JP2014168021A - Optical assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve miniaturization, without degrading light quality, in an optical assembly emitting a multicolor laser beam.SOLUTION: A red LD chip 14, a green LD chip 15, and a blue LD chip 16 are mounted on an optical assembly 1. The respective LD chips are mounted on the main surface 20 of a block 11 through sub-mounts 17, 18, and 19 corresponding to the LD chips respectively. An optical system 13 for a plurality of laser beams emitted from the plurality of LD chips is mounted on the block 11. The optical system 13 condenses the plurality of laser beams on a focus P1 being outside the optical assembly 1 through a condenser lens 4.

Description

The present invention relates to an optical assembly.

Patent document 1 discloses the technique which concerns on a light source device and a head mounted display. The light source device includes a green laser diode, a blue laser diode, a red laser diode, and a dichroic prism that selectively transmits and refracts light therefrom. The green laser diode generates the largest amount of heat and has a large radiator in the light source device. The green laser diode is provided at a position facing the emission port across the dichroic prism. The width of the radiator is formed to be narrower than the width from the outside of the blue laser diode to the outside of the red laser diode.

Patent document 2 discloses the technique which concerns on a multiwavelength light source device. The multi-wavelength light source device has a plurality of LD chips mounted in a coaxial module, and condenses each emitted light at one point by one condensing lens. The multi-wavelength light source device includes a light source, a condensing unit, and a light guiding unit. The light source includes a plurality of ignition points that emit light. A condensing means condenses the some light radiate | emitted from the some ignition point. The light guide means propagates so that a plurality of lights from a plurality of ignition points collected by the light collecting means are overlapped and mixed.

Patent Document 3 discloses a technique related to an image display device. The image display device collects red, blue, and green LD lights and displays a color image. The image display device displays an image by scanning light on the projection surface. The image display device includes a drive signal generation unit, a light source, a scanning unit, an irradiation position detection unit, and a correction unit. The drive signal generation unit generates a drive signal corresponding to the gradation signal indicating the display image. The light source generates light having a light amount corresponding to the drive signal. The scanning unit scans the light generated from the light source on the projection surface. The irradiation position detection means detects the irradiation position of light on the projection surface. The correction unit outputs a correction signal for correcting the drive signal according to the irradiation position to the drive signal generation unit. The drive signal generation unit corrects the drive signal based on the correction signal.

Patent Document 4 discloses a technique related to a design method of an LED light source device and the LED light source device. The LED light source device shapes red, green, and blue beams with collimating lenses, and combines the wavelengths with a dichroic mirror. The LED light source device includes an LED element, a plurality of collimator lens groups, a dichroic mirror group, a condenser lens group, and a light tunnel. The LED element emits each primary color light. Each light source of red, green, and blue is mounted in a separate package. The plurality of collimator lens groups modulate light emitted from the plurality of LED elements into parallel light, respectively. The dichroic mirror group synthesizes parallel light output from a plurality of collimator lens groups. The condenser lens group condenses the combined light of the dichroic mirror group. The light tunnel makes the light quantity distribution of the light collected by the condenser lens group uniform. The output light of the light tunnel 5 is optically modulated by the reflection type light modulation element. The LED light source device and the reflective light modulation element are mounted on the image projection device. The condenser lens group is adjusted in accordance with the element having the largest etendue among the reflection type light modulation elements that can be mounted on the image projection apparatus.

JP 2011-171535 A JP 2011-066028 A JP 2008-309935 A JP 2012-141383 A

In recent years, liquid crystal displays have become widespread. Technological development for mobile applications of LCDs is ongoing. On the other hand, a display using an LD light source is excellent in low power consumption, high definition, and versatility compared with a white LED used for a backlight of a liquid crystal display. Therefore, it has been studied to apply a display using an LD light source to a small projector, a head mounted display, a head up display, or the like. In such a display, a plurality of laser beams from a plurality of LD light sources of the three primary colors of red, green, and blue are superposed with each other in order to obtain a colorful image quality. In order to superimpose the three primary colors, a wavelength filter that combines the respective wavelengths, and the combined light, such as MEMS (Micro Electro Mechanical Systems), DLP (Digital Light Processing), LCOS (Liquid Crystal On Silicon), etc. An optical system for leading to the image sensor is required. In such a module including a plurality of LD light sources, wavelength filters, and an optical system, the LD light source is a point light source, but the beam divergence angle needs to be relatively narrow, such as about 10 degrees × 20 degrees. A relatively precise optical axis adjustment is required for the filter and the like.

When the three primary color LD light sources are mounted in separate packages, it is difficult to reduce the size of the module. When a plurality of LD light sources corresponding to red, green, and blue are mounted in separate packages, a plurality of lenses and a plurality of filters corresponding to the size of each package must be mounted. A large module. Further, when adjusting the LD light source and the lens, it is necessary to use a lens having a large focal length, that is, a lens having a large lens diameter, in order to increase the mounting tolerance. Patent Document 2 discloses one coaxial module on which a plurality of LD chips are mounted. However, since light from a plurality of LDs is collected by a single lens, chromatic aberration (wavelengths are different). Compensation of the focal length deviation due to the light becomes difficult, and the light quality deteriorates. Accordingly, an object of the present invention has been made in view of the above-described matters, and is to realize a reduction in size without degrading light quality in an optical assembly that emits multicolor laser light.

The optical assembly according to the present invention includes a plurality of LD chips, and each of the plurality of LD chips is mounted on a block via a submount corresponding to each of the plurality of LD chips. Above, an optical system for a plurality of laser beams emitted from the plurality of LD chips is mounted, and the optical system substantially converts each of the plurality of laser beams into collimated light. And As described above, the optical system included in the optical assembly converts the laser light emitted from each of the plurality of LD chips into collimated light and multiplexes them. Therefore, since the laser beams of a plurality of colors can be condensed at one point by only one optical system, the optical assembly can be downsized. In addition, if the optical system with which alignment was performed suitably is used, the light quality of an optical assembly will also be maintainable.

