JPH04107522A - Synthetic light generation device - Google Patents

Abstract

PURPOSE:To decrease the number of components by making light with wavelength which needs to have large energy intensity incident on a translucent film in a direction where the energy loss at the transparent film part is small and also making light with wavelength which may have small energy intensity incident in a direction where the energy loss is large. CONSTITUTION:A couple of light source blocks 1 and 2 are arranged for a multiplexing device X in the direction where the energy loss at the part of the translucent film 4a of a polarization beam splitter 4 is small as to the laser beam B1 of the component with wavelength lambda1 which needs to have the large energy intensity and in the direction where the energy loss at the part of the translucent film 4a of the polarization beams splitter 4 is large as to the laser beam B2 of the component with wavelength lambda2 which may have the small energy intensity. Consequently, any other optical element need not be interposed and the simple constitution is realized by using a small number of components.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is useful for obtaining combined light for wavelength multiplexing recording in, for example, a laser beam printer, or for simultaneously writing and monitoring an optical disk. A synthetic light generation device that generates synthetic light including a plurality of wavelengths by synthesizing lights of different wavelengths from a plurality of light sources for the purpose of obtaining synthetic light for The present invention relates to a combined light generating device in which the beam shapes of light of each wavelength are made uniform by making the polarization directions of the lights the same. Furthermore, in detail, a plurality of light sources that emit light of mutually different wavelengths composed of the same polarization direction component, and a semi-transparent film that reflects incident light from a first direction and reflects incident light from a second direction. The present invention relates to a combined light generation device that includes a multiplexing device that combines both incident lights by transmitting them through the semi-transparent membrane, and generates combined light that includes a plurality of wavelength components.

[Conventional technology]

In the above-mentioned combined light generation device, conventionally, as a multiplexing device, the P polarized light component in the semi-transparent membrane portion is approximately 10
0% transmission, while almost 100% for S polarized light component
In order to match the characteristics of the semi-transparent film described above, when using a polarizing beam splitter with reflective polarization selection characteristics to input and combine light consisting of components in the same polarization direction from two light sources into the multiplexing device, One of the lights is rotated by 90 degrees, for example, by rotating the plane of polarization of the P-polarized light component using a phase shifter such as a 1/1 wavelength plate, and then converted into S-polarized light, and then combined with the P-polarized light component by a multiplexer. It is known that the device is made to be incident on the
See publication. ) [Problems to be Solved by the Invention] However, in the conventional combined light generation device described above, light consisting of components in the same polarization direction is combined using a multiplexing device equipped with a semi-transparent film having polarization selection characteristics. A retarder is used to change the polarization direction of one of the lights, and when lights of different wavelengths and the same intensity are combined,
Although the intensities of both multi-wavelength components can be made almost the same in the resulting combined light, the need for a retarder increases the number of components.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide a combined light generation device that can reduce the number of parts.

[Means to solve the problem]

The characteristic configuration of the synthesized light generating device according to the present invention is that, depending on the required spectral composition of the synthesized light including a plurality of wavelength components, light of a wavelength that requires large energy intensity is transmitted semi-transparently, and incident light from the first direction is semi-transparent. The semi-transparent film portion of the first direction and the second direction in a multiplexing device that combines both incident lights by reflecting the light from the film and transmitting the incident light from the second direction through the semi-transparent film. The plurality of light sources are connected to the multiplexing device so that light of a wavelength that requires a small energy intensity is incident on the semi-transparent film from a direction with a low energy loss, and from a direction with a high energy loss. It's in the placement.

[For production]

In other words, when using such synthesized light containing multiple wavelength components, for example to write to an optical disk and monitor it at the same time, the energy intensity required for the monitoring light is lower than the energy intensity required for the writing light. The energy intensity required for the light may be small. Also, for example,
When color recording is performed by irradiating three photosensitive materials corresponding to the three primary colors with combined light containing light components of different photosensitive wavelengths, the energy intensity of each wavelength component in the combined light is the same. This is not necessarily necessary; if there is a difference in the sensitivity of each photosensitive material, it becomes necessary to make the energy intensity of each wavelength component different to correspond to the difference.

Focusing on the fact that the spectral composition required for combined light is not necessarily the same, and taking this into account, in a multiplexing device that uses a semi-transparent membrane, the spectral composition of the combined light is different depending on the direction of incidence on the semi-transparent membrane. Even if there is a difference in energy loss, this difference can be effectively utilized to allow light of a wavelength that requires a large energy intensity in the combined light to enter the semi-transparent membrane from a direction with less energy loss. Light of a wavelength that requires a small energy intensity in the combined light is incident from the direction of high energy loss in the semi-transparent membrane, and the light of the same wavelength is combined.
They discovered that synthesized light with the required spectral composition can be obtained without providing a retarder.

