Methods and apparatus for spectroscopic imaging

Abstract

The spectroscopic imaging apparatus (500) includes an illumination unit (110) for illuminating a linear region (REG1) of an object (OBJ1) with a linear pattern (PAT1) formed from a narrowband light pulse (B2), and an image (IMG1) of the illuminated linear region (REG1). λ The illumination unit (110) comprises a line scan camera (CAM1) for acquiring ), a light source (LS1) for generating broadband light pulses (B1), an adjustable Fabry-Perot interferometer (FPI1) ​​for forming narrowband light pulses (B2) by filtering the broadband light pulses (B1), and a beam shaping optical element (OPT1) for forming a linear pattern (PAT1) from the narrowband light pulses (B2), wherein the wavelength (λ) of the linear pattern (PAT1) is determined by the mirror spacing (d) of the Fabry-Perot interferometer (FPI1). GAP ) is determined by the instrument (500), and the mirror spacing (d) of the Fabry-Perot interferometer (FPI1) ​​is determined by the instrument (500). GAP It is configured to change ).

Description

[Technical Field]

[0001] This invention relates to spectral imaging. [Background technology]

[0002] In a typical push-bloom hyperspectral camera, only a single spatial line of a moving object is captured at a time. The captured line passes through a dispersive element (e.g., a diffraction grating) to decompose the multicolored line into multiple spatially separated monocolored lines. These spatially separated monocolored lines are acquired using an image sensor with a two-dimensional array of light-detecting pixels. In the acquired single image, one dimension (x-axis) represents the spatial dimension of the object, and the other dimension (y-axis), orthogonal to it, represents the spectral dimension.

[0003] A typical pushbloom hyperspectral camera images a single linear region of an object at a time. As the object moves relative to the camera's linear field of view, data can be collected from a larger area of ​​the object. Data from linear images acquired at different times can be combined to form a hyperspectral image cube that represents spectral information for a larger area of ​​the moving object. [Overview of the project] [Problems that the invention aims to solve]

[0004] Images acquired by a two-dimensional image sensor can represent the entire spectrum of an object from the minimum wavelength to the maximum wavelength. However, in certain applications where it is only necessary to measure spectral intensity at a few different wavelengths, acquiring the entire spectrum using a two-dimensional image sensor can be time-consuming.

[0005] In typical pushbloom hyperspectral camera operation, objects usually need to be illuminated with broadband illumination that simultaneously covers all wavelengths in the hyperspectral image cube. As a result, broadband illumination can impose an undesirable thermal load on the object. [Means for solving the problem]

[0006] The objective is to provide an apparatus for spectroscopic imaging. The objective is to provide a method for spectroscopic imaging.

[0007] According to one embodiment, an apparatus (500) for spectral imaging is provided. This device, - An illumination unit (110) for illuminating a linear region (REG1) of an object (OBJ1) with a linear pattern (PAT1) formed from a narrowband light pulse (B2), -Image of the illuminated linear region (REG1) (IMG1 λ A line scan camera (CAM1) is used to acquire ) and Equipped with, The aforementioned lighting unit (110) - A light source (LS1) for generating broadband optical pulses (B1), - An adjustable Fabry-Perot interferometer (FPI1) ​​for forming the narrowband light pulse (B2) by filtering the broadband light pulse (B1), -A beam shaping optical element (OPT1) for forming the linear pattern (PAT1) from the narrowband optical pulse (B2), The wavelength (λ) of the linear pattern (PAT1) is the mirror spacing (d) of the Fabry-Perot interferometer (FPI1). GAP ) is determined by, The apparatus (500) has the mirror spacing (d GAP It is configured to change ).

[0008] According to one embodiment, the apparatus described in claim 1 is provided.

[0009] Further embodiments are provided in other claims.

[0010] The scope of protection required for various embodiments of the present invention is defined by the independent claims. Where any embodiments described herein are not included within the scope of the independent claims, they should be interpreted as useful examples for understanding the various embodiments of the present invention.

[0011] The device forms a series of linear patterns for illumination at different wavelengths. The linear patterns may be projected onto a moving object. Each linear pattern may have a different wavelength and may illuminate different linear regions of the moving object. The line scan camera may synchronously acquire images of the illuminated linear regions such that each acquired image represents a different wavelength.

[0012] The Fabry-Perot interferometer may be scanned across a spectral scanning range, and the acquired image data may be combined to form a two-dimensional data matrix. Here, the first dimension of the data matrix represents the spatial dimension of the object in the short-axis direction, and the second orthogonal dimension of the data matrix represents the spectral dimension, as well as the spatial dimension of the object in the longitudinal direction in the direction of the object's movement.

[0013] Next, the Fabry-Perot interferometer may scan multiple times over the same spectral scanning range to measure the spectra of multiple different longitudinal regions of the object. Since the Fabry-Perot interferometer may scan multiple times over the same spectral scanning range, the data from the acquired images may be combined to form a three-dimensional data matrix, also called a hyperspectral data cube. The hyperspectral data cube is a three-dimensional data matrix in which the first dimension of the cube represents the short-space direction of the object, the second dimension represents the longitudinal direction of the object, and the third dimension represents the spectral dimension, i.e., wavelength.

[0014] The device may be a hyperspectral push-bloom camera configuration that provides spectrally selective illumination. The device may be implemented with a simple optical system. The spectral band used for imaging may be freely selectable (e.g., programmable). The device may be configured to compensate for the effects of background illumination. The heating effect of the illumination light on objects may be reduced.

[0015] This device does not necessarily require a complex optical system. It can be made less expensive. It can have greater resistance to variations in background illumination. It may be implemented, for example, by using a commercially available camera. It can reduce the thermal load on objects.

[0016] For example, the device may be configured to measure intensity values ​​at at least four wavelengths during a scanning period that may be less than, for example, 10 ms.

[0017] This device comprises an illumination unit, which includes an adjustable Fabry-Perot interferometer. The Fabry-Perot interferometer includes a first semi-transparent mirror and a second semi-transparent mirror. The second semi-transparent mirror is configured to move relative to the first semi-transparent mirror.

[0018] The passband wavelength of a Fabry-Perot interferometer depends on the mirror spacing. Mirror spacing refers to the distance between the semi-transparent mirrors of the Fabry-Perot interferometer. An adjustable Fabry-Perot interferometer may include one or more piezoelectric or electrostatic actuators for changing the mirror spacing. The Fabry-Perot interferometer may also include one or more actuators for moving a second semi-transparent mirror relative to a first semi-transparent mirror.

[0019] The illumination unit includes a light source for generating broadband light pulses. The light source may be, for example, a laser light source. The light source may be, for example, a supercontinuum light source. The Fabry-Perot interferometer may receive broadband light pulses from the pulsed broadband light source. The Fabry-Perot interferometer may form narrowband light pulses from the received broadband light pulses. The Fabry-Perot interferometer may form narrowband light pulses by filtering the received broadband light pulses according to the passband of the Fabry-Perot interferometer. A portion of the received light can pass through the Fabry-Perot interferometer at the wavelength of the passband. The wavelength of the passband is determined by the mirror spacing of the Fabry-Perot interferometer. Therefore, when the Fabry-Perot interferometer forms narrowband light pulses from the received broadband light pulses, the wavelength of the formed narrowband light pulses is also determined by the mirror spacing.

