Optical and Inspection Equipment

Abstract

To provide an optical device and an inspection device which can improve the thermal stability.SOLUTION: An optical device 1 includes: a housing 10 having an optical member 30 and receiving light; and a control unit 20 for controlling incident light L after change so that the energy obtained by integrating the power after change by a predetermined time will be equal to the energy obtained by integrating the power before change by a predetermined time in a case where the power of the incident light L to the housing 10 changes. When the power of the incident light L changes, the optical device may stop entrance of the incident light L or may resume the incident light L.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to optical devices and inspection devices. [Background technology]

[0002] Patent Document 1 describes an optical device that irradiates pulsed light by performing a pulse oscillation operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6462843 Summary of the Invention [Problem to be solved by the invention]

[0004] In optical devices using a light source such as a laser beam with pulsed oscillation, the operation of temporarily stopping the emission and re-emitting the light may be repeated. For example, in an exposure device using a CCD, the exposure light is stopped in synchronization with the transfer of the CCD after exposure. In this way, when emission and non-emission such as stopping are repeated, temperature changes occur in each part of the optical device including the optical path depending on the drive current and the presence or absence of light during emission and non-emission. If the time ratio of emission and non-emission is constant, a quasi-steady state is reached and the temperature can be stabilized. However, if the time ratio of emission and non-emission changes, the stable temperature changes, making it difficult to maintain the thermal stability of the optical device.

[0005] The object of the present disclosure is to solve such problems, and to provide an optical device and an inspection device that can improve thermal stability. [Means for solving the problem]

[0006] The optical device according to the present disclosure includes a housing having an optical member into which light is incident, and a control unit that controls the incident light after the power of the incident light entering the housing changes so that, when the power of the incident light changes, the energy obtained by integrating the power after the change over a predetermined time becomes equal to the energy obtained by integrating the power before the change over the predetermined time.

[0007] In the above optical device, when the power of the incident light changes, this includes stopping and restarting the incidence of the incident light, and the incident light before the change has a constant value of the power for the specified time, and the control unit may control the incident light after the change so that the energy obtained by integrating the power of the incident light, including the stopping and restarting, over the specified time is the same as the energy obtained by integrating the constant value over the specified time.

[0008] In the optical device described above, the control unit may add the constant value to the power of the incident light immediately after the resumption of the incident light for a period of time equal to the stoppage period during which the incident light was stopped.

[0009] In the above optical device, after the incident light is resumed, within the specified time from the stopping, the control unit may add the power of the incident light that is a constant multiple of the constant value for a period of time obtained by dividing the stoppage time during which the incident light was stopped by a constant number.

[0010] The optical device may further include a light source that generates the incident light, and an additional light source that is different from the light source and generates additional light that is added to the power of the incident light.

[0011] In the optical device described above, the incident light is pulsed light including a pulse train in which a plurality of pulses are repeatedly incident, and the control unit may add, immediately after the resumption, the power by an amount corresponding to the decrease in the power immediately before the resumption from the constant value.

[0012] In the optical device described above, the control unit may add the power that has decreased from the constant value by increasing the intensity of the pulse train immediately after the restart.

[0013] In the optical device described above, the control unit may add the power by an amount that has decreased from the constant value by increasing a repetition frequency of the pulse train immediately after the restart.

[0014] In the optical device, the control unit may control the predetermined time period including the stop and the restart.

[0015] The optical device may further include a memory unit that stores parameters including the power of the incident light after the change, corresponding to the power before the change, and the control unit may control the incident light after the change based on the parameters stored in the memory unit.

[0016] The optical device may further include a temperature sensor that detects a temperature inside the housing, and the control unit may control the incident light after it has changed based on the temperature detected by the temperature sensor.

[0017] An inspection apparatus according to the present disclosure includes the optical device described above, and inspects an inspection object with the incident light. Effect of the Invention

[0018] According to the present invention, it is possible to provide an optical device and an inspection device that can improve thermal stability. [Brief description of the drawings]

[0019] [Figure 1] 1 is a configuration diagram illustrating an optical device according to a first embodiment. [Diagram 2]1 is a graph illustrating the input power and temperature in an optical device of embodiment 1 when the control unit does not control the incident light, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light entering the housing, and the vertical axis on the right indicates the temperature inside the housing. [Diagram 3] FIG. 3 is a graph illustrating the input power and temperature when the control unit does not control the incident light in the optical device of embodiment 1, which is an enlarged view of around t=5000 in FIG. 2 with the pulse train contained in the incident light added. [Figure 4] 1 is a graph illustrating the input power and temperature when the control unit controls the incident light in the optical device of embodiment 1, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light entering the housing, and the vertical axis on the right indicates the temperature inside the housing. [Diagram 5] FIG. 5 is a graph illustrating the input power and temperature when the control unit controls the incident light in the optical device of embodiment 1, which is an enlarged view of around t=5000 in FIG. 4 with the pulse train contained in the incident light added. [Figure 6] FIG. 5 is a graph illustrating the input power and temperature when the control unit controls the incident light in the optical device of embodiment 1, which is an enlarged view of around t=5000 in FIG. 4 with the pulse train contained in the incident light added. [Figure 7] FIG. 11 is a configuration diagram illustrating an optical device according to a modified example of the first embodiment. [Figure 8] 4 is a graph illustrating an example of input power and temperature when a control unit controls incident light L in the optical device according to the first embodiment. [Figure 9] 11 is a graph illustrating the input power and temperature in an optical device of embodiment 2 when the control unit does not control the incident light, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light entering the housing, and the vertical axis on the right indicates the temperature inside the housing. [Figure 10]11 is a graph illustrating the input power and temperature when the control unit controls the incident light in an optical device of embodiment 2, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light entering the housing, and the vertical axis on the right indicates the temperature inside the housing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a specific configuration of the present embodiment will be described with reference to the drawings. The following description shows a preferred embodiment of the present disclosure, and the scope of the present disclosure is not limited to the following embodiment. In the following description, parts with the same reference numerals indicate substantially the same contents.

