JPH0621863B2 - Densitometer - Google Patents

Description

Detailed Description of the Invention a. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam scanning densitometer, and more particularly to a scanning mechanism thereof. There are two types of densitometers, one is to move the sample in zigzag for scanning, and the other is to move the light beam to perform scanning.However, in the case of moving the sample, the inertia of the moving part is large and high-speed scanning is difficult. A light beam scanning type is suitable for performing scanning.

B. 2. Description of the Related Art In a densitometer, a method of measuring a sample spot to be measured by dividing it into minute parts enables back ground correction, scatter correction, and the like, which improves quantitativeness. For this reason, the sample is irradiated with a thin light beam, and the sample and the light beam are relatively moved to scan the sample. As the scanning method, the method of moving the light beam has a small mechanical part that performs high-speed reciprocating motion, and high-speed scanning is not possible. It is possible. However, in this method, when the light flux emitted from the spectroscope is viewed locally, the energy is not uniform, and the direction of the light flux of the sample irradiation and the direction of the light flux irradiation point of the sample spot as seen from the photodetector change with scanning. Because
Since there is so-called locality in which the apparent sensitivity changes, the light flux scanning densitometer is only a proposal in principle, and a device that can withstand practical use as a device for quantitative measurement has not yet been known.

C. DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is intended to solve the above-mentioned locality in a light beam scanning densitometer.

D. Means for Solving the Problems Means for storing the correspondence between the position of the mechanism for moving the light beam for scanning and the photometric output of the sample photodetector, and the storage means for the photometric output of the photodetector. A means for performing a locality correction calculation using the stored data is provided, and the light source is scanned using a uniform sample plate to store the locality correction data in the storage means.

E. When performing a light beam scan using a uniform sample plate and storing the data of each position of the optical scanning mechanism at that time and the photometric output of the photodetector corresponding to that position in the storage means, these data are stored. Since the other side is a uniform plate, the same photometric value will correspond to all positions if there is no locality, but since there is locality, the photometric value is a function of the position of the optical scanning mechanism. This function becomes the locality correction data. At the time of measuring an actual sample, the measurement signal corrected for the locality by dividing the photometric output at each position of the light beam scanning mechanism by the photometric data corresponding to the position in the storage means, that is, the locality correction data. Is obtained.

F. Practical Example FIG. 1 shows an embodiment of the present invention. The part surrounded by the chain line M is a spectroscope, and the light source part is omitted in the figure. Reference numeral 1 is a diffraction grating, 2 is a concave mirror, and the light diffracted by the diffraction grating 1 is condensed on the exit slit surface of the spectroscope to form a spectral image.
The outlet slit extends in the vertical direction in the figure, and the scanning slit 3 is arranged along the outlet slit. The scanning slit 3 is movable in the vertical direction in the figure, and is vertically reciprocally driven by a motor 4. With this structure, the scanning slit 3
The light exit aperture h of the scans a certain wavelength position of the spectral image in the vertical direction. The monochromatic light emitted from the opening h is reflected by the mirrors 7 and 8 and illuminates the stage surface of the sample stage S. The mirror 7 is a concave mirror so that an image of the opening h is formed on the stage surface. When the opening h is reciprocated in the vertical direction, the image on the stage surface is reciprocated in the x-axis direction.
On the other hand, since the stage S is driven in the y direction by the y-direction feed motor Y, the light beam irradiation point moves in the y direction while reciprocating in the x direction with respect to the sample plate 9 set on the sample stage S. Zigzag scanning will be performed.

FIG. 2 shows the scanning slit 3 on an enlarged scale. A position detection hole array a is provided on one side of the opening h, and a scanning end detection hole array b is provided on the opposite side. Returning to FIG. 1, a photoelectric detector 5 and a photoelectric detector 6 are arranged on both sides of the scanning slit 3 so as to sandwich the hole array a and the hole array b. Fig. 3A
Is an output signal of the photoelectric detector 5, and one pulse is output every time one hole of the hole array a passes the photoelectric detector 5. Figure B
Is the output signal of the photodetector 6, and when the opening h of the scanning slit 3 comes to the end of the scanning range, one of the hole rows b comes to the position of the photoelectric detector 6, so the scanning slit is caused by the pulse in the signal of B. It is detected that the opening h of 1 comes to the end of the scanning range. When these signals are used to count the A pulses after the B pulse is detected, the count value becomes the data of the position of the opening h of the scanning slit.

In FIG. 1, 11 and 14 are photomultiplier tubes. A quartz plate 10 is obliquely inserted in the optical path of a light beam entering the sample 9 from the mirror 8, and a part of the sample irradiation light is reflected and made incident on the photomultiplier tube 11 for light source monitoring.
The photomultiplier tube 14 is adapted to receive the reflected light from the sample plate 9. The output of the photomultiplier tube 11 that receives the light source monitor light is applied to the high voltage generation circuit 13 via the preamplifier 12, and the output of the high voltage generation circuit 13 is fixed so that the output of the photomultiplier tube 11 is constant. The dynodes of the multipliers 11 and 14 are fed back to compensate the fluctuation of the sample irradiation light.

