JPH06326380A - Miniaturized laser pointer - Google Patents

Abstract

PURPOSE:To give sufficient light by a photooutput within the range exercising no unfavorable effect on human bodies without notably attenuating the light even in the case of pointing out a distant object. CONSTITUTION:A laser diode 1 is intermittently turned on/off by a switching circuit 8. Next, the output beams from the laser diode 1 are focussed on a laser rod 3 by a focussing lens 2. Next, the solid laser oscillation assuming the space between dichroic coats 6, 6 as a photo-resonator is controlled by a Q switch element 5 reversing the laser diode 1. Finally, the oscillating output in wavelength of 1.06mum from the solid laser is wavelength-converted into 0.53mum by a non-linear optical element 4 to be externally discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small laser pointer used for pointing a reference point with a spotlight in a presentation or the like, and is driven by, for example, one rechargeable AA battery, and is a fountain pen-sized chest. The present invention relates to a small laser pointer that can be carried in a pocket.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a laser pointer disclosed in Japanese Patent Application Laid-Open No. 2-235013. As shown in the figure, this laser pointer is composed of a laser diode 11 for generating a visible laser light and an optical system 12 including a lens for condensing the laser light output from the laser diode into a parallel light beam. The electronic circuit 13 for controlling the light emission of the laser diode 11 and a power source 14 such as a battery for driving the laser diode 11 and the electronic circuit 13 constitute a main part. It is housed in. Reference numeral 16 denotes a projection surface such as a screen onto which the light beam from the laser pointer is projected.

FIG. 4 is a circuit block diagram showing the structure of the electronic circuit 13 shown in FIG. As shown in the figure,
The electronic circuit 13 supplies an automatic light output control circuit (hereinafter referred to as an APC circuit) 17 connected between the power source 14 and the laser diode 11 and a current flowing from the power source 14 to the laser diode 11 through the APC circuit 17. It is configured to include a switching circuit 18 for controlling to turn on / off. The switching circuit 18 includes the APC circuit 1
A blinking control signal for controlling the frequency or pulse width of the switching pulse applied to 7 is input.

Next, the operation of the apparatus shown in FIGS. 3 and 4 will be described. The switching circuit 18 driven by the power supply 14 is controlled by an input blinking control signal to generate an ON / OFF signal having a constant frequency, which is applied to the AP.
It is transmitted to the C circuit 17. Based on this signal, the APC circuit 17 turns on / off the current flowing from the power supply 14 to the laser diode 11. As a result, the laser diode 1
1 blinks its optical output in synchronization with the on / off signal emitted from the switching circuit 18. The obtained light output is collimated by the optical system 12 and projected on the projection surface 16 at a distance.

Further, Japanese Utility Model Laid-Open No. 61-140315 discloses a laser pointer having a Ni-Cd battery, a booster circuit, a light emitting circuit, and a laser diode, and an outer frame having a charging terminal.

[0006]

The conventional laser pointer described above has the following problems because it uses the light emitted from the laser diode directly as the pointing light. (1) Since it is difficult to shorten the wavelength of the laser diode, the one that has been put into practical use is red, and the one that is also commonly used is red, which is close to infrared, so the relative luminous efficiency is low and very It was hard to see. Although it is technically possible to compensate for the low relative luminosity by increasing the output of the laser diode, this kind of product may cause the emitted light to enter the eyes of humans, so such measures should be taken for safety. I can't take it. According to "Outline of Measures to Prevent Obstacles Due to Laser Beams" (Ministry of Labor Labor Standards Bureau Issue No. 39) wavelength 400
In the range of nm to 700 nm, if the power is about 1 mW or less, it is said that the obstacle can be avoided by the defense reaction of the human body, but output higher than that should be avoided for safety (in the case of continuous oscillation). Therefore, it is impossible to provide a product with an output exceeding 1 mW. (2) In the laser diode, the astigmatism (misalignment of the vertical and horizontal focal points) is generally large due to its structure, and therefore the attenuation becomes large when the light is distantly emitted.