[0021] (Embodiment 1) An optical device according to the first embodiment will be described. FIG. 1 is a configuration diagram illustrating the optical device according to the first embodiment. As shown in FIG. 1, the optical device 1 includes a housing 10 and a control unit 20. The optical device 1 may further include a light source 40, a storage unit 50, and a temperature sensor 60. The light source 40 and the storage unit 50 may be provided separately from the optical device 1, and the temperature sensor 60 may not be provided in the optical device 1. The optical device 1 is, for example, an inspection device that inspects an inspection object. As long as the optical device 1 includes the housing 10 and the control unit 20, it may be a measurement device that measures a measurement object, an imaging device that images an imaging object, an exposure device that exposes an exposure object, a processing device that processes a processing object, or the like, without being limited to an inspection device.

[0022] The housing 10 has an optical member 30 therein. The optical member 30 is, for example, but not limited to, a mirror, a mirror holding member, a lens, a lens holding member, a stage, etc. The housing 10 is a space into which light L is incident from the light source 40. The inside of the housing 10 may be a space containing a predetermined gas, or may be a low-pressure space such as a vacuum. The housing 10 may have a temperature sensor 60 that measures temperature. The temperature sensor 60 measures the temperature of at least one of the optical path inside the housing 10 and the optical member 30. The temperature of at least one of the optical path inside the housing 10 and the optical member 30 measured by the temperature sensor 60 is called the temperature inside the housing 10.

[0023] The control unit 20 controls the incident light L incident from the light source 40 to the housing 10. The control unit 20 controls, for example, the power of the incident light L. When the incident light L is pulsed light including a plurality of pulses, the control unit 20 may control the repetition frequency of the pulsed light. The control unit 20 may control the incident light L by directly controlling the light emission and oscillation of the light source 40, or may control the incident light L by controlling an adjustment device that adjusts the power and repetition frequency of the light emitted from the light source 40.

[0024] 2 is a graph illustrating the input power and temperature in the optical device 1 according to the first embodiment when the control unit 20 does not control the incident light L, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light L incident on the housing 10, and the vertical axis on the right indicates the temperature inside the housing 10. Time (sometimes referred to as t), power (sometimes referred to as P), and temperature (sometimes referred to as T) are normalized by specific values.

[0025] 2, for example, until t=5000, incident light L with a constant power P=1.0 is incident on the housing 10. Note that the constant value does not only mean a strictly constant value, but also includes a constant value within a range that includes unavoidable measurement errors.

[0026] At t=5000, the power of the incident light L changes. Specifically, at t=5000, the power of the incident light L changes from P=1.0 to P=0.0. Then, from t=5000, the incident light L is repeatedly stopped and restarted. As a result, the power of the incident light L alternates between P=0.0 and P=1.0.

[0027] For example, during a 250-second interval from t=5000 to 5250, light emission is stopped, and the incidence of incident light L is stopped. During a 1500-second interval from t=5250 to 6750, the incidence of incident light L is resumed, and incident light L with power P=1.0 is incident.

[0028] During a 250 interval from t=6750 to 7000, light emission is stopped and the incidence of incident light L is stopped. During a 1500 interval from t=7000 to 8500, the incidence of incident light L is resumed and incident light L with power P=1.0 is incident. During a 250 interval from t=8500 to 8750, light emission is stopped and the incidence of incident light L is stopped.

[0029] Each time the incidence of the incident light L is stopped, the temperature inside the housing 10 drops. For example, the temperature inside the housing 10 before the power of the incident light L is changed is set to 1.0. Specifically, the temperature inside the housing 10 when the incident light L is being incident is set to 1.0. After the power of the incident light L is changed, the temperature inside the housing 10 gradually drops.

[0030] For example, the temperature inside the housing 10 drops by 0.01 from T=1.0 at 250 intervals from t=5000 to 5250. The temperature inside the housing 10 drops by 0.01 from T=0.99 at 250 intervals from t=6750 to 7000. The temperature inside the housing 10 drops by 0.01 from T=0.98 at 250 intervals from t=8500 to 8750. In other words, the temperature drops by 0.01 every time the incidence of the incident light L stops.

[0031] FIG. 3 is a graph illustrating the input power and temperature when the control unit 20 does not control the incident light L in the optical device according to the first embodiment, and is a diagram in which the portion around t=5000 in FIG. 2 is enlarged and a pulse train included in the incident light L is added. As shown in FIG. 3, the incident light L is, for example, pulse light including a pulse train in which a plurality of pulses are repeatedly incident. When the power of the incident light L changes, this includes stopping and restarting the incidence of the incident light L including the pulse train. The incidence of the pulse train is stopped for an interval of 250 from t=5000 to 5250. From t=5250, the incidence of the pulse train is restarted. During an interval of 250 from t=5000 to 5250, the temperature inside the housing 10 drops by 0.01 from T=1.0. In this way, when the control unit 20 does not control the incident light L, the amount of heat input drops according to the proportion of the time during which the incidence of the incident light L is stopped. Here, the control of the incident light L includes correction of parameters such as the power and repetition frequency of the incident light L. Specifically, the incident light L is controlled by parameters such as the intensity and repetition frequency of the pulse train contained in the incident light L. Correction of In the case where the control unit 20 does not control the incident light L, the energy obtained by integrating the power of the incident light L, including the power change, over a predetermined time after the power of the incident light L has changed will be different from the energy obtained by integrating the power of the incident light L over a predetermined time before the power of the incident light L has changed. Note that the predetermined time before the change and the predetermined time after the change are the same length of time. The same length of time does not only mean the exact same length of time, but also means the same length of time within a range including unavoidable measurement errors.