Photomultiplier tube 1 for receiving the reflected light from the sample plate 9
The output of 4 is taken into a computer 18 through a preamplifier 15, a switch 16 and an A / D converter 17. Reference numeral 19 denotes a motor drive circuit, which is a motor 4 and a motor Y.
To drive. The motor Y is a pulse motor, and its drive pulse is sent to the computer 18 to give information on the position of the sample plate in the y-axis direction. Reference numeral 20 is a data bus of the computer 18, and the output pulses of the photoelectric detectors 5 and 6 are also input to the computer 18 through this data bus.

FIG. 4 is a flow chart of the operation of the above-mentioned device.
FIG. 4A is a flow of an operation for obtaining the locality correction data. First, the motor 4 is driven in the forward direction by the start (a).
Then, the signal B in FIG. 2, that is, the presence or absence of the detection signal (B = 1) of one hole of the hole array b by the detector 6 is checked (B), and B =
The motor 4 is driven until 1 is detected, and when the step (b) becomes YES, the rotation direction of the motor 4 is reversed (c) and the driving is continued in that direction (d). By this operation, the scanning of the light beam is started from one end of the scanning range, and the presence or absence of the signal A shown in FIG. 2, that is, the detection signal (A = 1) of the holes in the hole array a is detected at step (e). Check, then step
When A = 0 is detected in (f), that is, when the trailing edge of the detection signal of the holes in the hole row a is detected, the switch 16 (FIG. 1) is turned on.
Then, the output of the photomultiplier tube 14 is taken into the computer 18 and stored (h) in the memory in the computer. Next, at step (i), it is checked whether or not B = 1. If B = 0, the operation returns to step (d) and the above operation is repeated until B = 1. In this way, the holes of the hole array a are detected one by one from one end, and the photometric output data is sampled at the falling edge of the detection signal and stored in the memory. FIG. 5 shows the inside of this memory, and the collected data are stored in the locations M1, M2, ... in order from the first photometric value, and when the step (i) is YES, one scan is performed. finish. Next, the data of M1 and M2 are read from the memory, and the maximum value Mx among them is searched (nu),
The value obtained by dividing Mx by each data M1, M2, ... Is replaced with the location of M1, M2 ,. Thus, the data (Mx / M1), (Mx / M) stored in the memory is
2), ... becomes the locality correction data.

FIG. 4B is a flow chart of the sample measuring operation. When the operation is started, the motor 4 is rotated in the normal direction as in the case of FIG. 4A.
(A) When the scanning slit 3 is driven until the scanning start end is reached until B = 1, the initial step (i) is NO (described later), the motor 4 is reversed, and A = 0 detected
(B) When it is done, switch 16 is turned on and photomultiplier tube 14
The photometric output of (1) is taken into the computer 18, the data Mx / M1 is read from the memory, the data of the photometric output just taken is multiplied, and the result is stored in the sample measurement data storage area of the memory (C). D) is repeated until B = 1 is detected, and the correction data is sequentially output M each time the operation is repeated once.
Change to x / M1, Mx / M2, ... Thus, when step (d) becomes YES, the motor Y is rotated by a certain amount to move the sample stage in the y direction by a certain amount (e), and the motor 4 is normally rotated (f). Photometric data is taken in according to the rise of the detection signal of the hole in row a, the correction data is taken out from Mx / Mn in the reverse order, and the data just taken in is multiplied and stored in the area of the sample measurement data in the memory. . This operation is repeated until B = 1 is detected (G). The measurement value is acquired at the rising edge of the signal A here. Since the data acquisition was performed at the falling edge of A in the previous stroke, the rising edge of A coincides with the previous stroke in the backward scan. Because it does. When B = 1 is detected at step (1), one reciprocating scan is completed, so the stage S is driven (ch) by a certain amount in the y direction, and the operation returns to point X. In this way, when the movement of the stage S in the y direction reaches a certain distance, the step (i) becomes YES and one measurement operation is completed.

In the above embodiment, the scanning slit 3 reciprocates, but it is also possible to make the scanning slit endless and perform only one-way scanning.

G. Effect The densitometer of the present invention is configured as described above and is capable of high-speed scanning since it is a light beam scanning type, and the locality due to the change in the light receiving efficiency of the sample photodetector due to the movement of the sample irradiation light beam is corrected, so that the quantitative Therefore, the background can be corrected, and the quantitativeness can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention, FIG. 2 is an enlarged front view of a scanning slit, FIG. 3 is a signal waveform diagram, and FIGS. An operation flow chart, FIG. 5 is a memory map showing an internal structure of a part of the memory in the above embodiment. M ... Spectrometer, 1 ... Diffraction grating, 3 ... Scanning slit,
4 ... Scan slit drive motors, 5, 6 ... Photoelectric detector, 9 ... Sample plate, 11, 14 ... Photomultiplier tube, S ... Sample stage, h ... Scan slit opening,
a: hole array for detecting the position of the scanning slit, b: hole array for detecting the scanning end.

Claims (1)

[Claims] 1. A mechanism for moving a light beam for scanning a sample, a means for detecting each position during the scanning operation of the mechanism, and a means for storing the output of a sample photodetector in association with the position of the mechanism. A means for splitting the light flux on the front surface of the sample to directly enter the photodetector, and a means for controlling the sensitivity of the photodetector and the sample photodetector so that the output of the photodetector becomes constant. A densitometer equipped with means for performing a locality correction operation on the photometric output of the sample photodetector using the data stored in the storage means.