[0020] The wavelength of the narrowband light pulse may be changed by varying the mirror spacing. The mirror spacing may be varied, for example, according to a sine function. Alternatively, the mirror spacing may be varied, for example, according to a sawtooth function. By varying the mirror spacing, the illumination unit can provide a series of narrowband light pulses having different wavelengths.

[0021] The illumination unit includes a beam shaping optical system for forming a linear pattern for illumination from a narrowband optical pulse. The beam shaping optical system may include, for example, a cylindrical lens. A linear region of an object may be illuminated by the linear pattern. By varying the mirror spacing, the illumination unit may provide a series of linear patterns for illumination having different wavelengths. The intensity of the linear pattern for illumination is concentrated in a narrow bandwidth and linear region, which can result in a maximized signal-to-noise ratio and / or minimized power waste. The intensity of the illumination pattern is high. As a result, problems caused by stray light, background illumination, and / or noise from electronic equipment can be reduced.

[0022] This device includes a line scan camera for acquiring images of illuminated linear regions of an object. The field of view of the line scan camera overlaps with the illuminated linear regions of the object. The field of view of the line scan camera may substantially coincide with the illuminated linear regions of the object.

[0023] The active area of ​​the camera's image sensor may have a linear shape. It is not necessary to acquire image data from areas outside the illuminated area. A line scan camera may be configured to acquire, for example, more than 100 images per second, or more than 1000 images per second. The image sensor of a line scan camera may have only one row of detection pixels. A line scan camera can be faster, smaller, and / or simpler than a camera that includes a two-dimensional image sensor.

[0024] The illumination unit may form a series of narrowband light pulses of different wavelengths. The object may be sequentially illuminated with a linear pattern having different wavelengths. A line scan camera may acquire images of the illuminated areas of the object. Image acquisition may be synchronized with the timing of the narrowband light pulses. Each acquired image may represent a different wavelength of the illumination pattern.

[0025] The repetition frequency of the light pulse may be, for example, 100 kHz. The Fabry-Perot interferometer may scan, for example, 1000 times per second over the same spectral scanning range. The scanning period for scanning over the spectral scanning range may be 1 ms each. The illumination unit may form 100 narrowband light pulses at different wavelengths during a 1 ms scanning period. The line scan camera may be configured to acquire images of the illuminated linear region of the object at a rate of 100 kHz. Thus, the device can collect 100 images of the illuminated region during a 1 ms scanning period, and each acquired image may represent a different wavelength. In the case of a moving object, each acquired image may represent a different linear region of the object.

[0026] The Fabry-Perot interferometer may be scanned multiple times across the same spectral scanning range to measure the spectra of several different longitudinal regions of an object. The data from the acquired images may be combined to form a hyperspectral data cube.

[0027] Using a Fabry-Perot interferometer, measuring the intensity of the generated narrowband light pulses may be easier because all generated light pulses propagate along the same optical path. The intensity of the generated broadband or narrowband light pulses may be measured, for example, by coupling a portion of the light pulse to a detector via a beam splitter. The measured intensity may be used, for example, as feedback to stabilize the intensity of the generated narrowband light pulses and / or to compensate for the effect of intensity variations on the acquired image.

[0028] The wavelength of the narrowband optical pulse may be freely selectable. The wavelength may be selected according to the specific application. By appropriately selecting the wavelength of the narrowband optical pulse, the collection of unnecessary data can be avoided. By appropriately selecting the wavelength of the narrowband optical pulse, the processing of unnecessary data can be avoided.

[0029] The device may also be configured to acquire one or more dark images, for example, to compensate for the effects of background lighting. The device may also be configured to acquire one or more dark images, for example, to compensate for the effects of dark current in the image sensor of a line scan camera.

[0030] A line scan camera may acquire a dark image when, for example, an object is not illuminated by a linear pattern. A line scan camera may also acquire a dark image when, for example, an object is illuminated by a linear pattern, but the wavelength of the linear pattern is outside the spectral detection range of the line scan camera.

[0031] The device may include an actuation unit for causing relative movement between an object and a lighting pattern. The device may include, for example, a conveyor belt for causing relative movement between an object and a lighting pattern. The device may include, for example, a robot for causing relative movement between an object and a lighting pattern. The device may include, for example, a motion system for causing relative movement between an object and a lighting pattern.

[0032] The device may be configured to acquire spectral images of objects moving on a conveyor belt. The device may be configured to acquire spectral images of objects moving on a production line. The device may be mounted on a vehicle and configured to acquire spectral images of objects. The device may be mounted on an aircraft and configured to acquire spectral images of objects located on the ground.

[0033] This device may be configured, for example, to recognize materials in a recycling process. This device may be configured, for example, to recognize materials in the food industry. This device may be configured, for example, to monitor the quality of materials in the food industry.

[0034] In the following embodiments, several modifications will be described in more detail with reference to the attached drawings. [Brief explanation of the drawing]

[0035] [Figure 1a] This figure shows an example of a spectroscopic imaging device. [Figure 1b] This figure shows an example of one row of detection pixels in the image sensor of a line scan camera. [Figure 1c] This figure shows an example of an image pixel obtained by one row of detected pixels. [Figure 2a] This figure shows an example of a spectroscopic imaging device in a three-dimensional view. [Figure 2b]This figure shows an example of a spectroscopic imaging device in a three-dimensional view. [Figure 3] This figure shows an example of determining reflectance values ​​from image pixels using calibration data. [Figure 4a] This figure shows an example of a light source for generating broadband light pulses. [Figure 4b] This figure shows an example of the spectrum of a broadband optical pulse. [Figure 4c] This figure shows an example of the timing and duration of a light pulse. [Figure 5a] This figure shows an example of forming light pulses of different wavelengths. [Figure 5b] This figure shows an example of forming light pulses of different wavelengths. [Figure 6a] This figure shows an example of a Fabry-Perot interferometer placed inside a vacuum chamber. [Figure 6b] This figure shows an example of a Fabry-Perot interferometer configured to operate in a gaseous environment. [Figure 7] This figure shows an example of an acquired image representing a different wavelength. [Figure 8] This figure shows an example of an acquired image and a dark image. [Figure 9a] This figure shows an example of the first row of detected pixels and the second row of detected pixels. [Figure 9b] This figure shows an example of a three-dimensional viewpoint of the field of view of the first row of detected pixels and the field of view of the second row of detected pixels. [Figure 10a] This figure shows an example of an image obtained using two rows of detected pixels. [Figure 10b] This figure shows an example of an image acquired by the first row of detected pixels and an example of a dark image acquired by the second row of detected pixels. [Figure 11a] This figure shows an example of two spectral transmittance peaks in a Fabry-Perot interferometer. [Figure 11b] This figure shows examples of optical filters for the first row of detected pixels and optical filters for the second row of detected pixels. [Figure 11c] This figure shows an example of an image obtained by the two rows of detected pixels in Figure 11b. [Figure 12] This is a top view showing an example of the spatial intensity distribution of a linear pattern. [Figure 13a] This is a top view showing an example of the positional relationship between the field of view of a line scan camera and the illuminated area on an object. [Figure 13b] This is a top view showing an example of the positional relationship between the field of view of a line scan camera and the illuminated area on an object. [Figure 14a] This figure shows an example of the spatial intensity distribution of an illumination pattern at a first wavelength and an example of the spatial intensity distribution of an illumination pattern at a second wavelength. [Figure 14b] This figure shows an example of a three-dimensional viewpoint in which calibration data is obtained by illuminating a reference surface with a linear pattern and acquiring an image of the illuminated area. [Figure 15] This is a side view showing an example of a configuration for measuring the intensity of a generated light pulse. [Modes for carrying out the invention]

[0036] Referring to Figure 1, the apparatus 500 comprises a broadband light source LS1, a Fabry-Perot interferometer FPI1, a beam shaping optical system OPT1, and a line scan camera CAM1.

