JPH03272425A - spectrophotometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multi-wavelength simultaneous measurement type spectrophotometer using an array sensor.

(Prior Art) A multi-wavelength simultaneous measurement type spectrophotometer using an array sensor has the advantage that the time required for measurement is significantly reduced compared to a wavelength scanning type spectrophotometer. On the other hand, since the spectral image is divided by the arrangement pitch of the unit elements of the array sensor and measurement is performed for each divided part, it is difficult to increase the wavelength resolution.For example, when measuring only the visible range, it is difficult to increase the wavelength resolution. When covering >700 nm, at least one unit element must be sandwiched between two peaks in order to distinguish between two peaks that are close to each other.
If a sensor with 1024 unit elements is used, the wavelength resolution will be approximately 0.6 nm at 3001512 nm, but in reality, the peak center may be in the non-light-sensitive area between two unit elements, so the wavelength resolution will be The limit is lnm. Furthermore, there is a large difference in the measured peak intensity between when the peak center is at the center of a unit element and when it is between two unit elements, and the measurement results are distorted.

(Problem to be Solved by the Invention) The above-mentioned problem that the photometric output differs significantly between when the center of the spectral peak is at the center of the unit element and when it is at the dead zone between the unit elements can be solved. This problem can be solved by making one peak span several unit elements, but in this case the number of unit elements corresponding to a unit wavelength difference increases and the wavelength resolution becomes even lower.

The present invention improves wavelength resolution without sacrificing the high speed of a simultaneous measurement type spectrophotometer using an array sensor, and the measurement output differs depending on where the above-mentioned spectral peak is located in the unit element array. It is an attempt to solve the problem.

(Means for Solving the Problem) A spectral image on a spectral image plane is moved in the wavelength expansion direction, with one plurality of the arrangement pitch of the unit elements of the array sensor on the same image plane being taken as one movement step. The entrance slit or the spectroscopic element of the spectrometer is moved stepwise by one pitch, or the entrance slit and the spectroscopic element are fixed and the array sensor itself is driven by the piezo element one element at a time as described above. In addition to being driven in stages by a mechanism,
The output of the array sensor for each step of the drive is recorded with a shift corresponding to the l-step movement.

(Function) By moving the entrance slit of the spectrometer or the spectroscopic element, the spectral image can be moved in the wavelength expansion direction on the spectral image plane. In the present invention, the entrance slit or the spectroscopic element for this purpose is driven in stages by a piezo element drive mechanism. Stepwise driving can be achieved by changing the voltage applied to the piezo element in steps, and the piezo element has an extremely fast response speed and can respond even in a time width of μS. For example, if the array sensor is a photodiode array, the time required for one measurement over the entire wavelength range is several tens of milliseconds.
It is extremely easy to drive a step that takes this much time.

In addition, in the present invention, the spectrum is moved by one pitch, with a plurality of pitches, for example, 1/4, of the arrangement pitch of the unit elements of the array sensor being moved by one pitch, so each unit element scans the wavelength between one pitch of the unit elements. This is equivalent to sampling the measurement output at each step. For example 1
Since we move 3 steps with 174 pitches as one step, even if we multiply several 100 m5 for each step, it will be approximately 0.
A single measurement can be completed in 4 seconds, maintaining the high speed of a multi-wavelength simultaneous spectrophotometer.

Furthermore, the measurement results are recorded by shifting the measurement output of each step by one step on the record, so on the spectrum recording surface, the measurement values of each step are lined up between one pitch of the unit element, and the sampling of the spectral image is performed. One spectral image can be recorded by setting the interval to a multiple of the unit element pitch, and the wavelength resolution is greatly improved.
This also solves the problem of differences in measurement output depending on whether the center of the spectral peak is at the center of the unit element or in the dead zone between the unit elements.

(Example) Fig. 1 shows an example of the present invention. In the figure, M is a spectrometer, P
is a drive power source for the piezo element drive mechanism, C is a control device that performs data processing and device control, and R is a display device. In the spectrometer M, G is a diffraction grating that is a spectroscopic element, S is an entrance slit, and it is installed on a rocking table B with the 0 point as a fulcrum. The tip of the drive element 1Q is brought into contact with the drive element, and the entrance slit S is moved in the direction of the arrow a according to the expansion and contraction of the drive element. D is an array-like sensor that uses a photodiode array, and a spectral image is formed on this surface, and as the entrance slit S moves in the direction of the arrow above, the spectral image moves on the array-like sensor surface in the direction of the arrow. do. L is the light source of the spectrophotometer, and K is the condenser lens.