[0032] For example, the energy obtained by integrating the power of incident light L, including the change after the change in the power of incident light L, over 1750 intervals from t = 5000 to 6750 is different from the energy obtained by integrating the power of incident light L that was incident before the change in the power of incident light L, over 1750 intervals from t = 3250 to 5000.

[0033] Therefore, the temperature inside the housing 10 changes before and after the change in the power of the incident light L. That is, the temperature of each part including the optical path changes depending on the driving current and the presence or absence of light when light is emitted and when it is not emitted. If the time ratio between light emission and non-light emission is constant, a quasi-steady state is reached and the temperature can be stabilized. However, if the time ratio between light emission and non-light emission changes, the stable temperature changes and the thermal stability of the optical device 1 cannot be maintained.

[0034] Figure 4 is a graph illustrating the input power and temperature when the control unit 20 controls the incident light L in the optical device 1 of embodiment 1, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light L entering the housing 10, and the vertical axis on the right indicates the temperature inside the housing 10.

[0035] As shown in Fig. 3, for example, until t = 4750, incident light L with a constant power P = 1.0 is incident on the housing 10. At t = 4750, the power of the incident light L changes. Specifically, at t = 4750, the power of the incident light L changes from P = 1.0 to P = 0.0. Then, from t = 4750, the incident light L is repeatedly stopped and restarted.

[0036] For example, for a 250-second interval from t=4750 to 5000, light emission is stopped and incidence of incident light L is stopped. For a 250-second interval from t=5000 to 5250, incidence of incident light L is resumed and incident light L with power P=2.0 is incident to compensate for the stop of light emission. For a 1250-second interval from t=5250 to 6500, incident light L with power P=1.0 is incident.

[0037] During a 250-second interval from t=6500 to 6750, light emission is stopped, and the incidence of incident light L is stopped. During a 250-second interval from t=6750 to 7000, the incidence of incident light L is resumed, and incident light L with power P=2.0 is incident to compensate for the stop of light emission. During a 1250-second interval from t=7000 to 8250, the incidence of incident light L is resumed, and incident light L with power P=1.0 is incident.

[0038] During a 250-second interval from t=8250 to 8500, light emission is stopped and incidence of incident light L is stopped. During a 250-second interval from t=8500 to 8750, incidence of incident light L is resumed and incident light L with power P=2.0 is incident to compensate for the stop of light emission. During a 1250-second interval from t=8750 to 10000, incident light L with power P=1.0 is incident.

[0039] Each time the incident light L is stopped, the temperature inside the housing 10 drops. However, the temperature inside the housing 10 returns to the original temperature each time the incidence of the incident light L is resumed and the incident light L with power P=2.0 is incident to compensate for the stop of the light emission.

[0040] For example, the temperature inside the housing 10 before the power of the incident light L is changed is set to 1.0. Specifically, the temperature inside the housing 10 when continuous light is incident is set to 1.0. When the incident light L is stopped at t=4750 to 5000 at an interval of 250, the temperature drops by 0.1. However, when the incident light L with power P=2.0 is incident at t=5000 to 5250 at an interval of 250 immediately after the incident is resumed, the temperature rises by 0.1. As a result, the temperature inside the housing 10 returns to the original temperature T=1.0. Then, when the incident light L with power P=1.0 is incident at t=5250 to 6500 at an interval of 1250, the temperature inside the housing 10 is maintained at T=1.0.

[0041] Similarly, the temperature drops by 0.1 due to the cessation of incident light L in the 250 interval from t=6500 to 6750. However, the temperature rises by 0.1 due to the incidence of incident light L with power P=2.0 in the 250 interval from t=6750 to 7000 immediately after the incidence is resumed. As a result, the temperature inside the housing 10 returns to the original temperature T=1.0. Then, the temperature inside the housing 10 is maintained at T=1.0 due to the incidence of incident light L with power P=1.0 in the 1250 interval from t=7000 to 8250.

[0042] The temperature drops by 0.1 due to the cessation of incident light L in the 250 interval from t=8250 to 8500. However, the temperature rises by 0.1 due to the incidence of incident light L with power P=2.0 in the 250 interval from t=8500 to 8750 immediately after the incidence is resumed. As a result, the temperature inside the housing 10 returns to the original temperature T=1.0. Then, the temperature inside the housing 10 is maintained at T=1.0 due to the incidence of incident light L with power P=1.0 in the 1250 interval from t=8750 to 10000.

[0043] In this way, when the control unit 20 controls the incident light L, the average heat input is kept constant, and therefore the temperature inside the housing 10 is kept constant. Specifically, when the power of the incident light L incident on the housing 10 changes, the control unit 20 controls the incident light L after the change so that the energy obtained by integrating the power after the change over a predetermined time is the same as the energy obtained by integrating the power before the change over the predetermined time. Therefore, the energy obtained by integrating the power including the change after the power change over a predetermined time is the same as the energy obtained by integrating the power before the power change over the predetermined time. Note that the energy being the same does not only mean that the energy is exactly the same, but also means that the energy is the same within a range including unavoidable measurement errors.

