JP2000146691A - Spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the light absorption by oxygen to make measurable at a high accuracy by making an optical path region from an optical source to an emitted light receiving part in the form of a partitioned space and replacing the atmosphere in the space with a gas inert to the wavelength of a used light. SOLUTION: A light source optical system chamber 10 contg. a light source 32 and an optical system and a light receiving chamber 18 having a photomultiplier tube 16 adjacent thereto are formed as spaces partitioned by the inner wall 14 inside the outer wall 12. Nitrogen gas is introduced from a gas inlet 56 to substitute the atmosphere in an optical path region by the nitrogen gas, a light is emitted from the light source 32, without setting a measuring sample in a sample chamber 20 and the light quantity is measured by the photomultiplier tube 16. The light source 32 uses a deutrium lamp to be capable of measuring in a wavelength range of about 110-320 nm. Now a sample is successively twice measured to obtain the dispersion of the light quantity values, and if about ±0.2% or less, the absorption by oxygen is little. According to this method, a control system/optical system not usable in vacuum can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrophotometer, and more particularly to a spectrophotometer for performing spectrophotometry using light having a wavelength of 300 nm or less.

[0002]

2. Description of the Related Art Generally, a spectrophotometer is used to measure the spectral characteristics of an optical material. In particular, wavelength 300n
In the measurement of the spectral characteristics of m or less, the amount of light having a wavelength of 190 nm or less is rapidly attenuated because the light is absorbed by oxygen in the air. Further, the light absorbed by oxygen converts oxygen into ozone, and this ozone may damage the optical system. In addition, ozone absorbs light having a wavelength within the range of 250 nm to 260 nm. For this reason, conventionally, measurement has been performed with the inside of the apparatus being set to a high vacuum. Further, the measurement may be performed in an atmosphere having a reduced oxygen concentration by replacing the atmosphere in the apparatus with a gas that is inert to light having a wavelength to be used, such as a nitrogen gas or a helium gas. .

[0003]

However, when measurement is performed under vacuum, the operation is not easy because a vacuum chamber is used. Also, the measurement system must be installed in a vacuum. Some members of the control system and the optical system cannot be used in a vacuum, so that the configurations of the control system and the optical system are limited. Therefore, high-precision measurement may not be performed. Further, vacuum-compatible members are relatively expensive.

In addition, when the measurement is performed while replacing the atmosphere in the apparatus (spectrophotometer) with an inert gas, there is a problem that it takes time to replace the entire apparatus with gas. Further, each time the measurement sample is replaced, the atmosphere in the apparatus must be replaced, which is troublesome. Further, there is a possibility that an organic substance resulting from contamination of the pipe or the like is mixed in the gas to be replaced. Therefore, there is a possibility that the measurement sample, the optical system, and the like are contaminated by the organic matter, and it becomes impossible to perform highly accurate measurement.

[0005] For this reason, there has been a demand for a spectrophotometer capable of preventing light absorption by oxygen and performing highly accurate measurement in a short time.

Further, there has been a demand for a spectrophotometer capable of preventing the adverse effects of organic substances in the replacement gas.

[0007]

For this reason, in the spectrophotometer of the present invention, an optical path region including an optical path until the light emitted from the light source reaches the light receiving section is defined as a partitioned space in the spectrophotometer. A gas replacement means for replacing the atmosphere of the space with a gas that is inert to light having a wavelength to be used is provided.

Therefore, there is no danger that the light emitted from the light source will be absorbed by oxygen in the atmosphere until the light emitted from the light source reaches the light receiving portion and the amount of light will be reduced. it can. Further, the gas replacement of the atmosphere is performed only in a partial area in the apparatus (spectrophotometer), that is, in an area including the optical path (optical path area). Therefore, gas replacement can be performed in a much shorter time than gas replacement of the entire atmosphere in the apparatus (spectrophotometer).

Further, according to the spectrophotometer of the present invention, there is provided a light source optical system room having a light source and an optical system, a sample room for installing a measurement sample, and a light receiving unit room having a light receiving unit. And the slit which lets the light from a light source pass is provided in the connection part of adjacent chambers, respectively.
Further, each chamber is provided with a gas inlet and a gas outlet as gas replacement means.