[0007]

A small laser pointer according to the present invention comprises a solid-state laser medium (3), a laser diode (1) for exciting the solid-state laser medium, and a wavelength derived from the solid-state laser medium (3). A non-linear optical element (4) for converting light, a battery (7), and a power supply circuit (8, 8a) for intermittently driving the laser diode, and an end face of the solid-state laser medium on the side far from the non-linear optical element. An optical resonator of a solid-state laser is formed by the dichroic coat (6) formed on the end face and the dichroic coat (6) formed on the end face of the nonlinear optical element on the side farther from the solid-state laser medium. I am trying. And
Preferably, a Q switch element (5) is arranged in the optical resonator of the solid-state laser, and the ON time of the laser diode once is set to be equal to or shorter than the fluorescence lifetime of the solid-state laser medium. To be done.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, 1 is a laser diode for excitation with an emission wavelength of 810 nm, 2 is a condensing lens, such as a SELFOC lens, which condenses the light emitted from the laser diode 1 into a solid laser medium (3). Is Nd: YVO ₄
4 is a nonlinear optical element made of potassium phosphotitanate (KTiOPO ₄ : hereinafter referred to as KTP), 5 is a Q switch element, 6 is an end face of the laser rod 3 near the laser diode 1, and nonlinear optical It is a dichroic coat formed on the end surface of the element 4 on the side far from the laser diode 1. Laser rod 3, Q
The switch element 5 and the nonlinear optical element 4 are arranged in close contact with each other. The optical resonator of the solid-state laser is formed between the two layers of dichroic coats 6, 6 and has a structure in which the nonlinear optical element 4 and the Q switch element 5 are inserted in the optical resonator.

Reference numeral 7 is a rechargeable AA type battery, 8 is a switching circuit for turning on / off a current supplied from the battery 7 to the laser diode 1, and 9 is for accommodating all of them, and a light is provided at the tip thereof. It is a storage case in which an emission window is formed. The output terminal of the switching circuit 8 is also the Q switch element 5
The switching circuit 8 controls the Q switch element so as to perform the inverting operation of the laser diode 1.

Next, the operation of the laser pointer of this embodiment will be described. The laser diode 1 is turned on / off by the switching circuit 8. When a current is supplied to the laser diode 1, that is, when the laser diode emits excitation light, the switching voltage output from the switching circuit 8 is applied to the Q switch element 5, so that the solid-state laser oscillates. Have stopped. When the current supplied to the laser diode 1 via the switching circuit 8 is turned off, the voltage applied to the Q switch element 5 becomes 0 V at the same time, the energy accumulated in the laser rod 3 is released, and the solid-state laser oscillates. Start. The oscillation output of the solid-state laser having a wavelength of 1.06 μm obtained between the dichroic coats 6 and 6 is obtained by the nonlinear optical element 4.
Is converted into green light having a wavelength of 0.53 μm and emitted. Next, when the laser diode 1 is again supplied with current, the solid-state laser is made to stop oscillating by the Q switch element 5, and the laser rod 3 starts accumulating energy again.

Next, the drive frequency of the laser diode in this embodiment will be described. In the present embodiment, considering the characteristics of the solid-state laser medium, the on-time of the switching circuit 8 is set to 90 times the fluorescence lifetime of Nd: YVO ₄ which is the laser rod.
It is about μsec or less. This is because if the solid-state laser medium is excited for more than the fluorescence lifetime, the excitation energy will not be accumulated in the solid-state laser medium and will drop to a lower energy level. Therefore, for example, the duty ratio is 1/1
In the case of 1, the switching cycle is set to 1 kHz or more and 1 kHz or more [f = 1 / (90 μsec × 11) ≈10.
00 / sec].

By the way, the most significant effect in reducing the size of the laser pointer is to reduce the battery size. However, since the current required to drive the laser diode is, for example, 0.2 A, it is extremely difficult to supply this current with a battery of about AA size. Therefore, in the present embodiment, the laser diode 1 is intermittently operated to enable driving with a small battery. For example, if the duty ratio is 1/100, the current consumption will be 1/100 of that in continuous driving, but this will greatly extend the operable time for one charge and enable driving with a small battery. Become.

Further, in this embodiment, green light having a wavelength of 0.53 μm is emitted, but this wavelength band corresponds to the region having the highest relative luminous efficiency, and even if the output is 1 mW, it is sufficiently clear. The reference point can be indicated with this. Further, since an infrared laser diode which has high efficiency and can be obtained at low cost is used as the excitation light source, it is possible to achieve high efficiency (low current consumption) and cost reduction at the same time. Furthermore, since the emitted laser light is in the TEM ₀₀ mode, even if the laser light is blown away, it is not greatly attenuated. Then, it is not necessary to use a condenser lens for the emitted laser light. Further, in this embodiment, since the oscillation of the solid-state laser is controlled by the Q switch, the excitation energy of the laser diode can be efficiently used for the oscillation of the solid-state laser.

