Infrared spectrophotometer

Abstract

To provide an infrared spectrophotometer capable of safely performing a start-up operation while avoiding dew condensation inside a sealed housing.SOLUTION: An infrared spectrophotometer 100 includes: an openable sealed housing 60 for storing optical members; an infrared light source 10 for radiating infrared light to an inner side of the housing; a dehumidifier 80 for dehumidifying the inner side of the sealed housing 60; a temperature / humidity sensor 82 for detecting humidity inside the sealed housing 60; and a light source control device 50 for controlling supply power to the infrared light source 10. The light source control device 50 performs: starting the infrared light source 10 while limiting the supply power to the infrared light source 10; determining presence / absence of the risk of dew condensation inside the sealed housing 60 based on a detection value of humidity detected in a state where the power is supplied to the infrared light source 10; and gradually increasing the supply power to the infrared light source 10 while balancing an increase rate of the detection value of the humidity detected in a state where the power is supplied to the infrared light source 10 and a decrease rate of the humidity by the dehumidifier 80 when there is the risk of dew condensation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a function for starting up an infrared light source in a safe startup mode to prevent condensation in an infrared spectrophotometer.

Background Art

[0002] A Fourier-transform infrared spectrophotometer (FTIR) uses an interferometer to non-dispersively detect the interference wave of measurement light, and performs Fourier transform on it by a computer to obtain the spectrum of the measurement light. By forming the interference wave of infrared light, each wavenumber component can be calculated by Fourier transform from the intensity signal consisting of all wavenumber components. Fourier transform spectroscopy is suitable for high-speed measurement and has become the mainstream in infrared spectrophotometers.

[0003] The interferometer used in this device is generally a Michelson interferometer, which comprises a beam splitter (BS) and two reflecting mirrors (a fixed mirror and a moving mirror). The moving mirror is configured to vary the optical path difference of the interferometer, and there is a one-to-one correspondence between the position of the moving mirror and the optical path difference. The interferometer generates an interference wave of measurement light corresponding to the optical path difference from infrared light emitted by the infrared light source. By detecting the intensity of this interference wave, an interferogram (interference curve) with optical path difference on the horizontal axis and intensity signal on the vertical axis can be obtained. The computer performs Fourier transform on the interferogram data to calculate the spectrum.

[0004] In conventional FTIR, optical components such as beam splitters and window materials are widely made of potassium bromide (KBr) in consideration of infrared light transmittance. However, these optical components are deliquescent and vulnerable to condensation. Therefore, in order to prevent the optical components from being directly exposed to water vapor in the atmosphere and causing condensation, it has been practiced to house the optical components together with a dehumidifying agent in a sealed enclosure (for example, Patent Document 1), or to purge the sealed enclosure with nitrogen gas (Patent Document 2, etc.). In addition, a device provided with a protection device in which a humidity sensor is arranged inside the sealed enclosure, and the cover of the beam splitter is closed when the detected humidity becomes higher than a reference value has also been proposed (Patent Document 3, etc.).

Prior Art Documents

[0005] [Patent Document 1] Official Gazette No. 2-101239 [Patent Document 2] Japanese Patent Application Publication No. 10-332574 [Patent Document 3] Japanese Patent Publication No. 126436 / 1983 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, the purposes for which FTIR is used have diversified, and there is a need for portability, meaning that FTIR can be taken to various measurement locations for measurements.

[0007] Most conventional FTIRs are stationary types, and typically, even when the power is turned off, the main power supply remains on, and a constant current is continuously supplied to the infrared light source to maintain its temperature (continuous power supply). This is because the temperature of the light source and the device housing stabilizes quickly when the power is turned on again. However, in the case of portable FTIRs, the power to the device is completely turned off for transport, resulting in a period during which the infrared light source cannot be powered. Therefore, the light source and the device housing cool down during transport, and there is a risk of condensation occurring inside the sealed housing, especially on the cooled surface of the optical element (BS), when the infrared light source is started up again.