In this spectrophotometer, first, in a light source optical system room, light emitted from a light source is condensed by a lens and reaches a spectroscope through a slit. The light split into monochromatic light by the spectroscope reaches a chopper after its traveling direction is determined by a mirror. Then, the measurement light and the reference light are separated by rotating the chopper at a high speed. The optical system includes the above lens, spectroscope, mirror, and chopper. Thereafter, the measurement light is introduced into a sample chamber provided in the light source optical system chamber, and is irradiated on a measurement sample in the sample chamber. Thereafter, the light passes from the sample chamber to the light receiving section through the light source optical system chamber, and is detected by the photomultiplier tube in the light receiving section. On the other hand, the reference light reaches the light receiving section through a light path different from that of the measurement light in the light source optical system room.

A gas inlet and a gas outlet for replacing the atmosphere in the room are provided in each room having an optical path from the light source to the light receiving section. Therefore, if the gas replacement of all the rooms (rooms) serving as the optical path is performed at the same time, the gas replacement of the area including the optical path can be performed in a short time. Further, by using a rare gas such as a nitrogen gas or a helium gas that is inert to light having a wavelength to be used as a replacement gas, light from a light source is not absorbed by oxygen.
High-precision spectroscopic measurement can be performed using light having a wavelength of 00 nm or less.

Further, the optical system includes means for changing the direction of the light, means for condensing the light, means for separating the light into measurement light and reference light, and a portion having an optical path for guiding the light to a light receiving section. In. For this reason, the chamber has a larger space than the light receiving section chamber and the sample chamber. Therefore, a plurality of gas inlets and gas outlets may be provided in the light source optical system room.

When the measurement sample is replaced, only the gas in the sample chamber is replaced again, and it is not necessary to replace the atmosphere in another chamber. Therefore, it is possible to reduce the time and effort required for replacing the measurement sample as compared with the related art.

The gas inlet of the spectrophotometer according to the present invention is preferably provided with a filter for adsorbing impurities in the gas.

In general, gas pipes used in factories may have impurities such as organic substances in the gas due to insufficient cleaning. If the measurement sample or the optical system is contaminated with an organic substance, accurate spectral characteristics of the measurement sample may not be obtained. Therefore, if a filter is provided at the gas inlet, it is possible to prevent the organic substance in the replacement gas from adversely affecting the measurement sample and the optical system.

Preferably, the filter is a filter provided with activated carbon. For example, a tubular container having a net structure and filled with activated carbon is attached to the gas inlet as a filter. Then, if the gas from the pipe is introduced into the room through this filter, the organic matter in the gas can be adsorbed on the activated carbon.

The gas outlet is preferably connectable to an exhaust means such as a vacuum pump so that the interior of the room can be evacuated.

Further, according to the spectrophotometer of the present invention, it is preferable that the gas flow pressure of the gas introduced from the gas inlet be at least 1.0 kgf / cm ² . As will be apparent from the results of the later examples, when the gas replacement is performed at a gas flow pressure lower than 1.0 kgf / cm ² , the replacement takes a long time, and when the optical system and the like are complicated, the room is sufficiently provided. Is not replaced, and oxygen may remain in the atmosphere.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A spectrophotometer according to the present invention comprises a light source,
It has an optical system, a sample chamber, and a light receiving section. Then, a double beam type device for separating light emitted from the light source into measurement light and reference light is used. As the light source, continuous light such as a deuterium lamp or single wavelength light such as a laser can be used depending on the purpose of use. The optical system includes a mirror as a means for changing the direction of light, a lens as a means for condensing light, and a chopper for separating light into measurement light and reference light by rotating at high speed. The sample chamber is a chamber in which a measurement sample is installed. The light receiving section includes a photomultiplier tube as a detector.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the drawings merely schematically show the shapes, sizes, and arrangements of the respective components so that the present invention can be understood, and therefore, the present invention is not limited to the illustrated examples.

<First Embodiment> FIG. 1 is a schematic structural explanatory view of a spectrophotometer according to a first embodiment.

The spectrophotometer according to the first embodiment includes a light source, an optical system, a sample chamber, and a light receiving section. The region in the spectrophotometer has an optical path region including an optical path until the light emitted from the light source reaches the light receiving unit as a partitioned space. The light source and the optical system are one light source optical system room 1
It is within 0. The light source optical system room 10 is a space partitioned by an inner wall 14 provided inside an outer wall 12 of the spectrophotometer. The light receiving unit includes a photomultiplier tube 16 and is provided in a light receiving unit chamber 18. This light receiving unit room 18 is also a space partitioned by the inner wall 14 of the spectrophotometer,
It is provided adjacent to the light source optical system room 10.

