JP2008015446A - Method and apparatus for displaying three-dimensional video - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for displaying a three-dimensional video capable of displaying uniform and clear three-dimensional video without limitations on viewable directions. <P>SOLUTION: When a first optical pulse 12 and a second optical pulse 13 having different wavelength from the first optical pulse 12 are made incident on fluorescent space 11 along one optical axis made incident on the fluorescent space 11 from the same direction so that incident timing may be lagged by predetermined time, the second optical pulse 13 overtakes the first optical pulse 23 by the wavelength dispersion of a refractive index, and strong multi-photon absorption by photons of both the first and second pulses 12 and 13 arises at a location where the first and second pulses 12 and 13 overlap each other, so that a cross-sectional image is formed. By forming a plurality of cross-sectional images so as to make their positions deviated, the three-dimensional video is displayed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a three-dimensional image display method and apparatus for displaying a three-dimensional image in a fluorescent space using light pulses.

  In the fields of medical CT devices, CAD devices, etc., there is an increasing demand for three-dimensional displays that display a large amount of three-dimensional information at high speed.

  Many conventional 3D video display methods display a pseudo 3D image in a two-dimensional plane. For example, 3D CG (Computer Graphics) expresses a solid using shadows, gradations of color density, and the like, and is a pseudo 3D image representation on a 2D plane.

  In addition, there are things that produce stereoscopic parallax by showing different images on the left and right eyes with deflection glasses etc. using a two-dimensional display, but the viewpoint is limited, long time Problems such as fatigue due to use are listed. Furthermore, although there is a method of three-dimensional display by holography technology, there are problems such as that it takes time to produce a hologram and only a still image can be handled.

  For this reason, there is an increasing need for an apparatus that actually displays a 3D image in a 3D space. As a method for actually displaying a three-dimensional image in a three-dimensional space, there is a volume scanning method (depth sampling method). Specifically, this method includes (a) a varifocal mirror method, (b) a moving display method, and (c) a moving screen method.

  The above (a) is a method of reflecting a two-dimensional image in synchronization with the vibration of a concave mirror that vibrates back and forth. The above (b) is a method of displaying a three-dimensional image by moving or rotating a cross-sectional image of a stereoscopic image at a high speed through a light emitting diode display or the like. The above (c) is a method of making a stereoscopic view by projecting a cross-sectional view of a stereoscopic image on a moving screen.

As another system, (d) a method of displaying an image in a three-dimensional space by arranging two two-dimensional laser arrays at right angles and generating fluorescence at the intersection of laser beams. (For example, refer to Patent Document 1).
JP-A-5-224608

  However, in the techniques (a) to (c) described above, there are problems such as (a) the varifocal mirror method that can be expressed and the size of the concave mirror must be increased when viewing with a large number of people. It is done. The (b) moving display method and the (c) moving screen method have problems such as that the range in which a 3D image can be seen is limited or the resolution is different depending on the direction of movement, and the image tends to be unclear.

  Further, the technique (d) uses infrared light as laser light, and the two laser lights are gradually absorbed as they travel through the display medium, and the light intensity is attenuated. Therefore, the laser array side is bright and the opposite side is a dark image. This phenomenon becomes more prominent when the size of the display medium is increased.

  Accordingly, an object of the present invention is to provide a 3D image display method and apparatus capable of displaying a uniform and clear 3D image without limitation in the viewing direction.

  In order to achieve the above object, one aspect of the present invention provides the following three-dimensional video display method and apparatus.

  [1] A first step of causing a first light pulse to enter a non-vacuum fluorescent space from a predetermined direction, and a second light pulse whose propagation speed in the fluorescent space is faster than that of the first light pulse. The first light pulse is incident on the fluorescence space from a direction substantially the same as the predetermined direction with a predetermined time delay, and the second light pulse catches up with the first light pulse and overlaps in the fluorescence space. A 3D image display method comprising: a second step of causing fluorescence at a position.

  [2] The 3D image display method according to [1], wherein cross-sectional information is written in either one of the first or second light pulses.

  [3] In the first and second steps, the first and second light pulses are caused to fluoresce at a plurality of different positions in the fluorescence space by controlling the timing of incidence of the first and second light pulses into the fluorescence space. The 3D video display method according to [1], wherein

[4] The speed of light in vacuum is c, the wavelength of the first light pulse is λ ₁ , the wavelength of the second light pulse is λ ₂ , and the refractive index in the fluorescence space at the wavelength λ is n (λ), When the time width of the optical pulse 1 is t ₁ and the time width of the optical pulse 2 is t ₂ , 1 × 10 ⁻⁴ [m] ≦ {c (t ₁ n (λ ₂ ) + t ₂ n (λ ₁ ) )} / {N (λ ₂ ) (n (λ ₁ ) −n (λ ₂ ))} ≦ 1 × 10 ⁻² [m] is satisfied, 3D video display according to the above [1] Method.

  [5] In the second step, a plurality of the second light pulses are incident on the fluorescence space at a predetermined repetition period with respect to one first light pulse, and the plurality of the light pulses in the fluorescence space are entered. The three-dimensional image display method according to [1], wherein fluorescence is generated at a position.

  [6] In the first step, a plurality of the first light pulses are incident on the fluorescence space at a predetermined repetition period, and the second step is performed at an N repetition period equal to the predetermined repetition period. The three-dimensional image display according to [1], wherein a plurality of pulse trains composed of the second light pulses are incident on the fluorescent space and are fluorescent at N positions in the fluorescent space. Method.

  [7] In the first step, M first light pulses are incident on the fluorescent space at a predetermined repetition period, and the second step has the same repetition period as the predetermined repetition period. [3] The method according to [1], wherein M pulse trains including N second light pulses are incident on the fluorescence space and are fluorescent at N × M positions in the fluorescence space. 3D image display method.

  [8] The 3D image display method according to [1], wherein the writing of the cross-sectional information to the second optical pulse is performed by spatial light modulation.

[9] First light pulse incident means for causing the first light pulse to enter a non-vacuum fluorescent space from a predetermined direction;
A second light pulse whose propagation speed in the fluorescent space is faster than the first light pulse is incident on the fluorescent space from the substantially same direction as the predetermined direction with a delay of a predetermined time from the first light pulse; Second light pulse incident means for causing the second light pulse to catch up with the first light pulse in the fluorescent space and to cause fluorescence at an overlapping position;
A three-dimensional image display device comprising:

  [10] The first and second light pulse incident means divide the light pulse emitted from the light pulse light source into two light pulses by dividing the light pulse emitted from the light pulse light source into two light pulses. [9] The optical system according to [9], further comprising: a splitting optical system in which one of the two optical pulses is the first optical pulse and the other optical pulse is the second optical pulse. 3D image display device.

  [11] The first optical pulse incident means includes a first optical pulse light source that emits the first optical pulse, and the second optical pulse incident means emits the second optical pulse. The 3D image display device according to [9], further including a second light pulse light source.

  [12] The spatial light modulation in which the first or second light pulse incident means writes the cross-sectional information in the light pulse according to a cross-sectional image signal to generate the first light pulse or the second light pulse. The three-dimensional image display device according to [9], further comprising a device.

  [13] The three-dimensional image display device according to [12], wherein the spatial light modulator is a liquid crystal spatial light modulator.

  [14] The first or second optical pulse incident means has a plurality of optical paths having different optical path lengths, and is provided in a branching section that distributes the incident optical pulses to the plurality of optical paths, and in the plurality of optical paths. A plurality of spatial light modulators for writing cross-sectional information to a plurality of optical pulses distributed to the plurality of optical paths, and the optical axes of the plurality of second optical pulses to which the cross-sectional information is written coincide with each other. The three-dimensional image display device according to [9], further including a merging unit that inputs a plurality of second light pulses into the fluorescent space.

  [15] The three-dimensional image display device according to [14], wherein the branching unit is an optical path switching unit that distributes an incident optical pulse by sequentially switching the plurality of optical paths.

  [16] The three-dimensional image display device according to [14], wherein the branching unit is a splitting optical system that splits an incident light pulse into a plurality of light pulses and distributes the light pulses to the plurality of optical paths.

  [17] The first or second optical pulse incident means includes an optical path length control unit that controls an optical path length of the first optical pulse or the second optical pulse. 9].

  [18] The first or second optical pulse incident means includes a plurality of optical media having different thicknesses, and the optical medium is placed on the optical axis of the first optical pulse or the second optical pulse. The three-dimensional image according to [9], further including a timing control unit that adjusts a timing at which the first light pulse or the second light pulse enters the fluorescent space by switching Video display device.

  [19] The three-dimensional image display device according to [9], wherein the first or second light pulse incident means includes a wavelength converter that converts a wavelength of the light pulse.

  [20] The first and second light pulse incidence means share an enlarged optical system that enlarges the apertures of the first and second light pulses and enters the fluorescence space. 9].

  [21] In the above [9], the fluorescent space is made of a fluorescent material or a gas, liquid, or solid containing the fluorescent material that is transparent with respect to the wavelengths of the first and second light pulses. The three-dimensional image display device described.

  [22] The above-mentioned [9], wherein the fluorescent space is made of a deuterium-substituted organic solvent containing a phosphor and transparent to the wavelengths of the first light pulse and the second light pulse. 3D image display device described in 1.

  [23] The three-dimensional image according to [9], wherein the fluorescence space causes the strongest multiphoton absorption at the position where the first light pulse and the second light pulse overlap each other. Display device.

  [24] In the first and second light pulse incidence means, the light intensity of the light pulse having the shorter wavelength of the first and second light pulses is lower than that of the light pulse having the longer wavelength, The fluorescence space is transparent to the first and second light pulses, and the excitation energy to the two-photon absorption level of the fluorescence space is greater than the energy of two photons of the light pulse having the longer wavelength. The three-dimensional image display device according to [23], which is equal to or smaller than an energy obtained by adding one photon of a light pulse having a shorter wavelength.