[0008] Generally, the light-emitting part of an infrared light source emits light through blackbody radiation, caused by the resistive heat of the electric current flowing through the metal wire, which heats the light-emitting material around the wire. This resistive heat makes the infrared light source a heat source, and naturally, the temperature of the outer periphery rises. For example, if the part close to the infrared light source, such as an insulating material, is hydrated, the water vapor will be released all at once as the temperature rises. If a certain amount of this water vapor reaches the vicinity of the optical element and condenses on the surface of the optical element, contamination of the optical element surface (deliquescent if it is hygroscopic) will occur. In particular, when the optical element is cold, it cools the warm water vapor emitted from the light source, making condensation more likely to occur.

[0009] Furthermore, if the interferometer is left in a humid environment for an extended period during transport, even with its sealed structure, it cannot completely prevent the inflow of air, and unexpected water vapor may enter the interferometer. In addition, water vapor may enter due to the following specific circumstances. • Opening of the interferometer chamber (sealed enclosure) for parts replacement, maintenance, etc. • Use or storage in high humidity environments for extended periods. • Transportation in environments with extreme temperature fluctuations • Operational errors, etc.

[0010] If excessive water vapor enters the sealed enclosure, it can be adsorbed onto the insulation material around the light source, the surface of the metal partition, and other surfaces. This adsorbed water vapor can be rapidly released back into the interferometer due to the heat generated by the light source, increasing the risk of condensation. Even if the humidity inside the sealed enclosure was checked (or if the enclosure was opened in a low-humidity environment to release internal water vapor) before activating the infrared light source, it would not have been possible to determine (or remove) the amount of adsorbed moisture.

[0011] As described above, when power is turned on after the light source and device housing have cooled down, especially after water vapor has entered the sealed housing, the heat generated by the infrared light source causes water vapor components adsorbed on the inner surface of the housing to be released all at once, causing a rapid increase in humidity inside the housing and increasing the likelihood of condensation in various places. In such cases, the dehumidifying capacity of desiccants and nitrogen gas purging devices is insufficient to keep up with the dehumidification, and the protection of optical components inside the housing cannot be said to be adequate.

[0012] While there are procedures such as slowly warming up the FTIR sensor beforehand and then activating the infrared light source, this results in a longer waiting time before measurements can be taken.

[0013] These challenges are not limited to FTIR, but are common to all spectrophotometers that use heat-generating elements as light sources and are sensitive to water vapor.

[0014] The objective of the present invention is to provide an infrared spectrophotometer that can safely perform startup operations while avoiding condensation inside a sealed enclosure. [Means for solving the problem]

[0015] The inventors diligently researched a special case in which the water vapor source is near an infrared light source (heat source) and the behavior of the water vapor occurs in a sealed enclosure over a relatively short period of time, leading to the completion of the present invention. In other words, the infrared spectrophotometer according to the present invention is A sealed enclosure that can be opened and closed houses optical components, An infrared light source that irradiates infrared light into the inside of the sealed enclosure, A dehumidifying means for dehumidifying the inside of the sealed enclosure, A temperature and humidity sensor for detecting the humidity inside the sealed enclosure, Control means for controlling the power supplied to the infrared light source, An infrared spectrophotometer comprising: extracting the infrared light as measurement light via an optical element in the sealed housing, irradiating a sample placed outside the sealed housing, and acquiring a spectrum based on the detected value of the light from the sample, The control means is The infrared light source is started while limiting the power supplied to the infrared light source to a level lower than the power supplied according to the temperature of the infrared light source during measurement use. Based on the detected humidity value obtained while power is being supplied to the infrared light source, the presence or absence of a risk of condensation inside the sealed enclosure is determined. If there is a risk of condensation, The rate of change in the detected humidity value while power is supplied to the infrared light source is obtained as the rate of increase, and the rate of change in the detected humidity value while power is stopped from supplying power to the infrared light source is obtained as the rate of decrease, and a balance is maintained between the rate of increase and the rate of decrease. The method is characterized by gradually increasing the power supplied to the infrared light source. Here, the power supply to the infrared light source may be controlled by controlling the duty cycle of the power supply, such that power is supplied during the ON period and stopped during the OFF period, according to a target value of the power supply.

