JP3750366B2 - Solid optical element mount cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state optical element mount cell for using a solid-state optical element used in a laser device at a constant temperature without damage or deterioration for a long period of time.
[0002]
[Prior art]
One of the main causes of damage to solid optical elements such as wavelength conversion elements and laser active media is that dust adheres to the surface of the solid optical element. Some solid state devices are deteriorated by moisture in the air. In order to use a solid optical element having such properties for a long time without damage or deterioration, it has been generally performed in an environment in which the solid optical element is sealed in a mount cell to block outside dust and moisture. It was.
[0003]
In addition, some solid optical elements such as wavelength conversion elements change their optical characteristics greatly due to minute temperature changes, and keep such solid optical elements at a constant temperature while protecting them from dust and moisture. In order to use it, it was necessary to use a solid optical element mount cell with a temperature adjusting device.
[0004]
FIG. 9 is a block diagram showing a conventional laser solid optical element mount cell disclosed in, for example, Japanese Patent Laid-Open No. 6-301426. In FIG. 9, 2 is a cell casing, 7 is a solid optical element, and 3 is a thermoelectric cooling element.
[0005]
In the solid optical element mount cell configured as shown in FIG. 9, the solid optical element 7 is in thermal contact with the thermoelectric cooling element 3 together with the housing 2, and the temperature is controlled by the thermoelectric cooling element 3.
[0006]
[Problems to be solved by the invention]
The conventional solid optical element mount cell is configured as described above, and not only the solid optical element but also the entire housing including the solid optical element is mounted on the thermoelectric cooling element. In order to control and exhibit predetermined performance, it is necessary to control the temperature of not only the solid optical element but also the entire housing. Therefore, the heat capacity of the object that the thermoelectric cooling element has to control is larger than necessary.
[0007]
Further, for example, when a wavelength conversion laser device that generates a wavelength conversion laser beam by inserting a wavelength conversion element into the laser resonator and converting the wavelength of the laser beam in the resonator to form a wavelength conversion laser beam is shown in FIG. When the above wavelength conversion element is sealed in a conventional solid optical element mount cell, the solid optical element mount cell has a large heat capacity, or some of the components constituting the cell are made of a material with low thermal conductivity. In such a case, when the temperature of the entire casing is controlled using the thermoelectric element, there is a drawback that it takes time until the entire mount cell including the solid optical element reaches a thermal equilibrium state.
[0008]
When attempting to operate the laser device in a state where the temperature control of the wavelength conversion element inserted in the resonator is not sufficient, the wavelength conversion element may not satisfy the phase matching condition unless it falls within the predetermined temperature range. Conversion efficiency becomes low, and the fundamental laser power inside the resonator cannot be consumed as harmonic laser power. For this reason, the fundamental wave intensity inside the resonator temporarily becomes very high, and optical elements such as wavelength conversion elements may be damaged.
[0009]
Also, when aligning the wavelength conversion element, the angle of the wavelength conversion element is slightly moved to monitor the laser output, and if the output increases, it is determined that the wavelength conversion element is moved in a direction that matches the phase matching condition. When the wavelength conversion element is moved in the same direction and the output decreases, it is judged that the wavelength conversion element has moved in the direction in which the phase matching condition is deviated, and the operation of moving the wavelength conversion element in the opposite direction is repeated to resonate. If the solid-state optical element mount cell as described above is used to hold the wavelength conversion element, the heat distribution of the wavelength conversion element is steady when the wavelength conversion element is moved. It may take time to settle down, complicating the work.
[0010]
The present invention has been made to solve the above-described problems. The solid optical element can be used for a long time without damage or deterioration, and the temperature control of the solid optical element is precise and responsive. It is an object of the present invention to provide a solid optical element mount cell that can be performed well.
[0011]
The solid-state optical element mount cell according to the configuration of the present invention is a solid-state optical element mount cell that performs temperature control by sealing the wavelength conversion element in a casing, and a thermoelectric cooling element that controls the temperature of the wavelength conversion element is provided in the casing. Each of the wavelength conversion elements is provided on both surfaces via a solid optical element holder, and a spring is attached to the solid optical element holder so as to press the heat transfer cooling element against the wavelength conversion element.