The sample chamber 20 is provided in the light source optical system room 10 and is separated from the light source optical system room 10 by partition plates 26 and 28 having slits 22 and 24 through which measurement light passes. In addition, a slit 30 through which light to be detected passes is provided in the inner wall portion 14a between the light receiving unit room 18 and the light source optical system room 10.

Thus, the spectrophotometer includes at least three of the light source optical system room 10, the sample room 20, and the light receiving unit room 18.
It has two rooms that communicate with each other through slits, and this room constitutes a space including an optical path until the light emitted from the light source reaches the light receiving unit (FIG. 1).

Regarding the structure of the spectrophotometer of this embodiment,
This will be described in more detail along the optical path of the light emitted from the light source. In FIG. 1, the optical path is indicated by an arrow. The light source system includes a first lens 34, a first slit 36, and a spectroscope 3.
8, a second slit 40, a second lens 42, a first chopper 44, a third slit 22, a fourth slit 24, a first mirror 46, a second chopper 48, a second mirror 50, and a fifth slit 30.

As the light source 32, a deuterium lamp is used. The light emitted from the light source 32 is condensed by the first lens (fluorite or magnesium fluoride) 34 and reaches the spectroscope 38 through the first slit 36. The light split into monochromatic light by the spectroscope 38 passes through the second slit 40. Thereafter, the light is collected again by the second lens 42 and
The chopper 44 is reached. The light that has arrived is measured light (indicated by solid arrows) due to the high-speed rotation of the first chopper 44.
And a reference light (indicated by a dashed arrow). Then, the traveling direction of the measurement light is changed by the second mirror 50 and enters the sample chamber 20 through the third slit 22 which is an entrance to the sample chamber 20. The measurement light is applied to a sample (not shown) installed in the sample chamber 20, and then passes through the fourth slit 24, the second chopper 48, and the light receiving section 1.
From the fifth slit 30 which is the entrance to the light receiving section 8, the light receiving section 18
To reach. Then, the light is detected by the photomultiplier tube 16 in the light receiving unit chamber 18. On the other hand, the first chopper 44
The reference light separated by is indicated by a dashed arrow,
It travels along an optical path different from the measurement light in the light source optical system room 10,
After the traveling direction is changed by the first mirror 46, the second
The light reaches the light receiving unit chamber 18 from the fifth slit 30 via the chopper 48. Then, it is detected by the photomultiplier tube 16 in the light receiving unit chamber 18 (FIG. 1).

The light source optical system chamber 10 includes a first partition plate 52 in which the first slit 36 is formed and a second slit 40.
The first chamber 10 a having the light source 32 and the first lens 34 and the spectroscope 3
8 is divided into a second chamber 10b having a second lens 42, a first chopper 44, a second chopper 48, a first mirror 46, and a second mirror 50.

Further, each of the light source optical system room 10, the sample room 20, and the light receiving unit room 18 is provided with a gas inlet 56 and a gas outlet 58, respectively.

In the vicinity of the first slit 36 and the second slit 40 in the light source optical system room 10, the replacement efficiency of the room atmosphere is lower than in other regions. This is because the gas introduced into the chamber 10 must pass through the narrow slits 36 and 40 in order to replace the atmosphere in the light source optical system chamber 10. Therefore, in this example, the first chamber 10a and the second chamber 10b are provided with the gas inlet 56 and the gas outlet 58, respectively. In the third room 10c,
Since the sample chamber 20 is provided in the chamber 10c,
The replacement gas is less likely to circulate. Also,
Since the optical path of the measurement light is different from the optical path of the reference light, an optical path area is separately provided in the third chamber 10c. For this reason,
The third chamber 10c has a gas inlet 56 and a gas outlet 5
8 are provided two at different positions.

Nitrogen gas is introduced from the gas inlet 56 of such a spectrophotometer to replace the atmosphere in the optical path region with nitrogen gas. Thereafter, the light is emitted from the light source 32 without setting the measurement sample in the sample chamber 20, and the amount of light reaching the photomultiplier tube 16 is measured. A deuterium lamp is used as the light source 32, and measurement can be performed for a wavelength in the range of 110 nm to 320 nm. In this example, the measurement of the light amount for the same wavelength is performed twice consecutively. Then, the dispersion of the values of the two obtained light amounts is obtained. The greater the variation, the greater the light absorption by oxygen in the optical path region. Here, the variation of the light amount is ± 0.
If it is within 2%, it can be said that the influence of oxygen is small.

In this example, 175n randomly selected
With respect to the wavelengths of m, 190 nm and 250 nm, the light amounts of the respective wavelengths are measured twice.