[0016] Here, "humidity" refers to relative humidity, with the unit being %RH, and "temperature" is in °C. Furthermore, "dehumidification means" shall include at least one of a desiccant such as silica gel, a dehumidifier, and a gas purging device such as nitrogen gas.

[0017] For example, even if the humidity threshold (reference humidity) is determined from dew point calculation, if there is a sudden rise in humidity, the water vapor content may exceed the threshold before feedback to light source control. Further, even when the supply power is cut off after a sudden rise in humidity, a certain amount of time is naturally required for heat radiation until the temperature decreases thereafter, so it takes a certain amount of time to stop the generation of water vapor. In contrast, with the configuration of the present invention, when starting the infrared light source, the infrared light source is started while limiting the power supplied to the infrared light source, so a sudden rise in humidity can be avoided.

[0018] Further, according to the configuration of the present invention, the infrared light source is started while limiting the power supplied to the infrared light source, and based on the humidity detected during this period, it is predicted whether the inside of the sealed housing will reach the dew point (100% RH). Then, when there is a possibility of reaching the dew point, control of the infrared light source is executed such that the power supplied to the infrared light source is gradually increased while balancing the rising rate of the detected humidity value detected in a state where power is supplied to the infrared light source and the falling rate of humidity by the dehumidification means. In such startup control for the infrared light source, since the rising rate of humidity in the state where power is supplied to the infrared light source and the falling rate of humidity by the dehumidification means are balanced, even if a large amount of water vapor components are adsorbed inside the housing, a sudden increase in humidity inside the housing is avoided, and the risk of dew condensation inside the housing does not arise.

[0019] As a result, even when water vapor is adsorbed inside the interferometer due to unexpected operations (such as opening the interferometer, storage in a non-energized state over a long period, transportation in cold regions, etc.), the device can be safely started up while avoiding dew condensation. Furthermore, in the infrared spectrophotometer of the present invention, it is preferable that the control means switches to a control that outputs a fixed value of supplied power corresponding to the temperature of the infrared light source during measurement use when it is determined that there is no risk of condensation.

[0020] Further, the control means is configured to: acquire, as a rising rate, the rate of change of the detected humidity value detected in a state where power is supplied to the infrared light source, and acquire, as a falling rate, the rate of change of the detected humidity value detected in a state where power supply to the infrared light source is stopped, The power supplied to the infrared light source is controlled to maintain a balance between the rising speed and the falling speed, and the power supplied to the infrared light source is controlled so that the detected humidity value approaches a reference humidity set lower than 100% humidity.

[0021] The dehumidifying means absorbs moisture faster at higher humidity levels. Therefore, by maintaining the highest possible humidity inside the sealed enclosure without causing condensation, water vapor can be captured more quickly. In the present invention, the control means balances the rate of increase and decrease in humidity and controls the power supplied to the infrared light source to approach a set reference humidity. This allows for a reduction in the total time required for moisture absorption while avoiding a rapid increase in humidity, and enables the infrared light source to reach a predetermined temperature quickly.

[0022] Furthermore, the control means is Based on the rate of change of the detected humidity value detected while power is being supplied to the infrared light source, and the temperature value detected inside the sealed enclosure by the temperature and humidity sensor, the total amount of water vapor components adsorbed inside the sealed enclosure is estimated. Based on the rate of change of the detected humidity value detected when the power supply to the infrared light source is stopped, the dehumidification rate by the dehumidification means is estimated. The system is characterized by notifying the user of the dehumidification time, which is obtained from the total amount of water vapor components and the dehumidification rate, as a waiting time.