[0012]
Solid optical element mount cell according to the inventions of the arrangement, it is provided with a refrigerant flow passage in the housing.
[0013]
The solid-state optical element mount cell according to the configuration of the present invention has a housing provided with a heater .
[0014]
In the solid optical element mount cell according to the configuration of the present invention , a temperature measurement device is installed near the wavelength conversion element in the solid optical element holder .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 and 2 are configuration diagrams showing the structure of a solid-state optical element mount cell according to Embodiment 1 of the present invention. FIG. 1 is a longitudinal sectional view of the solid-state optical element mount cell, and FIG. FIG. 2B is a cross-sectional view of the solid optical element mount cell. 1 and 2, 1 is a solid optical element mounting cell holding lid, 2 is a solid optical element mounting cell housing, 3 is a thermoelectric cooling element using a Peltier element, etc., 4 is an O-ring, and 5 is a pressing screw for the lid. , 6 is an optical window coated so as to be totally transmissive with respect to a predetermined wavelength, 7 is a solid optical element that requires temperature control, and 8 is a solid optical element made of a material having high thermal conductivity such as copper. A holder 9 is embedded in the solid optical element holder 8, and a temperature measuring device such as a thermistor for monitoring the temperature of the solid optical element holder 8, 12 gives a reference temperature to the waste heat side of the thermoelectric cooling element 3. It is a heat reservoir.
[0016]
1 and 2, the upper and lower surfaces of the solid optical element 7 are in contact with the solid optical element holder 8, and the solid optical element holder 8 is in contact with the thermoelectric cooling element 3. Further, the thermoelectric cooling element 3 is in contact with the solid optical element mount cell housing 2. Between the solid optical element 7 and the solid optical element holder 8, between the solid optical element holder 8 and the thermoelectric cooling element 3, and between the thermoelectric cooling element 3 and the housing 2, the contact surfaces of both are optically polished. However, measures are taken to improve heat conduction between the two, such as applying and fixing an adhesive with good heat conductivity, or applying heat conductive grease. The solid optical element mount cell housing 2 is sealed by an optical window 6 and a lid 1 through an O-ring 4, and the solid optical element 7 is protected from dust and moisture in the outside world. Although not shown in the figure, the temperature measuring device 9 and the thermoelectric cooling element 3 are connected to a temperature controller outside the cell.
[0017]
In the solid optical element mount cell configured as described above, the temperature of the solid optical element 7 is controlled as described below.
That is, the temperature of the solid optical element holder 8 is monitored by the temperature measuring device 9. Since the solid optical element holder 8 is made of a material having high thermal conductivity, and the temperature measuring device 9 is installed near the solid optical element 7, the absolute value of the temperature monitored by the temperature measuring device 9 can be obtained. The variation in temperature can be regarded as substantially the same as the surface portion of the surface of the solid optical element 7 in contact with the solid optical element holder 8. Based on the temperature monitored by the temperature measuring device 9, the current to the thermoelectric cooling element 3 is controlled, and as a result, the temperature of the solid optical element 7 is controlled. Moreover, the housing 2 of the apparatus shown in FIGS. 1 and 2 is configured to be in contact with the heat reservoir 12, and the entire cell can be maintained at a temperature that is not affected by the room temperature. Furthermore, as shown in FIGS. 1 and 2, the structure in which the opposite surfaces of the solid optical element 7 are cooled by two thermoelectric cooling elements has a higher temperature uniformity in the optical element than the structure in which only one surface is cooled. It can be significantly increased and the time to converge to a uniform temperature can be significantly shortened.
[0018]
When the optical element that needs to be adjusted by slightly changing the angle and position of the wavelength conversion element, the laser active medium, or the like is used as the solid optical element 7, the solid optical element mount cell shown in FIGS. The housing 2 can be mounted on a stage or holder with a goniometer capable of finely adjusting the angle and position so that the angle and position can be finely adjusted.