[0044] When the power of incident light L changes at t = 4750, the energy obtained by integrating the power, including the change after the power change, over 1750 intervals from t = 4750 to 6500 is the same as the energy obtained by integrating the power before the change over 1750 intervals from t = 3000 to 4750.

[0045] When the power of the incident light L changes, this may include stopping and restarting the incidence of the incident light L. Furthermore, the incident light L before the change may have a constant value of power for a predetermined time. In this case, the control unit 20 controls the incident light L after the change so that the energy obtained by integrating the power of the incident light L, including the stopping and restarting of the incident light L, over a predetermined time is the same as the energy obtained by integrating a constant value over a predetermined time.

[0046] Specifically, immediately after the restart of the incident light L, the control unit 20 adds a constant power value to the power of the incident light L for the same period as the stop period when the incident light L was stopped. For example, the control unit 20 adds a power of P=1.0 from t=5000 to 5250 immediately after the restart of the incident light L for the same 250 interval as t=4750 to 5000 when the incidence of the incident light L was stopped. As a result, the power becomes P=2.0 for the 250 interval from t=5000 to 5250. In this way, the stop of the incidence of the incident light L can be compensated for.

[0047] When adding power to compensate for the cessation of the incident light L, it is desirable to do so immediately after the incidence is resumed. This allows the temperature inside the housing 10 to be quickly returned to the original temperature. However, after the incidence is resumed and within a predetermined time from the cessation of incidence, the temperature inside the housing 10 can be returned to the original temperature, although the temperature may deviate from the original temperature for some time.

[0048] In addition, the method of compensating for the stop of the incident light L is described as the time of stoppage = the time to be added, but this is not limited thereto. For example, when the stoppage time during which the incident light L is stopped is divided by a certain number, the power of a certain number times a certain value may be added to the power of the incident light L for the time divided by the certain number. Specifically, it is assumed that the incident light L is stopped for 250 intervals from t=4750 to 5000. Dividing the stoppage time by 2 results in 125 intervals. Therefore, the power of P=2.0 may be added to the power of the incident light L for 125 intervals from t=5000 to 5125 immediately after the incident light L is resumed. In this case, the power of the incident light L for t=5000 to 5125 is a total of P=3.0. In this way, the control unit 20 may add the power of a certain number times a certain value to the power of the incident light L for the time obtained by dividing the stoppage time during which the incident light L was stopped by a certain number within a predetermined time after the restart of the incident light L. The constant number may be an integer.

[0049] FIG. 5 and FIG. 6 are graphs illustrating the input power and temperature when the control unit controls the incident light in the optical device according to Embodiment 1, which are enlarged views around t = 5000 in FIG. 4 and with a pulse train included in the incident light added thereto. As shown in FIGS. 5 and 6, the incident light L may be pulsed light including a pulse train in which a plurality of pulses are repeatedly incident. The control unit 20 adds power corresponding to the amount by which the power immediately before restart has decreased from a constant value immediately after the restart of the incident light L. At this time, as shown in FIG. 5, the control unit 20 may add power corresponding to the amount by which the power has decreased from the constant value by increasing the repetition frequency of the pulse train immediately after the restart of the incident light L. For example, when adding power twice the constant value, the control unit 20 doubles the repetition frequency of the pulse train. Also, as shown in FIG. 6, the control unit 20 may add power corresponding to the amount by which the power has decreased from the constant value by increasing the intensity of the pulse train immediately after the restart of the incident light L. For example, when adding power twice the constant value, the control unit 20 doubles the intensity of the pulse train.

[0050] FIG. 7 is a configuration diagram illustrating an optical device according to a modification of Embodiment 1. As shown in FIG. 7, the optical device 1a of the modification further includes an additional light source 41 in addition to the light source 40 that generates the incident light L. The additional light source 41 is a different member from the light source 40. The additional light source 41 generates additional light to be added to the power of the incident light L. Specifically, the additional light source 41 generates additional light that compensates for the stopped portion of the incident light L described above. By generating additional light using the additional light source 41, the power of the light source 40 does not change, so the light source 40 can be stabilized. The change in the power of the incident light L is not limited to the stop and restart of incidence, and may include a decrease and an increase in the incident light to be incident. That is, the change in the power of the incident light L is not limited to the repetition of power P = 0 and power P = 1, and may be a repetition of 0.0 < P < 1.0 and P ≧ 1. When the incident light L is pulsed light including a pulse train, the incident light L before the change may have a constant power for a predetermined time. The control unit 20 may control the pulsed light after the change so that the energy obtained by integrating the power of the pulsed light after the change in power over a predetermined time is the same as the energy obtained by integrating the constant value before the change over a predetermined time.

[0051] For example, the control unit 20 may add power immediately after the rising edge of each pulse train to compensate for the reduction in power immediately before the rising edge of each pulse train. As described above, the power reduced by stopping the incidence of the incident light L at t=4750-5000, t=6500-6750, and t=8250-8500 may be added to the pulse train at t=5000-5250, t=6750-7000, and t=8500-8750 immediately after the rising edge of each pulse train.

[0052] The optical device 1 may further include a storage unit 50. The storage unit 50 stores parameters including the power of the incident light L after the power has changed, in correspondence with the power of the incident light L before the power change. For example, the storage unit 50 stores that the incident light L with a power P=2.0 is to be incident at intervals of 250 as a parameter of the incident light L incident after t=250 after the incident light L with a power P=1.0 is stopped.

[0053] The control unit 20 may control the incident light after the change based on the parameters stored in the storage unit 50.