In the present invention, the plurality of LD chips emit laser light having wavelengths corresponding to red, green, and blue. Since it is possible to output red laser light, green laser light, and blue laser light, multicolor can be realized.

In the present invention, the optical system further includes a plurality of wavelength selective filters for multiplexing the plurality of collimated lights. A plurality of laser beams are combined as collimated light by a plurality of lenses mounted corresponding to each of the plurality of LD chips and a plurality of wavelength selective filters that combine the plurality of laser beams.

In the present invention, the optical system is mounted on a base. The optical system can be mounted on a single base and is configured compactly, so that the optical assembly can be miniaturized.

In the present invention, the base is made of glass and has a structure indicating a fixed position of the optical system. Since the base material is glass, it can be made of the same material as that of a plurality of lenses of the optical system. Therefore, the thermal expansion coefficient of the base can be made the same as that of the optical system. Further, the structure indicating the fixed position of the optical system makes the position of the optical system relative to the base more precise than when there is no such structure.

In the present invention, the structure is a plurality of recesses formed in the main surface of the base. When the structure indicating the fixing position of the optical system is a plurality of concave portions, the optical system can be mechanically adjusted to a suitable position by these concave portions.

In this invention, the said block has a recessed part which accommodates the said base, It is characterized by the above-mentioned. The base is stably held on the block by the recess of the block.

In the present invention, the depth of the concave portion of the block is the same as the thickness of the base. The main surface provided with the concave portion of the block and the main surface of the base can be provided on one surface without a step.

In the present invention, the plurality of LD chips are mounted on the block so that a light emission direction of one LD chip and a light emission direction of another LD chip form 90 degrees. It is characterized by that. Since a plurality of light emitting directions of the plurality of LD chips form 90 degrees with each other, a plurality of laser beams from the plurality of LD chips can be combined only by reflection of 90 degrees. Therefore, the configuration of the optical system can be simplified.

In the present invention, each of the plurality of lenses is a spherical lens.

According to the present invention, it is possible to reduce the size of an optical assembly that emits multi-color laser light without deteriorating light quality.

It is a figure which shows the structure of the optical assembly 1 which concerns on embodiment. FIG. 3 is a diagram illustrating a cross-sectional configuration of the optical assembly 1. 3 is a flowchart for explaining main steps of a method for manufacturing the optical assembly 1; 6 is a diagram for explaining a method of manufacturing the optical assembly 1. FIG. 6 is a diagram for explaining a method of manufacturing the optical assembly 1. FIG. 6 is a diagram for explaining a method of manufacturing the optical assembly 1. FIG. 6 is a diagram for explaining a method of manufacturing the optical assembly 1. FIG. It is a figure which shows the result of having calculated the position shift and magnitude | size of the light emission pattern of the laser beam accompanying the position shift (offset amount) of the lens which collimates a laser beam. It is a figure which shows the result of having calculated the change of the position shift of a light emission pattern when changing the position shift of a lens with 1 micrometer, 5 micrometers, and 10 micrometers from a design position.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, if possible, the same elements are denoted by the same reference numerals, and redundant description is omitted. First, the configuration of the optical assembly 1 will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram illustrating a configuration of an optical assembly 1 according to the embodiment.

The optical assembly 1 combines red laser light, green laser light, and blue laser light (a plurality of LD chips) and rides the combined laser light on the reference optical axis L1 of the optical assembly 1 (reference optical axis L1). (In parallel). The optical assembly 1 emits the combined laser light to the outside of the optical assembly 1 along the reference optical axis L1 of the optical assembly 1, and condenses it at one point (focal point P1) outside the optical assembly 1. The focal point P1 is on the reference optical axis L1 of the optical assembly 1.

The optical assembly 1 includes a stem 2, a cap 3, a condenser lens 4, a lead pin 5, a lead pin 6, a lead pin 7, and a lead pin 8. The cap 3 holds the condenser lens 4. The condenser lens 4 is above the main surface 9 of the stem 2 and on the reference optical axis L1 of the optical assembly 1. The main surface 9 has a diameter of 5.6 mm, for example. The lead pin 5 protrudes on the main surface 9 of the stem 2. The lead pin 5 is electrically insulated from the stem 2. The lead pin 6 protrudes on the main surface 9 of the stem 2. The lead pin 6 is electrically insulated from the stem 2. The lead pin 7 projects on the main surface 9 of the stem 2. The lead pin 7 is electrically insulated from the stem 2. The lead pin 8 is electrically connected to the stem 2.

The optical assembly 1 further includes a block 11, a base 12, an optical system 13, a red LD chip 14, a green LD chip 15, a blue LD chip 16, a submount 17, a submount 18, and a submount 19. Block 11, base 12, optical system 13, red LD chip 14, green LD chip 15, blue LD chip 16, submount 17, submount 18, and submount 19 are fixed on main surface 9 of stem 2, Hermetic sealing is performed by the stem 2 and the cap 3. The optical system 13 is fixed to the main surface 20 of the base 12. The block 11 extends vertically on the main surface 9 of the stem 2. The block 11 functions as a heat sink. The main surface 21 of the block 11 extends perpendicularly to the main surface 9 of the stem 2. The main surface 21 of the block 11 is electrically connected to the lead pin 8 via the stem 2. The material of the base 12 is, for example, glass having the same thermal expansion coefficient as the lens 22, the lens 23, the lens 24, the wavelength selective filter 25, and the wavelength selective filter 26 of the optical system 13. The external shape of the base 12 is, for example, 1 mm × 1 mm × 0.5 mm.

