Inspection apparatus, sensing apparatus, sensitivity control apparatus, inspection method, and program with pixel sensitivity control

1. An inspection apparatus comprising:

a reference plate:

an image detector configured to be disposed in opposition to the reference plate and an inspection target to be inspected, wherein the reference plate and the inspection target are in a field of view of the inspection apparatus, the image detector including a plurality of pixels configured to detect a plurality of different wavelength region components of a first portion of an ambient light reflected from the inspection target to be inspected and of a second portion of the ambient light reflected from the reference plate;

a memory storing program code; and

a processor that executes the program code to perform operations comprising

controlling a sensitivity of each of the plurality of pixels by calculating at least one histogram indicating a detection level by the image detector, and

determining, on a basis of respective histograms of particular ones of a plurality of spectroscopic components detected by the image detector, whether or not the sensitivity is properly set for the image detector.

2. The inspection apparatus according to claim 1 , wherein the operations further comprise calculating an index to be used for the inspection of the inspection target by using the particular ones of the plurality of spectroscopic components.

3. The inspection apparatus according to claim 2 , wherein the operations further comprise controlling the sensitivity in such a manner that the detection level with respect to the particular spectroscopic components is within a predetermined range, the particular spectroscopic components being used to calculate the index to be used for the inspection of the inspection target.

4. The inspection apparatus according to claim 3 , wherein the operations further comprise calculating the respective histograms indicating the detection level in every wavelength region of the first portion of the ambient light reflected from the inspection target that is detected by the image detector.

5. The inspection apparatus according to claim 4 , wherein the image detector further is configured to detect each of the spectroscopic components of the second portion of the ambient light reflected from the reference plate, the reference plate having known reflectance properties, and

the operations further comprise calibrating the particular spectroscopic components by reference to the spectroscopic components of the light reflected from the reference plate, the particular spectroscopic components being used to calculate the index to be used for the inspection of the inspection target.

6. The inspection apparatus according to claim 5 , wherein the operations further comprise determining a calibration gain for making corrections such that the particular spectroscopic components of the second portion of the ambient light reflected from the reference plate are at the same level, and correcting the particular spectroscopic components of the first portion of the ambient light reflected from the inspection target in accordance with the calibration gain.

7. The inspection apparatus according to claim 1 , wherein

the plurality of pixels are arranged in a planar array, and

the image detector includes a spectroscope configured so that optical filters for transmitting the spectroscopic components are each disposed for each pixel of the plurality of pixels.

8. The inspection apparatus according to claim 7 , wherein the image detector includes

a beam splitter configured to split light into a predetermined number of directions, and

a predetermined number of units of the spectroscope and of the plurality of pixels that are disposed for respective directions into which the light is split by the beam splitter.

9. The inspection apparatus according to claim 7 , wherein the spectroscope is configured to switch the spectroscopic components in a chronological order to disperse them, and

the operations further comprise performing a plurality of detection operations each time the spectroscope switches from one of the spectroscopic components to another.

10. The inspection apparatus according to claim 5 , wherein one unit of the image detector is individually provided to detect the first portion of the ambient light reflected from the inspection target, and another unit of the image detector is individually provided to detect the second portion of the ambient light reflected from the reference object.

11. The inspection apparatus according to claim 1 , further comprising:

an ambient light sensor configured to detect the ambient light.

12. A sensing apparatus comprising:

a reference plate:

an image detector configured to be disposed in opposition to the reference plate and an inspection target to be inspected, wherein the reference plate and the inspection target are in a field of view of the sensing apparatus, the image detector including pixels arranged in a planar array, the pixels configured to detect a plurality of different wavelength region components of a first portion of an ambient light reflected from the inspection target to be inspected and of a second portion of the ambient light reflected from the reference plate;

a memory storing program code; and

a processor that executes the program code to perform operations comprising

controlling a sensitivity of each of the pixels by calculating at least one histogram indicating a detection level by the image detector, and

determining, on a basis of respective histograms of particular ones of a plurality of spectroscopic components detected by the image detector, whether or not the sensitivity is properly set for the image detector.

13. The inspection apparatus according to claim 1 , wherein the image detector is configured to simultaneously detect the plurality of different wavelength region components of the first portion of the ambient light and of the second portion of the ambient light.

14. The inspection apparatus according to claim 1 , wherein the image detector is configured to detect the plurality of different wavelength region components of the first portion of the ambient light and, subsequently, to detect the plurality of different wavelength region components of the second portion of the ambient light.

15. An inspection method for use in a sensing apparatus comprising a reference plate and an image detector, the image detector including pixels arranged in a planar array, the method comprising:

disposing the image detector in opposition to the reference plate and an inspection target to be inspected, wherein the reference plate and the inspection target are in a field of view of the sensing apparatus;

detecting, by the pixels, a plurality of different wavelength region components of a first portion of an ambient light reflected from the inspection target to be inspected and of a second portion of the ambient light reflected from the reference plate;

controlling a sensitivity of each of the plurality of pixels by calculating at least one histogram indicating a detection level by an image detector including the plurality of pixels; and determining, on a basis of respective histograms of particular ones of a plurality of spectroscopic components detected by the image detector, whether or not the sensitivity is properly set for the image detector.

16. A non-transitory computer-readable medium storing program code for use in a sensing apparatus comprising a reference plate and an image detector, the program code being executable by a processor to perform operations comprising:

disposing the image detector in opposition to the reference plate and an inspection target to be inspected, wherein the reference plate and the inspection target are in a field of view of the sensing apparatus;

controlling a sensitivity of each the pixels by calculating at least one histogram indicating a detection level by an image detector including the plurality of pixels, the plurality of pixels configured to detect a plurality of different wavelength region components of a first portion of an ambient light reflected from the inspection target to be inspected and of a second portion of the ambient light reflected from the reference plate; and

determining, on a basis of respective histograms of particular ones of a plurality of spectroscopic components detected by the image detector, whether or not the sensitivity is properly set for the image detector.