Patent Publication Number: US-2021172578-A1

Title: Vehicle lamp

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle lamp, and more specifically, to a vehicle lamp that can be downsized and in which color blur is suppressed. 
     BACKGROUND ART 
     Examples of the vehicle lamp include a vehicle headlamp typified by a headlight for an automobile. The vehicle headlamp is configured to apply at least a low beam for illuminating the front at night. In order to form a light distribution pattern of the low beam, a shade that blocks some of light emitted from a light source is used. However, with the diversification of vehicle designs, there is a demand for downsizing of vehicle headlamps. 
     Patent Literature 1 below describes a vehicle headlamp that can form a light distribution pattern of a low beam without using a shade. The vehicle headlamp includes a hologram element and a light source that applies reference light to the hologram element. The hologram element is calculated such that diffracted light reproduced by applying the reference light forms a light distribution pattern of a low beam. Since the vehicle headlamp forms a light distribution pattern of a low beam by the hologram element in this way, the vehicle headlamp does not require a shade and can be downsized.
     [Patent Literature 1] JP2012-146621 A   

     SUMMARY OF INVENTION 
     White reference light is incident from a light source on the hologram element of the vehicle headlamp in above Patent Literature 1, and a light distribution pattern of a low beam is formed by diffracted light of the light. However, white light is light obtained by synthesizing pieces of light of a plurality of wavelengths. A hologram element, which is a kind of diffraction grating, has wavelength dependency. Therefore, pieces of light having different wavelengths contained in white tend to have light distribution patterns different from each other due to the hologram element. Therefore, when a low beam is applied by the vehicle headlamp described in Patent Literature 1, color blur of light occurs in which pieces of light of different colors emerge near the edge of the light distribution pattern of the low beam. 
     An object of the present invention is to provide a vehicle lamp that can be downsized and in which color blur of light applied can be suppressed. 
     To achieve the above object, a vehicle lamp of the present invention includes: a light source that emits light of a predetermined wavelength; a diffractive optical element that diffracts light emitted from the light source into a predetermined light distribution pattern; a wavelength conversion element in which light forming the light distribution pattern is projected, and that widens a wavelength band of incident light and emits the light; and a projection lens that projects the light distribution pattern projected on the wavelength conversion element. 
     Since this vehicle lamp can form a predetermined light distribution pattern without using a shade similarly to the vehicle headlamp described in Patent Literature 1, as similar to the vehicle headlamp of above Patent Literature 1, this vehicle lamp can be downsized as compared to a vehicle lamp using a shade. When the shade is not used, the light emitted from the light source can be effectively used. The light source of the vehicle lamp described above emits light having a predetermined wavelength. When the wavelength band of the light is narrower than that of white light, the color blur of the light diffracted by the diffractive optical element can be suppressed. Therefore, a predetermined light distribution pattern is formed by the light in which the color blur is suppressed, and the light is projected on the wavelength conversion element. In this way, the light emitted from the light source is light having a narrower wavelength band than that of white light at the time of being diffracted by the diffractive optical element, and after being diffracted by the diffractive optical element to have a predetermined light distribution pattern, the wavelength band is widened by the wavelength conversion element. Accordingly, the light forming the light distribution pattern projected by the projection lens has a wider wavelength band than that of the light emitted from the light source, and color blur can be suppressed. Therefore, the vehicle lamp described above can be a vehicle lamp that can be downsized and in which color blur of light applied can be suppressed. 
     It is preferable that the wavelength conversion element includes a phosphor. 
     When the wavelength conversion element includes a phosphor, at least some of the light emitted from the light source can be applied to the phosphor as pumping light. The pumped phosphor emits light having a wavelength different from the pumping light. Therefore, the wavelength conversion element can widen the wavelength band of the incident light and emit the light. 
     When the wavelength conversion element includes a phosphor, it is preferable that the wavelength conversion element emits some of the incident light without wavelength conversion. 
     When the wavelength conversion element is configured such that some of the light emitted from the light source is emitted without wavelength conversion, and the other part of the light is applied to the phosphor as pumping light, the wavelength conversion element emits light including light emitted from the light source and light emitted by the phosphor. Therefore, the wavelength conversion element can widen the wavelength band of the incident light and emit the light. 
     When the wavelength conversion element includes a phosphor, it is preferable that the wavelength conversion element includes a plurality of types of the phosphors that emit light having different wavelengths. 