  [25] The fluorescent space cuts only the wavelengths of the first and second light pulses on the side opposite to the incident side of the first and second light pulses, and transmits light having other wavelengths. The 3D image display device according to [9], further including a notch filter.

  [26] The timing control unit has a disk-like shape, and performs the rotational movement around a rotation axis parallel to the thickness direction of the disk-like shape, whereby the first optical pulse or the [3] The three-dimensional image display device according to [18], wherein the optical medium placed on the optical axis of the second optical pulse is switched.

  [27] The 3D image display device according to [26], wherein the center of gravity of the timing control unit substantially coincides with the center of rotation of the rotational motion.

  [28] In the timing control unit, among the plurality of optical media having different thicknesses, the optical media having substantially the same thickness are arranged symmetrically with respect to the rotation center [27]. ] The three-dimensional video display apparatus as described in any one of.

  In each of the above aspects, the substantially same direction means a direction in which the second light pulse catches up with the first light pulse in the fluorescent space and passes through the overlap, and both pulses The incident direction to the fluorescent space need not be completely coaxial and the same direction.

  According to the present invention, there is no restriction on the viewing direction, and a homogeneous and clear three-dimensional image can be displayed.

[Principle of the present invention]
The present invention utilizes a multiphoton absorption phenomenon (particularly a two-photon absorption phenomenon). When light energy is given to a phosphor, even if absorption does not occur due to insufficient energy for each photon, absorption may occur due to the addition of energy of a plurality of photons, which is called multiphoton absorption.

FIGS. 1A to 1C are diagrams showing the basic principle of the 3D video display method according to the present invention. In FIG. 1A, a first optical pulse 12 having a wavelength λ ₁ in the fluorescent space 11 from the same direction along one optical axis incident on the fluorescent space 11, and a wavelength λ ₂ different from λ ₁ are included. The second light pulse 13 is incident with the incident timing shifted by a predetermined time.

By the way, the speed of light propagating in the medium differs depending on the wavelength of light. Such a phenomenon is due to the chromatic dispersion of the refractive index. Among the chromatic dispersions, in particular, when the speed increases as the wavelength increases, normal dispersion, and when the speed increases as the wavelength decreases. Is called anomalous dispersion. The degree of chromatic dispersion and whether it becomes normal dispersion or abnormal dispersion depends on the properties of the medium. In the following description, it is assumed that the inside of the fluorescent space 11 shows normal dispersion, and the speed increases as the wavelength of light increases. Further, the wavelength of the second optical pulse is assumed to be larger than the wavelength of the first optical pulse (λ ₁ <λ ₂ ).

  As shown in FIG. 1A, when the first light pulse 12 and the second light pulse 13 are incident on the inside of the fluorescent space 11, the wavelength of each other is different. There is a difference in the propagation speed at. Specifically, since the first light pulse 12 that has previously entered the fluorescent space 11 has a wavelength larger than that of the second light pulse 13 that has entered later, the velocity is low, and the first light pulse 12 and the first light pulse 12 When the difference in the incident timing of the two optical pulses 13 is sufficiently small, the second optical pulse 13 is overtaken and overtaken.

  The fluorescent space 11 is filled with a phosphor or a gas, liquid or solid containing the phosphor. As the phosphor, a substance exhibiting high two-photon fluorescence efficiency such as a two-photon fluorescent dye is preferable.

  At the position where the first optical pulse 12 is caught up by the second optical pulse 13 and spatially overlaps with each other, two-photon absorption by the photons of the first optical pulse 12 and the second optical pulse 13 occurs. Compared with the position where the first light pulse 12 and the second light pulse 13 do not overlap, the phosphor in the fluorescent space 11 can obtain more energy. By obtaining energy, electrons in the phosphor are excited, and emit fluorescence in the process in which the excited electrons relax. Here, assuming that the energy obtained by the two-photon absorption by the photons of the first optical pulse 12 and the second optical pulse 13 occupies most of the absorbed energy, the first optical pulse 12 and the second optical pulse 13. Fluorescence occurs only at the position where the two overlap.

  FIG. 1 (b) shows the intensity of the first and second optical pulses 12, 13 (for simplicity, the pulse intensity and pulse width are shown as being equal), and FIG. 1 (c) shows the fluorescence intensity distribution. . Each horizontal axis represents the position of the optical pulse common to FIG. The first and second light pulses 12 and 13 start to overlap at position B in the fluorescence space 11 shown in FIG. 1A, completely overlap at position D, and end at position F. Assuming that the length from this position B to F is the overlap length ΔL, as shown in FIG. 1C, a fluorescence intensity distribution is generated in the range of the overlap length ΔL. Note that, at the position D where the overlap is the largest, two-photon absorption occurs most, so the fluorescence intensity increases.

  However, in general, the human eye cannot recognize fluorescence in the entire range of the overlap length ΔL, and the vicinity of the bottom of the fluorescence intensity distribution (near positions B and F) cannot be detected because the intensity is small. Therefore, for example, as shown in FIG. 1C, the half-value width of the fluorescence intensity distribution is set to a range that can be perceived by a human, and the thickness of the phosphor screen is set.

  By adjusting the overlapping position of the first light pulse 12 and the second light pulse 13, the position where fluorescence occurs in the fluorescent space 11 can be adjusted. In order to change the overlapping position, the difference in the incidence timing of the first light pulse 12 and the second light pulse 13 into the fluorescence space 11 is adjusted.

FIG. 2 is a conceptual diagram showing the relationship between the difference in the incidence timing of the first and second light pulses and the position where fluorescence occurs. L _a , L _b , and L _{c in} FIG. 2 represent intervals before incidence of the respective optical pulse sets of the first optical pulses 12a, 12b, and 12c and the second optical pulses 13a, 13b, and 13c. Since the second light pulse 13 catches up with the first light pulse 12 at an earlier time as the interval (difference in incidence timing) between the first light pulse 12 and the second light pulse 13 is smaller, the incident light enters the fluorescent space 11. Fluorescence occurs at a position close to the surface.

Therefore, the light pulse 12a intervals _{L a,} the 13a pair of fluorescent occurs near the entrance of the fluorescent space 11 is formed cross-sectional images 14a, spacing _{L b} of the optical pulse 12b, the 13b pair of fluorescence fluorescent occurs in the vicinity of the center of the space 11 is formed sectional image 14b, the light pulse 12c intervals L _c, the 13c sets of fluorescence in the vicinity of the rear cross-sectional image 14c is formed resulting in fluorescence space 11 . The shape of the cross-sectional image depends on the shape of the overlapping portion of the first light pulse 12 and the second light pulse 13. A three-dimensional image can be formed by combining cross-sectional images having these unique shapes. Although the sectional images 14a, 14b, and 14c are not formed at the same time, when each set of light pulses is made incident at a sufficiently short interval, it is recognized as if they were simultaneously displayed on the human eye due to the afterimage phenomenon. Is done.

  In order to make the shape of the cross-sectional image a desired shape, it is necessary to make the shape of the portion where the cross-sections of the two light pulses 12 and 13 overlap each other into a desired shape. Specifically, for example, the cross-sectional shape of the first light pulse 12 is set to a shape that covers a certain range in the fluorescent space 11, and the cross-sectional shape of the second light pulse 13 is set to a desired cross-sectional shape. Thereby, the cross-sectional shape of the second light pulse 13 is displayed in the fluorescent space 11 as the cross-sectional images 14a to 14c. Furthermore, a desired three-dimensional image can be obtained by changing the cross-sectional shape of the corresponding second optical pulse 13 in accordance with the position where the cross-sectional image is displayed.

  The principle of the above phenomenon and specific examples will be described below.

(Principle of fluorescence generation)
Next, the principle of fluorescence generation by multiphoton absorption will be described with reference to FIGS. The three-dimensional video display method according to the present invention enables display in a three-dimensional space by superimposing two light pulses in a fluorescent space and emitting fluorescence only at the overlapping point. In order to obtain a clear three-dimensional image, a high On / Off ratio is required between a place where light shines and a place where light does not shine. In the present invention, it is possible to obtain a high On / Off ratio by selecting the wavelength of the light pulse and the multiphoton absorption energy of the phosphor. However, the On / Off ratio represents the fluorescence intensity ratio between the place where the first light pulse 12 and the second light pulse 13 overlap and the place where they do not overlap. In a place where the first light pulse 12 and the second light pulse 13 do not overlap, multiphoton absorption occurs between the photons of the first light pulse 12 and between the photons of the second pulse 13, and thus overlaps. , In addition to multiphoton absorption by the photons of the first optical pulse 12 and by the photons of the second optical pulse 13, multiphoton absorption by the photons of the first optical pulse and the photons of the second optical pulse occurs. .

であることが必要であり、数式（１）、数式（２）、数式（３）を満たすとき、第１の光パルス１２と第２の光パルス１３が重なる場所で、二光子吸収が起きる。ただし、ｃは光の速度、ｈはプランク定数である。 When the wavelength of the first optical pulse 12 is λ ₁ , the optical intensity is I ₁ , the wavelength of the second optical pulse 13 is λ ₂ , the optical intensity is I _2, and the second optical pulse 13 is an optical pulse train In addition, the number of optical pulses included in the optical pulse train is N, and the excitation energy of the phosphor is Ea or more and Eb or less. At this time, in order to generate strong fluorescence only at the position where the first light pulse 12 and the second light pulse 13 overlap,

Therefore, when Expressions (1), (2), and (3) are satisfied, two-photon absorption occurs at the place where the first optical pulse 12 and the second optical pulse 13 overlap. Where c is the speed of light and h is the Planck's constant.