In particular, when three or more lights are synthesized using a plurality of multiplexing devices, as in claim 7, the light that requires the highest energy intensity in the synthesized light, If only one of the plurality of multiplexing devices is used to perform transmission or reflection for multiplexing and combine with other light, energy loss will be reduced and it will be more useful.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

As shown in Fig. 2, a pair of light source blocks (1), (
After the laser beams (B, ), (132) emitted from 2), both of which have P-polarized components and have different wavelengths, are combined by a combiner (X) into one combined light beam (B). The light is condensed and irradiated onto the optical disc (D) via a condensing optical system (C3), thereby forming an optical head for the optical disc. Each light source block (1),
The laser beams (Bl) and (B2) from (2) are both configured to be emitted as parallel light by a collimator.

As shown in FIG. 1, the multiplexing device (X) is composed of a polarizing beam splitter (4).

This polarizing beam splitter (4) is a semi-transparent film (4) with spectral transmittance characteristics as shown in Fig. 3 for P-polarized light.
a), and as shown in FIG. while transmitting a second laser beam (B
2) by the semi-transparent film (4a), the laser beams (B,
) and (B2) are combined into one.

Since both laser beams (Bl) and (B2) are combined at the semi-transparent film (4a) portion with the above-mentioned spectral transmission characteristics, both laser beams (Bυ , (B2) are the same, both ripple components (λ,
), (λ2) is configured to have a ratio of approximately 4:1.

Laser beams (B) of the two wavelengths (λ1) and (λ2)
l) and (B2) are both composed of P-polarized light components, and by combining lights of the same polarization direction components in this way, beam spots of both wavelengths can be created on the optical disc (D). The shapes can be made almost the same.

Both wavelengths (λ1).

One of the wavelengths (λ1) of (λ2) is the wavelength (λ1) of the optical disc (
D) and the other wavelength (λ
2) is used to monitor the recorded information at the same time as recording. Therefore, in the combined light after exiting from the multiplexer (X), the above-mentioned writing wavelength (λ1) component requires a large energy intensity, but the monitoring wavelength (λ2) component requires a small energy intensity. Energy intensity is sufficient.

Therefore, in order to match the spectral composition required in the above-mentioned combined light beam (B), for the laser beam (B1) of the wavelength (λ1) component that requires large energy intensity, the polarizing beam splitter (4) is used. semipermeable membrane (4
In part a), the energy intensity is smaller so as to be incident on the multiplexing device (X) from a direction with less energy loss, that is, from a direction that passes through the semi-transparent membrane (4a) and proceeds toward the optical disk (D). The laser beam (B2) having a wavelength (λ2) component that is sufficient for The pair of light source blocks (1) and (2) are arranged with respect to the multiplexing device (X) so that the light enters the multiplexing device (X) from the direction toward the optical disk (D).

That is, as described above, depending on the required spectral composition of the combined light beam (B), the laser beam (Bl) to the multiplexer (X) is adjusted to effectively utilize the spectral transmittance characteristics of the semi-transparent film.
By setting the incident direction of , (B2), a combined light generating device including a pair of light sources (1), (2) and a multiplexing device (X) can be used without intervening other optical elements (, A simple configuration is realized with a small number of parts.

The semi-permeable membrane (4a) is composed of a 24-layer interference multilayer film made of dielectric material, and the structure of each layer is as shown in Table 1 on the next page. The 0th layer and the 26th layer represent right angle prisms.

layer n nd/λ.

λo=1180nm Table 1 In the composite light generator configured as described above, the first wavelength (λo
The laser beam (B1) of the 1) component mostly passes through the semi-transparent film (4a) of the polarizing beam splitter (4), and the laser beam (B2) of the second wavelength (λ2) component passes through the polarizing beam splitter (4). Approximately 80% of the light is reflected from the semi-transparent film (4a) of (4) and is emitted as one combined light beam (B). If the initial energy intensities of both laser beams (B, ) and (B2) are the same, in the combined light beam (B) after synthesis, the first wavelength (λ1) component and the second wavelength (λ2) The components have an energy intensity ratio of approximately 5:4.

Of course, the above is just one example, and the composite light beam (
Depending on the proportion of each wavelength component required in B),
The configuration of the semipermeable membrane (4a) may be changed as appropriate.

[Another example]

Next, another example of the present invention will be listed.

<1> In the previous embodiment, for the two laser beams (Bl) and (B2) combined by the multiplexing device (X), in the combined light beam (B), the first wavelength (λ1) component In this case, two laser beams (B, ), (
B2), but conversely, if a higher energy intensity is required for the second wavelength (λ2) component, it is possible to combine the components with the same spectral transmission characteristics. The device (X) has two laser beams (Bl), (B
2), both of which are made up of S-polarized light components, or the two laser beams (Bl) and (B2), both of which are made up of P-polarized light components, are The second wavelength (λ1) has a lower transmittance than the first wavelength (λ1).
For example, the light may be made to enter a multiplexer having a high transmittance for λ2).

<2> The wavelengths included in the resulting synthesized light (B) are not limited to two, but the synthesized light (B) includes three or more wavelengths.
It is also possible to have a configuration that obtains the following. Next, the configuration for generating composite light (B) containing three wavelengths is determined depending on the magnitude of energy intensity required for each light (hereinafter, this is referred to as priority, and the order is referred to as priority). I will explain.

