JP2006317831A - Optical device for multipoint division - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a configuration that is compact, has a small number of components, and is superb in vibration-resistance properties in an optical device for multipoint division for dividing incident light into many points for emission. <P>SOLUTION: The optical device 100 for multipoint division for dividing an incident laser beam R into many points for emission comprises a first lens section 10 positioned at the incidence side of laser beam R and a second lens section 20 positioned at the emission side of the first lens section 10. The laser beam R enters from the first lens section 10 and are transmitted through the second lens section 20 for emission. The first lens section is composed as a corner cube prism 10 in which the number of incident surfaces 11 is equal to the number of divisions of the laser beam R. When the laser beam R enters the corner cube prism 10, the laser beam R emitted from the corner cube prism 10 are divided into many points and are emitted from the second lens section 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multipoint splitting optical device that splits incident light into multiple points and emits the light, and is particularly suitable for use in an optical system in a laser ignition device that is attached to an engine and ignites with laser light. .

  2. Description of the Related Art Conventionally, as this type of multipoint dividing optical apparatus, an optical system in a laser ignition apparatus that is attached to an engine and performs ignition with laser light has been proposed (for example, see Patent Document 1).

In this laser ignition device, the laser light emitted from the laser oscillator is incident and divided into multiple points by the optical system, and the divided laser light is led to the combustion chamber of the engine. . Thereby, the air-fuel mixture is ignited by laser light in the combustion chamber, and the engine is ignited.
Japanese Patent Laid-Open No. 1-193081

  However, conventionally, a plurality of beam splitters, half mirrors, and condensing lenses are necessary to divide and collect light from one light source into multiple points, and there are the following problems.

  (1) The number of parts constituting the optical device is large, and a holder for holding each part is also necessary.

  (2) When the number of lights to be divided increases, the number of parts also increases, and the configuration becomes more complicated.

  (3) For each component part, it is necessary to adjust the inclination, the distance between the parts, etc., and the adjustment takes time.

  (4) Since a certain distance is required between the parts, the optical device becomes large as a whole and requires space.

  (5) Since many parts must be placed on the base and adjusted and fixed, they are vulnerable to vibration.

  (6) Depending on the case, a plurality of light sources must be prepared, and a high output can be obtained, but this is a negative factor in terms of space cost.

  Due to the problems (1) to (6) above, the conventional multi-point dividing optical device is large and requires space, and has insufficient vibration resistance. It was difficult to install.

  The present invention has been made in view of the above problems, and in a multi-point division optical apparatus that divides incident light into multiple points and emits the light, it is small, has a small number of parts, and has excellent vibration resistance. The purpose is to realize the configuration.

  In order to achieve the above object, according to the first aspect of the present invention, in the multipoint splitting optical device that splits the incident light into multiple points and emits the light, the first position located on the light incident side is provided. It consists of a lens part (10) and a second lens part (20) located on the exit side, and the light enters from the first lens part (10) and passes through the second lens part (20). The first lens unit is configured as a corner cube prism (10) in which the number of incident surfaces (11) is equal to the number of divisions of the light. When the light is incident, the light emitted from the corner cube prism (10) is divided into multiple points and is emitted from the second lens unit (20).

  According to this, the incident light is divided into multiple points by the first lens unit (10), and is emitted from the second lens unit (20) as light divided into multiple points. Therefore, if these two lens portions (10, 20) are provided, the number of parts does not change even if the number of divisions is changed, the apparatus functions sufficiently, and the apparatus has only two component parts.

  Therefore, this optical device is small and space-saving, the need to adjust the interval and inclination between the components can be eliminated as much as possible, and the jig for fixing the components can be minimized. It can be made excellent in vibration resistance.

  As described above, according to the present invention, in the multipoint dividing optical device that divides incident light into multiple points and emits the light, a small size, a small number of parts, and an excellent vibration resistance can be realized. Can do.