The red LD chip 14 is fixed on the main surface 21 of the block 11 via the submount 17. The green LD chip 15 is fixed on the main surface 21 of the block 11 via the submount 18. The blue LD chip 16 is fixed on the main surface 21 of the block 11 via a submount 19. The material of the submount 17, the submount 18, and the submount 19 matches the material of the red LD chip 14, the green LD chip 15, and the blue LD chip 16, and for example, any of AlN, SiC, Si, diamond, etc. It is. Each of the submount 17, the submount 18, and the submount 19 is fixed to each of the red LD chip 14, the green LD chip 15, and the blue LD chip 16 by, for example, AuSn paste, SnAgCu paste, Ag paste, or the like. Has been.

The submount 17 is fixed to the main surface 21 of the block 11. The red LD chip 14 is fixed to the submount 17. The joint surface between the submount 17 and the red LD chip 14 is electrically connected to the main surface 21 of the block 11 via the wire W2. One electrode of the red LD chip 14 is electrically connected to the lead pin 8 via the joint surface of the submount 17 and the red LD chip 14, the wire W2, the main surface 21 of the block 11, and the stem 2. The The other electrode of the red LD chip 14 is electrically connected to the lead pin 5 through the wire W1.

The submount 18 is fixed to the main surface 21 of the block 11. The green LD chip 15 is fixed to the submount 18. The joint surface between the green LD chip 15 and the submount 18 is electrically connected to the main surface 21 of the block 11 through the wire W3. One electrode of the green LD chip 15 is electrically connected to the lead pin 8 via the joint surface of the submount 18 and the green LD chip 15, the wire W3, the main surface 21 of the block 11, and the stem 2. The The other electrode of the green LD chip 15 is electrically connected to the lead pin 6 through the wire W4.

The submount 19 is fixed to the main surface 21 of the block 11. The blue LD chip 16 is fixed to the submount 19. The joint surface between the blue LD chip 16 and the submount 19 is electrically connected to the main surface 21 of the block 11 via the wire W5. One electrode of the blue LD chip 16 is electrically connected to the lead pin 8 via the joint surface of the submount 19 and the blue LD chip 16, the wire W5, the main surface 21 of the block 11, and the stem 2. The The other electrode of the blue LD chip 16 is electrically connected to the lead pin 7 through the wire W6.

The main surface 20 of the base 12 extends parallel to the reference optical axis L1. The main surface 20 of the base 12 extends in parallel with the main surface 21 of the block 11. The base 12 is accommodated in the recess 28 of the block 11. The base 12 is supported by the side wall of the recess 28. The thickness D1 of the base 12 is the same as the depth D2 of the recess 28. The main surface 20 of the base 12 is connected to the main surface 21 of the block 11 without a step. The main surface 20 of the base 12 and the main surface 21 of the block 11 are both in one plane parallel to the reference optical axis L1.

The optical system 13 is fixed to the main surface 20 of the base 12. The optical system 13 includes a lens 22, a lens 23, a lens 24, a wavelength selective filter 25, and a wavelength selective filter 26. The lens 22, the lens 23, and the lens 24 are spherical lenses. The lens 22, the lens 23, and the lens 24 all function as a collimating lens. The lens 22 transmits the red laser light emitted from the red LD chip 14. The red laser light emitted from the lens 22 is substantially collimated light. The lens 23 transmits the green laser light emitted from the green LD chip 15. The green laser light emitted from the lens 23 is substantially collimated light. The lens 24 transmits the blue laser light emitted from the blue LD chip 16. The blue laser light emitted from the lens 24 is substantially collimated light. The wavelength selective filter 25 transmits the red laser light emitted from the red LD chip 14. The wavelength selective filter 25 reflects the green laser light emitted from the green LD chip 15. The wavelength selective filter 26 transmits the red laser light emitted from the red LD chip 14 and the green laser light emitted from the green LD chip 15. The wavelength selective filter 26 reflects the blue laser light emitted from the blue LD chip 16. The wavelength selective filter 25 multiplexes the collimated red laser light and the collimated green laser light. The wavelength selective filter 26 multiplexes the collimated red laser light, the collimated green laser light, and the collimated blue laser light. The wavelength of the red LD chip 14 is, for example, about 640 nm, the wavelength of the green LD chip 15 is, for example, about 535 nm, and the wavelength of the blue LD chip 16 is, for example, about 440 nm.

The red LD chip 14, the lens 22, the wavelength selective filter 25, the wavelength selective filter 26, and the condenser lens 4 are sequentially arranged from the side closer to the main surface 9 on the reference optical axis L1. The green LD chip 15, the lens 23, and the wavelength selective filter 25 are sequentially arranged in a direction that forms 90 degrees with the reference optical axis L1. The blue LD chip 16, the lens 24, and the wavelength selective filter 26 are sequentially arranged in a direction that forms 90 degrees with the reference optical axis L1.

The light emitting direction K1 of the red LD chip 14 coincides with the reference optical axis L1. The red laser light emitted from the red LD chip 14 in the light emission direction K1 is aligned with the reference optical axis L1 via the lens 22, the wavelength selective filter 25, and the wavelength selective filter 26, Progress toward the focal point P1. The red laser light emitted from the red LD chip 14 in the light emission direction K 1 passes through the center of the lens 22.

The light emitting direction K2 of the green LD chip 15 is a direction that forms 90 degrees with the reference optical axis L1. The green laser light emitted from the green LD chip 15 in the light emission direction K2 reaches the wavelength selective filter 25 through the lens 23, and the wavelength selective filter 25 causes the green laser light to be in a direction that forms 90 degrees with the light emission direction K2. The reflected light travels through the wavelength selective filter 26 along the reference optical axis L1 (in parallel with the reference optical axis L1) toward the condenser lens 4 and the focal point P1. The green laser light emitted from the green LD chip 15 in the light emission direction K2 passes through the center of the lens 23.