であるときは（図３参照）、励起エネルギーが、Ｅａ以上Ｅｂ以下における蛍光体の二光子吸収定数をβとすると、蛍光強度は吸収の大きさに比例するので、第１の光パルス１２と第２の光パルス１３が重なっている場所と重なっていない場所の蛍光強度比（Ｏｎ／Ｏｆｆ比）は、

のように表され、Ｎ＝１、Ｉ_１＝Ｉ_２で最大値２となり、Ｎが増えるほどＯｎ／Ｏｆｆ比は低くなる。 Furthermore,

(See FIG. 3), if the two-photon absorption constant of the phosphor with an excitation energy of Ea or more and Eb or less is β, the fluorescence intensity is proportional to the magnitude of absorption. The fluorescence intensity ratio (On / Off ratio) between the place where the second light pulse 13 overlaps and the place where it does not overlap is as follows.

The maximum value is 2 when N = 1 and I ₁ = I ₂ , and the On / Off ratio decreases as N increases.

であるときには（図４参照）、三光子吸収エネルギーがＥａ以上Ｅｂ以下における蛍光体の三光子吸収定数をγとすると、

となり、第２の光パルス１３による三光子吸収が無視できるほど小さい範囲では、

であれば、Ｏｎ／Ｏｆｆ比は大きくなる。 Also,

(Refer to FIG. 4), when the three-photon absorption constant of the phosphor in which the three-photon absorption energy is Ea or more and Eb or less is γ,

In the range where the three-photon absorption by the second light pulse 13 is so small that it can be ignored,

If so, the On / Off ratio increases.

であれば（図５参照）、Ｏｎ／Ｏｆｆ比は、

となり、β＞＞γであるから、数式（７）よりもさらに大きくなる。 further,

If so (see FIG. 5), the On / Off ratio is

Therefore, since β >> γ, it is larger than Expression (7).

もしくは（図７参照）、

であれば、光パルス同士が重なっていない場所では、ほとんど多光子吸収が起こらないため、Ｏｆｆはほぼ０となる。 Furthermore (see FIG. 6),

Or (see FIG. 7),

If so, multi-photon absorption hardly occurs in a place where the light pulses do not overlap with each other, so Off is almost zero.

  That is, in order to obtain a high On / Off ratio, it is desirable that the relationship between the phosphor and the light pulse satisfies the formulas (1), (2), (3), (6), and (8). , Formula (1), Formula (2), Formula (3), Formula (9) are more preferably satisfied, Formula (1), Formula (2), Formula (3), Formula (11), or Formula ( It is most desirable to satisfy 1), Formula (2), Formula (3), and Formula (12).

に比例する。数式（１）、数式（２）、数式（３）、数式（６）、数式（８）、もしくは数式（１）、数式（２）、数式（３）、数式（９）、を満たす以外に、蛍光体の二光子吸収係数βと光パルスの強度Ｉ_１・Ｉ_２が十分な大きさを有する必要がある。ただし、Φは蛍光体の量子効率を表す。 However, in order to obtain a clearer three-dimensional image, high fluorescence efficiency is required in addition to a high On / Off ratio. The fluorescence efficiency generated by the overlap of the first light pulse 12 and the second light pulse 13 is

Is proportional to In addition to satisfying formula (1), formula (2), formula (3), formula (6), formula (8), or formula (1), formula (2), formula (3), formula (9) The two-photon absorption coefficient β of the phosphor and the light pulse intensities I ₁ and I ₂ must be sufficiently large. Where Φ represents the quantum efficiency of the phosphor.

重なり長さはΔＬは、

となる。 (Overtaking by chromatic dispersion of optical pulse)
The speed of light in vacuum is c, the wavelength of the first light pulse 12 is λ ₁ , the wavelength λ _{2 of} the second light pulse 13, the refractive index in the fluorescent space 11 at the wavelength λ is n (λ), the first When the time width of the optical pulse 12 is t ₁ and the time width of the second optical pulse 13 is t ₂ , the overlap time ΔT of the first optical pulse 12 and the second optical pulse 13 is

The overlap length is ΔL

It becomes.

を満たすことが望ましく、さらに、

を満たすことがより望ましい。 Here, considering the spatial resolution of the human eye, ΔL is preferably 0.1 mm or more, and if it exceeds 10 mm, the phosphor screen becomes too thick.

It is desirable to satisfy

It is more desirable to satisfy.

ｔ_１＝ｔ_２＝１００ｆｓであるとすると、

となり、その半値幅をとると約１．３ｍｍになる。つまり蛍光面厚さは、１．３ｍｍ程度となる。 Here, assuming that λ ₁ = 400 nm and λ ₂ = 800 nm, and the fluorescent space 11 is filled with water, the refractive index of water at each wavelength is

If t ₁ = t ₂ = 100 fs,

When the full width at half maximum is taken, it becomes about 1.3 mm. That is, the phosphor screen thickness is about 1.3 mm.

  When the first light pulse 12 and the second light pulse 13 are incident on the fluorescence space 11 from opposite directions on the same optical axis, and the fluorescence is caused by the difference of the light pulses, the phosphor screen thickness is calculated by the same calculation. The thickness is about 10 μm. Therefore, when the first light pulse 12 and the second light pulse 13 are incident on the fluorescence space 11 from the same direction on the same optical axis, and the fluorescence is caused by passing the light pulse, the first light pulse 12 And the second light pulse 13 are incident on the fluorescent space 11 from opposite directions on the same optical axis, and a fluorescent screen thickness of 100 times or more can be obtained as compared with the case where fluorescence is caused by passing light pulses. .

  In addition, since the spatial resolution of the human eye is about 0.1 mm, a phosphor screen with a thickness of 10 μm has a brightness of 1/10 the actual brightness of a phosphor screen with a thickness of 0.1 mm. Looks like it exists. Therefore, when the first light pulse 12 and the second light pulse 13 are incident on the fluorescence space 11 from the same direction on the same optical axis and cause fluorescence by passing the light pulse, the first light pulse 12 and the second light pulse 13 Compared with the case where two light pulses 13 are incident on the fluorescent space 11 from the opposite direction on the same optical axis, and the fluorescent light is generated by passing the light pulses, the fluorescent screen appears to be about 10 times brighter to the human eye.

となり、重なり位置の入射面からの距離Ｘは、

となる。加えて、断面像の間隔をΔＸ、パルス組ごとのＬの差をＬ_ｂ−Ｌ_ａ＝Ｌ_ｃ−Ｌ_ｂ＝ΔＬ（図２参照）とすると、

となる。 (Relationship between incident timing of optical pulse and position of cross-sectional image)
The light speed in vacuum is c, the wavelength of the first light pulse 12 is λ ₁ , the wavelength λ ₂ of the second light pulse, the refractive index in the fluorescent space 11 at the wavelength λ is n (λ), the first light When the time width of the pulse 12 is t ₁ , the time width of the second optical pulse 13 is t ₂ , and the distance between the first optical pulse 12 and the second optical pulse 13 is L, the second optical pulse 13 is The time T until catching up with one optical pulse 12 is

The distance X from the incident surface at the overlapping position is

It becomes. In addition, if the interval between the cross-sectional images is ΔX and the difference of L for each pulse set is L _b −L _a = L _c −L _b = ΔL (see FIG. 2),

It becomes.

となり、第１の光パルス１２と第２の光パルス１３の距離Ｌは、例えば、１．３１
×１０^−５×ｎ（ｎ：１、２、３、・・・）であればよい。 Here, assuming that λ ₁ = 400 nm, λ ₂ = 800 nm, and t ₁ = t ₂ = 100 fs, and assuming that the fluorescent space 11 is filled with water, as described above, the phosphor screen thickness is 1.3 mm. Therefore, ΔX = 1.3 × 10 ⁻³ is sufficient to display a cross-sectional image without a gap. In this case, ΔL is expressed by Equation (22):

The distance L between the first optical pulse 12 and the second optical pulse 13 is, for example, 1.31.
It may be × 10 ⁻⁵ × n (n: 1, 2, 3,...).

  Hereinafter, the 3D image display method according to the embodiment of the present invention will be described more specifically.

[First Embodiment]
(Configuration of 3D image display device)
FIG. 8 is a configuration diagram of the 3D video display apparatus according to the first embodiment of the present invention. The three-dimensional image display device 1 includes an optical pulse light source 21 that emits optical pulses at a constant repetition period, and an optical pulse emitted from the optical pulse light source 21 as a first optical pulse 12 and a second optical pulse 13. A beam splitter 22 that divides the first optical pulse 12, an optical path length controller 23 that changes the optical path length of the first optical pulse 12, a wavelength converter 25 that changes the wavelength of the second optical pulse 13, and a second optical pulse 13. An optical path is formed by a spatial light modulation unit 26 for writing cross-sectional information corresponding to a cross-sectional image signal, an expansion optical system 27 for expanding the beam diameter of each of the first and second light pulses 13 and entering the fluorescent space 11. And a control unit (not shown) that controls each unit of the apparatus.

  As the optical pulse light source 21, for example, an optical pulse laser having a time width of 50 femtoseconds, a repetition frequency of 1 kHz, and a wavelength of 800 nm is used.

  The wavelength converter 25 converts the wavelength 800 nm of the second optical pulse 13 divided by the beam splitter 22 into, for example, a wavelength of 1300 nm, and an OPA (Optical Parametric Amplifier) can be used, for example.

  The optical path length control unit 23 adjusts the optical path length from the optical pulse light source 21 to the fluorescent space 11 under the control of the control unit. By adjusting the optical path length, the difference between the optical path lengths of the two optical pulses 12 and 13 can be changed, and the timing of incidence on the fluorescent space 11 can be controlled.