  Here, as in the invention described in claim 2, in the multipoint splitting optical device described in claim 1, the second lens portion (20) includes the entrance surface (21) and the exit surface (22). Are both configured as a drum lens having a convex shape.

  Further, as in the invention described in claim 3, in the multipoint dividing optical device described in claim 1, the second lens portion (20) has an incident surface (21) having a convex shape and an exit surface. (22) can be configured as a concave-convex lens having a concave shape.

  Further, as in the invention according to claim 4, in the multipoint dividing optical device according to claim 1, the first lens part (10) and the second lens part (20) are integrally molded. It may be what was done.

  Accordingly, the number of parts can be further reduced, and the configuration can be made smaller and excellent in vibration resistance.

  According to a fifth aspect of the present invention, in the optical device for multipoint division according to the first to fourth aspects, the second lens portion (20) is arranged in series spaced apart on the optical path. It consists of two lenses (20a, 20b).

  According to this, the focal length (L) of the emitted light can be made variable by adjusting the distance between the two lenses (20a, 20b) constituting the second lens portion (20), preferable.

  According to a sixth aspect of the present invention, in the optical device for multipoint division according to any one of the first to fifth aspects, the light is a laser beam, and the second lens unit (divided into the multipoints) The laser beam emitted from 20) is used for ignition by being guided to a combustion chamber of an engine.

  As described above, the multi-point splitting optical device according to claim 1 having a small size, a small number of parts, and excellent vibration resistance is used as an optical system in a laser ignition device attached to an engine. It is preferable.

  In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

  The optical device for multipoint division shown in each of the following embodiments is a laser igniter used for igniting the incident light being laser light and the emitted laser light being guided to the combustion chamber of the engine. Although applied to an optical system, the application is not particularly limited to this.

(First embodiment)
FIG. 1 is a schematic sectional view of an optical device 100 for multipoint division according to the first embodiment of the present invention. 2, (a) is a view seen from the direction of arrow A in FIG. 1, ie, a left side view, (b) is a view seen from the direction of arrow B in FIG. 1, ie, a right side view, and (c) is FIG. It is a figure which shows the condensing position of the emitted laser beam R seen from the arrow B direction, ie, focus R1, R2, R3.

  As shown in FIG. 1, the multipoint splitting optical device 100 of the present embodiment divides an incident laser beam R into multipoints R1 to R3 and emits them. The first lens unit 10 located on the second side and the second lens unit 20 located on the outgoing side, and the laser beam R enters from the first lens unit 10 and passes through the second lens unit 20 to be emitted. It has come to be.

  A laser ignition device having such a multipoint division optical device 100 as an optical system includes, for example, a laser unit that oscillates laser light R and the multipoint division optical device 100 in a case that divides the apparatus main body. It is what was stored.

  Here, the laser unit can include a pumping light source that emits pumping light when current is applied, and an optical resonator that oscillates laser light R when the pumping light is incident. The pumping light source is composed of a semiconductor laser, a flash lamp, etc., and the optical resonator is, for example, a laser medium and a saturable absorber as a passive Q switch element arranged on the resonant optical path, and mirrors at both ends thereof. It can be configured as an arranged resonator.

  In this case, the laser medium emits light when excited, and is excited when incident excitation light emitted from an excitation light source is incident.

  Further, the saturable absorber has a smaller absorption as the incident light power increases, and absorbs the incident light when the incident light power is equal to or lower than the absorption saturation threshold. However, the incident light power does not exceed the absorption saturation threshold. When it exceeds, absorption is saturated and transparent. The saturable absorber is used as a passive Q switch element by utilizing such properties.

  The optical resonator resonates the light emitted from the laser medium when the saturable absorber is transparent, and emits a part of the light from the saturable absorber. .

  Although not limited thereto, for example, the laser medium is an Nd: YAG crystal, and the saturable absorber is a Cr: YAG crystal. In this case, as a pumping light source, a semiconductor laser light source that outputs pumping light having a wavelength of about 808 nm that can pump Nd ions contained in the laser medium to an upper level is used.