The light emitting direction K3 of the blue LD chip 16 is a direction that forms 90 degrees with the reference optical axis L1. The blue laser light emitted from the blue LD chip 16 in the light emission direction K3 reaches the wavelength selective filter 26 via the lens 24, and the wavelength selective filter 26 forms 90 degrees with the light emission direction K3. The reflected light travels along the reference optical axis L1 (parallel to the reference optical axis L1) toward the condenser lens 4 and the focal point P1. The green laser light emitted from the blue LD chip 16 in the light emitting direction K3 passes through the center of the lens 24. The red laser light emitted from the red LD chip 14, the green laser light emitted from the green LD chip 15, and the blue laser light emitted from the blue LD chip 16 are combined and combined by the optical system 13. The wave light travels from the wavelength selective filter 26 of the optical system 13 toward the condenser lens 4 and the focal point P1 along the reference optical axis L1.

For example, the thickness of the submount 17 (the length from the main surface 20 to the bonding surface between the red LD chip 14 and the submount 17) is 0.15 mm, and the height of the light emitting layer (active layer) of the red LD chip 14 is high. When the length (the length from the joining surface of the red LD chip 14 and the submount 17 to the light emitting layer of the red LD chip 14) is 0.1 mm, the length from the main surface 20 to the light emitting position of the red LD chip 14 is 0.25 mm. In this case, when the lens 22 is, for example, BK-7 and has a diameter of 0.5 mm, the center of the lens 22 is at a position of 0.25 mm from the main surface 20, so when the lens 22 is placed on the surface of the submount 17. The center of the lens 22 and the light emission position of the red LD chip 14 substantially coincide with each other from the main surface 20.

FIG. 2 is a diagram showing a cross-sectional configuration of the optical assembly 1 taken along the line II shown in FIG. The cross section shown in FIG. 2 is perpendicular to the main surface 9 of the stem 2, is parallel to the reference optical axis L 1 of the optical assembly 1, and is parallel to the main surface 21 of the block 11. The red laser light emitted from the red LD chip 14 in the light emission direction K1 passes through the center of the lens 22, matches the reference optical axis L1, passes through the wavelength selective filter 25 and the wavelength selective filter 26, and Head toward the condenser lens 4. The green laser light emitted from the green LD chip 15 in the light emission direction K2 travels in a direction that forms 90 degrees with the reference optical axis L1, reaches the wavelength selective filter 25 through the center of the lens 23, and is wavelength selective. Reflected by the filter 25, the traveling direction changes by 90 degrees and becomes parallel to the reference optical axis L 1, passes through the wavelength selective filter 26, and travels toward the condenser lens 4. The blue laser light emitted from the blue LD chip 16 in the light emission direction K3 travels in a direction that forms 90 degrees with the reference optical axis L1, reaches the wavelength selective filter 26 through the center of the lens 24, and is wavelength selective. Reflected by the filter 26, the traveling direction changes by 90 degrees, becomes parallel to the reference optical axis L 1, and moves toward the condenser lens 4.

The condensing lens 4 receives a combined light in which the red laser light from the red LD chip 14, the green laser light from the green LD chip 15, and the blue laser light from the blue LD chip 16 are combined. The combined light is collected at the focal point P1. The red laser light, green laser light, and blue laser light constituting the combined light incident on the condenser lens 4 all travel in parallel to the reference optical axis L1 and enter the condenser lens 4.

FIG. 3 is a flowchart for explaining the main steps of the method for manufacturing the optical assembly 1. In step S1, as shown in FIG. 4, the block 11 in which the red LD chip 14, the green LD chip 15, and the blue LD chip 16 are fixed to the main surface 21 through the submount 17, the submount 18, and the submount 19, respectively. The base 12 is fitted into the recess 28 of the base plate, and the base 12 is fixed to the block 11 with UV curable resin. The submount 17 is provided with a mark indicating the fixing position of the red LD chip 14. The red LD chip 14 is arranged and fixed on the submount 17 in accordance with this mark provided on the submount 17. The submount 18 is provided with a mark indicating the fixing position of the green LD chip 15. The green LD chip 15 is arranged and fixed on the submount 18 according to the mark provided on the submount 18. The submount 19 is provided with a mark indicating the fixing position of the blue LD chip 16. The blue LD chip 16 is arranged and fixed on the submount 19 in accordance with this mark provided on the submount 19. On the main surface 21 of the block 11, a plurality of marks indicating the fixing positions of the submount 17, the submount 18, and the submount 19 are provided. Each of the submount 17, the submount 18, and the submount 19 is arranged and fixed in accordance with each of the plurality of marks provided on the main surface 21 of the block 11.

The red LD chip 14 is connected to the lead pin 5 via the wire W1, and the submount 17 is connected to the block 11 via the wire W2, so that a drive current can be supplied to the red LD chip 14 via the lead pin 5. It has become. The green LD chip 15 is connected to the lead pin 6 via the wire W4, and the submount 18 is connected to the block 11 via the wire W3, so that a drive current can be supplied to the green LD chip 15 via the lead pin 6. It has become. The blue LD chip 16 is connected to the lead pin 7 via the wire W6, and the submount 19 is connected to the block 11 via the wire W5. Therefore, the drive current can be supplied to the blue LD chip 16 via the lead pin 7. It has become.

In step S1, the optical system 13 is not mounted on the base 12 shown in FIG. On the main surface 20 of the base 12, an instruction mark M1, an instruction mark M2, an instruction mark M3, an instruction mark M4, and an instruction mark M5 are provided in advance. The instruction mark M1, the instruction mark M2, the instruction mark M3, the instruction mark M4, and the instruction mark M5 have a structure that indicates a fixed position of the optical system 13 with respect to the main surface 20 of the base 12. The instruction mark M1 indicates a fixed position of the lens 22. The instruction mark M2 indicates a fixed position of the lens 23. The instruction mark M3 indicates a fixed position of the lens 24. The instruction mark M4 indicates a fixed position of the wavelength selective filter 25. The instruction mark M5 indicates a fixed position of the wavelength selective filter 26. Note that each of the instruction mark M1, the instruction mark M2, the instruction mark M3, the instruction mark M4, and the instruction mark M5 can be a recess provided in the main surface 20.