Next, the operation of the above device will be explained using FIG. In FIG. 2, P indicates one peak of the spectrum. n is the n-th unit element of the array sensor, and n+1 is the n+1-th unit element. In the figure, point O is the initial spectral peak P
By moving the entrance slit S in three steps, the center of the spectral peak moves to point 1.2.3 in Fig. 2. At each step, all unit elements of the array element are The output of is taken into control device C. The table below shows the outputs of unit elements n and n+1 of the array sensor at spectral peak PK center positions 0.1 to 3.

Table peak position Ml Output of n Output of n+1 Left half of O Beak No peak 1 Left tail of peak Right tail of peak 2
No peak Right half of peak 3 No peak Entire peak In the present invention, the above output is displayed on display device R.
Record it in the form shown in Figure 3. In this figure, the symbols of each plotted point are (n) and (n+1) to indicate the unit element, and the numbers to the right indicate the peak positions O to 3. For example, (n)O is the output of unit element n when the peak center is at position O in FIG. 2, and is the top output in column n of the above table. In Figure 3, T corresponds to 1 pitch of the unit element of the array sensor, and the spectral peak moves in 3 steps between this 1 pitch, so 4 measurements are taken during this 1 pitch for each unit element. Outputs are obtained, and these outputs are sequentially shifted and recorded at four points between this one pitch. When these recorded points are connected, a peak profile is drawn as shown by curve F in Figure 3, and the peak profile with a width of 1/2 of the unit element arrangement pitch of the array sensor is measured at four points. Become.

In the above-mentioned example, the artificial slit is driven in the wavelength dispersion direction of the spectrometer, but a piezo drive mechanism is used to drive the spectroscopic element or the array sensor itself in the wavelength dispersion direction at a pitch of 17n, which is the arrangement pitch of the unit elements of the array sensor. It is also possible to record the spectrum using the same recording method as described above by driving it in steps.
It goes without saying that it is included in the present invention.

(Effect of the invention) When a spectral peak exists in the positional relationship shown in Figure 2, in the conventional method, the peak is measured to have half the original intensity, and when the beak center comes to the center of the unit element n. This results in a remarkable result, and furthermore, when the peak center is located between unit elements n and n+1, the peak itself is not detected. In order to avoid this, it is necessary to have 3 to 4 unit elements correspond to the peak in Figure 2, and if you try to cover a predetermined wavelength range with a certain number of unit elements, the wavelength Although resolution has to be degraded, in the present invention, one peak only needs to cover half the pitch of a unit element, so the wavelength resolution is significantly improved, the peak profile can be defined, and measurements can be made based on the peak position. The problem of changing values is also eliminated.

Furthermore, since a piezo element is used to drive the entrance slit or the spectroscopic element, high-speed operation is possible.

[Brief explanation of drawings]

FIG. 1 is a plan view of an apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the apparatus of the present invention, and FIG. 3 is an explanatory diagram of the recording format. M...Spectroscope, S...Entrance slit, Q...Diffraction grating, D...Array sensor, P...Piezo element drive mechanism drive power supply, C...Control device, R...・Display device.

Claims (2)

[Claims] (1) An entrance slit or dispersion element movable so as to move the spectral image in the wavelength dispersion direction on the spectral image plane of the spectrometer, an array-shaped sensor arranged on the spectral image plane, and the entrance slit or The piezo drive mechanism that drives the spectroscopic element and the movement of the spectrum on the spectral image plane.
The step is 1 of the arrangement pitch of the unit element of the array sensor.
The piezo drive mechanism is controlled to drive the entrance slit or spectroscopic element by (n-1) steps so that /n (n is plural), and the output of the array sensor for each step is A spectrophotometer consisting of a control device that records data by shifting the direction one step at a time. (2) A piezo drive mechanism that drives the array sensor arranged along the spectral image plane in the spectrometer in the wavelength dispersion direction along the spectral image plane, and a piezo drive mechanism that drives the array sensor arranged along the spectral image plane in the spectrometer. One step is 1/n (n is plural) of the arrangement pitch of the unit elements of the array sensor.
The piezo drive mechanism described above is controlled to drive the array sensor by (n-1) steps so that
A spectrophotometer comprising a control device that records the array sensor output for each step by shifting it by one step in the wavelength direction.