  As described above, in the laser ignition device according to the present embodiment, the laser light R is oscillated from the laser unit, and the laser light R is obtained by the multipoint splitting optical device 100 as an optical system shown in FIG. As the laser beam R divided into multipoints R1 to R3, it is led to the combustion chamber of the engine and used for ignition.

  In the multipoint splitting optical device 100 of the present embodiment, the first lens unit 10 is configured as a corner cube prism 10 in which the number of incident surfaces 11 is equal to the number of splits of the laser light R. The exit surface 12 of the corner cube prism 10 is a flat surface in this example.

  Further, the second lens unit 20 is configured as a thick drum lens 20 in which both the incident surface 21 and the emitting surface 22 are convex. Both convex surfaces 21 and 22 of the drum lens 20 are aspherical, and the aspherical shape is designed so that the light beam emitted from the corner cube prism 10 enters the incident surface 21 of the drum lens 20 perpendicularly. It is preferable.

  Both lens parts 10 and 20 are made of transparent glass or resin. However, particularly when used for engine ignition, a material having excellent heat resistance is preferable.

  In the corner cube prism 10 and the drum lens 20, the former exit surface 12 and the latter entrance surface 21 are arranged in contact with each other or in close proximity to each other. Is held by a holder such as the case (not shown).

  In such a multipoint splitting optical device 100, as indicated by a broken line in FIG. 1, when the laser light R is incident on the corner cube prism 10, the laser light R emitted from the corner cube prism 10 is multipoint. And is emitted from the drum lens 20 and condensed at the respective condensing positions R1 to R3.

  Here, the corner cube prism 10 changes the number of incident surfaces 11 depending on how many points the incident laser light R is divided into. In multipoint ignition, ignition at three points is considered to be the most efficient, and in this example, a division example of three points R1 to R3 is used. The shape connecting the three focal points (condensing positions) R1 to R3 of the divided laser beam R is a triangle having these three points R1 to R3 as vertices (see FIG. 2C). ).

  Here, the distance L1 from the exit surface 22 of the drum lens 20 to the focal points R1 to R3 in FIG. 1 is the back focus L1. FIG. 2C shows an inter-beam distance L2 that is a distance between the focal points R1 to R3, and a spot size D2 that is a beam size at the focal points R1 to R3 of the emitted laser light R. ing.

  That is, the incident surface 11 of the corner cube prism 10 of this example is divided into three incident surfaces 11 with the vertex 11a as the center when viewed from the incident side of the laser beam R as shown in FIG. .

  In this case, it is desirable that the vertex 11a of the corner cube prism 1 is one point. If the tip is missing or a surface is formed, four or more incident surfaces can be formed, and the vertex 11a is divided into four or more points. become. Therefore, when it wants to divide into 3 points | pieces R1-R3 like this example, a loss will become large.

  Note that the number of the incident surfaces 11 of the corner cube prism 10 may be equal to the number of divisions of the laser light R. In the example shown in FIG. 2A, the apex angle of the three incident surfaces 11 is 120 °, and each incident surface 11 is equally divided around the vertex 11a. However, each divided incident surface 11 is divided. May not be equivalent.

  For example, the area of each incident surface 11 may be different. By changing the area of the incident surface 11, the energy of the emitted laser light can be changed. Specifically, if the incident surface 11 is widened, the energy of the emitted laser light can be increased.

  In this example, the characteristics of the beam focused on the three points R1 to R3 and the parameters of the lens system have the following relationship.

  (1) To increase the inter-beam distance L2 between the three points R1 to R3, the prism apex angle θ (see FIG. 1) of the corner cube prism 10 which is the first lens unit is increased, or the second lens unit The diameter D2 (see FIG. 1) of the drum lens 20 is increased, or the back focus L1 is increased.