  Specifically, the switching mirrors 24a to 24e obtained by combining a pair of mirrors are arranged at a predetermined interval, and one of the switching mirrors 24a to 24e is selected, and the first switching mirrors 24a to 24e select the first. The light pulse 12 is reflected. At this time, since the optical path length varies depending on the switching mirrors 24a to 24e to be selected, the interval when the first optical pulse 12 and the second optical pulse 13 divided by the beam splitter 22 ride on the same optical axis again is obtained. As a result, the position at which the cross-sectional image is displayed in the fluorescent space 11 changes.

  Specifically, the switching mirrors 24 a to 24 e to be selected have an optical path length that increases in the order of 24 a, 24 b, 24 c, 24 d, and 24 e, and accordingly, the first optical pulse 12 divided by the beam splitter 22 and the second optical pulse 12 The intervals at which the light pulses 13 are incident on the fluorescence space 11 increase in order. As shown in FIG. 2, the position at which the cross-sectional image is formed in the fluorescence space 11 increases as the interval when the first light pulse 12 and the second light pulse 13 enter the fluorescence space 11 increases. 11 farther from the incident surface. In FIG. 8, when the switching mirrors 24a, 24b, 24c, 24d, and 24e are selected, cross-sectional images 14a, 14b, 14c, 14d, and 14e are formed in the fluorescent space 11, respectively. The intervals at which the cross-sectional images 14a to 14e are formed vary depending on the intervals at which the switching mirrors 24a to 24e are installed. In FIG. 8, five pairs of switching mirrors 24 a to 24 e are illustrated, but the number of switching mirrors is not limited to this, and the number of cross-sectional images formed in the fluorescent space 11. Is not limited to five of the cross-sectional images 14a to 14e.

  The spatial light modulator 26 includes a magnifying optical system 262 that magnifies the second light pulse 13 incident by the lens, and a spatial light modulator that writes cross-sectional information corresponding to the cross-sectional image signal to the magnified second light pulse 13. 261 and a reduction optical system 263 for reducing the second light pulse 13 in which the cross-sectional information is written by a lens.

  As the spatial light modulator 261, for example, a liquid crystal spatial light modulator can be used. By controlling the voltage applied to each pixel of the liquid crystal spatial light modulator based on the cross-sectional image signal, cross-sectional information corresponding to the cross-sectional image signal is written in the second light pulse 13, and a second light having a predetermined light pattern is obtained. Are generated. A micromirror array can also be used as the spatial light modulator.

  The change timing of the optical path length by the optical path length control unit 23 and the writing timing of the cross-sectional information by the spatial light modulation unit 26 are controlled to be synchronized by a control unit (not shown).

  The fluorescent space 11 is filled with a phosphor or a gas, liquid or solid containing the phosphor. As the phosphor, a substance exhibiting high two-photon fluorescence efficiency such as a two-photon fluorescent dye is preferable. Commonly known dyes such as Rhodamine dye, Fluorescein dye, DiI dye and Coumarin dye can be used as dyes having high two-photon fluorescence efficiency. For example, Rhodamine 6G in ethanol at a concentration of 1 wt% The dispersed material can be used by filling the fluorescent space 11. In addition, dyes exhibiting high two-photon fluorescence efficiency disclosed in JP-A Nos. 2004-123668, 2004-224746, 2001-520737, and 2004-29480 are also included in the present invention. Applicable. Here, when the fluorescent space 11 is made of a fluorescent material dispersed in an organic solvent, a deuterium substitution solvent transparent to the wavelengths of the first light pulse and the second light pulse is used as the solvent. preferable. Of the first light pulse and the second light pulse, the light pulse having the longer wavelength is considered to have a near-infrared to infrared wavelength in many cases, but a two-photon fluorescent material is dispersed in an organic solvent. When a thing is used as a fluorescent space, since many organic solvents have absorption in the infrared region, the energy of the light pulse cannot be used effectively. Therefore, the solvent containing the phosphor is preferably a deuterated solvent.

  Further, only the wavelengths (800 nm and 1300 nm) of the first and second optical pulses 12 and 13 are cut on the opposite side of the fluorescent space 11 from the incident surface of the first and second optical pulses 12 and 13, It is preferable to provide a notch filter 15 that transmits light having a wavelength other than. As a result, the observer can view the three-dimensional image without being affected by the pulsed light from the notch filter 15 side.

  Below, the example of operation | movement of the three-dimensional video display apparatus 1 which concerns on this Embodiment is shown.

(Operation of 3D image display device)
First, five pulsed light beams are emitted from the optical pulse light source 21 at a predetermined interval, and are separated by the beam splitter 22 so that five first optical pulses 12a to 12e and second optical pulses 13a to 13a, respectively. 13e.

  The first optical pulses 12a to 12e are incident on the optical path length control unit 23, and the first optical pulses 12a, 12b, 12c, 12d, and 12e are optical paths formed by the switching mirrors 24a, 24b, 24c, 24d, and 24e, respectively. Pass through.

  On the other hand, the second optical pulses 13a to 13e are converted in wavelength by the wavelength converter 25, and then the cross-sectional information corresponding to the cross-sectional image signal is written by the spatial light modulator 26, respectively. It rides on the same optical axis as 12e.

  FIG. 9 shows an example of the shape of the second light pulse in which the image information is written, and FIG. 10 shows an example of the shape of the first light pulse. The cross-section information is sequentially written into the five second pulses 13a to 13e by the spatial light modulator 26, and the second pulses 13a to 13e have a shape as shown in FIG. Note that the first light pulses 14a to 14e have the same shape as shown in FIG. 10 because the cross-sectional information is not written. The shape shown in FIG. 10 is an example, but preferably has a shape and a size that include all the shapes of the second pulses 13a to 13e in which image information is written.

FIG. 11 is a conceptual diagram showing the relationship between the first and second light pulses and the cross-sectional image. In FIG. 11, L _a , L _b , L _c , L _d , and _Le indicate the intervals before the first light pulse 12 and the second light pulse 13 are incident on the fluorescence space 11 of the respective light pulse sets. To express. The smaller the distance between the first optical pulse 12 and the second optical pulse 13 (difference in incident timing), the second optical pulse 13 catches up with the first optical pulse 12 at a position closer to the incident surface, and The set of second light pulses 12a and 13a is a cross-sectional image 14a, the set of first and second light pulses 12b and 13b is a cross-sectional image 14b, and the set of first and second light pulses 12c and 13c is a cross-sectional image 14c. The set of first and second light pulses 12d and 13d forms a cross-sectional image 14d, and the set of first and second light pulses 12e and 13e forms a cross-sectional image 14e. Note that the order of incidence of the set of the first and second optical pulses 12a to 12e and 13a to 13e (the order in which the cross-sectional images 14a to 14e are formed) is not limited to that shown in FIG.

  FIG. 12 shows an example of a three-dimensional image composed of cross-sectional images. When the second pulses 13a to 13e in which the image information is written are sequentially overlapped with the first light pulses 12a to 12e whose optical path lengths are adjusted in the fluorescent space 11, cross-sectional images 14a to 14h are obtained as shown in FIG. These are displayed as a three-dimensional image 14. Note that the thickness, interval, number, and the like of the cross-sectional images are not limited to those described above. If a large number of cross-sectional images are formed without gaps, a detailed three-dimensional image with higher resolution can be formed.

(Effects of the first embodiment)
According to the first embodiment, the first light pulse 12 and the second light pulse 13 having different wavelengths are incident on the fluorescence space 11 from the same direction on the same optical axis, and are caused by the wavelength dispersion of the refractive index. Fluorescence is generated by overtaking the light pulse, and a clear three-dimensional image 14 with uniform resolution and brightness can be displayed.

  In addition, the thickness and brightness of the first light pulse 12 and the second light pulse 13 are made to enter the fluorescent space 11 from opposite directions on the same optical axis and cause fluorescence due to the passing of the light pulses. Large cross-sectional images 14a to 14e can be formed, so that the image quality and brightness of the three-dimensional image 14 composed of the cross-sectional images 14a to 14e can be improved.

[Second Embodiment]
The second embodiment differs from the first embodiment in that two optical pulse light sources are used. The description of the same points as in the first embodiment, such as other components and operations, will be omitted.

(Configuration of 3D image display device)
FIG. 13 is a configuration diagram of a 3D video display apparatus according to the second embodiment of the present invention. The three-dimensional nesting display device 1 according to the present embodiment includes a first light pulse light source 21a and a second light pulse light source 21b as light pulse light sources.

  For example, an optical pulse laser having a time width of 50 femtoseconds, a repetition frequency of 1 kHz, and a wavelength of 800 nm is used for the first optical pulse light source 21a, and for example, a time width of 50 femtoseconds is repeated for the second optical pulse light source 21b. An optical pulse laser having a frequency of 1 kHz and a wavelength of 1300 nm is used. The first and second pulse light sources 21a and 21b are configured to emit light pulses in synchronization.

(Operation of 3D image display device)
The first optical pulses 12a to 12e emitted from the first optical pulse light source 21a enter the optical path length control unit 23, and the first optical pulses 12a, 12b, 12c, 12d, and 12e are respectively switched mirror 24a, It passes through the optical path formed by 24b, 24c, 24d, 24e.

  On the other hand, the second light pulses 13a to 13e emitted from the second light pulse light source 21b are each written with the cross-sectional information corresponding to the cross-sectional image signal by the spatial light modulator 25, and the first light pulses 12a to 12e. And ride on the same optical axis.

  Thereafter, the first light pulses 12a to 12e and the second light pulses 13a to 13e are incident on the fluorescence space 11, and the set of the first and second light pulses 12a and 13a is a cross-sectional image 14a, first and second images. The set of optical pulses 12b and 13b is a cross-sectional image 14b, the set of first and second optical pulses 12c and 13c is a cross-sectional image 14c, and the set of first and second optical pulses 12d and 13d is a cross-sectional image 14d. The set of the first and second light pulses 12e and 13e form a cross-sectional image 14e, respectively.