     Since the wavelength conversion element includes a plurality of types of phosphors that emit light of different wavelengths, different types of phosphors emit light of different wavelengths when light is incident on the wavelength conversion element. Therefore, the wavelength conversion element can widen the wavelength band of the incident light and emit the light. 
     Furthermore, it is preferable that the wavelength conversion element transmits light incident from the diffractive optical element side to the projection lens side. 
     By using a transmission type wavelength conversion element as described above, even if the position and inclination of the wavelength conversion element and the entrance angle of light incident on the wavelength conversion element slightly change due to vibration or the like, the shift of the optical axis of the light emitted from the wavelength conversion element can be suppressed as compared to the reflection type wavelength conversion element. As described above, the change in the position and inclination of the wavelength conversion element and the entrance angle of the light incident on the wavelength conversion element can be allowed to some extent, so that the arrangement of the optical element such as the wavelength conversion element can be facilitated. 
     Furthermore, it is preferable that the wavelength conversion element reflects light incident from the diffractive optical element side to the projection lens side. 
     By using the reflection type wavelength conversion element as described above, the diffractive optical element and the projection lens can be arranged close to each other, so that the vehicle lamp can be further downsized. By using the reflection type wavelength conversion element, a cooling member for cooling the wavelength conversion element can be arranged on the back side of the wavelength conversion element, that is opposite to the side on which the light emitted from the light source is incident. 
     Furthermore, it is preferable that a Fourier transform lens is provided between the diffractive optical element and the wavelength conversion element. 
     By providing the Fourier transform lens between the diffractive optical element and the wavelength conversion element, an operation equivalent to the case where the distance between the diffractive optical element and the wavelength conversion element is set to infinity can occur. Accordingly, by providing the Fourier transform lens between the diffractive optical element and the wavelength conversion element, it is possible to reduce the distance between the diffractive optical element and the wavelength conversion element as compared to a case where the Fourier transform lens is not provided, so that the vehicle lamp can be further downsized. 
     As described above, according to the present invention, a vehicle lamp that can be downsized and in which color blur of light applied can be suppressed can be realized. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view schematically showing a vehicle lamp according to a first embodiment of the present invention. 
         FIG. 2A  and  FIG. 2B  are diagrams showing light distribution patterns. 
         FIG. 3  is a diagram showing a cross section of a vehicle lamp according to a second embodiment of the present invention, similarly to  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments for implementing a vehicle lamp according to the present invention will be exemplified with reference to the accompanying drawings. The embodiments exemplified below are for the purpose of facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved from the following embodiments without departing from the gist thereof. 
     First Embodiment 
     First, the configuration of the vehicle lamp of the present embodiment will be described. 
       FIG. 1  is a cross-sectional view schematically showing the vehicle lamp according to the present invention. The vehicle lamp of the present embodiment is a vehicle headlamp  1  and includes a housing  10  and a lamp unit  20 . 
     The housing  10  mainly includes a lamp housing  11 , a front cover  12 , and a back cover  13 . The front of the lamp housing  11  is open, and a front cover  12  is fixed to the lamp housing  11  so as to close the opening. An opening smaller than the front is formed at the rear of the lamp housing  11 , and the back cover  13  is fixed to the lamp housing  11  so as to close the opening. 
     A space formed by the lamp housing  11 , the front cover  12  closing the front opening of the lamp housing  11 , and the back cover  13  closing the rear opening of the lamp housing  11  is a lamp room R. The lamp unit  20  is accommodated in this lamp room R. 
     The lamp unit  20  includes a heat sink  30 , a cooling fan  40 , and an optical system unit  50  as main components. Note that the lamp unit  20  is fixed to the housing  10  by a configuration not shown. 
     The heat sink  30  has a metal base plate  31  extending in a substantially horizontal direction, and a plurality of heat radiation fins  32  are provided integrally with the base plate  31  on a lower surface side of the base plate  31 . The cooling fan  40  is arranged with a gap from the heat radiation fin  32  and is fixed to the heat sink  30 . The heat sink  30  is cooled by the airflow generated by the rotation of the cooling fan  40 . 