[0019]
1 and 2 show the case where the solid optical element is simply sealed using the optical window 6, the sealing degree of the cell casing is improved as necessary, and the inside of the casing is pulled by a vacuum pump. Alternatively, the solid optical element may be sealed by purging with an inert gas such as nitrogen gas or dry air.
[0020]
Although not shown in FIGS. 1 and 2, if the solid optical element is prone to deterioration due to moisture in the air, a separate chamber containing a desiccant connected to the inside of the solid optical element mount cell housing is provided. The inside of the housing may be kept in a dry atmosphere.
[0021]
1 and 2 show only the state in which the solid optical element 7 is in contact with the holder 8, but avoid the situation in which only the holder and a part of the solid optical element are in contact with each other. A structure may be adopted in which a spring is attached and pressed so that the entire contact surface of the holder is in contact with the holder uniformly, or so that the holder is always pressed against the solid optical element with a constant pressure.
[0022]
In the solid-state optical element mount cell according to the first embodiment configured as shown in FIGS. 1 and 2, since the thermoelectric cooling element only controls the temperature of the solid-state optical element and the solid-state optical element holder, Compared to the case where the temperature of the entire mount cell shown in the example is controlled, the heat capacity of the object to be temperature controlled can be reduced.
[0023]
Further, air that has a relatively low thermal conductivity, such as air in the mount cell, optical window, and O-ring, and causes a long time to reach a thermal equilibrium state, can be excluded from the target of temperature control.
As a result, the time required for the solid optical element to reach a thermal equilibrium state can be shortened, and the solid optical element and the entire laser device including the solid optical element can be easily aligned in a short time. Become.
[0024]
Embodiment 2. FIG.
3 and 4 are configuration diagrams showing the structure of a solid-state optical element mount cell according to Embodiment 2 of the present invention, FIG. 3 is a longitudinal sectional view of the solid-state optical element mount cell, and FIG. 4A is a solid-state optical element. FIG. 4B is a cross-sectional view of the solid optical element mount cell, and FIG. 4C is a top view. In FIGS. 3 and 4, reference numeral 10 denotes a flow path provided in the housing 2 for flowing a liquid maintained at a predetermined temperature.
[0025]
In the solid-state optical element mount cell configured as shown in FIGS. 3 and 4, another heat reservoir is prepared by providing a flow path 10 for flowing a liquid maintained at a predetermined temperature in the housing 2. Thus, the solid-state optical element 7 can be maintained at a temperature that is not affected by the room temperature without configuring the device so as to be in contact with the housing.
[0026]
Embodiment 3 FIG.
5 and 6 are configuration diagrams showing the structure of a solid optical element mount cell according to Embodiment 3 of the present invention. FIG. 5 is a longitudinal sectional view of the solid optical element mount cell, and FIG. 6 (a) is a solid optical element. FIG. 6B is a cross-sectional view of the solid optical element mount cell, and FIG. 6C is a top view. 5 and 6, reference numeral 11 denotes a heater mounted in the casing.
[0027]
In the solid optical element mount cell configured as shown in FIGS. 5 and 6, since the heater is built in the housing 2, a separate heat reservoir is prepared and the apparatus is configured to contact the housing. At least, the solid optical element 7 can be kept at a temperature that is not affected by the room temperature.
[0028]
Embodiment 4 FIG.
7 and 8 are configuration diagrams showing the structure of a solid-state optical element mount cell according to Embodiment 4 of the present invention, FIG. 7 is a longitudinal sectional view of the solid-state optical element mount cell, and FIG. 8A is a solid-state optical element. FIG. 8B is a cross-sectional view of a solid optical element mount cell. 7 and 8, reference numerals 3 and 3a denote thermoelectric cooling elements.
[0029]
In the solid-state optical element mount cell configured as shown in FIGS. 7 and 8, the temperature of the entire casing is controlled by the thermoelectric cooling element 3 a and the heat reservoir 12 mounted outside the casing 2. Since the temperature of the solid optical element 7 is controlled by the mounted thermoelectric cooling element 3, precise temperature control can be performed. In addition, the solid optical element 7 can be kept at a temperature farther from the heat reservoir 12 than when the one-stage thermoelectric cooling element 3 is used.
