JPH04286Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a spectrophotometer that measures light by moving an output slit along the spectral plane of the spectrometer.

For example, when a fixed detector and a moving detector can be used together in a spectrometer for emission analysis, it is desirable that the wavelength range that can be covered by the moving detector is as wide as possible. However, in the case of a configuration in which the output slit is moved, conventionally a single photodetector was placed behind the output slit, so the measurable wavelength range was narrow, about 2500 Å to 3800 Å.

The present invention can cover a wide wavelength range by providing a movable slit with an output slit, two photodetectors, a mirror for optical path switching, and a mechanism for operating a filter for cutting interference light mounted on a common base. This is what we are trying to do. The present invention will be explained below with reference to Examples.

In FIG. 1, 8 is a base, 2 is an output slit, and 6 and 7 are photodetectors. The slit 2 and the photodetectors 6 and 7 are mounted on the base 8. 4
is a mirror that can move in and out at the rear of the output slit 2, and directs the optical path of the light emitted from the output slit 2 to A.
The light is reflected toward the photodetector 7 and is incident on the photodetector 7. When the mirror 4 is removed from behind the slit 2, the light emitted from the slit 2 travels straight, takes an optical path B, and enters the photodetector 6. The mirror 4 is attached to an arm 5 that rotates around an axis X that intersects the optical path passing through the slit 2 at an angle of 45°, and can be moved into and out of the optical path B by rotating the arm 5. A filter 3 is attached to the end of the arm 5 opposite to the mirror 4, and when the arm 5 is rotated 180 degrees from the position shown in FIG.
is inserted into optical path B.

In the above configuration, in the state shown in Figure 1, the exit slit 2
The emitted light is reflected by the mirror 4 and enters the photodetector 7. This state is a short wavelength measurement mode in the measurement wavelength range. Next, when arm 5 is rotated 90 degrees, mirror 4 comes off from behind slit 2, and slit 2
The emitted light travels straight and directly enters the photodetector 6. This state is an intermediate wavelength region measurement mode within the measurement wavelength range. When the arm 5 is further rotated by 90 degrees, a filter 3 is inserted after the output slit 2, and the light emitted from the slit 2 travels straight, passes through the filter 3, and then enters the photodetector 6. In this state, the filter 3 cuts out second-order and higher-order diffracted light, and the mode is a long-wavelength measurement mode within the measurement wavelength range.

9 is a motor that rotates the arm 5. Three pins 10, 10', 10'' are attached to the axis of arm 5 at angular distances.
They are planted 90° apart. Three limit switches 11 are installed on the sides of the axis of the arm 5 and parallel to this axis.
12 and 13 are fixed, and the actuator of each switch faces the path of passage of the pins 10, 10', 10''.The motor 9 and each limit switch are both mounted on the base 8.
FIG. 1 shows a state in which the pin 10' is in contact with the limit switch 12. In this state, when a signal to rotate the motor 9 is input, the motor 9 rotates and the pin 10 is in contact with the limit switch 11, causing the limit switch 11 to operate. The motor 9 is stopped by the signal emitted by the mirror 4, and the mirror 4 is removed from behind the exit slit 2. In this state, when a signal to rotate the motor 9 is input again, the motor 9 rotates and the pin 10'' hits the limit switch 13.
Motor 9 is stopped. In this state, the filter 3 is inserted between the output slit 2 and the photodetector 6. When the motor is further rotated, arm 5
Rotate 180°, pin 10' becomes limit switch 12
When this happens, the motor 9 stops and returns to the state shown in FIG.

FIG. 2 is a side view of the configuration shown in FIG. 1, and reference numeral 1 designates a mirror that reflects the separated light flux F coming from the spectroscopic element (not shown) and directs it toward the exit slit 2. Output slit 2, photodetectors 6, 7, mirrors 1, 4, filter 3
The motor 9 and the like are mounted on a base 8, and the entire mount scans the spectral plane by moving parallel to the plane of the paper in FIG. 1 and perpendicular to the plane of the paper in FIG.

Photodetector 7 has a sensitivity in the wavelength range of 1600 Å to 3200 Å, and photodetector 6 has sensitivity in the wavelength range of 2000 Å to 6000 Å. In FIG. 3, a indicates the spectrum of the first-order diffracted light, and b indicates the spectrum of the second-order diffracted light. The range from 1900 Å to 3200 Å on the primary spectrum is the area in which photometry is performed by the photodetector 7 shown in FIG. In this range, the second-order diffracted light is 959 Å to 1100 Å.
Since it has no sensitivity to the photodetector 7,
The range from 1900 to 2200 Å can be measured by the photodetector 7 without any interference light. Next, the range of 2200 to 3800 Å of the first-order diffracted light is the measurement area in the mode in which the arm 5 is rotated 90 degrees in Fig. 1 so that the emitted light from the slit 2 is directly incident on the photodetector 6. The second order diffracted light is 1100
It does not give any sensitivity to the photodetector 6 (which has sensitivity for 2000 to 6000 Å) at ~1900 Å. Therefore, photometry can be performed without a filter. 3800~5150 of the first order diffracted light
The range Å is the measurement area in the mode in which the arm 5 is rotated 180 degrees and the filter 3 is inserted between the slit 2 and the photodetector 6 in FIG. In this case, the photodetector 6 is sensitive to light of 3800 to 5150 Å, but at the same time it is also sensitive to the second-order diffracted light of 2000 to 2600 Å, so the filter 3 cuts out the second-order diffracted light, which is the interference light. That's what I'm doing.

The spectrophotometer of the present invention has the above-described configuration, with two photodetectors placed behind a single slit, and three measurement modes provided by switching the optical path and entering and exiting the filter. It can cover a wide wavelength range.

[Brief explanation of drawings]

FIG. 1 is a plan view of an output slit mount according to an embodiment of the present invention, FIG. 2 is a side view of the same, and FIG. 2 is a diagram showing the division of the measurement wavelength range. 2... Output slit, 3... Filter, 4...
Mirror, 5... Rotating arm, 6, 7... Photodetector, 8...
Base, 9... Motor, 10, 10', 10''...
Pins, 11, 12, 13...limit switch.

Claims (1)

[Scope of utility model registration request] This configuration performs spectrophotometry by moving a photometric means on the spectral image plane, with a movable base holding an exit slit that moves on the spectral image plane, and a visible light range detector placed on the straight optical path behind the exit slit. A first photodetector that is sensitive and a second photodetector that is sensitive only to the ultraviolet region and placed on an optical path that intersects this optical path.
a photodetector, a rotary arm having a rotation axis that intersects with the two optical paths and holding a mirror and a filter separated by an angle, and means for causing the arm to assume three different angular positions; At one corner position of the arm, the mirror is located on the branch point of the two optical paths to reflect the light emitted from the slit toward one optical path, and at the other corner position, the mirror is located on the optical path. In addition, at another angular position, the filter is located on the straight optical path behind the exit slit, and the filter is placed in the high-order grid of the recursive grating that overlaps the long wavelength region in the measurement wavelength range. A spectrophotometer with the characteristic of cutting light.