     The optical system unit  50  is arranged on the upper surface of the base plate  31  of the heat sink  30 . The optical system unit  50  includes a light source  51 , a collimating lens  52 , a diffractive optical element  53 , a Fourier transform lens  54 , a wavelength conversion element  55 , a projection lens  56 , and a cover  59 . 
     The light source  51  of the present embodiment is a laser element that emits a laser light having a predetermined wavelength. More specifically, the light source  51  of the present embodiment emits blue laser light having a power peak wavelength of 445 nm. The optical system unit  50  has a circuit board (not shown), the light source  51  is mounted on the circuit board, and power is supplied through the circuit board. 
     The collimating lens  52  is a lens that collimates the fast axis direction and the slow axis direction of the laser light emitted from the light source  51 . A collimating lens for collimating the fast axis direction of the laser light and a collimating lens for collimating the slow axis direction may be separately provided. 
     The diffractive optical element  53  diffracts the laser light emitted from the collimating lens  52  into a predetermined light distribution pattern. The diffractive optical element  53  of the present embodiment diffracts the laser light incident from the collimating lens  52  so that the light emitted from the light source  51  has a light distribution pattern of a low beam. This light distribution pattern includes a luminous intensity distribution. For this reason, the diffractive optical element  53  of the present embodiment diffracts the laser light incident from the collimating lens  52  so that the laser light emitted from the diffractive optical element  53  has a shape substantially similar to the outer shape of the light distribution pattern of the low beam L, and has a luminous intensity distribution based on the luminous intensity distribution of the light distribution pattern of the low beam L. In this way, the diffractive optical element  53  emits blue light that forms the light distribution pattern of the low beam L. However, since the low beam L is applied through the projection lens  56  as described later, the light distribution pattern formed by the diffractive optical element  53  is inverted upside down from the light distribution pattern of the low beam L applied from the vehicle headlamp  1 . 
     The Fourier transform lens  54  is a convex lens provided between the diffractive optical element  53  and the wavelength conversion element  55 . The wavelength conversion element  55  is provided at the focal position of the Fourier transform lens  54 . By providing the Fourier transform lens  54  in this manner, an operation equivalent to the case where the distance between the diffractive optical element  53  and the wavelength conversion element  55  is set to infinity can occur. Accordingly, by providing the Fourier transform lens  54  between the diffractive optical element  53  and the wavelength conversion element  55 , it is possible to reduce the distance between the diffractive optical element  53  and the wavelength conversion element  55  as compared to a case where the Fourier transform lens  54  is not provided, and the vehicle headlamp  1  can be further downsized. 
     Light forming a predetermined light distribution pattern by being diffracted by the diffractive optical element  53  is projected in the wavelength conversion element  55 , and the wavelength conversion element  55  widens the wavelength band of the incident light, and emits the light. The wavelength conversion element  55  of the present embodiment includes a phosphor. When the wavelength conversion element  55  includes the phosphor, at least some of the light emitted from the light source  51  can be applied to the phosphor as pumping light. The pumped phosphor emits light having a wavelength different from the pumping light. Therefore, the wavelength conversion element  55  can widen the wavelength band of the incident light and emit the light. 
     Such a wavelength conversion element  55  is formed of, for example, a transparent resin sheet in which a phosphor is dispersed. In this case, the wavelength conversion element  55  transmits and emits some of the incident light without wavelength conversion. When the wavelength conversion element  55  is configured such that some of the light emitted from the light source  51  is emitted without wavelength conversion, and the other part of the light is applied to the phosphor as pumping light, the wavelength conversion element  55  emits light including light emitted from the light source  51  and light emitted by the phosphor. Therefore, the wavelength conversion element  55  can widen the wavelength band of the incident light and emit the light. 
     As described above, the light source  51  of the present embodiment emits blue light. Accordingly, for example, when the phosphor included in the wavelength conversion element  55  is a yellow phosphor that emits yellow light, the wavelength conversion element  55  emits blue light and yellow light. Therefore, pseudo white light is synthesized with the blue light and the yellow light. 
     As the phosphor included in the wavelength conversion element  55 , a red phosphor that emits red light and a green phosphor that emits green light may be used in combination. In this case, the blue light transmitted through the wavelength conversion element  55 , the red light emitted by the red phosphor, and the green light emitted by the green phosphor are synthesized, so that the white light with improved color rendering can be synthesized as compared to the case where the yellow phosphor is used as described above. As described above, when the wavelength conversion element  55  includes a phosphor, it is preferable that the wavelength conversion element  55  includes a plurality of types of the phosphors that emit light having different wavelengths. Since the wavelength conversion element  55  includes a plurality of types of phosphors that emit light of different wavelengths, different types of phosphors emit light of different wavelengths when light is incident on the wavelength conversion element  55 . Therefore, the wavelength conversion element  55  can emit a wider wavelength band of the incident light as compared to the case where one kind of phosphor is included. 
     In the vehicle headlamp  1  of the present embodiment, the diffractive optical element  53 , the wavelength conversion element  55 , and the projection lens  56  are arranged on a straight line, and the wavelength conversion element  55  transmits light incident from the diffractive optical element  53  side to the projection lens side. By arranging the diffractive optical element  53 , the wavelength conversion element  55 , and the projection lens  56  on a straight line as described above, it is possible to suppress the occurrence of an optical path difference in the light forming the predetermined light distribution pattern, and to make formation of a desired light distribution pattern easy. 
     The projection lens  56  is an aspherical plano-convex lens, and an incident surface  56   i , which is a surface on which light emitted from the light source  51  is incident, is planar, and an emission surface  56   o , which is a surface on which light from the light source  51  is emitted, has a convex shape that swells toward the emitting direction of the light. Such a projection lens  56  projects a light source image formed on a rear focal plane, which is a focal plane including a rear focal point, as an inverted image. Therefore, the portion of the wavelength conversion element  55  where the light distribution pattern is projected is arranged on the rear focal plane or in the vicinity of the rear focal plane, so that the projection lens  56  can invert and project the light of the light distribution pattern projected on the wavelength conversion element  55 . 
     The cover  59  is fixed on the base plate  31  of the heat sink  30 . The cover  59  has a substantially rectangular shape, and is made of, for example, a metal such as aluminum. In a space inside the cover  59 , the light source  51 , the collimating lens  52 , the diffractive optical element  53 , the Fourier transform lens  54 , the wavelength conversion element  55 , and the projection lens  56  are arranged. However, an opening  59 H is formed in front of the cover  59 , and the emission surface  56   o  of the projection lens  56  is exposed at the opening  59 H. Note that the inner wall of the cover  59  is preferably made light-absorbing by black alumite processing or the like. By making the inner wall of the cover  59  light-absorbing, it is possible to suppress light applied to the inner wall of the cover  59  due to unintended reflection or refraction from being reflected and emitted from the opening  59 H in an unintended direction. 
     Next, light emission by the vehicle headlamp  1  will be described. 
     First, blue laser light is emitted from the light source  51  when power is supplied from a power supply (not shown). This laser light is collimated by the collimating lens  52 , and then, is incident on the diffractive optical element  53 . Then, the laser light incident on the diffractive optical element  53  is diffracted so as to form a predetermined light distribution pattern, and is projected on the wavelength conversion element  55  via the Fourier transform lens  54 . The light applied to the wavelength conversion element  55  is emitted from the wavelength conversion element  55  after the wavelength band is widened as described above. The light emitted from the wavelength conversion element  55  is incident on the projection lens  56 , passes through the projection lens  56  and the front cover  12 , and is applied toward the outside of the vehicle headlamp  1 . Note that the light distribution pattern of the light projected onto the wavelength conversion element  55  has a shape whose outer shape is substantially similar to and inverted upside down from the outer shape of the low beam L, and the light emitted from the projection lens  56  is the light distribution pattern of the low beam L. Since the light emitted from the diffractive optical element  53  is a luminous intensity distribution based on the luminous intensity distribution of the light distribution pattern of the low beam L as described above, the light emitted from the wavelength conversion element  55  also has the luminous intensity distribution of the low beam L. 
       FIG. 2A  and  FIG. 2B  are diagrams showing light distribution patterns for nighttime illumination. Specifically,  FIG. 2A  is a diagram showing a light distribution pattern of a low beam, and  FIG. 2B  is a diagram showing a light distribution pattern of a high beam. In  FIG. 2A  and  FIG. 2B , S indicates a horizontal line, and the light distribution pattern is indicated by a thick line. In the light distribution pattern of the low beam L, which is a light distribution pattern for night illumination shown in  FIG. 2A , a region LA 1  is the region having the highest luminous intensity, and the luminous intensity decreases in the order of a region LA 2  and a region LA 3 . That is, the diffractive optical element  53  diffracts the light emitted from the light source  51  so as to form a light distribution pattern including the luminous intensity distribution of the low beam L. Note that, as indicated by a broken line in  FIG. 2A , light having a lower luminous intensity than the low beam L may be applied to above the position where the low beam L is applied, from the vehicle headlamp  1 . This light is used as light OHS for sign recognition. In this case, it is preferable that the diffracted light emitted from the diffractive optical element  53  includes the light OHS for sign recognition. In this case, it can be understood that the low beam L and the light OHS for sign recognition form a light distribution pattern for night illumination. Note that the light distribution pattern for night illumination is not used only at night, but is also used in a dark place such as a tunnel. 
     As described above, the vehicle lamp  1  of the present embodiment includes: the light source  51  that emits light of a predetermined wavelength; the diffractive optical element  53  that diffracts light emitted from the light source  51  into a predetermined light distribution pattern; the wavelength conversion element  55  in which light forming the light distribution pattern is projected, and that widens a wavelength band of incident light and emits the light; and the projection lens  56  that projects the light distribution pattern projected on the wavelength conversion element  55 . 
     Since the vehicle headlamp  1  of the present embodiment as described above can form a predetermined light distribution pattern without using a shade similarly to the vehicle headlamp described in Patent Literature 1, as similar to the vehicle headlamp described in above Patent Literature 1, this vehicle headlamp  1  can be downsized as compared with a vehicle lamp using a shade. When the shade is not used, the light emitted from the light source  51  can be effectively used. 
     The light source  51  of the vehicle headlamp  1  of the present embodiment emits light having a predetermined wavelength. Since the wavelength band of the light is made narrower than that of the white light, the color blur of the light diffracted by the diffractive optical element  53  can be suppressed. Therefore, a predetermined light distribution pattern is formed by the light in which the color blur is suppressed, and the light is projected on the wavelength conversion element  55 . In this way, the light emitted from the light source  51  is light having a narrower wavelength band than that of white light at the time of being diffracted by the diffractive optical element  53 , and after being diffracted by the diffractive optical element  53  to have a predetermined light distribution pattern, the wavelength band is widened by the wavelength conversion element  55 . Accordingly, the light forming the light distribution pattern projected by the projection lens  56  has a wider wavelength band than that of the light emitted from the light source  51 , and color blur can be suppressed. Therefore, the vehicle headlamp  1  of the present embodiment can be a vehicle lamp that can be downsized and in which color blur of light applied can be suppressed. 
     In the vehicle headlamp  1  of the present embodiment, light is simultaneously applied to regions of the wavelength conversion element  55  where light forming a predetermined light distribution pattern is projected. Accordingly, as compared to the case where the region is scanned by the light emitted from the light source, flicker of the light emitted from the wavelength conversion element can be suppressed. Furthermore, by simultaneously applying the light to the entire region, it is possible to prevent the wavelength conversion element  55  from being locally applied with high-energy light, and to suppress deterioration of the wavelength conversion element  55 . Furthermore, by forming a predetermined light distribution pattern by the light diffracted by the diffractive optical element  53 , a fine light distribution pattern can be easily formed as compared to the case where the light emitted from the light source is scanned to form the predetermined light distribution pattern. 
     Further, in the vehicle headlamp  1  of the present embodiment, the wavelength conversion element  55  transmits light incident from the diffractive optical element  53  side to the projection lens  56  side. By using a transmission type wavelength conversion element  55  in this way, even if the position and inclination of the wavelength conversion element  55  and the entrance angle of light incident on the wavelength conversion element  55  slightly change due to vibration or the like, the shift of the optical axis of the light emitted from the wavelength conversion element  55  can be suppressed as compared to a reflection type wavelength conversion element. As described above, since the change of the position and inclination of the wavelength conversion element  55  and the entrance angle of the light incident on the wavelength conversion element  55  can be allowed to some extent, the arrangement of the optical element such as the wavelength conversion element  55  can be facilitated. 
     Second Embodiment 
     Next, a second embodiment of the present invention will be described in detail with reference to  FIG. 3 . Note that the same or equivalent constituent elements as those of the first embodiment are denoted by the same reference numerals, and redundant explanation will be omitted except when particularly described. 
       FIG. 3  is a diagram showing a cross section of a vehicle lamp according to the present embodiment, similarly to  FIG. 1 . As shown in  FIG. 3 , the optical system unit  50  in the vehicle headlamp  1  of the present embodiment is different from the optical system unit  50  of the first embodiment in that the diffractive optical element  53 , the wavelength conversion element  55 , and the projection lens  56  are arranged on a non-straight line, and the wavelength conversion element  55  reflects light incident from the diffractive optical element  53  side to the projection lens  56  side. 
     In the present embodiment, by using the reflection type wavelength conversion element  55  as described above, the diffractive optical element  53  and the projection lens  56  can be arranged close to each other, so that the vehicle headlamp  1  can be further downsized. By using the reflection type wavelength conversion element  55 , a cooling member (not shown) for cooling the wavelength conversion element  55  can be arranged on the back side of the wavelength conversion element  55 , that is opposite to the side on which the light emitted from the light source  51  is incident. 
     Also in the present embodiment, similarly to the first embodiment, the diffractive optical element  53  diffracts light so that the light emitted from the light source  51  forms a light distribution pattern of the low beam L. Note that, also in the present embodiment, as shown by a broken line in  FIG. 2A , light OHS for sign recognition may be emitted. In this case, as similar to the first embodiment, it is preferable that the diffracted light emitted from the diffractive optical element  53  includes the light OHS for sign recognition. 
     Although the present invention has been described above with the embodiments as examples, the present invention is not limited to these. 
     For example, in the above embodiment, the vehicle headlamp  1  that emits the low beam L has been described as an example. However, the vehicle lamp of the present invention may emit a high beam H. In that case, the light of the light distribution pattern of the high beam H, which is the light distribution pattern for night illumination shown in  FIG. 2B , is applied. Note that, in the light distribution pattern of the high beam H in  FIG. 2B , the region HA 1  is a region having the highest luminous intensity, and the region HA 2  is a region having a lower luminous intensity than the region HA 1 . That is, the diffractive optical element  53  diffracts the light so that the light emitted from the light source  51  forms a light distribution pattern including the luminous intensity distribution of the high beam H. 
     In the above embodiment, an example has been described in which the light distribution pattern formed by forming an image of the diffracted light formed by the diffractive optical element  53  is one predetermined light distribution pattern. However, the diffractive optical element  53  may be capable of freely changing the light distribution pattern formed by the diffracted light. For example, the diffractive optical element  53  can include a Si substrate having on the surface a plurality of pixel electrodes whose potentials are independently controlled, a transparent electrode, and a liquid crystal layer sandwiched between the pixel electrode and the transparent electrode. In this case, the light distribution pattern formed by forming an image of the diffracted light formed by the diffractive optical element  53  can be freely changed by independently controlling the potentials of the plurality of pixel electrodes. 
     In the above embodiment, the case where the light source  51  emits blue light has been described as an example. However, in the vehicle lamp of the present invention, the wavelength of the light emitted from the light source  51  is not limited. For example, the light source  51  may emit near-ultraviolet light. In this case, it is preferable that, for the wavelength conversion element  55 , a red phosphor that emits red light, a green phosphor that emits green light, and a blue phosphor that emits blue light are used in combination. With the light source  51  and the wavelength conversion element  55  configured as described above, red light, green light, and blue light are emitted from the wavelength conversion element  55 , and white light having high color rendering can be synthesized. 
     In the above embodiment, the optical system unit  50  including the Fourier transform lens  54  has been described as an example. However, the optical system unit  50  may not include the Fourier transform lens  54 . In this case, light emitted from the diffractive optical element  53  is directly incident on the wavelength conversion element  55 . With such a configuration, an increase in the number of components can be suppressed. 
     The vehicle lamp of the present invention is not limited to a vehicle headlamp, and may be, for example, a drawing lamp for displaying characters, figures, and the like outside a vehicle. 
     According to the present invention, a vehicle lamp that can be downsized and in which the color blur of light applied can be suppressed is provided, and can be utilized in the field of vehicle headlamps of an automobile or the like. 
     REFERENCE SIGNS LIST 
     
         
           1  vehicle headlamp 
           10  housing 
           20  lamp unit 
           30  heat sink 
           40  cooling fan 
           51  light source 
           53  diffractive optical element 
           54  Fourier transform lens 
           55  wavelength conversion element 
           56  projection lens