[0037] The apparatus 500 can illuminate object OBJ1 with a linear pattern PAT1. In particular, the apparatus 500 can illuminate the surface SRF1 of object OBJ1 with the linear pattern PAT1.

[0038] A broadband light source may be configured to generate broadband optical pulses at a repetition rate of, for example, 1 kHz or higher, 10 kHz or higher, or 100 kHz or higher. The repetition rate may be substantially equal to, for example, 100 kHz.

[0039] A Fabry-Perot interferometer FPI1 forms narrow-band optical pulses by filtering wide-band optical pulses. The second mirror of the Fabry-Perot interferometer FPI1 has a mirror spacing d GAP and can be moved by one or more actuators (ACU1) to change the mirror spacing d and the wavelength of the generated narrow-band optical pulse B2. The mirror spacing d GAP indicates the distance between the semi-transparent mirrors M1 and M2 of the Fabry-Perot interferometer FPI1.

[0040] The apparatus 500 is configured with the mirror spacing d GAP representative control signal S FPI1 and may be configured to provide said control signal S. The apparatus 500 may be configured to determine the wavelength of each generated optical pulse based on the control signal S FPI1 . The mirror spacing d GAP may be varied in accordance with the control signal S FPI1 .

[0041] The Fabry-Perot interferometer FPI1 may be arranged in a vacuum chamber, for example to increase the scanning speed of the Fabry-Perot interferometer FPI1. The absolute pressure in the vacuum chamber may be, for example, less than 10kPa (less than 100mbar).

[0042] The apparatus 500 may optionally comprise a beam splitter BS1 and a reference detector DET1 for measuring the energy and / or intensity of an optical pulse. The beam splitter BS1 can couple a portion of the light of the optical pulse to the reference detector DET1. The reference detector DET1 can measure the energy and / or intensity of the optical pulse received from the beam splitter BS1.

[0043] The beam shaping optical system OPT1 can form a linear pattern PAT1 for illumination from a narrowband light pulse B2 that has passed through the Fabry-Perot interferometer. The apparatus 500 can illuminate a linear region of object OBJ1 with the linear pattern PAT1. The apparatus 500 can illuminate a linear region REG1 on the surface of object OBJ1 with the linear pattern PAT1.

[0044] The beam shaping optical system OPT1 can form a linear pattern PAT1 for illumination having a wavelength (λ) determined by the wavelength (λ) of the spectral transmittance peak of the Fabry-Perot interferometer (FPI1). The object OBJ1 may be illuminated by the linear pattern PAT1 having wavelength (λ).

[0045] Each linear pattern PAT1 may have a different wavelength and may illuminate different linear regions REG1 of an object OBJ1. The apparatus 500 includes a line scan camera CAM1 for acquiring images of the illuminated linear regions REG1 of the object. The object OBJ1 can reflect, scatter, and / or transmit light toward the line scan camera CAM1. The line scan camera CAM1 can acquire images of the illuminated linear regions of the object's surface SRF1.

[0046] A linear pattern PAT1 for illumination is formed from a narrowband light pulse B2 using a beam shaping optical system OPT1. The line shaping optical system OPT1 may include, for example, a Powell lens for forming the linear pattern PAT1 from the narrowband light pulse B2. The line shaping optical system OPT1 may also include, for example, a diffractive optical element for forming the linear pattern PAT1 from the narrowband light pulse B2. The beam shaping optical system may include, for example, a cylindrical lens. The beam shaping optical system may also include, for example, a first cylindrical lens and a second cylindrical lens. The first cylindrical lens may form, for example, a diverging light beam, and the second cylindrical lens may form a collimated light beam from the diverging light beam.

[0047] Referring to Figure 1b, the image sensor SEN1 of the line scan camera CAM1 has detected pixels D1, D2, D3, D4, ...D M It may have only one active row. Image data can be read from this single row at a very high rate.

[0048] The image sensor (SEN1) of the line scan camera (CAM1) may have only one active row of detection pixels (D). The image sensor SEN1 of the line scan camera CAM1 may, for example, have a 1 × M linear array of active light detection pixels. The value of M may be, for example, in the range of 50 to 10000. The number of detection pixels D in one row may be, for example, in the range of 50 to 10000. The number of detection pixels D in one row can be 128, 256, 512, 1024, 2048, or 4096.

[0049] The device 500 may include a control unit CNT1 for controlling the operation of the device 500. The control unit CNT1 may, for example, control the mirror interval d GAP Control signal S for changing FPI1 The control unit CNT1 may be provided. The control unit CNT1 may be configured to perform data processing operations.

[0050] The device 500 acquired spectral image IMG1 λ1 IMG1 λ2 It may also have a memory MEM1 for storing the data.

[0051] The device 500 acquired spectral image IMG1 λ1 IMG1 λ2 It may also have a memory MEM2 for storing data values ​​determined from the acquired spectral image IMG1. λ1 IMG1 λ2The device may be configured to determine a hyperspectral data cube CUBE1 from the image data. The device 500 may also include a memory MEM2 for storing the determined data value (e.g., CUBE1).

[0052] The control unit CNT1 may be configured to determine the hyperspectral data cube CUBE1 from image data using, for example, calibration data CAL1. The device 500 may also include a memory MEM3 for storing the calibration data CAL1.

[0053] The control unit CNT1 may be configured to execute the spectroscopic imaging method steps by executing the program code PROG1. The apparatus 500 may include a memory MEM4 for storing the program code PROG1.

[0054] The device 500 may include a communication unit RXTX1 for receiving and / or transmitting data. The communication unit RXTX1 may communicate, for example, by wired or wireless communication. The communication unit RXTX1 may communicate, for example, with an industrial process control system. The communication unit RXTX1 may communicate, for example, via the Internet.

[0055] The device 500 may include a user interface UIF1 for providing information to the user and / or receiving user input from the user. The user interface UIF1 may include, for example, a touchscreen.

[0056] Figure 1c shows image IMG1 acquired by the image sensor SEN1 in Figure 1b. This image consists of image pixels P1, P2, P3, P4, ...P M Includes. Acquired image IMG1 λ1 This represents the wavelength of the illumination pattern PAT1 at the time of image acquisition. Acquired image IMG1 λ1 This can represent, for example, the wavelength λ1.

[0057] The image sensor SEN1 of the line scan camera CAM1 has image pixels P1, P2, P3, P4, ...P M A one-dimensional spectral image IMG1 containing a 1×M array can be obtained.

[0058] Referring to Figure 2a, the lighting unit 110 has a lighting pattern PAT1 with wavelength λ1. λ1 Therefore, region REG1 of object OBJ1 λ1 It can illuminate. The field of view FOV1 of the line scan camera CAM1 is the illumination pattern PAT1. λ1 and illumination area REG1 λ1 Overlapping with, illumination area REG1 λ1 It is configured to acquire images.

[0059] Object OBJ1 has a relative velocity v with respect to the illumination pattern PAT1. OBJ1 It may be moved by means of a conveyor belt or a robot. Object OBJ1 may be moved by an actuation unit ACU2. The actuation unit ACU2 may be, for example, a conveyor belt or a robot.