In step S2, the two-dimensional sensor 29 and the display device 30 shown in FIG. 5 are used. In step S <b> 2, a two-dimensional sensor 29 for imaging the light emission patterns of the red LD chip 14, the green LD chip 15, and the blue LD chip 16 is installed on the reference optical axis L <b> 1 of the optical assembly 1. The two-dimensional sensor 29 is, for example, a CCD camera. The display device 30 includes a monitor screen 31. The display device 30 is connected to the two-dimensional sensor 29. The monitor screen 31 displays a two-dimensional image picked up by the two-dimensional sensor 29, particularly a light emission pattern of the red LD chip 14, the green LD chip 15, and the blue LD chip 16 irradiated on the light incident surface 32 of the two-dimensional sensor 29. ,indicate. The screen center C1 of the monitor screen 31 is adjusted to coincide with the reference optical axis L1. The reference line A1 of the monitor screen 31 is adjusted so as to be parallel to the main surface 21. The light incident surface 32 of the two-dimensional sensor 29 is separated from the upper surface of the block 11 by a distance D3. The distance D3 in this embodiment is about 1 meter. The light incident surface 32 intersects and is orthogonal to the reference optical axis L1.

Furthermore, in step S2, the light reflector 33 and the light reflector 34 are used. The light reflector 33 and the light reflector 34 may be a prism, for example. The light reflector 33 includes a light reflecting surface 35. The light reflector 34 includes a light reflecting surface 36. The light reflector 33 changes the optical path of the green laser light emitted from the green LD chip 15 in the light emitting direction K2 by 90 degrees by the light reflecting surface 35 and directs it on the main surface 9 of the stem 2 so that green light is emitted. The green laser beam of the LD chip 15 is incident on the light incident surface 32. The light reflector 34 changes the optical path of the blue laser light emitted from the blue LD chip 16 in the light emitting direction K3 by 90 degrees by the light reflecting surface 35 and directs it on the main surface 9 of the stem 2 so that blue light is emitted. The blue laser light of the LD chip 16 is incident on the light incident surface 32. The light reflecting surface 35 is inclined 45 degrees with respect to the light emitting direction K2 of the green LD chip 15 and is inclined 45 degrees with respect to the reference optical axis L1. The light reflecting surface 36 is inclined 45 degrees with respect to the light emitting direction K3 of the blue LD chip 16 and is inclined 45 degrees with respect to the reference optical axis L1.

In step S3, the position of the lens 22 corresponding to the red LD chip 14 is adjusted on the main surface 20 of the base 12 so that the optical path of the red laser light emitted from the lens 22 coincides with the reference optical axis L1, After the adjustment, the lens 22 is fixed to the main surface 20 of the base 12. This will be specifically described. First, after the arrangement of the two-dimensional sensor 29, the display device 30, the light reflector 33, and the light reflector 34, the red LD chip 14 is caused to emit light in a state where the lens 22 is disposed on the indication mark M <b> 1 provided on the main surface 20. . Then, the fixing position of the lens 22 on the main surface 20 is adjusted while observing the light emission pattern of the red LD chip 14 displayed on the monitor screen 31. 6A shows a monitor screen 31 on which the light emission pattern of the red LD chip 14 is displayed. Adjust and adjust the fixed position of the lens 22 so that the light emission pattern of the red LD chip 14 displayed on the monitor screen 31 is displayed as a circle like the light emission pattern image B1 and on the screen center C1. Later, the lens 22 is fixed to the main surface 20 of the base 12 with a UV curable resin. When the light emission direction K1 of the red LD chip 14 does not pass through the center of the lens 22, the light emission pattern of the red LD chip 14 displayed on the monitor screen 31 is an elliptical shape such as the light emission pattern image B2 and the light emission pattern image B3. Or displayed at a location away from the center C1 of the screen. When the light emission direction K1 of the red LD chip 14 passes through the center of the lens 22, the light emission pattern of the red LD chip 14 displayed on the monitor screen 31 is displayed as a circle like the light emission pattern image B1 and the screen center C1. Displayed above. By step S3, the light emission direction K1 of the red LD chip 14 coincides with the reference optical axis L1 of the optical assembly 1.

In step S4, the position of the lens 23 corresponding to the green LD chip 15 is adjusted on the main surface 20 of the base 12 so that the optical path of the green laser light emitted from the lens 23 forms 90 degrees with the reference optical axis L1. After the adjustment, the lens 23 is fixed to the main surface 20 of the base 12 using a UV curable resin. This will be specifically described. The red LD chip 14 and the green LD chip 15 are caused to emit light while the lens 23 is disposed on the instruction mark M2 provided on the main surface 20. The fixing position of the lens 23 on the main surface 20 is adjusted while observing the light emission pattern of the red LD chip 14 displayed on the monitor screen 31 and the light emission pattern of the green LD chip 15 displayed on the monitor screen 31. . The adjustment of the lens 23 using the light emission pattern of the green LD chip 15 is performed in the same manner as the adjustment of the lens 22 described above. The light emission pattern of the green LD chip 15 (light emission pattern image B4 in part (B) of FIG. 6) is displayed in a circle on the monitor screen 31 after adjustment, and is displayed on the reference line A1.