FIG. 2 is a sectional view of another embodiment of the present invention. In FIG. 2, portions corresponding to those of the embodiment of FIG. 1 are designated by the same reference numerals, and a duplicate description will be omitted. However, in this embodiment, a Q switch element for controlling oscillation of a solid-state laser is used. Is eliminated, and the excitation light can be condensed into the laser rod only by the condensing characteristics of the laser diode 1 to eliminate the use of the SELFOC lens. Has been simplified. Further, in this embodiment, a pulse oscillation circuit is used as a means for driving the laser diode 1 instead of the switching circuit. The laser pointer of this embodiment can also emit a green laser beam, and the same effect as that of the previous embodiment can be obtained.

Having described the preferred embodiment,
The present invention is not limited to these examples, and various modifications can be made within the scope of the present invention described in the claims. For example, as a solid-state laser medium, N
Instead of d: YVO ₄ , another medium such as Nd: YAG can be used, and the nonlinear optical element can be formed by using a material other than KTP.

[0016]

As described above, the small laser pointer according to the present invention excites the solid-state laser medium by the laser diode and wavelength-converts the oscillation light of the solid-state laser by the non-linear optical element and emits it. According to the present invention, it is difficult to oscillate with a single laser diode,
It is possible to use green light having high relative luminous efficiency as the indicator light, and it is possible to indicate the reference point with sufficient brightness even with an output of 1 mW defined by the laser safety standard. Also, the emitted light can be in TEM ₀₀ mode,
Unlike the laser diode having astigmatism, the pointing light without attenuation can be used even when pointing a distant reference point.

Furthermore, by intermittently driving the laser diode, power consumption can be reduced and battery consumption can be suppressed. At this time, the output of the laser diode, that is, the laser pointer can be adjusted by changing the length of one ON time or the switching cycle. Further, when the Q switch element is used, the excitation energy is efficiently utilized for laser oscillation of the solid laser by setting the length of one ON time of the laser diode to be less than the fluorescence lifetime of the solid laser medium. be able to. In addition, since an infrared semiconductor laser diode that has high conversion efficiency and can be obtained at low cost can be used as a light source for excitation, it is possible to contribute to suppression of current consumption and cost reduction.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a sectional view of a conventional example.

FIG. 4 is a block diagram of an electronic circuit in the conventional example of FIG.

[Explanation of symbols]

1, 11 Laser diode 2 Condensing lens 3 Laser rod (Nd: YVO ₄ ) 4 Nonlinear optical element (KTP) 5 Q switch element 6 Dichroic coat 7 Battery 8 Switching circuit 8a Pulse oscillation circuit 9 Storage case 12 Optical system 13 Electronic circuit 14 power supply 15 housing 16 projection surface 17 automatic light output control circuit (APC circuit) 18 switching circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01S 3/02

Claims (7)

[Claims] 1. A solid-state laser medium, a laser diode that excites the solid-state laser medium, a nonlinear optical element that is installed in a resonator of the solid-state laser, wavelength-converts the oscillation output of the solid-state laser, and emits the wavelength to the outside. A battery and a power supply circuit for intermittently driving the laser diode, and a dichroic coat formed on an end face of the solid-state laser medium far from the nonlinear optical element, and a solid laser medium far from the nonlinear optical element. A compact laser pointer characterized in that an optical resonator of a solid-state laser is formed by a dichroic coat formed on the side end surface. 2. The miniature laser pointer according to claim 1, wherein a Q switch element is arranged in the optical resonator of the solid-state laser. 3. The compact laser pointer according to claim 2, wherein the solid-state laser medium, the Q switch element, and the non-linear optical element are arranged in close contact with each other. 4. The Q switch element is connected to the power supply circuit, and the operation timing of the Q switch element and the pump light output timing of the laser diode are inverted from each other. Small laser pointer. 5. The solid-state laser medium and the non-linear optical element are arranged in close contact with each other.
Small laser pointer described. 6. The compact laser pointer according to claim 1, further comprising a lens disposed between the laser diode and the solid-state laser medium, the lens condensing pumping light output from the laser diode. 7. The miniature laser pointer according to claim 1, wherein one turn-on time of the laser diode is set to approximately the fluorescence lifetime of the solid-state laser medium or shorter.