[0060] The device 500 may optionally include an actuation unit (ACU2) for causing relative movement between an object (OBJ1) and a linear pattern (PAT1).

[0061] The spectroscopic imaging method may include causing relative movement between the linear pattern (PAT1) and the object OBJ1.

[0062] The actuator unit ACU2 may also change the angular direction of the device 500 relative to the object OBJ1. The actuator unit ACU2 may be, for example, a turret and may be configured to rotate the device 500 relative to the stationary object OBJ1.

[0063] SX, SY, and SZ indicate directions that are orthogonal to each other. The longitudinal direction SY may be parallel to the direction of movement of object OBJ1. The linear pattern PAT1 may be substantially parallel to the transverse direction SX. SZ may indicate the vertical direction.

[0064] Directions SX, SY, and SZ correspond to the coordinate system of the device 500. Directions SU and SV correspond to the (moving) coordinate system of object OBJ1. Direction SU may be parallel to direction SX. Direction SV may be parallel to direction SY. Illumination pattern PAT1 may be stationary with respect to the device 500, and illumination pattern PAT1 may be stationary with respect to object OBJ1. As a result, illumination pattern PAT1 and field of view FOV1 can sweep over the moving object OBJ1 to acquire spectral images from different regions REG1 of object OBJ1.

[0065] Referring to Figure 2b, the lighting unit 110 illuminates multiple adjacent regions REG1 of object OBJ1. λ1 REG1 λ2 REG1 λ3 ,...REG1 λN The lights may be illuminated sequentially. The line scan camera CAM1 will illuminate at different times t1, t2, t3, ....t N In this region, illuminated area REG1 λ1 REG1 λ2 REG1 λ3 ,...REG1 λN Image IMG1 λ1 IMG1 λ2 IMG1 λ3 ,....IMG1 λN You may obtain them sequentially.

[0066] Referring to Figure 3, the device 500, for example, uses calibration data CAL1 to acquire spectral image IMG1 λ1 From the image pixel values, the spectral reflectance value R X1 , R X2 , R X3 ,...R XM It may be configured to determine this.

[0067] Code ARR1 λ1 These are different short-axis positions x1, x2, x3, ...x at wavelength λ1. M The corresponding spectral reflectance value R X1 , R X2 , R X3 ,...R XM The array is shown. Array ARR1 λ1 This is a linear pattern with wavelength λ1, PAT1 λ1 Linear region REG1 of object OBJ1 illuminated by λ1 This may also correspond to the region REG1 λ1 This is the image IMG1 of the aforementioned region. λ1 After it is acquired, it moves with the object OBJ1. The distance between the longitudinal position of the illuminated region REG1λ1 and the subsequent linear pattern PAT1 for illumination is, for example, the relative velocity v of the object (OBJ1). OBJ1 In contrast, the illumination pattern PAT1 at the current time t and wavelength λ1. λ1 It may also be determined by multiplying by the difference (t-t1) between the time (t1) at which it was generated.

[0068] The control unit CNT1 uses, for example, the calibration data CAL1 to obtain the spectral image IMG1. λ1 From the image pixel values, spectral reflectance value R X1 , R X2 , R X3 ,...R XM It may be configured to determine the following: The acquired image can represent, for example, the wavelength λ1 and the determined spectral reflectance value R X1 , R X2 , R X3 ,...R XM The same wavelength λ1 can also be represented. Calibration data CAL1 may be wavelength-specific and / or position-specific. Code R X1 This can show the spectral reflectance at position x1 in the short direction.

[0069] The apparatus 500 may also be configured to measure the spatial distribution of the spectral reflectance of object OBJ1.

[0070] The control unit (CNT1) uses the calibration data (CAL1) to obtain the image (IMG1) λ1 ) from the pixel value to the spectral reflectance value (R x1 ) may be configured to determine.

[0071] The apparatus 500 may be configured to measure the spatial distribution of the spectral transmittance of object OBJ1.

[0072] The apparatus may be configured to measure the spatial distribution of the scattering cross-section of object OBJ1 at multiple different wavelengths.

[0073] The control unit (CNT1) also captures the acquired image (IMG1) of the reference plane (SRF0, see Figure 14b). λ1 IMG1 λ2 The system may be configured to determine calibration data (CAL1) from ).

[0074] Referring to Figure 4a, the broadband light source LS1 may include, for example, a seed laser LAS1 and an optical fiber FIB1, and may be configured to repeatedly generate broadband optical pulses B1. The duration of a single broadband pulse may be, for example, 10 ns or less.

[0075] The light source (LS1) may include a laser light source (LAS1).

[0076] The broadband light source LS1 may include a laser light source LAS1 for generating a primary optical pulse B0. The broadband light source LS1 may also include an optical fiber FIB1 for forming a broadband optical pulse B1 from the primary optical pulse B0 by a nonlinear optical process. The bandwidth of the broadband optical pulse B1 may be configured to cover the spectral tuning range of the Fabry-Perot interferometer FPI1.

[0077] Figure 4b shows an example of the spectrum of a broadband optical pulse.

[0078] Figure 4c shows an example of the timing and duration of a narrowband light pulse. The illumination pattern has the same timing and duration as the narrowband light pulse. REP Δt indicates the time interval between consecutive light pulses. DUR This indicates the duration of a single light pulse.

[0079] The broadband laser source LS1 has a repetition rate of 1 / T REP and pulse duration Δt DUR The system may be configured to generate and emit multiple broadband laser pulses B1 having the following characteristics:

[0080] The repetition frequencies of optical pulses B1 and B2 are 1 / T. REP It is equal to the time interval T. REP Duration Δt of a single light pulse DUR The ratio to can be, for example, greater than 5.

[0081] Referring to Figure 5a, the mirror spacing of the Fabry-Perot interferometer is determined by the control signal S FPI1 Control signal S may be controlled accordingly. FPI1 This may be, for example, a control voltage applied to the actuator ACU1 of a Fabry-Perot interferometer. The wavelength of the narrowband optical pulse depends on the mirror spacing and the control voltage. The control voltage may be supplied by a signal source. The signal source may be implemented, for example, by a control unit CNT1. Control signal S FPI1 The control voltage may be supplied by the control unit CNT1. The control voltage may have, for example, a sinusoidal or sawtooth waveform. The control voltage is set at different times t1, t2, t3, t4, ... t N In this context, different wavelengths λ1, λ2, λ3, λ4, ...λ N It may be modified to form a narrowband optical pulse.

[0082] The lighting unit 110 forms a narrowband light pulse B2 using the Fabry-Perot interferometer FPI1, and the mirror spacing d of the Fabry-Perot interferometer FPI1 GAP By changing this, different wavelengths λ1, λ2, ...λ can be obtained.N may be configured to sequentially form the plurality of illumination patterns PAT1 therein.

[0083] Mirror spacing d GAP is within a scanning period (T SCAN ), for example, from a first value (d GAP,1 ) to a second value (d GAP,N ).

[0084] The apparatus 500 may be configured such that during a scanning period (T SCAN ), the mirror spacing (d GAP ) changes from a first value (d GAP,1 ) to a second value (d GAP,N ). The scanning period (T SCAN ) is shorter than 100 ms, the number of narrow-band optical pulses (B2) formed at different wavelengths (λ) during the scanning period (T SCAN ) is greater than 10, the number of images (IMG1) acquired at different wavelengths (λ) during the scanning period (T SCAN ) is greater than 10, and acquisition of the images (IMG1) is synchronized with the narrow-band optical pulses (B2).