(Effect of the second embodiment)
According to the second embodiment, an effect similar to that of the first embodiment can be obtained. Since the first optical pulse light source 21a and the second optical pulse light source 21b emit optical pulses having different wavelengths, the beam splitter 22 and the wavelength converter 25 in the first embodiment are not required. .

[Third Embodiment]
The third embodiment differs from the first embodiment in the configuration of the optical path length control unit 23. The description of the same points as in the first embodiment, such as other components and operations, will be omitted.

(Configuration of 3D image display device)
FIG. 14 is a configuration diagram of a 3D video display apparatus according to the third embodiment of the present invention. The optical path length control unit 23 includes rotating mirrors 28a to 28d that are a pair of rotating mirrors and a fixed mirror 29 that is a pair of fixed mirrors.

  FIG. 15 is an enlarged view of the rotating mirror and the fixed mirror. The rotating mirrors 28a to 28d and the fixed mirror 29 form different optical paths for the first optical pulse 12, respectively. The rotating mirrors 28a to 28d have an annular shape having a protrusion on the inside that closes a part of the hole, and can reflect or pass the first light pulse 12 according to the rotation angle. The fixed mirror 29 is disposed behind the row of rotating mirrors 28a to 28d.

  When the rotation mirrors 28a to 28d on the incident side are rotated at the same speed with a predetermined phase difference, and the light path is blocked by the protrusions of any one of the rotation mirrors 28a to 28d, the first rotation mirrors 28a to 28d The light pulse 12 is reflected and changes its path to the optical path formed by the rotating mirrors 28a to 28d. When the first light pulse 12 passes through all the rotating mirrors 28 a to 28 d, the first light pulse 12 is reflected by the fixed mirror 29 and travels along the optical path formed by the fixed mirror 29.

  The exit-side rotating mirrors 28a to 28d form an optical path with the paired incident-side rotating mirrors 28a to 28d, so that the incident-side and exit-side rotating mirrors 28a to 28d are synchronized as shown in FIG. Are configured to rotate.

  The change timing of the optical path length by the optical path length control unit 23 and the writing timing of the cross-sectional information by the spatial light modulation unit 26 are controlled to be synchronized by a control unit (not shown).

  Specifically, the optical path lengths of the optical paths to be formed increase in the order of the rotating mirrors 28a, 28b, 28c, 28d, and the fixed mirror 29, and accordingly, the first optical pulse 12 and the second optical pulse 13 are converted into the fluorescence space. 11 is increased in order. In FIG. 14, when optical paths are formed by the rotating mirrors 28 a, 28 b, 28 c, 28 d and the fixed mirror 29, cross-sectional images 14 a, 14 b, 14 c, 14 d, 14 e are formed in the fluorescent space 11, respectively. The intervals at which the cross-sectional images 14a to 14e are formed vary depending on the intervals at which the rotary mirrors 28a to 28d and the fixed mirror 29 are installed. 14 and 15, the four pairs of rotating mirrors 28 a to 28 d are shown as being provided, but the number of rotating mirrors is not limited to this, and a cross section formed in the fluorescent space 11. The number of images is not limited to five of the cross-sectional images 14a to 14e.

(Effect of the third embodiment)
According to the third embodiment, an effect similar to that of the first embodiment can be obtained. In addition, since the optical path length control unit 23 is composed of the rotary mirrors 28a to 28d and the fixed mirror 29 having high light utilization efficiency, it is possible to display a high-brightness and clear three-dimensional image with high contrast.

[Fourth Embodiment]
The fourth embodiment is different from the first embodiment in that a rotating light medium 30 is used instead of the optical path length control unit 23. The description of the same points as in the first embodiment, such as other components and operations, will be omitted.

(Configuration of 3D image display device)
FIG. 16 is a block diagram of a 3D video display apparatus according to the fourth embodiment of the present invention. The optical path length controller 23 includes a rotating optical medium 30 having a plurality of optical media having different thicknesses with respect to the optical axis.

  FIG. 17 is an enlarged view of the rotating light medium. The rotating optical medium 30 is configured by annularly arranging optical media 30a to 30e having the same refractive index and different thicknesses. Here, assuming that the high speed in vacuum is c, the light pulse passing through the plate of refractive index n and thickness d is (n−1) d / c seconds in time than the light pulse passing through the air. It will be late. Thereby, by rotating the rotating light medium 30 in synchronization with the operation of the spatial light modulation 261, the first light pulse 12 passes through the light media 30a to 30e having different thicknesses, and the incident timing to the fluorescent space 11 is reached. Can be adjusted. The plurality of optical media constituting the rotating optical medium 30 may have different refractive indexes.

  Specifically, the thickness increases in the order of the optical media 30a, 30b, 30c, 30d, and 30e, and the incident timing of the first light pulse 12 passing through the fluorescent space 11 is delayed. Accordingly, the interval at which the first light pulse 12 and the second light pulse 13 are incident on the fluorescence space 11 increases in order. In FIG. 16, when the first light pulse 12 passes through the optical media 30a, 30b, 30c, 30d, and 30e, cross-sectional images 14a, 14b, 14c, 14d, and 14e are formed in the fluorescent space 11, respectively. The intervals at which the cross-sectional images 14a to 14e are formed vary depending on the difference in thickness between the optical media 30a, 30b, 30c, 30d, and 30e. In FIG. 17, the five optical media 30 a to 30 e are illustrated as being provided. However, the number of optical media is not limited to this, and the number of cross-sectional images formed in the fluorescent space 11. Is not limited to five of the cross-sectional images 14a to 14e.

(Effect of the fourth embodiment)
According to the fourth embodiment, the same effects as those of the first embodiment can be obtained. In addition, the rotating light medium 30 is more compact than a device that adjusts the incident timing to the fluorescent space 11 by changing the optical path length, and the configuration is simple. Therefore, the 3D image display device 1 can be downsized. In addition, the manufacturing cost can be reduced.

[Fifth Embodiment]
The fifth embodiment differs from the first embodiment in that a plurality of spatial light modulators 26 are used. The description of the same points as in the first embodiment, such as other components and operations, will be omitted.

(Configuration of 3D image display device)
FIG. 18 is a configuration diagram of a 3D video display apparatus according to the fifth embodiment of the present invention. The three-dimensional image display device 1 includes an optical pulse light source 21 that emits optical pulses at a constant repetition period, and an optical pulse emitted from the optical pulse light source 21 as a first optical pulse 12 and a second optical pulse 13. A beam splitter 22 that divides into two, a wavelength converter 25 that changes the wavelength of the second optical pulse 13, and a branching unit 31 that selects the optical paths Ra to Re of the second optical pulse 13 divided by the beam splitter 22. , A plurality of spatial light modulators 26 that write cross-sectional information based on cross-sectional image signals to the second optical pulse 13 that travels along the optical paths Ra to Re, and a delay optical path 32 that adjusts the optical path length of the second optical pulse 13, respectively. A merging portion 33 for merging the optical paths Ra to Rh of the second light pulse 13, and a magnifying optical system 27 for enlarging the beam diameter of each of the first and second light pulses 13 and entering the fluorescence space 11. Includes a plurality of reflecting mirrors 36 for forming the optical path, and a controller (not shown) controls the respective units of the apparatus.

  The branch part 31 and the junction part 33 are composed of rotating mirrors 28 a to 28 d and a fixed mirror 29. The configuration and operation of the rotating mirrors 28a to 28d and the fixed mirror 29 used in the branching unit 31 and the merging unit 33 are a pair of rotating mirrors 28a to 28d used in the optical path length control unit 23 in the third embodiment. This is the same as the fixed mirror 29.

  The rotating mirrors 28a to 28d and the fixed mirror 29 of the branching unit 31 respectively form different optical paths Ra to Re of the second optical pulse 12, and the rotating mirrors 28a to 28d and the fixed mirror 29 of the merging unit 33 are respectively The optical paths Ra to Re of the second optical pulse 12 are merged.

  The spatial light modulator 26 includes a spatial light modulator 261 disposed on each of the optical paths Ra to Re selected by the branching unit 31, an expansion optical system 262 disposed in front of each spatial light modulator 261, and each And a reduction optical system 263 arranged at the subsequent stage of the spatial light modulator 261.

  The delay optical path 32 adjusts the incident timing of the second optical pulse 13 into the fluorescence space 11 by adjusting the optical path length of the second optical pulse 13 passing through the optical paths Ra to Re. A plurality of reflecting mirrors 321 are arranged at positions.

  In the delay optical path 32, an optical medium having a predetermined thickness is disposed on each of the optical paths Ra to Re, and the second optical pulse 13 is incident on the fluorescence space 11 depending on the thickness or refractive index of the optical medium. The structure which adjusts timing may be sufficient.

  The operation of selecting the optical paths Ra to Re of the branching unit 31, the operation of writing the cross-sectional information of the spatial light modulator 261, and the operation of joining the optical paths Ra to Re of the merging unit 33 are synchronized by a control unit (not shown). It is controlled.

(Operation of 3D image display device)
First, five pulsed light beams are emitted from the optical pulse light source 21 at a predetermined interval, and are separated by the beam splitter 22 so that five first optical pulses 12a to 12e and second optical pulses 13a to 13a, respectively. 13e.

  The second light pulses 13a to 13e travel along the optical paths Ra to Re by the rotating mirrors 28a to 28d and the fixed mirror 29 of the branching unit 31, respectively, and the spatial light modulation unit 26 provides cross-sectional information corresponding to the cross-sectional image signal, respectively. It is written and merged by the rotating mirrors 28a to 28d and the fixed mirror 29 of the merging unit 33, and rides on the same optical axis as the first light pulses 12a to 12e.

