enters the image capture device 5C, and transmitted light I4 is light that passes through the quartic function filter 37 and enters the image capture device 5C.

[0087] The image generation unit 7 of the computer 10 also has a function of acquiring kurtosis K0, which is the fourth-order moment of the wavelength spectrum of the incident light I0. That is, the image generation unit 7 calculates the fourth-order moment of the wavelength spectrum of the incident light I0 based on the light intensity I0 indicated by the pixel values ​​of the first image data, the light intensity I1 indicated by the pixel values ​​of the second image data, the light intensity I2 indicated by the pixel values ​​of the third image data, the light intensity I3 indicated by the pixel values ​​of the fourth image data, and the light intensity I4 indicated by the pixel values ​​of the fifth image data, to acquire kurtosis K0 of the wavelength spectrum of the incident light I0. The principle of this function is as follows. Here, assuming that the wavelength spectrum of the transmitted light I4 has a distribution of the function i4(λ) = I4 × f4(λ), the following equation holds:

number

number

[0088] According to the above principle, the image generating unit 7 calculates the light intensities I0 and I4 using the following formula (8):

number

[0089] According to the measurement system of the fourth embodiment described above, it is possible to obtain a distribution of characteristic values ​​related to the wavelength spectrum of incident light I0 from a wide range of an object S that moves relative to the detection area in even more types, including standard deviation σ0, skewness S0, and kurtosis K0. [Variations]

[0090] Although various embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments.

[0091] In the imaging devices 5, 5A, 5B, and 5C according to the first to fourth embodiments, the LRG filter, the quadratic function filter 33, the cubic function filter 35, or the quartic function filter 37 is arranged on the window portion 25, but these filters may be arranged on any of the first pixel portion 23a, the second pixel portion 23b, the third pixel portion 23c, the fourth pixel portion 23d, and the fifth pixel portion 23e.

[0092] The imaging device 5 according to the first embodiment may be modified to have the configuration of an imaging device 5D as shown in Fig. 12. In the imaging device 5D, a neutral density filter 39 that attenuates incident light I0 is disposed above the AR coating 29 on the surface of the window portion 25 facing the first pixel portion 23a so as to cover only the first pixel portion 23a.

[0093] With such a configuration, the intensity difference of the measurement light detected by the first pixel unit 23a and the second pixel unit 23b can be reduced, and saturation of the first detection signal can be prevented. As a result, characteristic values regarding the wavelength spectrum of the incident light I0 can be accurately obtained. For example, in order to ensure sufficient light detection amount by the second pixel unit 23b, it is necessary to increase the intensity of the light La from the light source unit 3. In this case, when the intensity of the light La is increased, each pixel of the first pixel unit 23a may be saturated. According to the configuration of the imaging device 5D, pixel saturation can be prevented. When the configuration of the above modification is adopted, when the image generation unit 7 of the computer 10 has a configuration in which the dimming filter 39 reduces the intensity of the incident light I0 by a factor of a (0 < a < 1), during the calculation of the characteristic values, the intensity I0 is obtained based on the intensity a×I0 obtained from the first detection signal and then the calculation is performed.

[0094] Also, the configuration of the imaging device 5D according to the above modification may be applied to the second to fourth embodiments.

[0095] In the measurement system according to the first to fourth embodiments, in order to prevent saturation of the first detection signal, the computer 10 may control to vary the exposure time in one imaging between the first pixel unit 23a and the second pixel unit 23b. Specifically, the exposure time for one detection of the incident light I0 in the first pixel unit 23a may be set shorter than the exposure time for one detection of the transmitted light I1 in the second pixel unit 23b. FIG. 13 shows the imaging timings of the first pixel unit 23a and the second pixel unit 23b controlled by the computer 10, and shows a control example corresponding to the control examples shown in FIGS. 4(c) and 4(d). Also in this case, characteristic values regarding the wavelength spectrum of the incident light I0 can be accurately obtained. However, also in this case, as in the above-described modification, the image generation unit 7 of the computer 10 corrects the value obtained from the first detection signal to the intensity I0 and then calculates the characteristic values. <00​In the first to fourth embodiments, the imaging devices 5, 5A, 5B, and 5C or the computer 10 may have a region of interest (ROI) function for selecting pixels from the first pixel to the last pixel from which a detection signal is to be acquired from a pixel row constituting the first pixel unit 23 a, the second pixel unit 23 b, the third pixel unit 23 c, or the fourth pixel unit 23 d. With this ROI function, even if the positions of the pixel units are misaligned in the pixel array direction on the substrate 21, it is possible to adjust the detection range for the object S and accurately calculate a characteristic value related to the wavelength spectrum of the incident light I0.

[0097] In the first to fourth embodiments, the imaging devices 5, 5A, 5B, 5C or the computer 10 may perform FFC (flat field correction) on the detection signals acquired from multiple pixel units in order to correct luminance unevenness, color unevenness of the light source unit 3, or errors in the spectral sensitivity of the line sensor unit itself.