[0085] The Fabry-Perot interferometer (FPI1) has a first mirror spacing (d GAP,1 ) at a first time (t1), and may be configured to form a first narrow-band optical pulse (B2) having a first wavelength (λ1). The illumination unit (110) has a first linear pattern (PAT1 λ1 ) and may be configured to illuminate a first linear region (PAT1 λ1 ) of an object (OBJ1). The line scan camera (CAM1) captures the first linear region (PAT1 λ1 ) illuminated by the first linear pattern (PAT1 λ1 ) as an image (IMG1 λ1 ). The Fabry-Perot interferometer (FPI1) has a second mirror spacing (d GAP,2The illumination unit (110) may be configured to form a second narrowband light pulse (B2) having a second wavelength (λ2), which has a second linear pattern (PAT1) having a second wavelength (λ2). λ2 ) in the second linear region (PAT1) of the object (OBJ1). λ2 ) may be configured to illuminate the second linear pattern (PAT1). The line scan camera (CAM1) is configured to illuminate the second linear pattern (PAT1). λ2 The second linear region (PAT1) illuminated by ) λ2 ) Image (IMG1 λ2 ) may be configured to obtain.

[0086] First linear region (PAT1 λ1 ) and the second linear region (PAT1 λ2 The object OBJ1 is illuminated at different times (t1, t2), and the first linear region (PAT1 λ1 ) and the second linear region (PAT1 λ2 ) may be configured to move in different positions in the longitudinal direction SU relative to object OBJ1.

[0087] The repetition frequencies of the optical pulses B1 and B2 may be, for example, 1 kHz or higher, 10 kHz or higher, or 100 kHz or higher.

[0088] The imaging rate (rate of capturing images) of the line scan camera CAM1 may be, for example, 1 kHz or higher, 10 kHz or higher, or 100 kHz or higher.

[0089] The Fabry-Perot interferometer FPI1 measures wavelengths λ1 to λ N It may be configured to scan at high speed over the wavelength scanning range. In particular, without stopping the movement of the mirror M2 of the Fabry-Perot interferometer FPI1, the mirror spacing d GAP The time t1, t2, ...t of the light pulse B2 may be changed. N In this case, without stopping the movement of mirror M2, the mirror interval d GAP You may change this.

[0090] The lighting unit 110 has a scanning period (T SCAN ) The mirror spacing (d) of the Fabry-Perot interferometer (FPI1) GAP By changing the wavelength (λ1, λ2, ...λ), different wavelengths can be obtained. N It may be configured to generate multiple narrowband optical pulses B2 during the scanning period (T SCAN During this time, the movement of the movable mirror (M2) of the Fabry-Perot interferometer (FPI1) ​​is not stopped.

[0091] The mirror M2 of the Fabry-Perot interferometer FPI1 has a scanning period T SCAN During this time, the movement may be continued without stopping, such that the wavelength of each generated narrowband optical pulse B2 is different from the wavelength of the previous narrowband optical pulse B2.

[0092] The timing of the narrowband optical pulse B2 may be synchronized with the timing of image IMG1 acquisition by the line scan camera CAM1.

[0093] The bottom of Figure 5a shows the exposure time of the image sensor SEN1 of the line scan camera CAM1. (Decline Δt) EX This indicates the exposure time for a single acquired image, IMG1.

[0094] Each image frame IMG1 acquired by the line scan camera CAM1 may be illuminated by a single light pulse formed by the illumination unit 110. The line scan camera CAM1 may be configured to acquire the spectral image IMG1 such that only one narrowband light pulse B2 at a single wavelength (e.g., λ1) contributes to the exposure of a single acquired spectral image IMG1 representing the wavelength (e.g., λ1).

[0095] In one embodiment, the imaging rate of the line scan camera CAM1 may be equal to the repetition frequency of the light pulse.

[0096] In one embodiment, the imaging rate by the line scan camera CAM1 may also be lower than the repetition frequency of the light pulses.

[0097] In one embodiment, the imaging rate by the line scan camera CAM1 may also be higher than the repetition frequency of the light pulses, for example, to acquire a dark image.

[0098] Referring to Figure 5b, the first scanning period T is performed without stopping the movement of mirror M2. SCAN Multiple first optical pulses B2 may be generated during the first scanning period T SCAN Multiple images IMG1 may be acquired during this time. Image acquisition may be synchronized with the light pulse.

[0099] First scanning period T SCAN After this, the direction of movement of mirror M2 may be reversed. Without stopping the movement of mirror M2, the second scanning period T SCAN,2 Multiple second optical pulses B2 may be generated during the second scanning period T SCAN,2 Multiple second images IMG1 may be acquired during this time. The light pulse is, for example, at time t a t b t c t d t e The image may be generated in the following location. Image acquisition may be synchronized with the light pulse. For example, if the illumination pattern is wavelength λ N Time t a In image IMG1 λN,ta For example, the time t when the illumination pattern has wavelength λ1 may be obtained. e In image IMG1 λ1,te It may be obtained.

[0100] Multiple consecutive scanning periods T SCAN , T SCAN,2 During this time, a light pulse B2 may be generated and image IMG1 may be acquired. This allows spectral data to be obtained from multiple illumination regions REG1 of object OBJ1.

[0101] Referring to Figure 6a, the Fabry-Perot interferometer may be configured to operate under vacuum VAC1 to facilitate the movement of mirror M2. The presence of ambient air can hinder or delay the movement of mirror M2. The Fabry-Perot interferometer FPI1 may be configured to operate under reduced pressure to reduce or avoid the influence of ambient gas on the movement of mirror M2. In particular, the Fabry-Perot interferometer FPI1 may be configured to operate under vacuum VAC1. The absolute pressure of vacuum VAC1 may be, for example, less than 10 kPa.

[0102] The Fabry-Perot interferometer may be placed inside a vacuum chamber CHM1. The vacuum chamber CHM1 may optionally have optical feedthroughs WIN1 and WIN2 for transmitting optical pulses B1 and B2 to and / or from the Fabry-Perot interferometer. The vacuum chamber CHM1 may optionally provide a control voltage S to the actuator ACU1 of the Fabry-Perot interferometer. FPI1 It may have an electrical feedthrough FEED1 for supplying signal S. FPI1 This may be applied to one or more actuators ACU1 via, for example, conductors CON1 and CON2.

[0103] The vacuum chamber CHM1 may be configured to have a permanent vacuum VAC1. The vacuum chamber CHM1 may also optionally be connected to a vacuum pump PUMP1 via a duct DUC1 to provide a vacuum during operation. The internal pressure of the vacuum chamber CHM1 may be reduced by using the vacuum pump so that the absolute pressure is less than 10 kPa during operation of the apparatus 500, for example.

[0104] The Fabry-Perot interferometer (FPI1) ​​may be placed inside a vacuum chamber (CHM1), and the absolute pressure of the vacuum chamber (CHM1) may be configured to be less than 10 kPa.

[0105] Referring to Figure 6b, the Fabry-Perot interferometer may be configured to operate in a low-density gas GAS1 to facilitate the movement of the mirror M2. Specifically, the density of the gas GAS1 may be lower than the density of ambient air at normal pressure and temperature. The gas GAS1 may be, for example, helium or hydrogen. The gas GAS1 may be sealed within the chamber CHM1.