  The first and second light pulses 12a to 12e and 13a to 13e enter the fluorescent space 11, and the set of the first and second light pulses 12a and 13a is a cross-sectional image 14a and the first and second light pulses 12b. , 13b is a sectional image 14b, the first and second light pulses 12c, 13c are sectional images 14c, and the first and second light pulses 12d, 13d are sectional images 14d, first and second. Each pair of optical pulses 12e and 13e forms a cross-sectional image 14e.

  In FIG. 18, the five spatial light modulators 261 are illustrated as being provided. However, the number of the spatial light modulators 261 is not limited to this, and a cross section formed in the fluorescent space 11. The number of images is not limited to five of the cross-sectional images 14a to 14e.

(Effect of 5th Embodiment)
According to the fifth embodiment, an effect similar to that of the first embodiment can be obtained. Further, by using a plurality of spatial light modulators 261 in the spatial light modulator 26, each spatial light modulator 261 is configured to write one cross-section information in the second light pulses 13a to 13e, respectively. Therefore, even when the interval between the second light pulses 13a to 13e is short, the cross-sectional information can be written relatively easily.

[Sixth Embodiment]
The sixth embodiment is different from the above embodiments in that a three-dimensional image 14 is formed by a pulse train 131 composed of one first optical pulse 12 and a plurality of second optical pulses 13. Note that description of other components, operations, and the like that are the same as those of each of the above embodiments is omitted.

(Configuration of 3D image display device)
FIG. 19 is a configuration diagram of a 3D video display apparatus according to the sixth embodiment of the present invention. The 3D image display apparatus 1 includes first and second optical pulse light sources 21 a and 21 b that emit first and second optical pulses 12 and 13 at a constant repetition period, and an optical path of the second optical pulse 13. A branching unit 31 that selects Ra to Re, a plurality of spatial light modulation units 26 that write cross-sectional information based on cross-sectional image signals to the second optical pulse 13 that travels along the optical paths Ra to Re, and the second optical pulse 13, respectively. The delay optical path 32 for adjusting the optical path length of the light beam, the merging portion 33 for merging the optical paths Ra to Rh of the second optical pulse 13, and the first and second optical pulses 13 by expanding the beam diameter, respectively. Magnifying optical system 27 that enters the light, a plurality of reflecting mirrors 36 that form an optical path, and a control unit (not shown) that controls each part of the apparatus.

  For example, an optical pulse laser having a time width of 50 femtoseconds, a repetition frequency of 1 kHz, and a wavelength of 800 nm is used for the first optical pulse light source 21a, and for example, a time width of 50 femtoseconds is repeated for the second optical pulse light source 21b. An optical pulse laser having a frequency of 1 kHz and a wavelength of 1300 nm is used. The second light pulse light source 21b continuously emits the second light pulses 13a to 13h at a predetermined cycle in accordance with the timing at which the first light pulse light source 21a emits one first light pulse 12a. As a result, the optical pulse train 131 is emitted.

(Operation of 3D image display device)
First, the second optical pulse light source 21b emits a pulse train 131 composed of the second optical pulses 13a to 13h in synchronization with the timing at which the first optical pulse light source 21a emits one first optical pulse 12a. .

  The second optical pulses 13a to 13h constituting the pulse train 131 travel on the optical paths Ra to Rh by the rotating mirrors 28a to 28g and the fixed mirror 29 of the branch unit 31, respectively, and correspond to the cross-sectional image signal by the spatial light modulator 26. The cross-sectional information thus written is respectively written, merged by the rotating mirrors 28a to 28g of the merging portion 33 and the fixed mirror 29 to become the pulse train 131 again, which is on the same optical axis as the first optical pulse 12a.

  FIG. 20 is a conceptual diagram showing the relationship between the first and second light pulses and the cross-sectional image. When a pulse train 131 composed of the first light pulse 12a and the second light pulses 13a to 13h is incident on the fluorescence space 11, the second light pulses 13a to 13h catch up with the first light pulse 12a in order, and are respectively cross-sectional images. 14a-14h are formed, and the 3D image 14 is displayed.

  Specifically, since the interval (difference in incidence timing) with the first light pulse 12a before entering the fluorescence space 11 is small in the order of the second light pulses 13a to 13h, the second light pulses 13a to 13h. 13h catches up with the first optical pulse 12a at a position close to the incident surface, and the set of the first and second optical pulses 12a and 13a is the cross-sectional image 14a, and the set of the first and second optical pulses 12a and 13b is The cross-sectional image 14b, the first and second light pulses 12a, 13c are set as a cross-sectional image 14c, and the first and second light pulses 12a, 13d are set as a cross-sectional image 14d, the first and second light pulses 12a, 13e is a sectional image 14e, the first and second light pulses 12a, 13f are sectional images 14f, and the first and second light pulses 12a, 13g are sectional images 14g, first and second Optical pulses 12a, 13h Set to form cross-sectional images 14h, respectively.

  In FIG. 19, the eight spatial light modulators 261 are illustrated as being provided. However, the number of the spatial light modulators 261 is not limited to this, and a cross section formed in the fluorescent space 11. The number of images is not limited to eight of the cross-sectional images 14a to 14h.

(Effect of 6th Embodiment)
According to the sixth embodiment, a plurality of cross-sectional images are formed by a pulse train 131 composed of one first light pulse 12 and a plurality of second light pulses 13, and the display of the three-dimensional image 14 is performed. Can be done quickly. Thereby, it becomes easy to display the moving image by continuously switching the displayed 3D video at a short interval.

[Seventh Embodiment]
The seventh embodiment differs from the sixth embodiment in that a branching optical system 34 and a combining optical system 35 are used instead of the branching unit 31 and the joining unit 33. The description of the same points as in the sixth embodiment, such as other components and operations, will be omitted.

(Configuration of 3D image display device)
FIG. 21 is a configuration diagram of a 3D video display apparatus according to the seventh embodiment of the present invention. The branching optical system 34 and the combining optical system 35 are configured to include a plurality of beam splitters 341 and 351 and reflecting mirrors 342 and 352, respectively, and have the same roles as the branching unit 31 and the joining unit 33, respectively.

(Operation of 3D image display device)
First, eight pulse lights are emitted from the optical pulse light source 21 at a predetermined interval, and these are separated by the beam splitter 22 so that one first optical pulse 12a and one second optical pulse 13 are respectively obtained. Become.

  Next, after one wavelength of the second optical pulse 13 is converted by the wavelength converter 25, the second optical pulse 13 is separated at various places by the beam splitter 341 of the branching optical system 34, and five second optical pulses 13 a to 13 h are obtained. Become.

  The second optical pulses 13a to 13h travel on optical paths Ra to Rh formed by the beam splitter 351 and the reflection mirror 352, respectively, and cross-sectional information corresponding to the cross-sectional image signal is written by the spatial light modulation unit 26, respectively, and synthesized. The beams are merged by the beam splitter 351 and the reflection mirror 352 of the optical system 35 and are placed on the same optical axis as the first optical pulse 12a.

  Thereafter, when the first light pulse 12a and the second light pulses 13a to 13h are incident on the fluorescent space 11, the second light pulses 13a to 13h are changed to the first light pulse 12a as shown in FIG. The three-dimensional images 14 are displayed by catching up in order, forming cross-sectional images 14a to 14h, respectively.

  FIG. 21 shows that eight spatial light modulators 261 are provided, but the number of spatial light modulators 261 is not limited to this, and a cross section formed in the fluorescent space 11. The number of images is not limited to eight of the cross-sectional images 14a to 14h.

(Effect of 7th Embodiment)
According to the seventh embodiment, by using the branching optical system 34 and the combining optical system 35 configured to include the beam splitters 341 and 351, one second optical pulse 13 is converted into eight second optical pulses 13. Therefore, it is possible to form one first optical pulse 12a and eight second optical pulses 13a to 13h from one optical pulse light source 21.

[Eighth Embodiment]
In the eighth embodiment, each of the above-described embodiments is provided in that a three-dimensional image is formed by using a plurality of sets of pulse trains 131 including one first optical pulse 12 and a plurality of second optical pulses 13. The form is different. Note that description of other components, operations, and the like that are the same as those of each of the above embodiments is omitted.

(Configuration of 3D image display device)
FIG. 22 is a configuration diagram of a 3D video display apparatus according to the eighth embodiment of the present invention. The 3D image display apparatus 1 includes first and second optical pulse light sources 21 a and 21 b that emit first and second optical pulses 12 and 13 at a constant repetition period, and an optical path of the second optical pulse 13. A branching unit 31 that selects Ra to Re, a plurality of spatial light modulation units 26 that write cross-sectional information based on cross-sectional image signals to the second optical pulse 13 that travels along the optical paths Ra to Re, and the second optical pulse 13, respectively. The delay optical path 32 for adjusting the optical path length of the light beam, the merging portion 33 for merging the optical paths Ra to Rh of the second optical pulse 13, and the first and second optical pulses 13 by expanding the beam diameter, respectively. Magnifying optical system 27 that enters the light, a plurality of reflecting mirrors 36 that form an optical path, and a control unit (not shown) that controls each part of the apparatus.

  For example, an optical pulse laser having a time width of 50 femtoseconds, a repetition frequency of 1 kHz, and a wavelength of 800 nm is used for the first optical pulse light source 21a, and for example, a time width of 50 femtoseconds is repeated for the second optical pulse light source 21b. An optical pulse laser having a frequency of 1 kHz and a wavelength of 1300 nm is used. In synchronization with the timing at which the first optical pulse light source 21a emits one first optical pulse 12a, the second optical pulse light source 21b applies four second optical pulses 13a, 13c, 13e, and 13g to a predetermined level. The second optical pulse light source 21b is divided into four in accordance with the timing at which the first optical pulse light source 21a emits one first optical pulse 12b by emitting the pulse train 131a by continuously emitting in a cycle. The pulse train 131b is emitted by continuously emitting the second optical pulses 13b, 13d, 13f, and 13h at a predetermined cycle.

(Operation of 3D image display device)
First, in accordance with the timing at which the first light pulse light source 21a emits one first light pulse 12a, the second light pulse light source 21b is changed from four second light pulses 13a, 13c, 13e, and 13g. The second optical pulse light source 21b emits four second optical pulses in accordance with the timing at which the first optical pulse light source 21a emits one first optical pulse 12b. A pulse train 131b composed of 13b, 13d, 13f, and 13h is emitted.

  The second optical pulses 13a, 13c, 13e, and 13g constituting the pulse train 131a travel on the optical paths Ra to Rd by the rotating mirrors 28a to 28c and the fixed mirror 29 of the branching unit 31, respectively. On the other hand, the second optical pulses 13b, 13d, 13f, and 13h constituting the pulse train 131b follow the second optical pulses 13a, 13c, 13e, and 13g, the rotating mirrors 28a to 28c of the branching unit 31, and the fixed mirrors. 29, respectively, travels along the optical paths Ra to Rd. That is, the second optical pulses 13a and 13e are in the optical path Ra, the second optical pulses 13b and 13f are in the optical path Rb, the second optical pulses 13c and 13g are in the optical path Rc, and the second optical pulses 13d and 13h are in the optical path Rd. move on.

  Next, the second light pulses 13 a, 13 c, 13 e, and 13 g are written with cross-sectional information corresponding to the cross-sectional image signal by the spatial light modulator 26, respectively, and the rotating mirrors 28 a to 28 c and the fixed mirror 29 of the merging unit 33. Are combined to form a pulse train 131a again on the same optical axis as the first optical pulse 12a. Subsequently, the second optical pulses 13b, 13d, 13f, and 13h are cross-sectional image signals by the spatial light modulator 26. Are respectively written by the rotary mirrors 28a to 28c and the fixed mirror 29 of the merging portion 33, and again become a pulse train 131b and ride on the same optical axis as the first optical pulse 12b.

  FIG. 23 is a conceptual diagram showing the relationship between the first and second light pulses and the cross-sectional image. When the pulse train 131a composed of the first light pulse 12a and the second light pulses 13a, 13c, 13e, and 13g is incident on the fluorescence space 11, the second light pulses 13a, 13c, 13e, and 13g are converted into the first light. The laser beam catches up with the pulse 12a in order to form cross-sectional images 14a, 14c, 14e, and 14g, respectively, and a pulse train 131b including the first light pulse 12b and the second light pulses 13b, 13d, 13f, and 13h is incident on the fluorescence space 11. Then, the second light pulses 13b, 13d, 13f, and 13h catch up with the first light pulse 12b in order to form cross-sectional images 14b, 14d, 14f, and 14h, respectively, and the three-dimensional image 14 is displayed.

  Specifically, in the set of the first light pulse 12a and the second light pulses 13a, 13c, 13e, and 13g, the light beams enter the fluorescent space 11 in the order of the second light pulses 13a, 13c, 13e, and 13g. Since the interval (difference in incidence timing) with the previous first optical pulse 12a is small, the second optical pulse 13a, 13c, 13e, 13g catches up with the first optical pulse 12a at a position close to the incident surface in order. The set of first and second light pulses 12a and 13a is a cross-sectional image 14a, the set of first and second light pulses 12a and 13c is a cross-sectional image 14c, and the set of first and second light pulses 12a and 13e is A set of the cross-sectional image 14e and the first and second optical pulses 12a and 13g forms a cross-sectional image 14g, respectively.

  On the other hand, in the set of the first optical pulse 12b and the second optical pulse 13b, 13d, 13f, 13h, the second optical pulse 13b, 13d, 13f, 13h in the order before entering the fluorescence space 11 Since the interval (difference in incidence timing) with the first optical pulse 12b is small, the first optical pulse 12b catches up with the first optical pulse 12b in the order of the second optical pulses 13b, 13d, 13f, and 13h, The set of second optical pulses 12b and 13b is a cross-sectional image 14b, the set of first and second optical pulses 12b and 13d is a cross-sectional image 14d, and the set of first and second optical pulses 12b and 13f is a cross-sectional image 14f. The set of the first and second light pulses 12b and 13h form a cross-sectional image 14h, respectively.

  The present embodiment is configured to display one 3D image 14 by using two sets of one first light pulse 12 and four light pulses. The number is not limited to the above, and the combination of the second optical pulse 13 and the first optical pulse 12 is not limited to the above (for example, the first optical pulse 12a and the second optical pulse). 13a to 13d may be one set, and the first optical pulse 12b and the second optical pulses 13e to 13h may be one set). In other words, M × N cross-sectional images 14 are formed using M sets of pulse trains composed of N second optical pulses (one first optical pulse 12 corresponds to one set of pulse trains). I just need it.

(Effect of 8th Embodiment)
According to the eighth embodiment, by using a plurality of sets of pulse trains 131 including one first optical pulse 12 and a plurality of second optical pulses 13, a plurality of cross-sectional images are formed. Although the display speed of the three-dimensional image 14 is inferior to that of the sixth embodiment, the number of spatial light modulators 261 can be reduced to reduce the size of the apparatus. In comparison, although the number of spatial light modulators 261 increases, the 3D image 14 can be displayed quickly.

[Ninth Embodiment]
The ninth embodiment differs from the fourth embodiment in the configuration of the rotating light medium 30. Note that the description of the same points as in the fourth embodiment, such as other components and operations, is omitted.

  As illustrated in FIG. 17, the rotating optical medium 30 includes a plurality of optical media having different thicknesses, and the first light pulse 12 is allowed to pass through the plurality of optical media to thereby generate the first light. The incident timing of the pulse 12 to the fluorescence space 11 is adjusted.

  However, since the plurality of optical media have different thicknesses, their weights are also different. Therefore, the center of gravity of the rotating light medium 30 changes depending on the arrangement of each light medium. In order to rotate the rotating light medium 30 at high speed and stably and accurately adjust the incident timing of the first light pulse 12 to the fluorescent space 11, the center of gravity of the rotating light medium 30 rotates on the rotation axis. It is desirable to be near the center.

  24 and 25 are enlarged views of the rotating light medium according to the ninth embodiment of the present invention.

  FIG. 24 shows a configuration example in the case where the rotating optical medium 30 has two optical media 30a to 30e each having five different thicknesses. Here, the thickness increases in the order of the optical media 30a, 30b, 30c, 30d, and 30e. As shown in the figure, optical media having the same thickness are arranged at positions symmetrical with respect to the rotation center, and the center of gravity of the rotation optical medium 30 coincides with the rotation center. Note that they do not have to be completely coincident with each other as long as the rotating light medium 30 is close enough to rotate at high speed and stably.

  FIG. 25 shows a configuration example in the case where the rotating optical medium 30 has ten optical media 30a to 30j having different thicknesses one by one. Here, the thickness increases in the order of the optical media 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, and 30j. As shown in the figure, optical media having close thicknesses are respectively arranged at symmetrical positions with respect to the rotation center, and the center of gravity of the rotation light medium 30 is brought close to the rotation center.

  Note that the number and arrangement of the plurality of optical media are not limited to those described above, and may be any as long as the center of gravity of the rotating optical medium 30 is near the center of rotation. Further, a weight having a predetermined weight may be provided on the rotating light medium 30 so that the center of gravity approaches the center of rotation.

(Effect of 9th Embodiment)
According to the fourth embodiment, the rotating light medium 30 can be rotated at high speed and stably, and the incident timing of the first light pulse 12 into the fluorescence space 11 can be accurately adjusted.

[Other embodiments]
The present invention is not limited to the above embodiments and the above examples, and various modifications can be made without departing from the scope of the invention. For example, in each of the above embodiments, the spatial light modulator 25 writes the cross-sectional information corresponding to the cross-sectional image signal to the second optical pulse 13, but the cross-sectional information is written to the first optical pulse 12. It may be a configuration. Further, the first optical pulse 12 has been described as being caught up by the second optical pulse 13 in the fluorescent space 11, but the second optical pulse 12 may be followed up by the first optical pulse 13. .

  In addition, as described above, when the fluorescent space 11 is a material in which a fluorescent material is dispersed in an organic solvent such as ethanol or acetone, the wavelength of the first light pulse and the second light pulse is reduced. It is preferable to use a transparent deuterium substitution solvent as a solvent. When hydrogen is replaced with deuterium, there is no significant change in the characteristics as a solvent, and therefore the wavelength selectivity can be improved without impairing the properties as a fluorescent space. In addition to deuterium, the absorption peak shifts even when hydrogen is replaced with chlorine, fluorine, or the like, which can be used to improve wavelength selectivity.

  Moreover, although the inside of the fluorescence space 11 was demonstrated as what shows normal dispersion, the structure which shows anomalous dispersion | distribution may be sufficient.

  In addition, any combination of the constituent elements of each embodiment and each example is possible without departing from the scope of the present invention.