In step S5, the position of the lens 24 corresponding to the blue LD chip 16 is adjusted on the main surface 20 of the base 12 so that the optical path of the blue laser light emitted from the lens 24 forms 90 degrees with the reference optical axis L1. After the adjustment, the lens 24 is fixed to the main surface 20 of the base 12 using a UV curable resin. This will be specifically described. The red LD chip 14, the green LD chip 15, and the blue LD chip 16 are caused to emit light with the lens 24 disposed on the instruction mark M <b> 3 provided on the main surface 20. The light emission pattern of the red LD chip 14 displayed on the monitor screen 31, the light emission pattern of the green LD chip 15 displayed on the monitor screen 31, and the light emission pattern of the blue LD chip 16 displayed on the monitor screen 31. While observing, the fixing position of the lens 24 on the main surface 20 is adjusted. Adjustment of the lens 24 using the light emission pattern of the blue LD chip 16 is performed in the same manner as the adjustment of the lens 22 described above. The light emission pattern of the blue LD chip 16 (light emission pattern image B5 in part (B) of FIG. 6) is displayed in a circle on the monitor screen 31 after adjustment, and is displayed on the reference line A1. Note that the execution order of step S4 and step S5 can be the reverse of the order shown in FIG.

6B, the light emission pattern image B1 after adjustment of the red LD chip 14, the light emission pattern image B4 after adjustment of the green LD chip 15, and the light emission pattern image B5 after adjustment of the blue LD chip 16 are shown. Is shown on the monitor screen 31. The light emission pattern image B1 after adjustment of the red LD chip 14, the light emission pattern image B4 after adjustment of the green LD chip 15, and the light emission pattern image B5 after adjustment of the blue LD chip 16 are the reference lines on the monitor screen 31. It is arranged in a row on A1.

In step S6, the wavelength selective filter 25 corresponding to the green LD chip 15 is set so that the optical path of the green laser light reflected by the wavelength selective filter 25 is parallel to the reference optical axis L1, as shown in FIG. It adjusts on the main surface 20 of the base 12, and it fixes to the main surface 20 of the base 12 using UV hardening resin after adjustment. This will be specifically described. The red LD chip 14 and the green LD chip 15 emit light while the wavelength selective filter 25 is disposed on the instruction mark M4 provided on the main surface 20. The fixed position of the wavelength selective filter 25 on the main surface 20 while observing the light emission pattern of the red LD chip 14 displayed on the monitor screen 31 and the light emission pattern of the green LD chip 15 displayed on the monitor screen 31. (Mainly, the inclination of the reflection surface of the wavelength selective filter 25 with respect to the reference optical axis L1 is adjusted). The fixed position of the wavelength selective filter 25 is adjusted so that the light emission pattern image B4 of the green LD chip 15 shown in part (B) of FIG. 6 overlaps the light emission pattern image B1.

In step S7, the position of the wavelength selective filter 26 corresponding to the blue LD chip 16 is set so that the optical path of the blue laser light reflected by the wavelength selective filter 26 is parallel to the reference optical axis L1, as shown in FIG. As described above, the adjustment is performed on the main surface 20 of the base 12, and the wavelength selective filter 26 is fixed to the main surface 20 of the base 12 using the UV curable resin after the adjustment. This will be specifically described. The red LD chip 14, the green LD chip 15, and the blue LD chip 16 are caused to emit light in a state where the wavelength selective filter 26 is disposed on the instruction mark M 5 provided on the main surface 20. The light emission pattern of the red LD chip 14 displayed on the monitor screen 31, the light emission pattern of the green LD chip 15 displayed on the monitor screen 31, and the light emission pattern of the blue LD chip 16 displayed on the monitor screen 31. While observing, the fixed position of the wavelength selective filter 26 on the main surface 20 is adjusted (mainly adjusting the inclination of the reflection surface of the wavelength selective filter 26 with respect to the reference optical axis L1). The fixed position of the wavelength selective filter 26 is adjusted so that the light emission pattern image B5 of the blue LD chip 16 shown in part (B) of FIG. 6 overlaps the light emission pattern image B1.

After step S7, the red laser light of the red LD chip 14, the green laser light of the green LD chip 15, and the blue laser light of the blue LD chip 16 are combined and applied to the light incident surface 32 of the two-dimensional sensor 29. Therefore, the light emission pattern of the adjusted red LD chip 14 displayed on the monitor screen 31, the light emission pattern of the adjusted green LD chip 15 displayed on the monitor screen 31, and the adjustment displayed on the monitor screen 31. The light emission pattern of the subsequent blue LD chip 16 overlaps each other on the screen center C1 and is displayed on the monitor screen 31 as a light emission pattern image B6, as shown in part (C) of FIG. The light emission pattern image B6 is on the screen center C1.

The wavelength selective filter 25 and the wavelength selective filter 26 are arranged on the reference optical axis L1, so that the optical path of the red laser light emitted from the red LD chip 14 is the wavelength selective filter 25, the wavelength. Depending on the refractive index of each of the selectivity filters 26, the wavelength selectivity filter 25 and the wavelength selectivity filter 26 allow the monitor screen 31 to compare the wavelength selectivity filter 25 and the wavelength selectivity filter 26 before arrangement. Although slightly shifted, since the light incident surface 32 is approximately 1 m away from the upper surface of the base 12, this shift is almost negligible. By arranging the wavelength selective filter 26 on the reference optical axis L 1, the optical path of the green laser light after being emitted from the green LD chip 15 and reflected by the wavelength selective filter 25 is the wavelength selective filter 26. Depending on the refractive index, the wavelength selective filter 26 slightly shifts on the monitor screen 31 compared to before the wavelength selective filter 26 is arranged, but the light incident surface 32 is substantially from the top surface of the base 12. Since it is 1 meter away, this shift is almost negligible.