[0106] Referring to Figure 7, the apparatus 500 uses different wavelengths λ1, λ2, λ3, ...λ N Multiple images representing IMG1 λ1 IMG1 λ2 IMG1 λ3 ,...IMG1 λN You may obtain them sequentially.

[0107] IMG1: A continuous linear image of an object acquired by line scan camera CAM1. λ1 IMG1 λ2 IMG1 λ3 ,...IMG1 λN These are different wavelengths λ1, λ2, ...λ N This may also represent the following: Each image shows objects at different wavelengths λ1, λ2, ...λ N It may be obtained when illuminated with a linear pattern having [a certain characteristic].

[0108] In one embodiment, one acquired image frame may be illuminated by one pulse from the light source LS1.

[0109] Referring to Figure 8, the line scan camera CAM1 of the apparatus 500 may be configured to acquire one or more dark images DARK1. The dark images may be acquired, for example, without illumination, at different wavelengths λ1, λ2, ...λ N The same dark image may be used to correct the background of multiple acquired images representing the same object.

[0110] Dark images may be acquired without illumination. For example, the broadband light source LS1 may be configured to be temporarily shut down in order to acquire dark images.

[0111] For example, a line scan camera may be configured to acquire dark images during periods when the broadband light source LS1 does not generate light pulses.

[0112] For example, a line scan camera may be configured to acquire a dark image when the wavelength of the linear pattern for illumination is outside the spectral detection range of the line scan camera.

[0113] Different wavelengths λ1, λ2, ...λ N The same dark image DARK1 may be used to correct the background of multiple acquired images representing the same subject.

[0114] The line scan camera (CAM1) may be configured to acquire a dark image (DARK1) when the object (OBJ1) is not illuminated by the linear pattern (PAT1), or when the wavelength (λ) of the linear pattern (PAT1) is outside the spectral detection range of the line scan camera (CAM1).

[0115] Referring to Figure 9a, the image sensor SEN1 of the line scan camera CAM1 has a detection pixel D A,1 , D A,2 , D A,3 ,...D A,M The active first row consists of and the detected pixel D B,1 , D B,2 , D B,3 ,...D B,M The system may also include an active second row consisting of , and the second row may be used, for example, for measuring dark images. The number of active rows of detected pixels may be, for example, 2, 3, 4, or 5. A smaller number of active rows allows for faster reading of image data from the sensor.

[0116] The image sensor SEN1 of the line scan camera CAM1 may, for example, have a 2×M array of active light-detecting pixels. The value of M may be, for example, in the range of 50 to 10000.

[0117] The image sensor SEN1 of the line scan camera CAM1 may, for example, have a 3×M array of active light-detecting pixels. The value of M may be, for example, in the range of 50 to 10000.

[0118] The image sensor (SEN1) of the line scan camera (CAM1) may have two rows of detection pixels (D). The two rows may be configured to acquire images simultaneously. In one embodiment, the method may further include averaging the pixel values ​​at the same short-axis position in two images acquired by the two rows of detection pixels.

[0119] Referring to Figure 9b, different rows of detected pixels may simultaneously have different fields of view on object OBJ1. For example, the first row may have a first field of view FOV1A, and the second row may have a second field of view FOV1B.

[0120] The two rows of detection pixels may be configured to acquire an image simultaneously. In one embodiment, the first row of detection pixels may correspond to a first field of view that overlaps with the area illuminated by the linear pattern. The second row of detection pixels may correspond to a different second field of view outside the area illuminated by the linear pattern. The second row of detection pixels may be configured to acquire, for example, a dark image. The dark image may be used to correct the background of the first image acquired by the first row of detection pixels.

[0121] Referring to Figure 10a, different rows of detected pixels simultaneously appear in multiple images IMG1A. λ1 IMG1B λ1 The system may be configured to acquire these images, and these images may represent the same wavelength λ1.

[0122] Referring to Figure 10b, the first row of detected pixels is in spectral image IMG1A λ1 IMG1A λ2 IMG1A λ3 ,...IMG1A λNIt may be used to obtain the second row of detected pixels. The second row of detected pixels may be used to obtain the dark image DARK1. Spectral image IMG1A λ1 The dark image IMG1 may be acquired at the same time.

[0123] Referring to Figure 11a, the apparatus 500 may be configured to operate such that its spectral measurement range includes, for example, one or more spectral transmittance peaks PEAK1A, PEAK1B of a Fabry-Perot interferometer.

[0124] When using a single spectral transmittance peak PEAK1A, the illumination pattern PAT1 has only a single wavelength (e.g., λ1), and the acquired image IMG1 represents that single wavelength.

[0125] When using two spectral transmittance peaks PEAK1A, the illumination pattern PAT1 has two wavelengths. The first spectral transmittance peak PEAK1A is at the first wavelength λ1, and the second spectral transmittance peak PEAK1B is at the second wavelength λ 1+FSR It is located at Δλ, the free spectral range of the Fabry-Perot interferometer FPI1. FSR It represents.

[0126] Referring to Figure 11b, the first row of detection pixels may have a first optical filter FIL1A to provide the first row with a first spectral detection range.

[0127] The second row of detection pixels may have a second optical filter FIL1B to provide the second row with a second different spectral detection range. The first filter FIL1A may be, for example, an optical low-pass filter, and the second filter FIL1B may be, for example, an optical high-pass filter.

[0128] At least one row of detected pixels in the line scan camera (CAM1) is the first row (D) of detected pixels. A The spectral sensitivity of the second row (D) of the detected pixel is BAn optical filter (FIL1A) may be provided to have a different spectral sensitivity than that of the device.

[0129] Referring to Figure 11c, the line scan camera CAM1 may have two active rows of detection pixels such that the image IMG1A obtained from the first row is acquired using light transmitted through the first spectral transmittance peak PEAK1A, and as a result, light transmitted through the second spectral transmittance peak PEAK1B does not contribute to the image IMG1A. The second image IMG1B obtained from the second row is acquired using light transmitted through the second spectral transmittance peak PEAK1B, such that light transmitted through the first spectral transmittance peak PEAK1A does not contribute to the image IMG1B. The first image IMG1A may represent wavelength λ1, and the second image IMG1B may represent wavelength λ 1+FSR This may represent the following. Images IMG1A and IMG1B may be acquired simultaneously or substantially simultaneously.

[0130] Figure 12 shows an example of the spatial intensity distribution of a linear pattern PAT1 for illumination in the short direction, and the spatial intensity distribution of a linear pattern for illumination in the long direction (i.e., the direction of movement of the object). The linear pattern PAT1 has a width w in the long direction (SY). PAT1 and the length L in the shorter direction (SX). PAT1 It may have both.

[0131] Dimensions L of lighting pattern PAT1 PAT1 The dimensions are w PAT1 It is significantly larger than L. PAT1 / w PAT1 For example, it may be greater than 10, greater than 100, or greater than 1000. Ratio L PAT1 / w PAT1 This could be, for example, within the range of 10 to 10000.

[0132] Dimensions of lighting pattern PAT1 (w PAT To define the spatial resolution according to the dimensions (w) of the longitudinal direction SY of the illumination pattern PAT1, PAT) may be substantially smaller than the dimension of the direction SY of the field of view FOV1.