[0054] The change in power of the incident light L may include multiple stops and restarts of the incidence of the incident light L. In that case, the control unit 20 controls the incident light L so that the energy obtained by integrating the power of the incident light L including multiple stops and restarts of the incident light L over a predetermined time period is equal to the energy obtained by integrating, over the predetermined time period, a constant value that the power showed for the predetermined time period before the power change.

[0055] The temperature sensor 60 detects the temperature inside the housing 10. For example, the temperature sensor 60 detects the temperatures of the optical members 30, such as a mirror, a mirror holding member, a lens, a lens holding member, and a stage. The temperature sensor 60 outputs the detected temperature inside the housing 10 to the control unit 20.

[0056] The control unit 20 may control the incident light L after the change based on the temperature detected by the temperature sensor 60. For example, the storage unit 50 stores that when the temperature inside the housing 10 drops by T=0.01, the incident light L with power P=1.0 is added. Therefore, based on the temperature detected by the temperature sensor 60, the control unit 20 controls the incident light L after the power change to be added with P=1.0.

[0057] Next, the effect of this embodiment will be described. When the power of the incident light L changes, the optical device 1 of this embodiment controls the incident light L after the change so that the energy obtained by integrating the power of the incident light L over a predetermined time before and after the change is equal to that before and after the change. Specifically, for example, the power of the incident light L is temporarily increased in response to the stop of the incident light L. This makes it possible to increase the amount of heat input in response to the amount of time the incident light L is stopped. Therefore, the thermal stability of the optical device 1 can be improved.

[0058] The control unit 20 may add power by increasing the intensity of the pulse train included in the incident light L, or may add power by increasing the repetition frequency of the pulse train. The control unit 20 may also add power by combining the intensity and repetition frequency of the pulse train. In this way, the control unit 20 controls the addition of power, so that the amount of heat input can be controlled with high precision.

[0059] As a method for increasing the power of the incident light L, in addition to a method for increasing the power of a single incident light L, a method using a plurality of incident lights L emitted from the light source 40 and the additional light source 41, etc., as in the modified example, may be adopted. Furthermore, when controlling the power of the incident light L so as to compensate for the stop of the incident light L, the stop time may be set to equal the increase time. Furthermore, additional light with twice the power may be added to the incident light L for half the stop time of the incident light L (resulting in three times the power). This does not require a change in the power of the light source 40, stability can be improved.

[0060] In the optical device 1, the incident light L incident on the housing 10 can be continuous light or pulsed light. FIG. 8 is a graph illustrating the input power and temperature when the control unit 20 controls the incident light L in the optical device 1 according to the first embodiment. In FIG. 8, the intensity of the incident light L (scale not shown) is indicated by a dotted line. As shown in FIG. 8, the incident light L may be continuous light that is continuously oscillated before and after a change in the input power. Also, the incident light L may change from continuous light to pulsed light, or from pulsed light to continuous light, before and after a change in the input power. This improves the degree of freedom in the application of the optical device 1. For example, the optical device 1 can be used in an inspection device that inspects an inspection object with the incident light L.

[0061] Moreover, the storage unit 50 of the optical device 1 stores in advance the parameters of the incident light L after the change in correspondence with the power before the change. This makes it possible to quickly respond to the change in the power of the incident light L. This makes it possible to improve the thermal stability of the optical device 1.

[0062] (Embodiment 2) Next, an optical device according to embodiment 2 will be described. The optical device of this embodiment is adapted to cases where the repetition frequency of pulsed light changes as well as the power of incident light L, and where the period of stopping and restarting incident light L changes. Fig. 9 is a graph illustrating the input power and temperature when the control unit 20 does not control the incident light L in the optical device according to embodiment 2, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light entering the housing, and the vertical axis on the right indicates the temperature inside the housing.

[0063] As shown in FIG. 9, in the optical device 1 of this embodiment, the incident light L includes a plurality of pulse trains. The power of the incident light L also changes in the optical device 1. The change in the power of the incident light L according to this embodiment includes two changes. The first change is the stopping and restarting of the incident light L. One period including one pulse train in the incident light L includes the stopping and restarting of the incident light L. The second change is a change in the period of stopping and restarting the incident light L. The incident light L includes a short exposure condition and a long exposure condition having different periods of stopping and restarting the incidence.

[0064] The optical device 1 causes the incident light L to be incident on the housing 10 under a short-time exposure condition until t=50000. From t=50000, the incident light L is caused to be incident on the housing 10 under a long-time exposure condition. In each condition, the incident light L may include a pulse train.

[0065] The short-time exposure condition, for example, stops the incident light L for 100 intervals in a cycle of t=1650. In other words, stopping the incident light L (100 intervals) and entering the incident light L with power P=1.0 (1550 intervals) are repeated. Under the short-time exposure condition, the incident light L includes a plurality of pulse trains with a width of 1550 intervals at power P=1.0. Under the short-time exposure condition, the power of the incident light L changes from P=1.0 in each cycle.

[0066] Under the short-time exposure condition, the temperature inside the housing 10 drops every time the incident light L is stopped. For example, at t=0, the temperature inside the housing 10 is T=1.0, but at t=50000, it drops to T=0.87. In this way, under the short-time exposure condition, the temperature inside the housing 10 gradually drops.

[0067] Under short-time exposure conditions, one period including one pulse train includes the stopping and restarting of incident light L. A pulse train is incident when the incident light L is restarted. The energy obtained by integrating the power of the incident light including the stopping and restarting of the incident light over a predetermined time is different from the energy obtained by integrating the power before the incident light is stopped over a predetermined time. Specifically, for example, the energy integrated over 200 intervals, which is the sum of the 100 intervals after the incident light is stopped and the 100 intervals after the incident light is restarted, is different from the energy integrated over the 200 intervals before the incident light is stopped.