FIG. 8 is a diagram illustrating a result of calculating the positional deviation and the size of the light emission pattern of the laser light accompanying the positional deviation (offset amount) of the lens that collimates the laser light. A lens similar to lens 22 (excluding the focal length) was used for the calculation. The light emission pattern is obtained from an image of laser light emitted from the LD chip through the lens and incident on the two-dimensional sensor. The light incident surface of the two-dimensional sensor is assumed to be at a distance of 1 m from the lens. The positional deviation of the lens was 1 μm from the design position. The horizontal axis in FIG. 8 indicates the focal length (mm) of the lens. The vertical axis on the left side of FIG. 8 indicates the amount of displacement (mm). The vertical axis on the right side of FIG. 8 indicates the diameter (mm) of the light emission pattern. A curve G1 is a calculation result of the correlation between the focal length and the positional deviation. A curve G2 is a calculation result of the correlation between the focal length and the diameter of the light emission pattern. The focal length of the lens (the distance between the lens and the LD) is a conventional pickup (or small projector) module (in recent optical drives attached to a PC, LDs with multiple wavelengths (blue, red, etc.) are mounted. In the case of the optical assembly 1 according to the present embodiment, it is about 5.0 mm in the case of CD, DVD, blue-ray, etc. (see reference A2). Since the LD such as the red LD chip 14 and the lens such as the light emitting direction K1 are mounted, it is less than 1 mm and is about 0.5 mm (see A3).

Therefore, according to the calculation result of FIG. 8, in the case of the optical assembly 1 according to the present embodiment, even if the lens position shift is only about 1 μm, the light emission pattern position shift is several mm (1.5 mm or more). 2.0 mm or less). Thus, in the case of the optical assembly 1 according to the present embodiment, adjustment (alignment) of the fixed position of the lens must be performed very precisely, but the light incident surface 32 of the two-dimensional sensor 29 is connected to the stem 2. This precise alignment is possible by separating sufficiently from the main surface 9 (1 m away).

FIG. 9 is a diagram illustrating a calculation result of a change in the positional deviation of the light emission pattern when the positional deviation (offset amount) of the lens is changed from the design position to 1 μm, 5 μm, and 10 μm. A lens similar to lens 22 (excluding the focal length) was used for the calculation. The light emission pattern is obtained from an image of laser light emitted from the LD chip through the lens and incident on the two-dimensional sensor. The light incident surface of the two-dimensional sensor is assumed to be at a distance of 1 m from the lens. The horizontal axis in FIG. 9 indicates the focal length (mm) of the lens. The vertical axis on the left side of FIG. 9 indicates the amount of displacement (mm). A curve G3 is a calculation result of the correlation between the focal length and the positional deviation when the positional deviation of the lens is 1 μm from the design position. A curve G4 is a calculation result of the correlation between the focal length and the positional deviation when the positional deviation of the lens is 5 μm from the design position. A curve G5 is a calculation result of the correlation between the focal length and the positional deviation when the positional deviation of the lens is 10 μm from the design position.

According to the results shown in FIG. 9, in the case of a lens having a focal length of 1 mm or less, such as the lens 22 according to the present embodiment, if the lens position shift is greater than 1 μm, for example, 5 μm or more, the lens position shift is Compared to the case of 1 μm, the positional deviation of the light emission pattern becomes very large, which is not preferable. As described above, in the case of a lens having a focal length of 1 mm or less, such as the lens 22 according to the present embodiment, it is preferable to reduce the positional deviation of the lens as much as possible (for example, 1 μm or less). Must be done with sufficient precision.

Note that the optical assembly 1 according to the present embodiment may be regarded as an ideal point light source as an LD light source (near field pattern). When the light emitting point of the LD is positioned on the focal length of the lens, the light emitted from the lens becomes substantially parallel light. Therefore, no matter where the condenser lens 4 is arranged on the reference optical axis L1, the condenser lens 4 is composed of the red laser light of the red LD chip 14, the green laser light of the green LD chip 15, and the blue LD. The combined light combined with the blue laser light of the chip 16 can be condensed at almost one point (for example, the focal point P1) on the reference optical axis L1. Therefore, the condenser lens 4 can be provided relatively freely as long as it is on the reference optical axis L1. Even when the condenser lens 4 is not provided, three beams (red laser light, green laser light, and blue laser light) can be used as parallel light. The condensing lens 4 can also make three beams into parallel beams. In that case, the three beams are incident on the condenser lens 4 as a condensed or divergent beam. The condensing lens 4 can condense three beams into a beam that can be optically coupled to a single mode fiber (SMF) or a multimode fiber (MMF).

In the optical assembly 1 according to the present embodiment described above, the optical system 13 included in the optical assembly 1 includes the red laser light and the green laser light emitted from the red LD chip 14, the green LD chip 15, and the blue LD chip 16, respectively. The blue laser light is substantially converted into collimated light. The optical system 13 combines the red laser light, the green laser light, and the blue laser light emitted from the red LD chip 14, the green LD chip 15, and the blue LD chip 16, respectively, and a focal point P <b> 1 outside the optical assembly 1. Then, the light is condensed through the condenser lens 4. Therefore, since the laser beams of a plurality of colors can be condensed at one point by only one optical system 13, the optical assembly 1 can be downsized. In addition, if the optical system 13 in which alignment is suitably performed is used, the light quality of the optical assembly 1 can be maintained. In the optical assembly 1 according to the present embodiment, the red LD chip 14, the green LD chip 15, and the blue LD chip 16 emit laser beams having wavelengths corresponding to red, green, and blue. Therefore, since red laser light, green laser light, and blue laser light can be output, multicolor can be realized.