[0023] With this configuration, the control means acquires the total amount of water vapor components inside the sealed enclosure and the dehumidification rate, and calculates the required dehumidification time from these values, so that the user can be notified of the approximate waiting time. Therefore, the user can start the measurement work efficiently. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram of the FTIR configuration according to one embodiment. [Figure 2]This is a flowchart illustrating the startup of an infrared light source according to one embodiment. [Figure 3] This is a schematic diagram showing the change in humidity when an infrared light source according to one embodiment is started up. [Figure 4] This is a flowchart illustrating the activation of an infrared light source in a modified form. [Modes for carrying out the invention]

[0025] Preferred embodiments of the present invention will be described below with reference to the drawings. The infrared spectrophotometer of the present invention can be applied to Fourier transform infrared spectrophotometers (FTIR) and infrared microscopes. Here, in particular, the case in which it is applied to an FTIR100 as illustrated in Figure 1 will be shown. The FTIR100 comprises an infrared light source 10, an interferometer 12 that forms infrared interference waves, a sample holder 26 that holds a sample, an infrared detector 14 that detects the intensity of interference waves obtained by irradiating a sample with infrared interference waves, and a computer 16 that calculates spectral information of the sample based on the detection signal from the infrared detector 14. The computer 16 consists of a microcomputer built into the main body of the FTIR100, or a separate computer.

[0026] The housing (sealed housing) 60 of the interferometer 12 is configured to be openable and closable, and the sealed state is maintained by a sealing material between the lid material and the housing body. The following optical instruments are built into the housing 60. Specifically, an infrared light source 10, a beam splitter 20 that splits the infrared light, fixed mirrors 22 that reflect the split light respectively, and a movable mirror 24 are arranged inside the housing 60 to generate an infrared interference wave by combining two light beams with different optical path lengths. The movable mirror 24 is provided so as to be movable in both directions, towards and away from the beam splitter 20.

[0027] The infrared interference wave emitted from the emission window 64 irradiates the sample in the sample holder 26, which is located between the emission window 64 and the infrared detector 14. The infrared detector 14 receives the infrared interference wave from the sample and outputs its intensity signal. The detection signal from the infrared detector 14 is input to the computer 16 via the amplifier 14a and the A / D converter 14b.

[0028] The optical components housed in the housing 60 include the beam splitter 20 and window material 64, which are made of hygroscopic material and are therefore most susceptible to condensation. Even optical components that do not exhibit hygroscopicity can be contaminated by condensation on their surfaces. Mirrors and lenses, for example, can become cloudy due to condensation, which can affect measurements.

[0029] The housing 60 of the interferometer 12 houses a desiccant 80 for adsorbing and removing water vapor contained in the internal space, and a temperature and humidity sensor 82 for constantly detecting the temperature and humidity (relative humidity) inside the housing at a position close to the infrared light source 10. For example, silica gel is used for the desiccant 80. The temperature and humidity sensor 82 may be a combination of a temperature sensor and a humidity sensor. The temperature and humidity sensor 80 usually has both a thermometer (such as a thermistor) and a hygrometer (capacitance-changing type or electrical resistance-changing type). The hygrometer measures absolute humidity, that is, the amount of water vapor per unit volume (g / m³). 3 The temperature and humidity sensor 80 detects the amount of saturated water vapor (g / m³) at the temperature detected by the thermometer. 3 The system reads the data from a table or similar source and calculates the relative humidity (%RH) from the ratio of the detected water vapor amount to the saturated water vapor amount.

[0030] The infrared light source 10 consists of a ceramic light-emitting element 86 that emits light due to the resistive heat of the applied current flowing through a metal wire, and an insulating material 88 provided around the light-emitting element 86. The insulating material 88 (such as a ceramic fiber molded body) has, for example, a cone-shaped opening in the direction of light emission from the light-emitting element 86, and the infrared light source 10 is fixed to the housing 60 via a sealing material so that the cone-shaped opening coincides with an opening formed in the housing 60, thereby directly irradiating the inside of the housing 60 with infrared light. The insulating material 88 is provided for purposes such as suppressing temperature fluctuations of the light source, preventing the surface temperature from becoming too high, and preventing overheating of nearby components.

[0031] The thermal insulation material 88 is generally porous and readily adsorbs water vapor from the atmosphere. Furthermore, the water vapor adsorbed by the thermal insulation material 88 is rapidly released from the thermal insulation material 88 upon heating. In this embodiment, since the cone-shaped opening of the thermal insulation material 88 is directly connected to the internal space of the housing 60, the thermal insulation material 88 can become a source of water vapor when the light source 10 is started up.