[0068] Under the long exposure condition, for example, the incident light L is stopped for 100 intervals in a cycle of t=3300. In other words, stopping of the incident light L (100 intervals) and incidence of the incident light L with power P=1.0 (3200 intervals) are repeated. Under the long exposure condition, the incident light L includes a train of multiple pulses with a width of 3200 intervals at power P=1.0. Even under the long exposure condition, the power of the incident light L changes from P=1.0 in each cycle.

[0069] Under long exposure conditions, the temperature inside the housing 10 rises each time the incidence of the incident light L is resumed. For example, at t=50000, the temperature inside the housing 10 is T=0.87, but at t=100000, it rises to T=0.93. Thus, under long exposure conditions, the temperature inside the housing 10 gradually rises. However, the temperature inside the housing 10 does not recover until T=1.0, when the incidence of the incident light L begins.

[0070] Under long-time exposure conditions, one period including one pulse train includes the stopping and restarting of incident light L. A pulse train is incident when the incidence is restarted. The energy obtained by integrating the power of the incident light including the stopping and restarting of incidence over a predetermined time is different from the energy obtained by integrating the power before the incidence is stopped over a predetermined time. Specifically, for example, the energy integrated over 200 intervals, which is the sum of the 100 intervals after the incidence is stopped and the 100 intervals after the incidence is restarted, is different from the energy integrated over the 200 intervals before the incidence is stopped.

[0071] In this way, under both the short exposure condition and the long exposure condition, the energy integrated over a certain time period before and after the first change, i.e., the change in the power of the incident light L in one pulse train, is different.

[0072] The second change, that is, the energy obtained by integrating the power of the incident light L over a predetermined time under the short exposure condition and the long exposure condition with different periods of stopping and restarting the incident light L, is also different. Specifically, the energy obtained by integrating the power of the incident light L from t=0 to 50000 under the short exposure condition is different from the energy obtained by integrating the power of the incident light L from t=50000 to 100000 under the long exposure condition.

[0073] Therefore, when the control unit 20 does not control the incident light L, the energy obtained by integrating the power of the incident light L over a predetermined time differs before and after the power of the incident light L changes. Specifically, the amount of heat input changes according to the rate at which the incidence of the incident light L is stopped and restarted. Also, the amount of heat input changes according to the period at which the incident light L is stopped and restarted. When the control unit 20 does not control the incident light L, it is difficult to stabilize the temperature inside the housing 10 under both short-time exposure conditions and long-time exposure conditions.

[0074] Figure 10 is a graph illustrating the input power and temperature when the control unit 20 controls the incident light L in the optical device 1 of embodiment 2, where the horizontal axis indicates time, the vertical axis on the left indicates the power of the incident light L entering the housing 10, and the vertical axis on the right indicates the temperature inside the housing 10.

[0075] As shown in FIG. 10, in the optical device 1 of this embodiment, the incident light L is repeatedly incident as a series of multiple pulses. In this embodiment, the power of the incident light L also changes. The change in the power of the incident light L includes two changes, as in FIG. 9. The first change is the stopping and restarting of the incidence of the incident light L. The second change is a change in the period in which the incidence of the incident light L is stopped and restarted.

[0076] The optical device 1 causes the incident light L to be incident on the housing 10 under a short-time exposure condition until t=50000. After t=50000, the incident light L is caused to be incident on the housing 10 under a long-time exposure condition. The short-time exposure condition and the long-time exposure condition have different periods for stopping and restarting the incident light L.

[0077] In the short-time exposure condition, for example, the incident light L is stopped for 100 intervals in a cycle of t=1650. Then, the incident light L with power P=2.0 is incident for 100 intervals immediately after restart. After that, the incident light with power P=1.0 is incident. In other words, the incident light L is stopped (100 intervals), the incident light L with power P=2.0 is incident (100 intervals), and the incident light L with power P=1.0 is incident (1450 intervals) are repeated. In the short-time exposure condition, the incident light L includes a plurality of pulse trains with a width of 1550 intervals at powers P=2.0 and P=1.0. In the short-time exposure condition, the power of the incident light L changes from P=1.0 due to the stopping of the incident light L in each cycle.

[0078] Under the short-time exposure condition controlled by the control unit 20, the temperature inside the housing 10 drops every time the incidence of the incident light L is stopped. However, the temperature inside the housing 10 returns to the original temperature every time the incidence of the incident light L is resumed and the incident light L with a power of 2.0 is incident to compensate for the stop of the light emission.

[0079] For example, the temperature before the incident light L is stopped is set to T=1.0. Specifically, the temperature inside the housing 10 when the incident light L with power P=1.0 is incident is set to T=1.0. When the incident light L is stopped at 100 intervals, the temperature drops by 0.01. However, when the incident light L with power P=2.0 is incident at 100 intervals immediately after the incident light L is resumed, the temperature rises by 0.01. As a result, the temperature inside the housing 10 returns to the original temperature T=1.0. Then, when the incident light L with power P=1.0 is incident at 1450 intervals, the temperature inside the housing 10 is maintained at T=1.0.

[0080] Under short-time exposure conditions, one period including one pulse train includes the cessation and restart of incident light L. The energy obtained by integrating the power of incident light L, including the cessation and restart of incidence, over a specified time is the same as the energy obtained by integrating the power before the cessation of incidence over the specified time.