[0098] Furthermore, in the first to fourth embodiments, the LRG filter 31 may have transmission characteristics in which the transmittance changes linearly in each of a plurality of mutually different wavelength regions, as shown in Fig. 14. Such transmission characteristics may be realized by designing a dielectric multilayer film of a single inclined dichroic mirror, or may be realized by stacking a plurality of inclined dichroic mirrors or by switching between them using a filter changer.

[0099] In the example of FIG. 14, the transmittance of the LRG filter 31 varies linearly and independently with respect to the wavelength region including the central wavelength λ1, the wavelength region including the central wavelength λ3, and the wavelength region including the central wavelength λ5. In this case, the transmittance of the LRG filter 31 varies from approximately 0% to approximately 100% in each wavelength region, so the gradient of the change in the transmittance of the LRG filter 31 for each wavelength region is greater than in the examples of the first to fourth embodiments. The greater gradient of the change in the transmittance of the LRG filter 31 results in a greater change in the relative value between the transmittance and the reflectance relative to the amount of wavelength shift when a wavelength shift occurs. This improves the wavelength resolution of the centroid wavelength. Therefore, characteristic values ​​related to the wavelength spectrum of the incident light I0 in the target S can be acquired with greater accuracy.

[0100] As shown in Fig. 15, LRG filter 31 may have transmission characteristics in which wavelength regions in which the transmittance increases linearly and wavelength regions in which the transmittance decreases linearly alternately. In the example of Fig. 15, the transmittance of LRG filter 31 increases linearly in the wavelength region including center wavelength λ1, decreases linearly in the wavelength region including center wavelength λ3, and increases linearly in the wavelength region including center wavelength λ5. Such an LRG filter 31 allows for easier design of a dielectric multilayer film than the LRG filter 31 having the transmission characteristics shown in Fig. 14.

[0101] Furthermore, in the first to fourth embodiments, the transport unit 2 may be modified to have the configuration of a transport unit 2A as shown in FIG. 16. The transport unit 2A includes an XY stage 2a arranged to face the imaging devices 5, 5A to 5C. The object S is placed on the XY stage 2a. When measuring the object S, the XY stage 2a operates to move the imaging area IR formed by the first pixel unit 23a, the second pixel unit 23b, etc. in the Y-axis direction intersecting the pixel arrangement direction of the first pixel unit 23a at a predetermined speed v, shift it in the X-axis direction, and then move it again in the Y-axis direction. This allows the measurement range of the object S to be scanned over the surface of the object S.

[0102] In the first to fourth embodiments, some of the functions of the computer 10 may be executed by the imaging device 5.

[0103] Moreover, the imaging devices 5, 5A to 5C according to the first to fourth embodiments are realized, for example, by the structure shown in Fig. 17. Fig. 17 shows an example of the structure of an imaging device 5B.

[0104] As shown in FIG. 17, the imaging device 5B includes a pixel unit 41 and a data readout unit 43. The pixel unit 41 and the data readout unit 43 are formed on a single chip and integrated with each other. The pixel unit 41 is configured by N (N is an integer of 2 or more, for example, 4) × M (M is an integer of 2 or more) pixels 22 that perform photoelectric conversion, arranged in a two-dimensional matrix. Four columns of the pixel array 12, each consisting of these M pixel columns, respectively configure a first pixel portion 23a, a second pixel portion 23b, a third pixel portion 23c, and a fourth pixel portion 23d. Each pixel 22 is formed, for example, in a rectangular shape in a plan view.

[0105] Each pixel 22 is electrically connected to the data readout unit 43 via the wiring unit 42. When an image is captured by each pixel array 12 under the control of the image capture timing by the computer 10 as described above, a charge signal corresponding to light detected in the pixel 22 included in each pixel array 12 is output to the data readout unit 43. The data readout unit 43 converts the charge signal output from the pixel 22 included in each pixel array 12 into a digital value and outputs it to the computer 10 as a detection signal. [Explanation of symbols]

[0106] 1...measurement system (optical information acquisition device), 10...computer (calculation unit), 22...pixel, 23a, 23b, 23c, 23d, 23e...pixel unit, 25...window unit (plate member), 31...LRG filter (monotone function filter), 33...quadratic function filter (first curve function filter), 35...cubic function filter (second curve function filter), 37...quartic function filter (third curve function filter), 39...neutral attenuation filter, Lb...measurement light, S...object.

Claims

1. a first line sensor unit having a first pixel unit in which a plurality of pixels are arranged, detecting measurement light from an object moving relatively to the first pixel unit, and outputting a first detection signal; a second line sensor unit including a second pixel unit having a plurality of pixels arranged in parallel with the first pixel unit, and a monotonic function filter disposed to cover the second pixel unit and having a characteristic that transmittance changes monotonically according to wavelength in a predetermined wavelength range, the second line sensor unit detecting measurement light from an object moving relatively to the second pixel unit and outputting a second detection signal; a calculation unit that acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal and the second detection signal, a predetermined time difference exists between the detection timing of the measurement light of the first line sensor unit and the detection timing of the measurement light of the second line sensor unit; Optical information acquisition device.