[0032] Not only the insulating material 88, but also the surface of the metal partition of the housing 60 and the surface of the metal parts of the optical components housed within it can easily adsorb water vapor components and therefore become sources of water vapor within the housing 60.

[0033] The computer 16 comprises a control unit 40 that controls each component of the computer 16, a calculation unit 42 that calculates spectral information of a sample based on detection signals from the infrared detector 14 and performs spectral analysis, and a memory 44 that stores data processing programs executed by the calculation unit 42, calculated spectral information, analysis results, and background information. A display device 46 and a user interface 48 are also connected to the computer 16.

[0034] The light source control device 50 is responsible for supplying power to the infrared light source 10. The light source control device 50 is composed of a programmable logic device such as an FPGA and operates in response to commands from the computer 16. The light source control device 50 converts AC power from an external AC power source 52 into predetermined DC power and supplies it to the infrared light source 10. The light source control device 50 can start the infrared light source 10 in two ways: "normal mode" and "safe start mode". In safe start mode, the power supplied to the infrared light source is controlled so that the detected humidity value does not exceed the reference humidity. The safe start mode of the light source control device 50 may also be analog control that supplies a target value of power to the infrared light source 10, or it may be duty cycle control of turning the power supply on and off according to the target value.

[0035] <How to start an infrared light source> The method for starting the infrared light source 10 will be explained based on the processing flow diagram (processing flow S1 to S7) in Figure 2.

[0036] First, if the light source control device 50 needs to start the infrared light source 10 while confirming the safety of the FTIR 100, that is, if there is concern about a rapid generation of water vapor accompanying the start of the infrared light source 10, it slowly and gradually increases the power supplied to the infrared light source 10 from a low level (processing flow S1). In controlling the infrared light source 10 here, it is desirable to control the amount of fluctuation in the humidity detected by the temperature and humidity sensor 82 using PID control or a similar method, in order to minimize fluctuations in the humidity detected value. Furthermore, the adjustment parameters of the infrared light source 10 should preferably be analog control of the power supplied value or duty cycle control of the on / off state.

[0037] In parallel with processing flow S1, the temperature and humidity sensor 82 monitors the change in humidity over time to detect the rate at which the humidity inside the enclosure 60 is rising (processing flow S2). Then, the temporal correlation between the monitored change in humidity over time and the control of the infrared light source 10 is obtained to predict whether the humidity will reach the dew point (100%RH) (processing flow S3). This prediction may also be performed by comparing the monitored change in humidity over time with the change in humidity over time in several stored experimental data.

[0038] If processing flow S3 determines that there is no risk of condensation, the control of the infrared light source 10 in processing flow S1 is stopped, and the system switches to a process (normal mode) that outputs a fixed power supply so that the infrared light source 10 reaches the temperature used for measurement. If the fluctuation amount of the detected humidity value is being controlled by PID, it is advisable to fix the power supply output to 100%. On the other hand, if the processing flow S3 determines that there is a risk of condensation, the power supply to the infrared light source 10 is completely cut off once, and the rate of decrease in humidity is monitored and detected as the moisture absorption rate of the desiccant 80 (processing flow S4).

[0039] Next, in processing flow S5, if the detected moisture absorption rate is low and it is determined that the dehumidification effect is insufficient, all processing flows are stopped and a message prompting the user to replace the desiccant is notified by some means. On the other hand, in processing flow S5, if the detected moisture absorption rate is above the specified level and it is determined that there is no problem with the dehumidification effect, the process proceeds to processing flow S6.

[0040] In processing flow S6, a control value for the light source (the amount of water vapor released per unit time, or in other words, the change in the command value of the supplied power) that balances the humidity increase rate (processing flow S2) and the humidity decrease rate (processing flow S4) used to determine the risk of condensation is derived, and light source control is resumed with this control value. If a state in which the water vapor release rate and the moisture absorption rate are balanced can be maintained, at least a rapid release of water vapor can be avoided.