[0030]
7 and 8, the temperature of the housing 2 is monitored by attaching a temperature measuring device to the housing 2 in the solid optical element mount cell configured as shown in FIGS. The current to the thermoelectric cooling element 3a may be controlled so as to control the current.
[0031]
7 and 8 show the case where the thermoelectric cooling elements are used in two stages and the temperature of the solid optical element is controlled. However, the thermoelectric cooling elements may be used in three or more stages.
[0032]
【The invention's effect】
The solid optical mount cell according to the configuration of the invention, provided each thermoelectric cooling element to control the temperature of the wavelength conversion element via a solid optical element holder on both sides of the wavelength conversion element to the housing, the heat Since the spring is attached to the solid optical element holder so that the cooling element is pressed against the wavelength conversion element, the heat capacity of the object to be temperature controlled can be reduced, and the temperature control can be performed even if a temperature adjustment element having a small heat capacity is used. Make it possible to do. In addition to having a small heat capacity, a material having a low thermal conductivity can be removed from the target to be temperature controlled, so that it is possible to shorten the time required to reach the thermal equilibrium state. Furthermore, the entire contact surface between the wavelength conversion element and the holder is in uniform contact, and the holder can always be pressed against the wavelength conversion element with a constant pressure, and the temperature uniformity in the optical element is significantly increased. The time for convergence to temperature can be significantly reduced.
[0033]
Solid optical element mount cell according to configuration of the present invention, it is provided with the flow path of the coolant in the housing itself of the mount cell, the solid-state optical element can be easily kept at a constant temperature that is not affected by ambient temperature.
[0034]
Solid optical element mount cell according to configuration of the present invention, since there is provided a heater in the housing itself of the mount cell, the solid-state optical element can be easily kept at a constant temperature that is not affected by ambient temperature.
[0035]
Solid optical element mount cell according to configuration of the invention, the temperature measuring device is installed in the vicinity of the wavelength conversion element in the solid-state optical element holder, the absolute value and temperature of which is monitored by a temperature measuring device Can be regarded as substantially the same as the surface portion of the surface of the solid optical element in contact with the solid optical element holder .
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a solid-state optical element mount cell according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram showing a solid-state optical element mount cell according to Embodiment 1 of the present invention.
FIG. 3 is a configuration diagram showing a solid-state optical element mount cell according to a second embodiment of the present invention.
FIG. 4 is a configuration diagram showing a solid-state optical element mount cell according to a second embodiment of the present invention.
FIG. 5 is a configuration diagram showing a solid-state optical element mount cell according to a third embodiment of the present invention.
FIG. 6 is a configuration diagram showing a solid-state optical element mount cell according to a third embodiment of the present invention.
FIG. 7 is a configuration diagram showing a solid-state optical element mount cell according to a fourth embodiment of the present invention.
FIG. 8 is a configuration diagram showing a solid-state optical element mount cell according to a fourth embodiment of the present invention.
FIG. 9 is a block diagram showing a conventional solid optical element mount cell.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid optical element mount self data, 2 Solid optical element mount cell housing, 3, 3a Thermoelectric cooling element, 4 O-ring, 5 Lid cap screw, 6 Optical window, 7 Solid optical element, 8 Solid optical element holder, 9 Temperature measuring device, 10 refrigerant flow path, 11 heater, 12 heat reservoir.

Claims (4)

In a solid optical element mount cell that controls temperature by sealing a wavelength conversion element in a casing, a thermoelectric cooling element that controls the temperature of the wavelength conversion element is provided on both sides of the wavelength conversion element in the casing. A solid optical element mount cell, wherein a spring is attached to the solid optical element holder so as to press the heat transfer cooling element against the wavelength conversion element.   The solid optical element mount cell according to claim 1, wherein a flow path for the refrigerant is provided in the housing.   The solid optical element mount cell according to claim 1, wherein a heater is provided in the housing.   2. The solid optical element mount cell according to claim 1, wherein a temperature measuring device is installed near the wavelength conversion element in the solid optical element holder.

Images