阅读说明：本技术 一种高能量高重频高光束质量266nm脉冲固体激光器 (266nm pulse solid laser with high energy, high repetition frequency and high beam quality ) 是由 豆西博 张普 朱香平 韦永林 杨军红 赵卫 于 2021-08-19 设计创作，主要内容包括：本发明提供的高能量高重频高光束质量266nm脉冲固体激光器,采用双端面脉冲泵浦方式,有效的提高了激光晶体对泵浦光的吸收,在没有放大级的情况下,利用降压工作调Q,获得了高单脉冲能量的基频光,这使得高单脉冲能量的激光器体积变小、效率更高；采用腔外倍频技术,将基频光束腰通过成像设计变换到二倍频晶体中,极大的提高了二倍频转换效率,四倍频晶体采用非临界相位匹配高温工作设计大大的提高了266nm激光光束质量,同时也有效的防止了CLBO晶体的潮解,四倍频晶体二维移点设计可有效的延长激光器的寿命。(The 266nm pulse solid laser with high energy, high repetition frequency and high beam quality provided by the invention adopts a double-end-face pulse pumping mode, effectively improves the absorption of a laser crystal to pumping light, and obtains fundamental frequency light with high single pulse energy by utilizing the Q-switching of voltage reduction under the condition of no amplification stage, so that the volume of the laser with high single pulse energy is reduced, and the efficiency is higher; the external cavity frequency doubling technology is adopted, the fundamental frequency beam waist is converted into the double-frequency crystal through the imaging design, the double-frequency conversion efficiency is greatly improved, the quality of a 266nm laser beam is greatly improved by adopting a noncritical phase matching high-temperature working design for the quadruple frequency crystal, the deliquescence of a CLBO crystal is effectively prevented, and the service life of a laser can be effectively prolonged by adopting the two-dimensional point shifting design for the quadruple frequency crystal.)

1. A high energy, high frequency, high beam quality 266nm pulsed solid state laser comprising: an LD pumping source (1), a collimating lens (2), a focusing lens (3), a dichroic mirror (4), a laser crystal Nd, a YAG (5), a resonant cavity front end mirror (6), a focusing lens (7), a collimating lens (8), an LD pumping source (9), a resonant cavity rear end mirror (14), a Q-switched crystal BBO (15), a 1064nm 1/4 wave plate (16), a polarization beam splitter prism (17), a focusing lens (18), an LBO crystal (19), a dichroic mirror (21), a collimating lens (22), a 532nm 1/4 wave plate (23), a dichroic mirror (24), a four-dimensional translation stage (25), a high-temperature oven (26) and a CLBO crystal (27), wherein the resonant cavity front end mirror (6) and the resonant cavity rear end mirror (14) form a resonant cavity, the high-temperature oven (26) is arranged on the four-dimensional translation stage (25), and the CLBO crystal (27) is arranged in the high-temperature oven (26), wherein:

when 1/4 wave voltage is not applied to the Q-switched crystal BBO (15), pulsed light emitted by the LD pumping source (1) sequentially passes through the collimating lens (2), the focusing lens (3) and the dichroic mirror (4) and is converged into the laser crystal Nd, namely YAG (5); meanwhile, pulsed light emitted by the LD pumping source (9) is converged into the laser crystal Nd: YAG (5) through the collimating lens (8), the focusing lens (7) and the resonant cavity front end mirror (6) in sequence, the LD pumping source (1) and the LD pumping source (9) are synchronously pumped in a pulse mode, the laser crystal Nd: YAG (5) absorbs pumping light to form the inversion of the number of particles, and laser energy is stored in the laser crystal Nd: YAG (5);

a 1/4 wave voltage is added on the Q-switched crystal BBO (15), laser energy is released into the resonant cavity from the laser crystal Nd, YAG (5), when the voltage on the Q-switched crystal BBO (15) is reduced, laser is released from the position of the polarization beam splitter prism (17) under the combined action of the 1064nm 1/4 wave plate (16) and the polarization beam splitter prism (17), and a fundamental frequency 1064nm laser giant pulse is formed;