[0041] For example, after the light source control is restarted, if the amount of water vapor released increases and the amount of water vapor adsorbed decreases, the detected humidity value will decrease accordingly, and it will be considered that the amount of water vapor released has decreased. As a result, in order to return the control value (amount of water vapor released) to its original value, the process of increasing the light source temperature, that is, increasing the supplied power, will proceed.

[0042] Furthermore, since the desiccant absorbs moisture faster at higher humidity levels, maintaining the humidity inside the enclosure 60 at the highest possible level (reference humidity) while preventing condensation allows for faster capture of water vapor. Therefore, the infrared light source 10 is activated using an appropriate light source control value predicted by balancing the initial humidity increase and decrease, while monitoring humidity changes and adjusting the power supplied to the infrared light source 10 with feedback to ensure it always maintains the target humidity (reference humidity). This allows the inside of the interferometer to be maintained at a humidity level (reference humidity) with a certain humidity margin relative to 100% humidity (processing flow S6). By maintaining a balance between the water vapor release rate and the moisture absorption rate, and keeping the detected humidity value as close as possible to the reference humidity (humidity obtained by subtracting a certain margin from 100% humidity), condensation can be avoided while stabilizing the infrared light source 10 quickly.

[0043] As a simple way to implement the above processing flow S6, for example, the infrared light source 10 can be controlled using PID control with enhanced differential control to suppress humidity overshoot while maintaining a constant humidity as the target value (reference humidity). By controlling the infrared light source 10 while feeding back the detected humidity value to the target value, the total amount of adsorbed water vapor in the infrared light source 10, etc., gradually decreases, and the light source temperature gradually rises in an attempt to obtain the same amount of water vapor release as before.

[0044] In the processing flow described above, if experimental values ​​have been obtained beforehand, the total amount of adsorbed moisture can be predicted with a reasonable degree of accuracy from the initial humidity increase rate (processing flow S2) and the detected temperature. Then, using the detected humidity decrease rate inside the enclosure (processing flow S4), the time until the adsorbed moisture is adsorbed by the desiccant (waiting time until the device becomes usable) can be notified to the user as a predicted value. Furthermore, at least one of the humidity increase rate and decrease rate may be remeasured, the waiting time until the device becomes usable may be recalculated, and the latest waiting time may be notified to the user again.

[0045] Finally, if it is determined that the possibility of simultaneous release of water vapor adsorption, which was a risk of condensation, has been eliminated based on some judgment value, such as the temperature of the infrared light source 10 reaching a certain level, the control of the infrared light source 10 is stopped and the output is switched to a fixed value to the temperature used during measurement. The user is also notified by some means that the device is ready for use (processing flow S7).

[0046] Figure 3 schematically shows an example of humidity change when the infrared light source 10 according to this embodiment is started up.

[0047] In this embodiment, the FTIR100 uses a desiccant 80 as a dehumidifying agent, but a dehumidifier or nitrogen gas purging device may be provided instead of, or in conjunction with, the desiccant 80, and the effects of this embodiment can be obtained in the same way. For example, if it is determined that the dehumidification effect is insufficient (processing flow S5), all processing flows will be stopped (including the moving mirror control), and a message prompting the user to replace the desiccant or to perform an operation to improve dehumidification efficiency (an operation to increase the flow speed of the dehumidifier or gas purging) may be notified by some means.

[0048] Furthermore, in this embodiment, the temperature and humidity inside the housing 60 are monitored using a temperature and humidity sensor 82. However, in terms of condensation prevention, the goal is to avoid the phenomenon where saturated moisture precipitates and condenses from the air cooled by contact with the surface of the cold optical element. Therefore, the relative coolness of the optical element to the air is a major parameter. By adding a sensor that measures the temperature near the optical element where condensation is to be avoided, the required margin humidity can be determined with greater accuracy.