2. the first line sensor unit further includes a neutral density filter that is disposed to cover the first pixel unit and that attenuates the measurement light; The optical information acquisition device according to claim 1 .

3. an exposure time for one detection of the measurement light in the first line sensor unit is set shorter than an exposure time for one detection of the measurement light in the second line sensor unit; The optical information acquisition device according to claim 1 .

4. a plate member that is arranged to cover the second pixel portion and transmits the measurement light; the monotonic function filter is disposed on a surface of the plate member facing the second pixel unit. The optical information acquisition device according to any one of claims 1 to 3.

5. a third line sensor unit that includes a third pixel unit in which a plurality of pixels are arranged in parallel with the first pixel unit and the second pixel unit, and a first curve function filter that is arranged to cover the third pixel unit and has a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range, detects measurement light from an object that moves relatively to the third pixel unit, and outputs a third detection signal; the calculation unit acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, and the third detection signal. The optical information acquisition device according to any one of claims 1 to 3.

6. 6. The optical information acquisition device according to claim 5, wherein the first curve function filter is a filter formed by stacking two monotonic function filters each having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range.

7. a fourth line sensor unit that includes a fourth pixel unit in which a plurality of pixels are arranged in parallel with the first pixel unit, the second pixel unit, and the third pixel unit, and a second curve function filter that is arranged to cover the fourth pixel unit and has a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range, detects measurement light from an object that moves relatively to the fourth pixel unit, and outputs a fourth detection signal; the calculation unit acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, and the fourth detection signal. The optical information acquisition device according to claim 5 .

8. 8. The optical information acquisition device according to claim 7, wherein the second curve function filter is a filter formed by stacking three monotonic function filters each having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range.

9. a fifth line sensor unit that includes a fifth pixel unit in which a plurality of pixels are arranged in parallel with the first pixel unit, the second pixel unit, the third pixel unit, and the fourth pixel unit, and a third curve function filter that is arranged to cover the fifth pixel unit and has a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range, detects measurement light from an object that moves relatively to the fifth pixel unit, and outputs a fifth detection signal; the calculation unit acquires a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal, the second detection signal, the third detection signal, the fourth detection signal, and the fifth detection signal. The optical information acquisition device according to claim 7 .

10. 10. The optical information acquisition device according to claim 9, wherein the third curve function filter is a filter formed by stacking four monotonic function filters each having a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range.

11. a first light detection step of detecting measurement light from an object moving relatively to a first pixel unit by using a first pixel unit having a plurality of pixels arranged therein, and outputting a first detection signal; a second light detection step of detecting measurement light from an object moving relatively to the second pixel unit using a second pixel unit having an array of multiple pixels and a monotonic function filter that is arranged to cover the second pixel unit and has a characteristic that transmittance changes monotonically depending on wavelength in a predetermined wavelength range, and outputting a second detection signal; a calculation step of acquiring a characteristic value related to the wavelength spectrum of the measurement light based on at least the first detection signal and the second detection signal, a predetermined time difference exists between the detection timing of the measurement light in the first light detection step and the detection timing of the measurement light in the second light detection step; Optical information acquisition method.

12. a third light detection step of detecting measurement light from an object moving relatively to the third pixel unit using a third pixel unit having an array of a plurality of pixels and a first curve function filter that is arranged to cover the third pixel unit and has a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range, and outputting a third detection signal; In the calculation step, a characteristic value related to the wavelength spectrum of the measurement light is acquired based on at least the first detection signal, the second detection signal, and the third detection signal. The optical information acquisition method according to claim 11 .

13. a fourth light detection step for detecting measurement light from an object moving relatively to the fourth pixel unit using a fourth pixel unit having an array of a plurality of pixels and a second curve function filter arranged to cover the fourth pixel unit and having a characteristic that transmittance changes in a curved manner depending on wavelength in a predetermined wavelength range, and outputting a fourth detection signal; In the calculation step, a characteristic value related to the wavelength spectrum of the measurement light is acquired based on at least the first detection signal, the second detection signal, the third detection signal, and the fourth detection signal. The optical information acquisition method according to claim 12.

14. a fifth light detection step of detecting measurement light from an object moving relatively to the fifth pixel unit using a fifth pixel unit having an array of a plurality of pixels and a third curve function filter that is arranged to cover the fifth pixel unit and has a characteristic that transmittance changes curvedly depending on wavelength in a predetermined wavelength range, and outputting a fifth detection signal; In the calculation step, a characteristic value related to the wavelength spectrum of the measurement light is acquired based on at least the first detection signal, the second detection signal, the third detection signal, the fourth detection signal, and the fifth detection signal. The optical information acquisition method according to claim 13.

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