  (2) In order to reduce the spot size D2 at the focal points R1 to R3, it is desirable that the light beam emitted from the corner cube prism 10 is incident on the incident surface 21 of the drum lens 20 as perpendicularly as possible.

  (3) In order to divide the laser beam R equally into the three points R1 to R3, the laser beam R must be evenly incident on the three incident surfaces 11 of the corner cube prism 10.

  (4) In order to reduce loss factors such as light scattering to other than the main three points R1 to R3, the boundary portion of the incident surface 11 of the corner cube prism 10, for example, the boundary of each incident surface 11 in FIG. It is desirable to prevent the laser light R from entering the line or the vertex 11a.

  This will be specifically described with reference to FIG. As shown in FIG. 3A, the donut-shaped laser light R excluding the vertex 11 a is incident on the incident surface 11 of the corner cube prism 10. Further, as shown in FIG. 3B, the laser beam R is divided into three and is incident only on the three incident surfaces 11. In FIG. 3, hatched hatching is applied to the portion where the laser beam R is incident for convenience.

  The shape of the laser beam R shown in FIGS. 3A and 3B is preferably a symmetrical shape with the vertex 11a as the center, and these shapes are the light sources of the laser beam R. This can be easily realized by providing a shielding plate corresponding to each shape on the laser unit side.

  By the way, according to the present embodiment, in the multipoint splitting optical device 100 that divides and emits the incident laser beam R into multiple points, the first lens unit 10 positioned on the incident side of the laser beam R and the exit. The second lens unit 20 is located on the side, and the laser beam R is incident on the first lens unit 10 and emitted through the second lens unit 20. The lens portion is configured as a corner cube prism 10 in which the number of incident surfaces 11 is equal to the number of divisions of the laser light R. When the laser light R is incident on the corner cube prism 10, the laser emitted from the corner cube prism 10. It is possible to provide the multipoint splitting optical device 100 characterized in that the light R is split into multiple points and emitted from the second lens unit 20.

  Here, in the multipoint splitting optical device 100 of the present embodiment, the second lens unit 20 is configured as a drum lens in which both the incident surface 21 and the exit surface 22 are convex.

  Accordingly, the incident laser beam R is divided into multiple points by the corner cube prism 10 as the first lens unit, and the drum lens 20 as the second lens unit is divided into the laser beam R divided into multiple points. It is emitted from.

  As described above, in the present optical device 100, the laser beam R can be divided (beam split) and imaged by the number of two components, and the number of the incident surfaces 11 of the corner cube prism 10 can be changed. The number of points to be divided can be changed.

  Therefore, in the present optical device 100, if there are two lens portions 10 and 20, the number of parts does not change even if the number of divisions is changed, the device functions sufficiently, and the number of components of the device is at least two. That's it.

  In addition, the corner cube prism 10 and the drum lens 20 are two pieces, and they are in contact with each other at one point. Therefore, the space is saved, and there is almost no need to adjust the interval and inclination between the lens portions 10 and 20. Absent. Moreover, these two lens parts 10 and 20 can be simultaneously fixed with one holder.

  For this reason, the optical device 100 is small and space-saving, and it is possible to eliminate the necessity of adjusting the interval and inclination between the components as much as possible, and the jig for fixing the components is also minimized. The number can be reduced and the vibration resistance can be improved.

  As described above, according to the present embodiment, the multi-point dividing optical device 100 that divides incident light into multiple points and emits the light has a small size, a small number of parts, and an excellent vibration resistance. can do.

  Further, in the multipoint splitting optical device 100 of this embodiment, the light used is the laser light R, and the laser light R split into multiple points and emitted from the second lens unit 20 is the combustion of the engine. Used to ignite by being led into the chamber.

  The multi-point splitting optical device 100 of this embodiment having a small size and a small number of parts and excellent vibration resistance is suitable for use as an optical system in a laser ignition device attached to an engine. Simultaneous ignition is possible.