In this example, a nitrogen cylinder is connected to the gas inlets, and B grade (99.
(99% purity) nitrogen gas at a gas flow pressure of 3.5 kgf / cm ² for 5 minutes. While flowing nitrogen gas,
The atmospheric gas in the room is discharged from the gas discharge port. Thereafter, the light source was turned on, and after the light source was stabilized, the light amount was measured twice in the same manner as in measuring the transmittance. Nitrogen gas is kept introduced during the measurement.

As a result, at the wavelengths of 175 nm, 190 nm and 250 nm, the variation of the light amount by the two measurements was within ± 0.05 to ± 0.1%.

Therefore, when measuring spectral characteristics using light having a wavelength of 300 nm or less, absorption of light by oxygen can be prevented without performing measurement in a vacuum. Therefore,
Since a control system and an optical system that cannot be used in a vacuum can be used, highly accurate measurement can be performed.

Further, in order to remove oxygen from the inside of the spectrophotometer, the atmosphere in the apparatus is replaced with an inert gas. Since the volume of the light path area of the partitioned space is smaller than that of the entire area in the spectrophotometer, the atmosphere of only the light path area of the light from the light source to the light receiving unit is replaced. In this example, the partitioned space (optical path region) is further partitioned into three rooms, and each room is provided with one or more gas inlets and gas outlets as gas replacement means. Therefore, it does not take much time for gas replacement. In this example, the partitioned space in the spectrophotometer has a volume of about 20% of the entire area. It should be noted that the higher the precision, the more the ratio of the regions changes, so that the configuration may be such that they can be replaced independently and sufficiently.

The optical path region from the light source to the light receiving section is
Since the light source optical system room, the sample room, and the light receiving room are separated, when replacing the measurement sample, only the atmosphere in the sample room needs to be replaced.

In this example, nitrogen gas is used as the replacement gas. However, the present invention is not limited to this, as long as the gas is inert to light having the wavelength to be used. A rare gas such as helium gas or argon gas may be used. In addition, one of these inert gases may be used,
More than one kind of gas may be mixed and used.

Further, for example, a pipe made of Teflon may be used as a pipe from a source of the replacement gas such as a nitrogen cylinder to the gas inlet. Teflon-made piping generates less organic gas that contaminates the atmosphere in the spectrophotometer, so that more accurate measurement can be performed.

Further, as shown in FIG.
It is preferable to provide a filter 60 provided with activated carbon for adsorbing impurities in the gas. FIG. 2 is a configuration diagram of the spectrophotometer of the present invention in which a filter 60 is provided at the gas inlet 56 of each chamber. For example, a tubular container having a net structure and filled with activated carbon is attached to the gas inlet 56 as a filter 60. Then, if gas from the pipe is introduced into the room through the filter 60, organic substances in the gas can be adsorbed on the activated carbon. Thereby, highly accurate measurement can be performed.

The spectrophotometer of the present invention may further include components other than the components shown in FIGS. Further, the arrangement of the components can be appropriately changed to such an extent that the present invention can be implemented.

<Second Embodiment> As a second embodiment, the same nitrogen gas as in the first embodiment was applied at a gas flow pressure of 1 kgf / cm ² using the spectrophotometer of the first embodiment. The gas is replaced by flowing for 5 minutes.

Then, as in the first embodiment, the light quantity is measured twice while the nitrogen gas is kept flowing. And 2
The variation in the amount of light is determined from the results of the measurement.

As a result, the variation in the amount of light at wavelengths of 175 nm, 190 nm and 250 nm is ± 0.05 to ± 0.05.
It was within 0.1%.

Thus, it was found that the atmosphere in the optical path region was sufficiently replaced even when the gas replacement was performed at a gas flow pressure of 1 kgf / cm ² . Therefore, light is not absorbed by oxygen, and highly accurate measurement can be performed.

(Comparative Example 1) In the spectrophotometer of the first embodiment, the light source was turned on without replacing the atmosphere in the optical path region with nitrogen gas, and the spectrophotometer was continuously operated as in the first embodiment. The light intensity is measured twice.

As a result, it was not possible to measure a wavelength of 185 nm or less. This is considered to be because the amount of light decreased due to the absorption of light by oxygen in the device.

At a wavelength of 185 nm to 200 nm, the variation between the two measured values was about ± 10%, which was very large. At a wavelength near 260 nm, the amount of light decreased. This is considered to be because oxygen absorbed light to form ozone, and the ozone absorbed light having a wavelength around 260 nm.