the fundamental frequency 1064nm laser giant pulse passes through the focusing lens (18), falls into the LBO crystal (19) through the beam waist, generates 532nm laser due to a frequency doubling mechanism LBO crystal 19, residual 1064nm laser (20) which is not converted into 532nm is reflected by the dichroic mirror (21), the 532nm laser is collimated by the collimating lens (22) and then sequentially passes through the 532nm 1/4 wave plate (23) and the dichroic mirror (24) to enter the CLB0 crystal (27), the CLB0 crystal (27) generates 266nm laser, the residual 532nm laser which is not converted into 266nm is filtered by the dichroic mirror, and finally pure 266nm laser (30) is obtained.

2. The high-energy high-repetition-frequency high-beam-quality 266nm pulse solid-state laser device according to claim 1, wherein the LD pump source (1) and the LD pump source (9) are the same type, have the maximum power of 40-100W, are fiber coupling output, and have the fiber core diameter of 400um or 105um or 200 um.

3. The high-energy high-repetition-frequency high-beam-quality 266nm pulse solid-state laser according to claim 1, wherein the collimating lens (2) and the collimating lens (8) have the same model and the focal length of 25-100 mm; the focusing lens (3) and the focusing lens (7) are the same in type, and the focal length is 50-100 mm.

4. The high energy high repetition frequency high beam quality 266nm pulsed solid state laser of claim 1, wherein said dichroic mirror (4) is 45 ° incident, AR @808nm and HR @1064nm coated, with a 1064nm reflectivity of greater than 99.5% and a 808nm transmittance of greater than 95%; the dichroic mirror (21) is incident at 45 degrees and plated with HR @1064nm and AR @532nm, the reflectivity of 1064nm is more than 99.5 percent, and the transmissivity of 532nm is more than 95 percent.

5. The high energy high repetition frequency high beam quality 266nm pulsed solid state laser of claim 1, wherein said laser crystal Nd: YAG (5) has a size of 4 x 40mm3, is coated with AR @808&1064nm film on both ends, and has reflectivities of 808nm and 1064nm of less than 0.2%.

6. The high energy high repetition frequency high beam quality 266nm pulsed solid state laser of claim 1, characterized by said resonator front end mirror (6) and said resonator back end mirror (14) both being flat mirrors, HR @1064nm coated, 1064nm reflectivity greater than 99.5%.

7. A high energy high frequency high beam quality 266nm pulsed solid state laser as claimed in claim 1 wherein said focusing lens (18) has a focal length of 30mm and said collimating lens (22) has a focal length of 50 mm.

8. A high energy high frequency high beam quality 266nm pulsed solid state laser as claimed in claim 1 wherein said LBO crystal (19) is 3 x 15mm in size³The cutting angle is Theta 90 degrees, Phi 11.2 degrees, and two end faces are plated with AR @1064&532 nm; the size of the CLB0 crystals (27) is 11 x 11mm³The cutting angle is theta62 degrees and phi45 degrees.

9. The high energy high frequency high beam quality 266nm pulsed solid state laser according to claim 1, characterized in that part of the remaining 532nm laser light (29) not converted to 266nm is filtered by a dichroic mirror (28), another part of the laser light (10) is filtered by a dichroic mirror (11), and the remaining laser light (13) is filtered by the dichroic mirror (11) and then by the dichroic mirror (12) to finally obtain pure 266nm laser light (30).

10. The high energy high repetition frequency high beam quality 266nm pulsed solid state laser of claim 9, wherein said dichroic mirror (24), dichroic mirror (28), dichroic mirror (11) and dichroic mirror (12) are of the same type, are 45 ° incident, are coated with HR @266nm and AR @532nm films, have a 266nm reflectance of greater than 99.5%, and have a 532nm transmittance of greater than 95%.

Technical Field

The invention relates to the technical field of solid lasers, in particular to a 266nm pulse solid laser with high energy, high repetition frequency and high beam quality.

Background

The wavelength of 266nm laser is short, the single photon energy is high, smaller focusing light spots can be realized, and the laser is widely applied to the fields of biological detection, spectral analysis, medical treatment, precise micromachining, aviation and the like. The high-energy high-repetition-frequency 266nm laser is mainly generated by modulating Q to generate a pulse fundamental frequency 1064nm laser, then amplifying the fundamental frequency light through an amplifier, and then carrying out continuous twice frequency multiplication.

The existing high-energy high-repetition-frequency 266nm laser generates nanosecond 1064nm fundamental frequency light by single-end pumping and combining an active Q-switching technology, then amplifies the fundamental frequency light by an amplifier, and generates 266nm laser by continuous twice frequency multiplication.

Disclosure of Invention

In view of the above, it is desirable to provide a 266nm pulse solid-state laser with high energy, high repetition frequency and high beam quality, which has compact structure, low cost and high reliability.

In order to solve the problems, the invention adopts the following technical scheme:

a high energy high frequency high beam quality 266nm pulsed solid state laser comprising: an LD pumping source (1), a collimating lens (2), a focusing lens (3), a dichroic mirror (4), a laser crystal Nd, a YAG (5), a resonant cavity front end mirror (6), a focusing lens (7), a collimating lens (8), an LD pumping source (9), a resonant cavity rear end mirror (14), a Q-switched crystal BBO (15), a 1064nm 1/4 wave plate (16), a polarization beam splitter prism (17), a focusing lens (18), an LBO crystal (19), a dichroic mirror (21), a collimating lens (22), a 532nm 1/4 wave plate (23), a dichroic mirror (24), a four-dimensional translation stage (25), a high-temperature oven (26) and a CLBO crystal (27), wherein the resonant cavity front end mirror (6) and the resonant cavity rear end mirror (14) form a resonant cavity, the high-temperature oven (26) is arranged on the four-dimensional translation stage (25), and the CLBO crystal (27) is arranged in the high-temperature oven (26), wherein:

when 1/4 wave voltage is not applied to the Q-switched crystal BBO (15), pulsed light emitted by the LD pumping source (1) sequentially passes through the collimating lens (2), the focusing lens (3) and the dichroic mirror (4) and is converged into the laser crystal Nd, namely YAG (5); meanwhile, pulsed light emitted by the LD pumping source (9) is converged into the laser crystal Nd: YAG (5) through the collimating lens (8), the focusing lens (7) and the resonant cavity front end mirror (6) in sequence, the LD pumping source (1) and the LD pumping source (9) are synchronously pumped in a pulse mode, the laser crystal Nd: YAG (5) absorbs pumping light to form the inversion of the number of particles, and laser energy is stored in the laser crystal Nd: YAG (5);

a 1/4 wave voltage is added on the Q-switched crystal BBO (15), laser energy is released into the resonant cavity from the laser crystal Nd, YAG (5), when the voltage on the Q-switched crystal BBO (15) is reduced, laser is released from the position of the polarization beam splitter prism (17) under the combined action of the 1064nm 1/4 wave plate (16) and the polarization beam splitter prism (17), and a fundamental frequency 1064nm laser giant pulse is formed;

the fundamental frequency 1064nm laser giant pulse passes through the focusing lens (18), falls into the LBO crystal (19) through the beam waist, generates 532nm laser due to a frequency doubling mechanism LBO crystal 19, residual 1064nm laser (20) which is not converted into 532nm is reflected by the dichroic mirror (21), the 532nm laser is collimated by the collimating lens (22) and then sequentially passes through the 532nm 1/4 wave plate (23) and the dichroic mirror (24) to enter the CLB0 crystal (27), the CLB0 crystal (27) generates 266nm laser, the residual 532nm laser which is not converted into 266nm is filtered by the dichroic mirror, and finally pure 266nm laser (30) is obtained.

In some embodiments, the LD pump source (1) and the LD pump source (9) have the same model, the maximum power is 40-100W, the fiber core diameter is 400um or 105um or 200um, and the fiber core is coupled and output by the optical fiber.

In some embodiments, the collimating lens (2) and the collimating lens (8) are the same in model, and the focal length is 25-100 mm; the focusing lens (3) and the focusing lens (7) are the same in type, and the focal length is 50-100 mm.

In some of these embodiments, the dichroic mirror (4) is 45 ° incident, coated with AR @808nm and HR @1064nm films, with a 1064nm reflectance of greater than 99.5%, and a 808nm transmittance of greater than 95%; the dichroic mirror (21) is incident at 45 degrees and plated with HR @1064nm and AR @532nm, the reflectivity of 1064nm is more than 99.5 percent, and the transmissivity of 532nm is more than 95 percent.

In some of these embodiments, the laser crystal Nd: YAG (5) is 4 × 40mm3 in size, with AR @808&1064nm films on both ends, and with 808nm and 1064nm reflectivities of less than 0.2%.

In some of these embodiments, the resonator front mirror (6) and the resonator back mirror (14) are flat mirrors, coated with an HR @1064nm film, with a 1064nm reflectivity of greater than 99.5%.

In some of these embodiments, the focusing lens (18) has a focal length of 30mm and the collimating lens (22) has a focal length of 50 mm.

In some of these embodiments, the LBO crystals (19) have a size of 3 x 15mm³The cutting angle is Theta 90 degrees, Phi 11.2 degrees, and two end faces are plated with AR @1064&532 nm; the size of the CLB0 crystals (27) is 11 x 11mm³The cutting angle is theta62 degrees and phi45 degrees.

In some embodiments, part of laser light (29) in the residual 532nm laser light which is not converted into 266nm is filtered by a dichroic mirror (28), the other part of laser light (10) is filtered by a dichroic mirror (11), and the rest of laser light (13) is filtered by the dichroic mirror (11) and then by the dichroic mirror (12), so that pure 266nm laser light (30) is finally obtained.

In some of these embodiments, the dichroic mirror (24), dichroic mirror (28), dichroic mirror (11), and dichroic mirror (12) are of the same type, are 45 ° incident, are coated with HR @266nm and AR @532nm films, have a 266nm reflectance of greater than 99.5%, and have a 532nm transmittance of greater than 95%.

By adopting the technical scheme, the invention has the following technical effects:

the 266nm pulse solid laser with high energy, high repetition frequency and high beam quality provided by the invention adopts a double-end-face pulse pumping mode, effectively improves the absorption of a laser crystal to pumping light, and obtains fundamental frequency light with high single pulse energy by utilizing the Q-switching of voltage reduction under the condition of no amplification stage, so that the volume of the laser with high single pulse energy is reduced, and the efficiency is higher; the external cavity frequency doubling technology is adopted, the fundamental frequency beam waist is converted into the double-frequency crystal through the imaging design, the double-frequency conversion efficiency is greatly improved, the quality of a 266nm laser beam is greatly improved by adopting a noncritical phase matching high-temperature working design for the quadruple frequency crystal, the deliquescence of a CLBO crystal is effectively prevented, and the service life of a laser can be effectively prolonged by adopting the two-dimensional point shifting design for the quadruple frequency crystal.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention or in the description of the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a 266nm pulse solid-state laser with high energy, high repetition frequency and high beam quality according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "horizontal", "inside", "outside", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

Referring to fig. 1, a schematic structural diagram of a 266nm pulse solid-state laser with high energy, high repetition frequency and high beam quality according to an embodiment of the present invention includes: LD pump source (1), collimating lens (2), focusing lens (3), dichroic mirror (4), laser crystal Nd: YAG (5), a resonant cavity front end mirror (6), a focusing lens (7), a collimating lens (8), an LD pumping source (9), a resonant cavity rear end mirror (14), a Q-switched crystal BBO (15), a 1064nm 1/4 wave plate (16), a polarization beam splitter prism (17), a focusing lens (18), an LBO crystal (19), a dichroic mirror (21), a collimating lens (22), a 532nm 1/4 wave plate (23), a dichroic mirror (24), a four-dimensional translation stage (25), a high-temperature constant temperature furnace (26) and a CLBO crystal (27), the resonant cavity front end mirror (6) and the resonant cavity rear end mirror (14) form a resonant cavity, the high-temperature constant-temperature furnace (26) is arranged on the four-dimensional translation table (25), the CLBO crystal (27) is placed in the high-temperature constant-temperature furnace (26).

In some embodiments, the LD pump source (1) and the LD pump source (9) have the same model, the maximum power is 40-100W, the fiber core diameter is 400um or 105um or 200um, and the fiber core is coupled and output by the optical fiber.

It can be understood that the double-end pumping adopted by the laser has high efficiency, no amplification stage and weak thermal lens effect, and is beneficial to improving the laser output energy.

In some embodiments, the collimating lens (2) and the collimating lens (8) are the same in model, and the focal length is 25-100 mm; the focusing lens (3) and the focusing lens (7) are the same in type, and the focal length is 50-100 mm.

In some of these embodiments, the dichroic mirror (4) is 45 ° incident, coated with AR @808nm and HR @1064nm films, with a 1064nm reflectance of greater than 99.5%, and a 808nm transmittance of greater than 95%; the dichroic mirror (21) is incident at 45 degrees and plated with HR @1064nm and AR @532nm, the reflectivity of 1064nm is more than 99.5 percent, and the transmissivity of 532nm is more than 95 percent.

In some of these embodiments, the laser crystal Nd: YAG (5) has a size of 4 x 40mm³Two end faces are coated with AR @808&The reflectivity of the 1064nm film is less than 0.2% at 808nm and 1064 nm.

In some of these embodiments, the resonator front mirror (6) and the resonator back mirror (14) are flat mirrors, coated with an HR @1064nm film, with a 1064nm reflectivity of greater than 99.5%.

In some of these embodiments, the focusing lens (18) has a focal length of 30mm and the collimating lens (22) has a focal length of 50 mm.

In some of these embodiments, the LBO crystals (19) have a size of 3 x 15mm³The cutting angle is Theta 90 degrees, Phi 11.2 degrees, and two end faces are plated with AR @1064&532 nm; the size of the CLB0 crystals (27) is 11 x 11mm³The cutting angle is theta62 degrees and phi45 degrees.

It can be understood that because the acceptance angle of the LBO crystal (19) is large, the acceptance angle of the CLB0 crystal (27) is small, and the frequency doubling efficiency is effectively improved by adopting the mode that fundamental frequency light is focused into the LBO crystal 19 and double frequency light is collimated into the CLBO crystal 27.

It can be understood that because the CLBO crystal (27) is designed to be noncritical phase matching, the cutting angle is theta62 degrees, phi45 degrees and no discrete angle, the fundamental frequency light and the frequency doubling light are overlapped and not separated, the frequency doubling efficiency is high, and the light beam quality is good; the service life of a single point of the CLBO crystal (27) is short, and the service life of the CLBO crystal (27) can be prolonged by moving the CLBO crystal (27) up and down, left and right in cooperation with the four-dimensional translation stage 25.

Furthermore, 532nn laser single pulse energy is high, and the CLBO crystal (27) is not coated with an antireflection film, so that the CLBO crystal (27) is effectively prevented from being damaged.

The operation of the 266nm pulse solid-state laser with high energy, high repetition frequency and high beam quality provided by this embodiment is described in detail as follows:

when 1/4 wave voltage is not applied to the Q-switched crystal BBO (15), pulsed light emitted by the LD pumping source (1) sequentially passes through the collimating lens (2), the focusing lens (3) and the dichroic mirror (4) and is converged into the laser crystal Nd: YAG (5), meanwhile, pulsed light emitted by the LD pumping source (9) sequentially passes through the collimating lens (8), the focusing lens (7) and the resonant cavity front end mirror (6) and is converged into the laser crystal Nd: YAG (5), the LD pumping source (1) and the LD pumping source (9) are synchronously pulse pumped, the number of particles formed by the laser crystal Nd: YAG (5) absorbing pumping light is reversed, and laser energy is stored in the laser crystal Nd: YAG (5).

As can be understood, because two pump sources are synchronously pulse-pumped, the pulse width is 200us, the laser crystal Nd: YAG (5) absorbs the pump light to form the inversion of the number of particles, and at the moment, because of the existence of a 1064nm 1/4 wave plate (16) and a polarization beam splitter Prism (PBS)17, the loss in a resonant cavity formed by a resonant cavity front end mirror (6) and a resonant cavity rear end mirror (14) is large, no laser oscillation exists in the resonant cavity, and the laser energy is stored in the laser crystal Nd: YAG 5.

When 1/4 wave voltage is applied to the Q-switched crystal BBO (15), laser in a resonant cavity formed by a resonant cavity front end mirror (6) and a resonant cavity rear end mirror (14) oscillates in a cavity due to the combined action of a 1064nm 1/4 wave plate (16) and a polarization beam splitter Prism (PBS) (17), laser energy is released from the laser crystal Nd: YAG (5) into the resonant cavity, and when the voltage on the Q-switched crystal BBO (15) is reduced, laser is released from the position of the polarization beam splitter prism (17) under the combined action of the 1064nm 1/4 wave plate (16) and the polarization beam splitter prism (17), and a fundamental 1064nm laser giant pulse is formed.

It can be understood that when the signals of the LD pump source (1), the LD pump source (9) and the Q-switched crystal BBO (15) are given in cycles, a laser giant pulse with a fundamental frequency of 1064nm can be formed.

The fundamental frequency 1064nm laser giant pulse passes through the focusing lens (18), falls into the LBO crystal (19) through the beam waist, generates 532nm laser due to a frequency doubling mechanism LBO crystal 19, residual 1064nm laser (20) which is not converted into 532nm is reflected by the dichroic mirror (21), the 532nm laser is collimated by the collimating lens (22) and then sequentially passes through the 532nm 1/4 wave plate (23) and the dichroic mirror (24) to enter the CLB0 crystal (27), the CLB0 crystal (27) generates 266nm laser, the residual 532nm laser which is not converted into 266nm is filtered by the dichroic mirror, and finally pure 266nm laser (30) is obtained.

In some embodiments, part of laser light (29) in the residual 532nm laser light which is not converted into 266nm is filtered by a dichroic mirror (28), the other part of laser light (10) is filtered by a dichroic mirror (11), and the rest of laser light (13) is filtered by the dichroic mirror (11) and then by the dichroic mirror (12), so that pure 266nm laser light (30) is finally obtained.

It can be understood that pure 266nm laser light is obtained by transmitting 532nm laser light by three consecutive reflections of the 266nm laser light using a dichroic mirror (28), a dichroic mirror (11) and a dichroic mirror (12) having high reflectivity for 266nm, and this light splitting method has a small loss for the 266nm laser light. Furthermore, the dichroic mirror (24), the dichroic mirror (28), the dichroic mirror (11) and the dichroic mirror (12) are of the same model, are incident at 45 degrees and are coated with films of HR @266nm and AR @532nm, the reflectivity of 266nm is more than 99.5 percent, and the transmissivity of 532nm is more than 95 percent.

The 266nm pulse solid laser with high energy, high repetition frequency and high beam quality provided by the invention adopts a double-end-face pulse pumping mode, effectively improves the absorption of a laser crystal to pumping light, and obtains fundamental frequency light with high single pulse energy by utilizing the Q-switching of voltage reduction under the condition of no amplification stage, so that the volume of the laser with high single pulse energy is reduced, and the efficiency is higher; the external cavity frequency doubling technology is adopted, the fundamental frequency beam waist is converted into the double-frequency crystal through the imaging design, the double-frequency conversion efficiency is greatly improved, the quality of a 266nm laser beam is greatly improved by adopting a noncritical phase matching high-temperature working design for the quadruple frequency crystal, the deliquescence of a CLBO crystal is effectively prevented, and the service life of a laser can be effectively prolonged by adopting the two-dimensional point shifting design for the quadruple frequency crystal.

The foregoing is considered as illustrative only of the preferred embodiments of the invention, and is presented merely for purposes of illustration and description of the principles of the invention and is not intended to limit the scope of the invention in any way. Any modifications, equivalents and improvements made within the spirit and principles of the invention and other embodiments of the invention without the creative effort of those skilled in the art are included in the protection scope of the invention based on the explanation here.