(Second Embodiment)
FIG. 4 is a schematic sectional view of an optical device 200 for multipoint division according to the second embodiment of the present invention.

  The multipoint splitting optical device 200 of the present embodiment also includes the first lens unit 10 located on the incident side of the laser light R and the second lens unit 20 located on the emission side, and the first lens unit. Is configured as a corner cube prism 10 in which the number of incident surfaces 11 is equal to the number of divisions of the laser beam R, and when the laser beam R is incident on the corner cube prism 10, the laser beam R emitted from the corner cube prism 10 is large. It is the same as that of the said 1st Embodiment that it divides | segments into a point and is radiate | emitted from the 2nd lens part 20. FIG.

  In this case, the forms of laser light incident and output on the multipoint splitting optical device 200 are substantially the same as those shown in FIG. 1 although there are changes in the focal length and the inter-beam distance. Three-point division is possible. Therefore, also in the present embodiment, it is possible to realize a configuration that is small in size, has a small number of parts, and has excellent vibration resistance.

  Here, in the first embodiment, the second lens unit 20 is the drum lens 20 in which the incident surface 21 and the exit surface 22 are both convex. However, in the second embodiment, the second lens unit 20 is shown in FIG. As described above, the second lens unit 20 is configured as a concave-convex lens in which the incident surface 21 has a convex shape and the output surface 22 has a concave shape.

  As described above, the second lens unit 20 may be an uneven lens. Also in this embodiment, the function of dividing the laser light incident by the corner cube prism 10 is the same, but by changing the surface shape, lens length, lens diameter, etc. of the second lens unit 20, The quality of the emitted laser light and the position of the focal point can be changed.

(Third embodiment)
FIG. 5 is a schematic sectional view of an optical device 300 for multipoint division according to the third embodiment of the present invention.

  The multipoint splitting optical device 300 of the present embodiment also includes the corner cube prism 10 as the first lens unit located on the incident side of the laser light R and the second lens unit 20 located on the emission side, When the laser light R is incident on the corner cube prism 10, the laser light R emitted from the corner cube prism 10 is divided into multiple points and emitted from the second lens unit 20. It is the same as that of the said embodiment.

  Therefore, also in the present embodiment, it is possible to realize a configuration that is small in size, has a small number of parts, and has excellent vibration resistance.

  Here, in the above embodiment, the first lens unit 10 and the second lens unit 20 are separate lens members. However, in the multipoint division optical device 300 of the present embodiment, FIG. As shown, the corner cube prism 10 that is the first lens unit 10 and the second lens unit 20 are formed integrally.

  In this case, the incident laser beam is divided into multiple points by the corner cube prism 10 as the first lens unit, and the laser beam divided into multiple points passes through the second lens unit 20 and is emitted. The light is emitted from the surface 22.

  Also in this case, the form of the laser beam incident on and output from the multipoint splitting optical device 300 is substantially the same as that shown in FIG. 1 although there are changes in the focal length, the inter-beam distance, and the like. Yes, 3-point division is possible.

  According to the present embodiment, the number of components is substantially one, and the number of components can be reduced as compared with each of the above-described embodiments, so that a configuration that is smaller and excellent in vibration resistance is realized. can do.

(Fourth embodiment)
FIG. 6 is a schematic sectional view of an optical device 400 for multipoint division according to the fourth embodiment of the present invention.

  The multipoint splitting optical device 400 of the present embodiment also includes the corner cube prism 10 as the first lens unit located on the incident side of the laser light R and the second lens unit 20 located on the emission side, When the laser light R is incident on the corner cube prism 10, the laser light R emitted from the corner cube prism 10 is divided into multiple points and emitted from the second lens unit 20. It is the same as that of the said embodiment.

  Therefore, also in the present embodiment, it is possible to realize a configuration that is small in size, has a small number of parts, and has excellent vibration resistance.