As a result, it was found that by replacing the atmosphere in the optical path region with nitrogen gas as in the first and second embodiments, the above-mentioned adverse effects of oxygen can be greatly reduced.

(Comparative Example 2) In the spectrophotometer of the first embodiment, the same nitrogen gas as in the first embodiment was flowed at a gas flow pressure of 0.5 kgf / cm ² into the optical path region for 5 minutes before measurement. The light quantity is measured twice consecutively as in the first embodiment.
During the measurement, the gas is kept flowing at a gas flow pressure of 0.5 kgf / cm ² .

As a result, at a wavelength of 180 nm,
The amount of light detected was too small to measure. Also,
Even at wavelengths in the range of 250 nm to 260 nm, the detected light quantity was reduced.

Therefore, the gas flow pressure of the replacement gas is 0.5 kg
At f / cm ² , it was found that the atmosphere in the optical path region could not be sufficiently replaced and oxygen remained.

The present invention can be applied to a spectrophotometer for measuring the spectral characteristics of an optical component used in a polarization optical system. In this case, as shown in FIG. 3, a third partition plate 66 forming a polarizing element 62 and a sixth slit 64 is newly provided between the second lens 42 and the first chopper 44 of the spectrophotometer of FIG. It is equipped.

[0053]

As is apparent from the above description, the spectrophotometer of the present invention separates the optical path region including the optical path until the light emitted from the light source reaches the light receiving portion from the other regions, and Gas replacement means is provided for replacing the atmosphere in the optical path region with a gas that is inert to light of the used wavelength.

For this reason, there is no possibility that the light emitted from the light source is absorbed by the oxygen in the atmosphere until the light emitted from the light source reaches the light receiving portion and the amount of light is reduced. it can. In addition, since the gas replacement of the atmosphere is performed only for the partitioned space (light path area) including the optical path, the gas replacement of the atmosphere in the entire area in the apparatus (spectrophotometer) is performed in a much shorter time than the gas replacement. Gas replacement can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the configuration of a spectrophotometer according to a first embodiment.

FIG. 2 is a configuration diagram of a spectrophotometer in which a filter is provided at a gas inlet.

FIG. 3 is a schematic structural explanatory view of a spectrophotometer when measuring spectral characteristics of an optical component used in a polarization optical system.

[Description of Signs] 10: light source optical system room 10a: first room 10b: second room 10c: third room 12: outer wall 14: inner wall 14a: inner wall portion 16: photomultiplier tube 18: light receiving unit room 20: sample room 22 : Slit (third slit) 24: Slit (fourth slit) 26, 28: Partition plate 30: Slit (fifth slit) 32: Light source 34: First lens 36: First slit (slit) 38: Spectroscope 40 : Second slit (slit) 42: second lens 44: first chopper 46: first mirror 48: second chopper 50: second mirror 52: first partition plate 54: second partition plate 56: gas inlet 58 : Gas outlet 60: filter 62: polarizing element 64: sixth slit 66: third partition plate

Continued on the front page F term (reference) 2G020 AA05 BA02 CB05 CB33 CB54 CC04 CC31 CC43 CD04 CD13 CD23 2G059 AA02 BB01 BB04 BB08 EE01 EE12 GG05 GG07 HH03 JJ05 JJ11 JJ19 JJ24 KK02 NN01 NN07

Claims (5)

[Claims] When an optical path region including an optical path until light emitted from a light source reaches a light receiving unit is provided as a partitioned space in a spectrophotometer, an atmosphere in the space is converted into light having a wavelength to be used. A spectrophotometer comprising gas replacement means for replacing with an inert gas. 2. A spectrophotometer comprising a light source, an optical system, a sample chamber for installing a measurement sample, and a light receiving unit, wherein the light source optical system room having the light source and the optical system, the sample chamber, and the light receiving unit A light-receiving unit chamber having: a slit for transmitting light from the light source is provided at a connection portion between adjacent chambers, and each chamber is provided with a gas inlet and a gas outlet. A spectrophotometer. 3. The spectrophotometer according to claim 2, wherein a filter for adsorbing impurities in the gas is provided at the gas inlet. 4. The spectrophotometer according to claim 3, wherein said filter is a filter provided with activated carbon. 5. The spectrophotometer according to claim 2, wherein a gas flow pressure of the gas introduced from the gas inlet is at least 1.0 kgf / cm ² . A spectrophotometer characterized in that: