JP2009252910A - Solid-state laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress total current consumption when an use environmental temperature is changed. <P>SOLUTION: A solid-state laser device detects the use environmental temperature Ts and changes it to a control temperature Tc having a smaller difference from the use environmental temperature Ts between control temperatures of at least two usable semiconductor lasers. Consequently, the drive current of the semiconductor laser becomes larger compared with the case when the temperature Tc is fixed, but a Peltier current Ip is made small. A portion where the Peltier current Ip is made smaller is larger than a portion where the drive current of the semiconductor laser is increased, so the total current consumption is suppressed. Then a battery life can be made longer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state laser device, and more particularly to a solid-state laser device capable of suppressing the total current consumption.

2. Description of the Related Art Conventionally, a solid-state laser device that controls the temperature of an optical element included in a semiconductor laser or a laser optical system to a control temperature at which the optical output can be maintained constant and the driving current of the semiconductor laser is minimized is known (for example, patents). Reference 1).
JP 2004-235551 A

In the above conventional solid-state laser device, the driving current Id of the semiconductor laser for maintaining the optical output constant at different control temperatures Tc is measured, and the control temperature at which the driving current Id of the semiconductor laser is minimized is the control temperature at the time of use. It was adopted as. For example, as shown in FIG. 5, when Tc = 25 ° C., the semiconductor laser drive current Id is about 180 mA, 35 ° C. is about 150 mA, and 45 ° C. is about 180 mA, as shown in FIG. Regardless of the environmental temperature Ts, the control temperature Tc was kept constant at 35 ° C. As a result, the driving current Id of the semiconductor laser can be reduced to about 150 mA regardless of the use environment temperature Ts.
However, paying attention to the Peltier current Ip supplied to the Peltier element, when the control temperature Tc = 35 ° C. is constant, for example, as shown in FIG. However, when the use environment temperature Ts is −10 ° C., the Peltier current Ip needs about 800 mA, and when the use environment temperature Ts is 50 ° C., the Peltier current Ip needs about 600 mA. In other words, when the control temperature Tc is kept constant regardless of the use environment temperature Ts, even if the drive current Id of the semiconductor laser can always be kept at a minimum, it is very high when the use environment temperature Ts is −10 ° C. or 50 ° C. A large Peltier current Ip is required, and there is a problem that the total current consumption cannot be suppressed. Therefore, when the solid-state laser device is driven by a battery, there is a problem that the life of the battery is shortened.
Therefore, an object of the present invention is to provide a solid-state laser device capable of suppressing the total current consumption.

In a first aspect, the present invention provides a semiconductor laser that generates excitation laser light, a drive circuit that supplies a drive current to the semiconductor laser, a solid-state laser medium that is excited by the excitation laser light, and the solid-state laser medium. A nonlinear optical crystal that outputs a harmonic of a fundamental wave that is oscillated in the optical resonator, and that includes a temperature control unit that controls the temperature of the semiconductor laser, and A monitoring photodetector for detecting a part, an output adjustment circuit for controlling the output of the monitoring photodetector to be output to the outside by feeding back the output of the monitoring photodetector to the drive circuit, and use Use environment temperature detection means for detecting the environment temperature, and change the oscillation wavelength of the semiconductor laser by switching the control temperature of the semiconductor laser according to the detected use environment temperature. Serial to provide a solid-state laser apparatus characterized by comprising a control temperature switch means for absorbing band the use of at least two locations of the solid-state laser medium.
Since there are at least two absorption bands in the solid-state laser medium, at least two wavelengths of excitation laser light can be used according to the absorption bands. In other words, since the wavelength of the excitation laser light can be controlled by the temperature of the semiconductor laser, the control temperatures of at least two semiconductor lasers can be used.
Therefore, in the solid-state laser device according to the first aspect, the use environment temperature is detected, and the control temperature is switched from the control temperatures of at least two usable semiconductor lasers to a control temperature that reduces the difference from the use environment temperature. . As a result, the driving current of the semiconductor laser increases as compared with the case where the control temperature is kept constant, but the current for temperature adjustment can be reduced. And since the part which can make the electric current for temperature control small can be larger than the part which the drive current of a semiconductor laser increases, total current consumption can be suppressed.

  According to the solid-state laser device of the present invention, the total current consumption can be suppressed when the use environment temperature changes. Therefore, the battery life can be extended in the portable battery-driven solid-state laser device.

  Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is an explanatory diagram illustrating a solid-state laser device 100 according to the first embodiment.
This solid-state laser device 100 includes a semiconductor laser 1 that generates excitation laser light, a condensing lens system 2 that condenses the excitation laser light, a reflection surface formed on the incident surface of the excitation laser light, and is excited by the excitation laser light. The reflecting surface that forms an optical resonator between the solid-state laser medium 3 that generates the fundamental wave light, the nonlinear optical crystal 4 that generates the second harmonic light when the fundamental wave light is incident, and the reflecting surface of the solid-state laser medium 3 An output-side mirror 5, a beam splitter 6 that transmits a part of the output laser light output from the output-side mirror 5 to the outside and branches the remainder, and a photodiode 7 that receives the branched light and converts it into an electrical signal. A temperature control unit 8 having a Peltier element and a temperature sensor for controlling the temperature of the semiconductor laser 1, the solid-state laser medium 3, and the nonlinear optical crystal 4, a housing 10, and a use environment temperature Ts. Operating temperature detector 9 for controlling the semiconductor laser 1, a semiconductor laser driving circuit 14 for supplying a driving current Id to the semiconductor laser 1, and controlling the Peltier current Ip so that the actual temperature Tp of the temperature control unit 8 coincides with the control temperature Tc. The temperature control circuit 15 for controlling the semiconductor laser and the semiconductor laser drive circuit 14 to supply the semiconductor laser 1 with a drive current Id so that the intensity of the branched light received by the photodiode 7 is constant. And a control unit 16 that switches the temperature Tc according to a change in the use environment temperature Ts.

FIG. 2 is an exemplary diagram showing the temperature-excitation laser light wavelength characteristics of the semiconductor laser 1.
It is assumed that the temperature is near 795 nm at a temperature of 0 ° C., the wavelength is near 804 nm at a temperature of 30 ° C., and the wavelength is near 809 nm at a temperature of 45 ° C.

FIG. 3 is an exemplary diagram of an absorption spectrum when an Nd: YAG crystal is used as the solid-state laser medium 3.
There are several peaks having a large intensity of the absorption spectrum in the wavelength range of 0.79 μm to 0.83 μm. When three locations are selected from the larger, they are a peak near 809 nm, a peak near 795 nm, and a peak near 804 nm. These three absorption bands shall be used.

FIG. 4 is a characteristic diagram showing the relationship between the use environment temperature Ts, the control temperature Tc to be switched accordingly, and the Peltier current Ip necessary for maintaining the temperature Tp of the semiconductor laser 1 at the control temperature Tc.
The control temperature Tc is 0 ° C. when the use environment temperature Ts is −10 ° C. to 10 ° C., the control temperature Tc is 30 ° C. when the use environment temperature Ts is 10 ° C. to 32.5 ° C., and the use environment temperature Ts is When the temperature is 32.5 ° C. to 50 ° C., the control temperature Tc is switched to 45 ° C.
The maximum value of the Peltier current Ip required at the use environment temperature Ts of −10 ° C. to 50 ° C. can be suppressed to about 300 mA.

  According to the solid-state laser device 100 of the first embodiment, the use environment temperature Ts is detected, and the control temperature Tc is changed so that the difference from the use environment temperature Ts does not become so large. In comparison, the drive current Id of the semiconductor laser 1 increases, but the Peltier current Ip can be reduced. Since the amount by which the Peltier current Ip can be reduced is larger than the amount by which the drive current Id of the semiconductor laser 1 increases, the total current consumption | Ip | + | Id | can be suppressed. Therefore, the battery life when driven by a dry battery can be extended.

  The solid-state laser device of the present invention can be used in the bioengineering field and the measurement field. Moreover, it is useful for, for example, a laser pointer driven by a dry battery.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. It is an illustration figure which shows the characteristic of semiconductor laser temperature and an excitation laser beam wavelength. It is an illustration figure which shows the absorption spectrum of a solid-state laser medium. It is a characteristic view which shows the relationship between the control temperature switched according to use environment temperature, and the Peltier current required according to it. FIG. 10 is a characteristic diagram showing a change in the driving current of the semiconductor laser for maintaining the optical output constant with respect to a change in the temperature of the semiconductor laser. It is a characteristic view which shows the relationship between fixed control temperature and the Peltier current required according to it regardless of use environment temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Condensing lens system 3 Solid state laser medium 4 Nonlinear optical crystal 5 Output side mirror 6 Beam splitter 7 Photodiode 8 Temperature control unit 9 Environment temperature detector 14 Semiconductor laser drive circuit 15 Temperature control circuit 16 Control part 100 Solid state laser apparatus

Claims (1)

A semiconductor laser that generates pump laser light, a drive circuit that supplies a drive current to the semiconductor laser, a solid-state laser medium that is pumped by the pump laser light, and an optical resonator that includes the solid-state laser medium A non-linear optical crystal that outputs harmonics of a fundamental wave that is oscillated by the optical resonator, temperature control means that controls the temperature of the semiconductor laser, and a monitoring photodetector that detects part of the harmonics An output adjusting circuit for controlling the output of the monitor photodetector to be output to the outside by feeding back the output of the monitor photodetector to the drive circuit, and an operating environment temperature detecting means for detecting the operating environment temperature And by switching the control temperature of the semiconductor laser according to the detected use environment temperature, the oscillation wavelength of the semiconductor laser is changed to reduce the amount of the solid laser medium. Also solid state laser device is characterized in that and a control temperature switch means for absorbing band use two.

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