  Here, in the above embodiment, the second lens unit 20 is a single lens member. However, in this embodiment, as shown in FIG. 6, the second lens unit 20 is placed on the optical path. It is assumed to be composed of two lenses 20a and 20b spaced apart and arranged in series.

  In the example shown in FIG. 6, the two lenses 20a and 20b are formed by dividing the drum lens 20 in the middle of FIG. 1 and the second lens 20a and 20b are used to form the second lens 20a and 20b. The lens unit 20 is configured.

  According to this embodiment, the back focus L1 of the emitted light (see FIG. 1 above) can be varied by adjusting the distance L3 between the two lenses 20a and 20b constituting the second lens unit 20. And is preferable.

(Other embodiments)
The light used for the multipoint dividing optical device may be light other than laser light. In the above embodiment, the light that is divided into multiple points and emitted from the second lens unit 20 is used for ignition by being guided to the combustion chamber of the engine. It is not limited.

  In short, the present invention provides a first lens unit positioned on the light incident side and a second lens unit positioned on the output side in the multipoint splitting optical device that divides incident light into multiple points and emits the light. The light is incident from the first lens unit and emitted through the second lens unit, and the first lens unit has the number of incident surfaces equal to the number of divisions of the light. It is configured as an equal corner cube prism, and when light enters the corner cube prism, the light emitted from the corner cube prism is divided into multiple points and emitted from the second lens unit. The other parts can be appropriately changed in design.

1 is a schematic cross-sectional view of a multipoint splitting optical device according to a first embodiment of the present invention. (A) is a side view as viewed from the arrow A in FIG. 1, (b) is a side view as viewed from the arrow B in FIG. 1, and (c) is a laser beam R emitted when viewed from the direction of arrow B in FIG. FIG. (A) is a figure which shows the example which made the incident shape of the laser beam a donut shape, (b) is a figure which shows the example which made the incident shape of the laser beam a division | segmentation shape. It is a schematic sectional drawing of the optical apparatus for multipoint division | segmentation which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing of the optical apparatus for multipoint division | segmentation which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing of the optical apparatus for multipoint division | segmentation which concerns on 4th Embodiment of this invention.

Explanation of symbols

10 ... Corner cube prism as the first lens unit,
11: Entrance surface of the corner cube prism, 12 ... Output surface of the corner cube prism,
20 ... 2nd lens member, 20a, 20b ... Lens which comprises 2nd lens member,
21 ... Incident surface of the second lens member, 22 ... Output surface of the second lens member.

Claims (6)

In the multi-point splitting optical device that splits the incident light into multiple points and emits it,
The first lens portion (10) located on the light incident side and the second lens portion (20) located on the emission side,
The light is incident from the first lens portion (10), passes through the second lens portion (20), and is emitted.
The first lens unit is configured as a corner cube prism (10) in which the number of incident surfaces (11) is equal to the number of divisions of the light,
When the light is incident on the corner cube prism (10), the light emitted from the corner cube prism (10) is divided into multiple points and emitted from the second lens unit (20). An optical device for multipoint division characterized by the above. 2. The multi-point splitting device according to claim 1, wherein the second lens portion is configured as a drum lens having both a light incident surface and a light exit surface. Optical device. The multiplicity according to claim 1, wherein the second lens portion (20) is configured as a concave-convex lens in which the incident surface (21) has a convex shape and the output surface (22) has a concave shape. Optical device for point division. The multipoint splitting optical device according to claim 1, wherein the first lens portion (10) and the second lens portion (20) are integrally formed. The said 2nd lens part (20) consists of two lenses (20a, 20b) spaced apart and arranged in series on the optical path, In any one of Claim 1 thru | or 4 characterized by the above-mentioned. The optical device for multipoint division as described. The light is laser light, and the laser light divided into the multiple points and emitted from the second lens unit (20) is guided to the combustion chamber of the engine and used for ignition. The optical device for multipoint division according to any one of claims 1 to 5.

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