[0081] Specifically, for example, the energy integrated over 200 intervals, which is the sum of the 100 intervals when the injection is stopped and the 100 intervals when the power after the injection is restarted is P=2.0, is the same as the energy integrated over the 200 intervals before the injection is stopped. The control unit 20 adds power to the rising edge of each pulse train by the amount of power reduction just before the rising edge of each pulse train. In this way, the control unit 20 makes the energy before and after the power change the same energy.

[0082] In the long exposure condition, for example, the incident light L is stopped for 100 intervals in a cycle of t=3300. Then, the incident light L with power P=2.0 is made incident for 100 intervals immediately after restart. After that, the incident light with power P=1.0 is made incident. In other words, the stopping of the incident light L (100 intervals), the incidence of the incident light L with power P=2.0 (100 intervals), and the incidence of the incident light L with power P=1.0 (3100 intervals) are repeated. In the long exposure condition, the incident light L includes a plurality of pulse trains with a width of 3200 intervals at powers P=2.0 and P=1.0. In the long exposure condition, the power of the incident light L changes from P=1.0 due to the stopping of the incident light L in each cycle.

[0083] Under the long exposure condition when the control unit 20 controls, the temperature inside the housing 10 drops every time the incidence of the incident light L is stopped. However, the temperature inside the housing 10 returns to the original temperature every time the incidence of the incident light L is resumed and the incident light L with a power of 2.0 is incident to compensate for the stop of the light emission.

[0084] For example, the temperature before the incident light L is stopped is set to T=1.0. Specifically, the temperature inside the housing 10 when the incident light L with power P=1.0 is incident is set to T=1.0. When the incident light L is stopped at 100 intervals, the temperature drops by 0.01. However, when the incident light L with power P=2.0 is incident at 100 intervals immediately after the incident light L is resumed, the temperature rises by 0.01. As a result, the temperature inside the housing 10 returns to the original temperature T=1.0. Then, when the incident light L with power P=1.0 is incident at 3100 intervals, the temperature inside the housing 10 is maintained at T=1.0.

[0085] Under long exposure conditions, one period including one pulse train includes the cessation and restart of incident light L. The energy obtained by integrating the power of incident light L, including the cessation and restart of incidence, over a given time is the same as the energy obtained by integrating the power before the cessation of incidence over the given time.

[0086] Specifically, for example, the energy integrated over 200 intervals, which is the sum of the 100 intervals when the injection is stopped and the 100 intervals when the power after the injection is restarted is P=2.0, is the same as the energy integrated over the 200 intervals before the injection is stopped. The control unit 20 may add power immediately after the rise of each pulse train to compensate for the drop in power immediately before the rise of each pulse train. In this way, the control unit 20 makes the energy before and after the power change the same energy.

[0087] In this way, under both the short-exposure conditions and the long-exposure conditions, the energy obtained by integrating the power after the first change, i.e., the change in the power of the incident light L in one pulse train, over a specified time is the same as the energy obtained by integrating the power before the change over a specified time.

[0088] The second change, that is, the energy obtained by integrating the power of the incident light L over a predetermined time under the short exposure condition and the long exposure condition with different periods of stopping and restarting the incident light L, is also the same. The control unit 20 controls the incident light L after the period has been changed so that the energy obtained by integrating the power of the pulsed light over a predetermined time after the period of stopping and restarting the incident light L has been changed is the same as the energy obtained by integrating the power of the pulsed light over a predetermined time before the period was changed. Specifically, for example, the energy obtained by integrating the power of the incident light L over t=0 to 50000 under the short exposure condition is the same as the energy obtained by integrating the power of the incident light L over t=50000 to 100000 under the long exposure condition.

[0089] Therefore, when the control unit 20 controls the incident light L, the control unit 20 controls the incident light L so that the energy obtained by integrating the power of the incident light L over a predetermined time is the same before and after the change in power of the incident light L. The control unit 20 controls the incident light L after the change in power so that the amount of heat input is the same depending on the rate at which the incident light L is stopped and restarted. The control unit 20 also controls the incident light L so that the amount of heat input is the same depending on the cycle at which the incident light L is stopped and restarted. The control unit 20 controls the predetermined time including the stop and restart of the incident light L.

[0090] Next, the effects of this embodiment will be described. The optical device 1 of this embodiment causes incident light L, which is repeatedly incident with a plurality of pulse trains. Therefore, when the power of the incident light L changes, this includes a change in the period of stopping and restarting the incident light L. Even in such a case, the control unit 20 can control the incident light L so that the energy integrated over a predetermined time is the same before and after the power of the incident light L changes. Therefore, the thermal stability of the optical device 1 can be improved.

[0091] The change in the power of the incident light L may include not only stopping and restarting the incident light L, but also decreasing or increasing the power of the incident light L. Even in such a case, the control unit 20 may control the incident light after the change so that the energy obtained by integrating the power after the change over a predetermined time period is the same as the energy obtained by integrating the power before the change over a predetermined time period. Other configurations and effects are included in the description of the first embodiment.

[0092] Although the embodiments of the present disclosure have been described above, the present disclosure includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the above-mentioned embodiments. In addition, the configurations of the first and second embodiments may be combined as appropriate. [Explanation of symbols]

[0093] 1, 1a Optical device 10. Chassis 20 Control section 30 Optical Components 40 light source 41 Additional Light Source 50 Storage section 60 Temperature Sensor L Incident light

Claims

1. a housing having an optical member and into which light is incident; a control unit that controls the incident light after a power change occurs so that an energy obtained by integrating the power after the power change over a predetermined time period becomes equal to an energy obtained by integrating the power before the power change over a time period having the same length as the predetermined time period; and Equipped with When the power of the incident light is changed, the change includes stopping and restarting the incidence of the incident light, the incident light before the change has a constant value of the power for a period of time equal to the predetermined period of time; the control unit controls the incident light after the power has changed so that the energy obtained by integrating the power over the predetermined time period including the time point at which the power is stopped and the time point at which the power is restarted is equal to the energy obtained by integrating the constant value over a time period having the same length as the predetermined time period. optical equipment.