(A)-(c) is a figure which shows the basic principle of the three-dimensional video display method which concerns on this invention. It is a conceptual diagram which shows the relationship between the difference of the incident timing of the 1st and 2nd optical pulse which concerns on this invention, and the position where fluorescence generate | occur | produces. It is the 1st figure which shows the principle of the fluorescence generation by multiphoton absorption. It is the 2nd figure which shows the principle of the fluorescence generation by multiphoton absorption. It is the 3rd figure which shows the principle of the fluorescence generation by multiphoton absorption. It is the 4th figure which shows the principle of the fluorescence generation by multiphoton absorption. It is the 5th figure which shows the principle of the fluorescence generation by multiphoton absorption. 1 is a configuration diagram of a 3D video display apparatus according to a first embodiment of the present invention. It is a schematic diagram which shows an example of the shape of the 2nd optical pulse in which the image information which concerns on the 1st Embodiment of this invention was written. It is a schematic diagram which shows an example of the shape of the 1st optical pulse which concerns on the 1st Embodiment of this invention. It is a conceptual diagram which shows the relationship between the 1st and 2nd optical pulse which concerns on the 1st Embodiment of this invention, and a cross-sectional image. An example of the three-dimensional image comprised by the cross-sectional image which concerns on the 1st Embodiment of this invention is shown. It is a block diagram of the three-dimensional video display apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram of the three-dimensional video display apparatus which concerns on the 3rd Embodiment of this invention. It is an enlarged view of the rotating mirror and fixed mirror which concern on the 3rd Embodiment of this invention. It is a block diagram of the three-dimensional video display apparatus which concerns on the 4th Embodiment of this invention. It is an enlarged view of the rotating light medium based on the 4th Embodiment of this invention. It is a block diagram of the three-dimensional video display apparatus which concerns on the 5th Embodiment of this invention. It is a block diagram of the three-dimensional video display apparatus which concerns on the 6th Embodiment of this invention. It is a conceptual diagram which shows the relationship between the 1st and 2nd optical pulse which concerns on the 6th Embodiment of this invention, and a cross-sectional image. It is a block diagram of the three-dimensional video display apparatus which concerns on the 7th Embodiment of this invention. It is a block diagram of the three-dimensional video display apparatus which concerns on the 8th Embodiment of this invention. It is a conceptual diagram which shows the relationship between the 1st and 2nd optical pulse which concerns on the 8th Embodiment of this invention, and a cross-sectional image. It is an enlarged view of the rotating light medium based on the 9th Embodiment of this invention. It is an enlarged view of the rotating light medium based on the 9th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3D image display apparatus 11 Fluorescent space 12, 12a-12h 1st light pulse 13, 13a-13h 2nd light pulse 14 3D image 14a-14h Cross-sectional image 15 Notch filter 21 Optical pulse light source 21a 1st light Pulse light source 21b Second light pulse light source 22 Beam splitter 23 Optical path length control units 24a to 24e Switching mirror 25 Wavelength converter 26 Spatial light modulation unit 261 Spatial light modulator 262 Expansion optical system 263 Reduction optical system 27 Expansion optical system 28a to 28a 28 g Rotating mirror 29 Fixed mirror 30 Rotating light mediums 30 a to 30 j Optical medium 31 Branching portion 32 Delay optical path 321 Reflecting mirror 33 Joining portion 34 Branching optical system 341 Beam splitter 342 Reflecting mirror 35 Synthetic optical system 351 Beam splitter 352 Reflecting mirror 36 Reflecting mirror Ra ~ Rh Light path

Claims (26)

A first step of causing a first light pulse to enter a non-vacuum fluorescent space from a predetermined direction;
A second light pulse whose propagation speed in the fluorescent space is faster than the first light pulse is incident on the fluorescent space from the substantially same direction as the predetermined direction with a delay of a predetermined time from the first light pulse; A second step in which the second light pulse catches up with the first light pulse in the fluorescence space and causes fluorescence to overlap at the overlapping position;
A 3D image display method comprising:   The three-dimensional image display method according to claim 1, wherein cross-sectional information is written in either one of the first light pulse and the second light pulse.   In the first and second steps, the first and second light pulses are caused to fluoresce at a plurality of different positions in the fluorescence space by controlling the timing of incidence of the first and second light pulses into the fluorescence space. The 3D image display method according to claim 1. The speed of light in vacuum is c, the wavelength of the first light pulse is λ ₁ , the wavelength of the second light pulse is λ ₂ , the refractive index in the fluorescence space at the wavelength λ is n (λ), and the light pulse 1 _{t 1} the time width of, when the time width optical pulses 2 and _{t 2,} ^{a, 1 × 10 -4 [m]} ≦ {c (t 1 n (λ 2) + t 2 n (λ 1))} / The three-dimensional image display method according to claim 1, wherein {n (λ ₂ ) (n (λ ₁ ) −n (λ ₂ ))} ≦ 1 × 10 ⁻² [m] is satisfied.   In the second step, a plurality of second light pulses are incident on the fluorescence space at a predetermined repetition period with respect to one first light pulse, and fluorescence is emitted at a plurality of positions in the fluorescence space. The 3D image display method according to claim 1, wherein: In the first step, a plurality of the first light pulses are incident on the fluorescent space at a predetermined repetition period,
In the second step, a plurality of pulse trains made up of N second light pulses are incident on the fluorescence space at the same repetition period as the predetermined repetition period, and the N positions in the fluorescence space are entered. The three-dimensional image display method according to claim 1, wherein the three-dimensional image display method is made to cause fluorescence. In the first step, M first light pulses are incident on the fluorescent space at a predetermined repetition period,
In the second step, M pulse trains composed of the N second light pulses are incident on the fluorescence space at the same repetition period as the predetermined repetition period, and N × M in the fluorescence space. The three-dimensional image display method according to claim 1, wherein fluorescence is emitted at said position.   2. The 3D image display method according to claim 1, wherein writing of the cross-sectional information into the second light pulse is performed by spatial light modulation. First light pulse incident means for causing the first light pulse to enter a non-vacuum fluorescent space from a predetermined direction;
A second light pulse whose propagation speed in the fluorescent space is faster than the first light pulse is incident on the fluorescent space from the substantially same direction as the predetermined direction with a delay of a predetermined time from the first light pulse; Second light pulse incident means for causing the second light pulse to catch up with the first light pulse in the fluorescent space and to cause fluorescence at an overlapping position;
A three-dimensional image display device comprising: The first and second light pulse incident means include one light pulse light source that emits a light pulse;
The optical pulse emitted from the optical pulse light source is divided into two optical pulses, one of the two optical pulses is used as the first optical pulse, and the other optical pulse is used as the second optical pulse. A splitting optical system and
The three-dimensional image display apparatus according to claim 9, further comprising: The first light pulse incident means includes a first light pulse light source that emits the first light pulse,
The three-dimensional image display apparatus according to claim 9, wherein the second light pulse incident means includes a second light pulse light source that emits the second light pulse.   The first or second light pulse incident means includes a spatial light modulator that writes the cross-sectional information into an optical pulse according to a cross-sectional image signal and generates the first optical pulse or the second optical pulse. The three-dimensional image display apparatus according to claim 9, wherein   The three-dimensional image display apparatus according to claim 12, wherein the spatial light modulator is a liquid crystal spatial light modulator.   The first or second optical pulse incident means has a plurality of optical paths having different optical path lengths, and is provided in a branching section that distributes the incident optical pulses to the plurality of optical paths, and in the plurality of optical paths, A plurality of spatial light modulators for writing cross-sectional information to a plurality of optical pulses distributed to a plurality of optical paths, and a plurality of second optical pulses in which the cross-sectional information is written are aligned with the optical axes of the plurality of second optical pulses. The three-dimensional image display device according to claim 10, further comprising: a confluence unit that makes two light pulses incident on the fluorescent space.   The three-dimensional image display device according to claim 14, wherein the branching unit is an optical path switching unit that distributes an incident optical pulse by sequentially switching the plurality of optical paths.   The three-dimensional image display device according to claim 14, wherein the branching unit is a splitting optical system that splits an incident light pulse into a plurality of light pulses and distributes the light pulses to the plurality of light paths.   The said 1st or 2nd optical pulse incident means was equipped with the optical path length control part which controls the optical path length of the said 1st optical pulse or the said 2nd optical pulse, It is characterized by the above-mentioned. 3D image display device.   The first or second optical pulse incident means has a plurality of optical media having different thicknesses, and switches the optical medium placed on the optical axis of the first optical pulse or the second optical pulse. The three-dimensional image display apparatus according to claim 9, further comprising: a timing control unit that adjusts a timing at which the first light pulse or the second light pulse enters the fluorescent space.   The three-dimensional image display apparatus according to claim 9, wherein the first or second light pulse incident means includes a wavelength converter that converts a wavelength of the light pulse.   The said 1st and 2nd optical pulse incident means shares the expansion optical system which expands the aperture of the said 1st and 2nd optical pulse, and injects into the said fluorescence space, It is characterized by the above-mentioned. 3D image display device.   10. The three-dimensional image according to claim 9, wherein the fluorescent space is made of a phosphor, or a gas, a liquid, or a solid containing the phosphor that is transparent with respect to the wavelengths of the first and second light pulses. Video display device.   The tertiary space according to claim 9, wherein the fluorescent space is made of a deuterium-substituted organic solvent containing a phosphor and transparent to the wavelengths of the first light pulse and the second light pulse. Original video display device.   10. The three-dimensional image display device according to claim 9, wherein the fluorescent space causes the strongest multiphoton absorption at the position where the first light pulse and the second light pulse overlap each other. The first and second light pulse incident means has a light intensity of a light pulse having a shorter wavelength of the first and second light pulses lower than that of a light pulse having a longer wavelength,
The fluorescence space is transparent to the first and second light pulses, and the excitation energy to the two-photon absorption level of the fluorescence space is greater than the energy of two photons of the light pulse having the longer wavelength. 24. The three-dimensional image display device according to claim 23, wherein the three-dimensional image display device is larger and equal to or smaller than the energy obtained by adding one photon of the light pulse having a shorter wavelength.   The fluorescent space has a notch filter that cuts only the wavelengths of the first and second optical pulses on the side opposite to the incident side of the first and second optical pulses and transmits light having other wavelengths. The three-dimensional image display apparatus according to claim 9, wherein   The timing control unit has a disk-like shape, and performs the rotational motion around a rotation axis parallel to the thickness direction of the disk-like shape, whereby the first light pulse or the second light pulse The three-dimensional image display apparatus according to claim 18, wherein the optical medium placed on the optical axis of the optical pulse is switched.

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