[0133] The spatial intensity distribution of the linear illumination pattern PAT1 is different for different wavelengths λ1, λ2, λ3, ...λ N The linear illumination pattern PAT1 may differ for each location. The spatial intensity distribution of the linear illumination pattern PAT1 may be wavelength-specific. Wavelength-specific effects may be compensated for, for example, by using wavelength-specific calibration data CAL1. For example, the spectral reflectance distribution may be calculated from the acquired image IMG1 using wavelength-specific calibration data CAL1.

[0134] Referring to Figure 13a, the field of view (FOV) 1 of the line scan camera CAM1 may overlap with the region REG1 illuminated by the linear pattern PAT1. The field of view (FOV) 1 of the line scan camera CAM1 has dimensions w in the longitudinal direction SY. FOV1 It has. The linear pattern PAT1 has dimensions w in the longitudinal direction SY. PAT1 It has the dimensions of the field of view (FOV) w FOV1 The dimensions of the linear pattern PAT1 are w PAT1 It may be smaller than this, in which case the spatial resolution in the longitudinal direction SY may be determined by the line scan camera CAM1.

[0135] Referring to Figure 13b, the field of view (FOV) of the line scan camera CAM1 may overlap with the region REG1 illuminated by the linear pattern PAT1. Dimensions w of the linear pattern PAT1 PAT1 The dimensions of the field of view (FOV1) are w FOV1 It may be smaller than this, in which case the spatial resolution in the longitudinal direction SY may be determined by the beam shaping optical system OPT1 of the illumination unit 110. By determining the spatial resolution by the linear pattern PAT1, for example, the influence of the vertical position of the object OBJ1 on the intensity detected by the line scan camera CAM1 can be reduced.

[0136] In particular, dimension wPAT1 is dimension w FOV1It may be smaller than the above, and the light beam acting as a linear pattern PAT1 is the intensity distribution I of the illumination pattern PAT1 on the illumination region REG1. PAT1 (x,λ1) may be collimated or substantially collimated such that it does not substantially depend on the distance between the lighting unit 110 and the object OBJ1.

[0137] Referring to Figure 14a, the spatial intensity distribution of the linear pattern PAT1 may have, for example, a Gaussian shape. Spatial intensity distribution I at the first wavelength λ1 PAT1 (x, λ1) is the spatial intensity distribution I at the second wavelength λ2. PAT1 (x,λ2) may be different from this.

[0138] The first detection pixel D1 of sensor SEN1 may be configured to detect light from a position x1 in the short direction on the surface SRF1 of object OBJ1. The detection pixel D1 may correspond to the position x1 in the short direction. M It may be configured to detect light from a position xM in the short direction on the surface SRF1 of object OBJ1. Detected pixel D M This is the position x in the short direction. M It may also be possible to accommodate this.

[0139] Referring to Figure 14b, the apparatus 500 may be configured to acquire calibration data CAL1 by illuminating a reference surface SRF0 with a linear pattern PAT1 and acquiring an image IMG1 of the illuminated area REG1. Wavelength-specific calibration data CAL1 for wavelength λ1 is obtained by illuminating a reference surface SRF0 with a linear pattern PAT1 of wavelength λ1 and acquiring an image IMG1 of the illuminated area REG1. λ1 The calibration data CAL1 may be obtained by acquiring the calibration data CAL1. The calibration data CAL1 may be stored in memory MEM3, for example. The control unit CNT1 may be configured to determine the calibration data from the image IMG1 of the illumination area REG1 of the reference surface SRF0. The reference surface SRF0 may be, for example, a white or gray surface having a known reflectance.

[0140] In a later stage, the calibration data CAL1 may be obtained from memory MEM3, and the calibration data CAL1 may be used to determine the reflectance value from the pixel values ​​of one or more acquired images IMG1 of the illumination region REG1 of object OBJ1.

[0141] Referring to Figure 15, the apparatus 500 may be configured to measure the intensity and / or energy of the generated light pulse B2. A portion of the light from the light pulse B2 may be coupled to a reference detector DET1 via a beam splitter BS1. The reference detector DET1 may generate a reference signal INTREF1 indicating the intensity and / or energy of the generated light pulse B2. The reference signal INTREF1 may be used, for example, as a feedback signal to stabilize the operation of the illumination unit 110. The reference signal INTREF1 may also be used, for example, to compensate for the effect of fluctuations in the intensity and / or energy of the generated light pulse B2 on the measured pixel values.

[0142] The lighting unit (110) may include a beam splitter (BS1) and a reference detector (DET1), and a portion of the light from the light pulses (B1, B2) may be guided to the reference detector (DET1) via the beam splitter (BS1) to measure the energy and / or intensity of the light pulses (B1, B2).

[0143] This method uses different wavelengths λ1, λ2, λ3, ...λ N This may include measuring the intensity and / or energy of each optical pulse B2 generated for each pulse.

[0144] Wavelength-specific calibration data CAL1 is obtained for different wavelengths λ1, λ2, λ3, ...λ N Each may be determined, stored, and used separately. Calibration CAL1 may be stored in memory (MEM3) as a data matrix or as a parameter of a regression function. For example, the spatial intensity distribution of the illumination pattern PAT1 may be substantially a Gaussian distribution, and calibration CAL1 may be stored in memory MEM3 as a parameter of a Gaussian regression function.

[0145] It will be apparent to those skilled in the art that modifications and variations of the devices and methods according to the present invention are perceptible. The figures are schematic. The specific embodiments described above with reference to the accompanying drawings are illustrative and not intended to limit the scope of the invention as defined by the accompanying claims. [Explanation of Symbols]

[0146] 500 Spectroscopic Imaging System LS1 broadband light source FPI1 Fabry-Perot Interferometer M1 First Mirror M2 Second Mirror d GAP Mirror spacing λ wavelength DET1 Reference detector for monitoring pulse energy and / or intensity BS1 Beam Splitter INTREF1 signal from the reference detector OPT1 Beam Shaping Optics OBJ1 Object v OBJ1 Relative velocity of an object SRF1 Surface of an object 110 Lighting Unit CAM1 Line Scan Camera LNS1 camera imaging optics SEN1 Camera Image Sensor D Image Sensor Detection Pixels Δt EX Exposure time of detected pixels IMG1 Acquired image P Pixels of the acquired image DARK1 Dark Image PAT1 Linear pattern for lighting L PAT1 Short-side dimension of the lighting pattern w PAT1 Longitudinal dimensions of the lighting pattern I PAT (x,λ1) Spatial intensity distribution of the illumination pattern at wavelength λ1 w FOV1 Longitudinal dimension of the field of view REG1 lighting area CNT1 Control Unit LAS1 Seed Laser FIB1 Optical Fiber B0 Primordial Laser Pulse B1 Broadband optical pulse B2 Narrowband Optical Pulse CHM1 Vacuum Chamber VAC1 vacuum GAS1 Gas PUMP1 Vacuum Pump DUC1 Duct WIN1 Vacuum Chamber Window WIN2 Vacuum Chamber Window FEED1 Electrical Feedthrough CON1 conductor CON2 conductor FOV1 field of view FOV1A Field of view of the first row of detected pixels FOV1B Field of view of the second row of detected pixels D A First row of detected pixels D B Second row of detected pixels P A Image pixels acquired by the first row of detected pixels P B Image pixels acquired by the second row of detected pixels FIL1A Optical filter for the first row of detected pixels FIL1B Optical filter for the second row of detected pixels MSR1 Measurement Spectrum Range λ LP First limit of the measurement spectral range λ SP Second limit of the measurement spectral range T(λ) Spectral transmittance PEAK1A Fabry-Perot interferometer spectral transmittance peak PEAK1B Fabry-Perot interferometer spectral transmittance peak FSR is an acronym for Free Spectrum Range. Δλ FSR Free spectral range MEM1 memory MEM2 memory MEM3 memory MEM4 memory PROG1 Computer Program Code ACU2 Actuation Unit ACU1 Fabry-Perot interferometer actuator SX Short direction SY Longitudinal Direction SZ vertical direction CUBE1 Hyperspectral Data Cube ARR1 reflectance data array R X1 Reflectance at position X1 CAL1 Calibration Data RXTX1 Communication Unit UIF1 User Interface t time T REP The period between consecutive light pulses Δt DUR Duration of a single pulse S FPI1 Control signals for Fabry-Perot interferometers T SCAN Scanning period SRF0 Reference Plane