[0049] Figure 4 shows a flowchart of the activation of the infrared light source according to a modified example. This flowchart is simpler than the processing flowchart in Figure 2 according to this embodiment. For example, in the activation of the infrared light source 10 in processing flowchart S11, there is no condition to gradually increase the supplied power from a low level as in processing flowchart S1, and the infrared light source 10 may be activated by supplying a constant power as in the normal flowchart. Furthermore, as in processing flowchart S21, it is not necessarily required to detect the rate of humidity increase; it is sufficient to detect some degree of humidity increase, and the presence or absence of condensation risk may be determined by comparing it with past data stored in memory 44. In addition, as in processing flowchart S41, the infrared light source 10 may be controlled by determining a control amount that balances the degree of humidity increase with the degree of dehumidification pre-stored in memory 44, etc.

[0050] Furthermore, the housing 60 of the FTIR100 in this embodiment has a sealed structure, and under normal use, there is almost no intrusion of water vapor from the outside. The light source startup method in this embodiment takes longer to start up compared to simply starting the infrared light source 10 with a constant power (referred to as "normal mode"). Therefore, it is preferable to apply this light source startup method when starting up the infrared light source 10, only when necessary. Accordingly, it is preferable to provide the computer 16 with a mode switching function so that the computer 16 can determine if a special circumstance such as the intrusion of water vapor has occurred, and only if such a circumstance exists, it can start the light source startup method of this embodiment as "safe startup mode". The following is an example of a case where the special circumstance of water vapor intrusion occurs.

[0051] (1) First startup when the power has been completely cut off The FTIR100 is often kept powered on even when not in use, to maintain low humidity inside the enclosure 60 and to quickly stabilize the light source during startup, thereby keeping the infrared light source 10 heated at a low temperature (constant power supply). Therefore, the power is usually completely cut off only in special cases such as transportation, long-term storage, or power outages. Accordingly, when the computer 16 recognizes the recovery from these complete power outage conditions, it is configured to automatically select "safe startup mode" for startup.

[0052] (2) When there is access to the inside of the enclosure 60 The FTIR100 may require users to replace optical elements such as the beam splitter 20 to change the measurement wavenumber bandwidth. When the infrared light source 10 is running and at a high temperature, even if some humid outside air enters, adsorption will not occur, and the risk of condensation is not high. However, if an unexpected operation occurs, such as opening the casing 60 to replace an optical element while the device is constantly powered on, there is a risk that the invading water vapor will be adsorbed. Therefore, the optical element immediately before the device is constantly powered on is recognized by a dedicated sensor, and when the device is started from the constantly powered state, the sensor recognizes that optical element again. If it is determined that the optical element has been changed, the computer 16 will automatically select "safe startup mode" for startup.

[0053] (3) When maintenance is performed When engineers perform maintenance on the FTIR100, they may need to open the sealed enclosure 60 to work on it. Therefore, when restarting after such maintenance, the system should automatically select "safe startup mode." For example, it would be beneficial to implement a hardware or software user interface 48 on the FTIR100 that allows engineers to specify the startup mode themselves.

[0054] Even when starting up the infrared light source 10 in normal mode rather than safe startup mode, the light source control device 50 may use the simple criteria included in this embodiment (whether the initial rise in humidity is greater than the criterion) to determine whether there is an unexpected risk. For example, even when starting up the infrared light source 10 at a constant power without controlling the power supply, the humidity is monitored, and if it is determined that there is a risk of condensation, the startup at the constant power is stopped at that point. After that, it is advisable to proceed with processes such as notifying the user of the condensation risk, or automatically switching to safe startup mode and starting up again. Furthermore, if the humidity inside the enclosure 60 suddenly rises due to user error or other reasons, the computer 16 may be configured to perform actions such as issuing a warning to the user. [Explanation of symbols]

[0055] 10 Infrared light sources 12 Interferometer 14 Infrared detectors 20. Beam splitter (light beam splitting section) 22 Fixed mirror 24 movable mirrors 50 Light source control device (control means) 60 sealed enclosure 82 Temperature and Humidity Sensor 86 Light-emitting body 88 Insulation 100 Fourier Transform Infrared Spectrophotometer (FTIR)