2. the control unit adds the constant value to the power of the incident light for a period of time equal to a period of time during which the incident light was stopped, immediately after the restart of the incident light.

2. The optical device of claim 1.

3. the control unit, after the restart of the incident light, within the predetermined time from the stop, adds the power of the incident light that is the constant multiple of the constant value to the power of the incident light for a period obtained by dividing a stop time during which the incident light was stopped by a constant number.

2. The optical device of claim 1.

4. a light source generating the incident light; The optical fiber further includes an additional light source that generates additional light different from the light source and that adds to the power of the incident light.

4. An optical device according to claim 2 or 3.

5. the incident light is pulsed light including a pulse train in which a plurality of pulses are repeatedly incident, The control unit adds, immediately after the restart, the power by an amount corresponding to a decrease in the power immediately before the restart from the constant value.

2. The optical device of claim 1.

6. The control unit increases the intensity of the pulse train immediately after the restart to add the power by an amount corresponding to the decrease from the constant value.

6. The optical device according to claim 5.

7. the control unit increases a repetition frequency of the pulse train immediately after the restart to add the power by an amount corresponding to the decrease from the constant value.

6. The optical device according to claim 5.

8. The control unit controls the predetermined time including the stop and the restart.

6. The optical device according to claim 5.

9. a storage unit configured to store a parameter including the power of the incident light after the change in correspondence with the power before the change; The control unit controls the changed incident light based on the parameters stored in the storage unit.

2. The optical device of claim 1.

10. Further comprising a temperature sensor for detecting a temperature inside the housing, The control unit controls the incident light after the change based on the temperature detected by the temperature sensor.

2. The optical device of claim 1.

11. The optical device according to any one of claims 1 to 3 and 5 to 10 is provided, An inspection device that inspects an object to be inspected using the incident light.

12. a housing having an optical member and into which light is incident; a control unit that controls the incident light after a power change occurs so that an energy obtained by integrating the power after the change over a predetermined time period is equal to an energy obtained by integrating the power before the change over the predetermined time period; and Equipped with When the power of the incident light is changed, the change includes stopping and restarting the incidence of the incident light, the incident light before the change has a constant value of the power during the predetermined time; the control unit controls the incident light after the change so that the energy obtained by integrating the power of the incident light including the stop and the restart over the predetermined time period becomes equal to the energy obtained by integrating the constant value over the predetermined time period; the control unit adds the constant value to the power of the incident light for a period of time equal to a period of time during which the incident light was stopped, immediately after the restart of the incident light. optical equipment.

13. a housing having an optical member and into which light is incident; a control unit that controls the incident light after a power change occurs so that an energy obtained by integrating the power after the change over a predetermined time period is equal to an energy obtained by integrating the power before the change over the predetermined time period; and Equipped with When the power of the incident light is changed, the change includes stopping and restarting the incidence of the incident light, the incident light before the change has a constant value of the power during the predetermined time; the control unit controls the incident light after the change so that the energy obtained by integrating the power of the incident light including the stop and the restart over the predetermined time period becomes equal to the energy obtained by integrating the constant value over the predetermined time period; the control unit, after the restart of the incident light, within the predetermined time from the stop, adds the power of the incident light that is the constant multiple of the constant value to the power of the incident light for a period obtained by dividing a stop time during which the incident light was stopped by a constant number. optical equipment.

14. a light source generating the incident light; The optical fiber further includes an additional light source that generates additional light different from the light source and that adds to the power of the incident light.

14. An optical device according to claim 12 or 13.

15. a housing having an optical member and into which light is incident; a control unit that controls the incident light after a power change occurs so that an energy obtained by integrating the power after the change over a predetermined time period is equal to an energy obtained by integrating the power before the change over the predetermined time period; and Equipped with When the power of the incident light is changed, the change includes stopping and restarting the incidence of the incident light, the incident light before the change has a constant value of the power during the predetermined time; the control unit controls the incident light after the change so that the energy obtained by integrating the power of the incident light including the stop and the restart over the predetermined time period becomes equal to the energy obtained by integrating the constant value over the predetermined time period; the incident light is pulsed light including a pulse train in which a plurality of pulses are repeatedly incident, The control unit adds, immediately after the restart, the power by an amount corresponding to a decrease in the power immediately before the restart from the constant value. optical equipment.

16. The control unit increases the intensity of the pulse train immediately after the restart to add the power by an amount corresponding to the decrease from the constant value.

16. The optical device according to claim 15.

17. the control unit increases a repetition frequency of the pulse train immediately after the restart to add the power by an amount corresponding to the decrease from the constant value.

16. The optical device according to claim 15.

18. The control unit controls the predetermined time including the stop and the restart.

16. The optical device according to claim 15.

19. a storage unit configured to store a parameter including the power of the incident light after the change in correspondence with the power before the change; The control unit controls the changed incident light based on the parameters stored in the storage unit.

19. The optical device according to claim 12, 13, or 15 to 18.

20. Further comprising a temperature sensor for detecting a temperature inside the housing, The control unit controls the incident light after the change based on the temperature detected by the temperature sensor.

19. The optical device according to claim 12, 13, or 15 to 18.

21. The optical device according to any one of claims 12, 13 and 15 to 18, An inspection device that inspects an object to be inspected using the incident light.

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