In the optical assembly 1 according to the present embodiment, the optical system 13 includes a lens 22, a lens 23, and a lens 24 that are mounted corresponding to the red LD chip 14, the green LD chip 15, and the blue LD chip 16, respectively. A wavelength selective filter 25 and a wavelength selective filter 26 for multiplexing a plurality of laser beams are provided. Accordingly, the lens 22, the lens 23, and the lens 24 that are mounted corresponding to the red LD chip 14, the green LD chip 15, and the blue LD chip 16, respectively, the wavelength selective filter 25 that combines a plurality of laser beams, and the wavelength The selective filter 26 allows a plurality of laser beams to be condensed via the condenser lens 4 at a focal point P1 outside the optical assembly. In the optical assembly 1 according to this embodiment, the optical system 13 is mounted on the base 12. Therefore, the optical system 13 can be mounted on the single base 12 and is configured to be compact, so that the optical assembly 1 can be downsized.

Further, in the optical assembly 1 according to the present embodiment, the base 12 is made of glass and has a structure (instruction marks M1 to M5) indicating the fixing position of the optical system 13. Therefore, since the material of the base 12 is glass, it can be made of the same material as the lens 22, the lens 23, the lens 24, etc. of the optical system 13. It can be an expansion coefficient. Further, the structure (instruction mark M1 to instruction mark M5) indicating the fixed position of the optical system 13 allows the position of the optical system 13 relative to the base 12 to be more precise than when there is no such structure. Become. Further, in the optical assembly 1 according to the present embodiment, the indication marks M1 to M5 indicating the fixed position of the optical system 13 can be a plurality of concave portions formed on the main surface 20 of the base 12. Therefore, when the indication marks M1 to M5 indicating the fixed position of the optical system 13 are a plurality of concave portions, the optical system 13 can be mechanically adjusted to a suitable position by these concave portions.

Further, in the optical assembly 1 according to the present embodiment, the block 11 has a recess 28 that accommodates the base 12. Therefore, the base 12 is stably held by the block 11 by the concave portion 28 of the block 11. In the optical assembly 1 according to the present embodiment, the depth D2 of the recess 28 of the block 11 is the same as the thickness D1 of the base 12. Therefore, the main surface 21 provided with the concave portion 28 of the block 11 and the main surface 20 of the base 12 can be provided on one surface without a step. In the optical assembly 1 according to the present embodiment, the red LD chip 14, the green LD chip 15, and the blue LD chip 16 have the light emission direction K1 of the red LD chip 14, the light emission direction K2 of the green LD chip 15, and the blue color. The LD chip 16 is mounted on the block 11 so that the light emission direction K3 of the LD chip 16 forms 90 degrees. Accordingly, since the light emission directions of the red LD chip 14, the green LD chip 15, and the blue LD chip 16 form 90 degrees with each other, the red LD chip 14, the green LD chip 15, and the blue LD chip 16 are only reflected by 90 degrees. Multiple laser beams can be combined. Therefore, the configuration of the optical system 13 can be simplified.

In the optical assembly 1 according to the present embodiment, each of the lens 22, the lens 23, and the lens 24 is a spherical lens. In the optical assembly 1 according to the present embodiment, the emitted light from the lens 22, the lens 23, and the lens 24 is substantially collimated light. Accordingly, the lens 22, the lens 23, and the lens 24 included in the optical system 13 can collimate the laser light emitted from each of the red LD chip 14, the green LD chip 15, and the blue LD chip 16.

According to the above configuration of the optical assembly 1 according to the present embodiment, the optical assembly 1 can emit multi-color laser light and can be miniaturized without deteriorating light quality.

While the principles of the invention have been illustrated and described in the preferred embodiments, it will be appreciated by those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific configuration disclosed in the present embodiment. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

DESCRIPTION OF SYMBOLS 1 ... Optical assembly, 11 ... Block, 12 ... Base, 13 ... Optical system, 14 ... Red LD chip, 15 ... Green LD chip, 16 ... Blue LD chip, 17, 18, 19 ... Submount, 2 ... Stem, 20 , 21, 9... Main surface, 22, 23, 24... Lens, 25, 26... Wavelength selective filter, 28 .. Recessed part, 29. Light incident surface, 33, 34, 35, 36 Light reflector, 4 Condensing lens, 5, 6, 7, 8 Lead pin, A1 Reference line, A2, A3 Symbol, B1, B2, B3 B4, B5, B6 ... emission pattern image, C1 ... center of screen, D1 ... thickness, D2 ... depth, D3 ... distance, G1, G2, G3, G4, G5 ... curve, K1, K2, K3 ... light emission direction, L1: Reference optical axis, M1, M2, M3, M4 M5 ... indication mark, P1 ... focus, W1, W2, W3, W4, W5, W6 ... wire.

Claims (10)

An optical assembly mounting a plurality of LD chips,
Each of the plurality of LD chips is mounted on a block via a submount corresponding to each of the plurality of LD chips.
An optical system for a plurality of laser beams emitted from the plurality of LD chips is mounted on the block,
The optical system substantially converts each of the plurality of laser beams into collimated light;
An optical assembly characterized by that. The plurality of LD chips emit laser light having wavelengths corresponding to red, green, and blue.
The optical assembly according to claim 1. The optical system further includes a plurality of wavelength selective filters that multiplex the plurality of collimated lights.
The optical assembly according to claim 1, wherein the optical assembly is an optical assembly. The optical system is mounted on a base,
The optical assembly according to any one of claims 1 to 3, wherein: The base is made of glass and has a structure indicating a fixed position of the optical system.
The optical assembly according to claim 4. The structure is a plurality of recesses formed in the main surface of the base.
The optical assembly according to claim 5. The block has a recess for accommodating the base.
The light assembly according to claim 4, wherein the light assembly is a light assembly. The depth of the concave portion of the block is the same as the thickness of the base.
An optical assembly according to any one of claims 4 to 7, characterized in that The plurality of LD chips are mounted on the block such that the light emitting direction of one LD chip and the light emitting direction of another LD chip form 90 degrees.
The optical assembly according to claim 1, wherein the optical assembly is an optical assembly. Each of the plurality of lenses is a spherical lens.
The optical assembly according to claim 1, wherein the optical assembly is an optical assembly.

Images