Claims

1. A sealed enclosure that can be opened and closed houses optical components, An infrared light source that irradiates infrared light into the inside of the sealed enclosure, A dehumidifying means for dehumidifying the inside of the sealed enclosure, A temperature and humidity sensor for detecting the humidity inside the sealed enclosure, Control means for controlling the power supplied to the infrared light source, An infrared spectrophotometer comprising: extracting the infrared light as measurement light via an optical element in the sealed housing, irradiating a sample placed outside the sealed housing, and acquiring a spectrum based on the detected value of the light from the sample, The control means is The infrared light source is started while limiting the power supplied to the infrared light source to a level lower than the power supplied according to the temperature of the infrared light source during measurement use. Based on the detected humidity value obtained while power is being supplied to the infrared light source, the presence or absence of a risk of condensation inside the sealed enclosure is determined. In the event of the aforementioned risk of condensation, the infrared spectrophotometer is characterized by obtaining the rate of change of the detected humidity value detected while power is being supplied to the infrared light source as the rate of increase, and the rate of change of the detected humidity value detected while power is being stopped from being supplied to the infrared light source as the rate of decrease, and gradually increasing the power supplied to the infrared light source in order to maintain a balance between the rate of increase and the rate of decrease.

2. In the infrared spectrophotometer according to claim 1, The infrared spectrophotometer is characterized in that, when the control means determines that there is no risk of condensation, it switches to a control that outputs a fixed value of supplied power corresponding to the temperature of the infrared light source during measurement.

3. In the infrared spectrophotometer according to claim 1, An infrared spectrophotometer characterized in that the control means controls the power supplied to the infrared light source to maintain a balance between the rising speed and the falling speed, and controls the power supplied to the infrared light source so that the detected humidity value approaches a reference humidity set lower than 100% humidity.

4. In the infrared spectrophotometer according to any one of claims 1 to 3, The control means is Based on the rate of change of the detected humidity value detected while power is being supplied to the infrared light source, and the temperature value detected inside the sealed enclosure by the temperature and humidity sensor, the total amount of water vapor components adsorbed inside the sealed enclosure is estimated. Based on the rate of change of the detected humidity value detected when the power supply to the infrared light source is stopped, the dehumidification rate by the dehumidification means is estimated. An infrared spectrophotometer characterized by notifying the user of the dehumidification time obtained from the total amount of water vapor components and the dehumidification rate as a waiting time.

5. A sealed housing that can be opened and closed and houses an optical component, An infrared light source that irradiates infrared light into the inside of the sealed enclosure, A dehumidifying means for dehumidifying the inside of the sealed enclosure, A temperature and humidity sensor for detecting the humidity inside the sealed enclosure, Control means for controlling the power supplied to the infrared light source, An infrared spectrophotometer comprising: extracting the infrared light as measurement light via an optical element in the sealed housing, irradiating a sample placed outside the sealed housing, and acquiring a spectrum based on the detected value of the light from the sample, The control means is The infrared light source is started while limiting the power supplied to the infrared light source to a level lower than the power supplied according to the temperature of the infrared light source during measurement use. Based on the detected humidity value obtained while power is being supplied to the infrared light source, the presence or absence of a risk of condensation inside the sealed enclosure is determined. If there is a risk of condensation, the power supplied to the infrared light source is gradually increased while balancing the rate of increase in the detected humidity value, which is detected while power is being supplied to the infrared light source, with the rate of decrease in the humidity due to the dehumidification means. Furthermore, the control means is Based on the rate of change of the detected humidity value detected while power is being supplied to the infrared light source, and the temperature value detected inside the sealed enclosure by the temperature and humidity sensor, the total amount of water vapor components adsorbed inside the sealed enclosure is estimated. Based on the rate of change of the detected humidity value detected when the power supply to the infrared light source is stopped, the dehumidification rate by the dehumidification means is estimated. An infrared spectrophotometer characterized by notifying the user of the dehumidification time obtained from the total amount of water vapor components and the dehumidification rate as a waiting time.

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