Claims

1. Apparatus for spectral imaging (500), - An illumination unit (110) for illuminating a linear region (REG1) of an object (OBJ1) with a linear pattern (PAT1) formed from a narrowband light pulse (B2), - Image (IMG1) of the illuminated linear region (REG1) λ A line scan camera (CAM1) to acquire ) and Equipped with, The aforementioned lighting unit (110) - A light source (LS1) for generating broadband optical pulses (B1), - An adjustable Fabry-Perot interferometer (FPI1) ​​for forming the narrowband optical pulse (B2) by filtering the broadband optical pulse (B1), - A beam shaping optical element (OPT1) for forming the linear pattern (PAT1) from the narrowband optical pulse (B2) is provided, The wavelength (λ) of the linear pattern (PAT1) is the mirror spacing (d) of the Fabry-Perot interferometer (FPI1). ＧＡＰ ) is determined by, The apparatus (500) has the mirror spacing (d) of the Fabry-Perot interferometer (FPI1). ＧＡＰ It is configured to change Device.

2. During a scanning period (T ＳＣＡＮ ), by changing the mirror interval (d ＧＡＰ ) of said Fabry-Perot interferometer (FPI1), different wavelengths (λ １ , λ ２ , ... λ Ｎ ) are configured to generate a plurality of narrow-band optical pulses (B2), and movement of the movable mirror (M2) of said Fabry-Perot interferometer (FPI1) is not stopped during said scanning period (T ＳＣＡＮ ), The apparatus (500) according to claim 1.

3. The apparatus according to claim 1 or 2, wherein the Fabry-Perot interferometer (FPI1) ​​is placed in a vacuum chamber (CHM1) and configured such that the absolute pressure of the vacuum chamber (CHM1) is less than 10 kPa.

4. The apparatus (500) according to any one of claims 1 to 3, wherein the image sensor (SEN1) of the line scan camera (CAM1) comprises only one active row of detection pixels (D).

5. The apparatus (500) according to any one of claims 1 to 3, wherein the image sensor (SEN1) of the line scan camera (CAM1) comprises two rows of detection pixels (D).

6. The apparatus (500) according to claim 5, wherein at least one row of detection pixels of the line scan camera (CAM1) includes an optical filter (FIL1A) such that the spectral sensitivity of the first row (DA) of detection pixels is different from the spectral sensitivity of the second row (DB) of detection pixels.

7. Scanning period (T ＳＣＡＮ ) between the mirror interval (d ＧＡＰ ) is the first value (d ＧＡＰ，１ ) to the second value (d ＧＡＰ，Ｎ It is configured to operate so as to change during the scanning period (T ＳＣＡＮ ) is less than 100 ms, and the scanning period (T ＳＣＡＮ The number of narrowband optical pulses (B2) formed at different wavelengths (λ) during the scanning period (T) is greater than 10. ＳＣＡＮ The apparatus (500) according to any one of claims 1 to 6, wherein the number of images (IMG1) acquired at different wavelengths (λ) during the interval is greater than 10, and the acquisition of the images (IMG1) is synchronized with the narrowband light pulse (B2).

8. The apparatus (500) according to any one of claims 1 to 7, wherein the light source (LS1) comprises a laser light source (LAS1).

9. The apparatus (500) according to any one of claims 1 to 8, wherein the illumination unit (110) comprises a beam splitter (BS1) and a reference detector (DET1), and a portion of the light from the light pulses (B1, B2) is directed to the reference detector (DET1) via the beam splitter (BS1) in order to measure the energy and / or intensity of the light pulses (B1, B2).

10. The apparatus (500) according to any one of claims 1 to 9, wherein the line scan camera (CAM1) is configured to acquire a dark image (DARK1) when the object (OBJ1) is not illuminated by the linear pattern (PAT1), or when the wavelength (λ) of the linear pattern (PAT1) is outside the spectral detection range of the line scan camera (CAM1).

11. The apparatus (500) according to any one of claims 1 to 10, further comprising an operating unit (ACU2) for causing relative movement between the object (OBJ1) and the linear pattern (PAT1).

12. The apparatus (500) according to any one of claims 1 to 11, wherein the operating unit (ACU2) comprises a conveyor belt and / or a robot.

13. Using calibration data (CAL1), the acquired image (IMG1) λ１ ) From the pixel value, the spectral reflectance value (R ｘ１ The apparatus (500) according to any one of claims 1 to 12, comprising a control unit (CNT1) configured to determine ).

14. Image (IMG1) acquired from the reference plane (SRF0) λ１ IMG1 λ２ The apparatus (500) according to any one of claims 1 to 13, comprising a control unit (CNT1) configured to determine calibration data (CAL1) from ).

15. The Fabry-Perot interferometer (FPI1) ​​detects a first wavelength (λ １ To form a first narrowband optical pulse (B2) having ) a first time (t １ ) with the first mirror interval (d ＧＡＰ，１ The lighting unit (110) is configured to have the first wavelength (λ １ A first linear pattern (PAT1) having ) λ１ ) in the first linear region (PAT1) of the object (OBJ1) λ１ The line scan camera (CAM1) is configured to illuminate the first linear pattern (PAT1) λ１ The first linear region (PAT1) illuminated by ) λ１ Image (IMG1) λ１ The Fabry-Perot interferometer (FPI1) ​​is configured to acquire a second wavelength (λ ２ To form a second narrowband optical pulse (B2) having ) a second time (t ２ ) with the second mirror interval (d ＧＡＰ，２ The lighting unit (110) is configured to have the second wavelength (λ ２ A second linear pattern (PAT1) having ) λ２ ) in the second linear region (PAT1) of the object (OBJ1) λ２ The line scan camera (CAM1) is configured to illuminate the second linear pattern (PAT1) λ２ The second linear region (PAT1) illuminated by ) λ２ Image (IMG1) λ２ The apparatus (500) according to any one of claims 1 to 14, configured to obtain ).

16. - To generate broadband optical pulses (B1), - Using an adjustable Fabry-Perot interferometer (FPI1), a narrowband optical pulse (B2) is formed from a broadband optical pulse (B1), - Using a beam shaping optical system (OPT1), a linear pattern (PAT1) is formed from the narrowband optical pulse (B2), - The linear pattern (PAT1) illuminates the linear region (REG1) of the object (OBJ1), - To acquire an image (IMG1λ) of the illuminated linear region (REG1), - The mirror spacing (d) of the Fabry-Perot interferometer (FPI1) ＧＡＰ ) to change, Methods for spectroscopic imaging, including those mentioned above.

17. The method according to claim 16, comprising causing relative movement between the object (OBJ1) and the linear pattern (PAT1).

Images