In the following embodiments, the combined light generating device according to the present invention is incorporated into a recording device. As shown in FIG. 4, this recording device has three light source blocks (1),
Laser beams (Bl), (B2), (B2) emitted from (2) and (3) with mutually different wavelengths are combined by a combiner (X) to form one combined light laser beam. After (B), a polygon mirror that rotates at high speed (
5) and a scanning optical system (SS) consisting of an fθ lens (6)
The photosensitive material (7) is scanned through the photosensitive material (7).
It is constructed so that recording is performed on the photosensitive material (7).

In such a recording device, priority is given to each light, for example, when the photosensitive material (7) has three colors corresponding to the three primary colors.
This is a case where two photosensitive material layers are combined, each photosensitive material layer is exposed to light of a different wavelength, and the sensitivity is different for each photosensitive material layer. Some of the configurations of the combined light generation device in such a case are listed below.

a) The priority in the combined light (B) is [λ.

λ2-λ3], as shown in FIG.
4B), and three light source blocks (1), (2), and (3
) are arranged. First polarizing beam splitter (4A
The semipermeable membrane (4Aa) of ) has a 25-layer structure, and the refractive index of each layer (
n) and optical film thickness (nd/λ.) are as shown in Table 2 on page 16. Note that the 0th layer and the 26th layer represent right angle prisms. The spectral characteristics for the polarized light components are as shown in FIG. The semi-transparent film (4Ba) of the second polarizing beam splitter (4B) has a 21-layer structure, and the refractive index (n) and optical thickness (nd/λ0) of each layer are as follows.
As shown in Table 3 on page 17. Note that the 0th layer and the 22nd layer represent right angle prisms. The spectral characteristics for the P polarized light component are as shown in FIG.

λ, = 1180 nm Second surface layer Third table nd/λ0 λ. = 1100 nm In the composite light generator configured as described above, the first wavelength (λ
Most of the laser beam (B,) of the component 1) passes through the semi-transparent film (4Ba) of the second polarizing beam splitter (4B). In addition, a laser beam (B
2) is the semi-transparent membrane (
After 85% of the light passes through the portion 4Aa), approximately 90% of the light is reflected by the semi-transparent film (4Ba) of the second polarizing beam splitter (4B). Furthermore, about 80% of the laser beam (B3) having the third wavelength (λ3) component is reflected by the semi-transparent film (4Aa) of the first polarizing beam splitter (4A), and then the second
Approximately 95% of the light is reflected by the semi-transparent film (4Ba) of the polarizing beam splitter (4B). Therefore, each laser beam (B
If the initial energy intensities of l), (B2), and (B3) are the same, each wavelength (λ1), (λ2), and (λ3) component in the combined light beam (B) is about 38:
The energy intensity ratio is 31:30.

Of course, if the ratio of energy intensity required in the combined light beam (B) changes, the double-sided optical beam splitter (4
The configurations of the semipermeable membranes (4Aa) and (4Ba) in A) and (4B) may be changed as appropriate.

In addition, as shown in the above embodiment, the wavelength component with the highest priority ((λ1) in this example) is transmitted or reflected for multiplexing in a composite light generator incorporating multiple multiplexers. It is preferable to minimize the number of times in order to reduce energy loss.

b) When the priority order of the combined light (B) is [λ1-λ, -λ31 as in the previous a), as shown in Fig. 6, two polarizing beam splitters (4A
), (4B), and for them, laser beams (B, ), (B2), (
Three light source blocks (1), (2) that emit light (B,)
, (3) are arranged. The semi-transparent film (4Aa) of the first polarizing beam splitter (4A) has the same configuration as the semi-transparent film (4Aa) of the first polarizing beam splitter (4A) in a) above. The semi-transparent film (4Ba) of the second polarizing beam splitter (4B) has a 39-layer structure, and the refractive index (n) and optical thickness (nd/λ) of each layer are 21
As shown in Table 4 on page 4. In addition, the 0th layer and the 40th layer
Layer refers to a right-angled prism. The spectral characteristics for the P polarized light component are as shown in FIG. In addition,
The energy intensity ratio of each wavelength component is determined in the same manner as in a) above, so the details will be omitted.

C) Priority in composite light (B), also [λ, −
λ2-λ3], as shown in FIG.
4B), and for them, laser beams (Bl), (B2), (B,l), all of which have S polarization components, are used.
Three light source blocks (1), (2),
(3) is placed. First polarizing beam splitter (4
The semipermeable membrane (4Aa) in A) has a 17-layer structure, and the refractive index (n) and optical thickness (nd/λ) of each layer are as shown in page 5 on page 23.
As shown in the table. Note that the 0th layer and the 18th layer represent right angle prisms. The spectral characteristics for the S-polarized light component are as shown in FIG. The semi-transparent film (48a) of the second polarizing beam splitter (4B) has an 11-layer structure, and each layer has a refractive index (n) and an optical thickness (nd/λ).

) are shown in Table 6 on page 24. Note that the 0th layer and the 12th layer represent right angle prisms.

The spectral characteristics for the S-polarized light component are as shown in FIG. Note that details regarding the energy intensity ratio of each wavelength component will be omitted.

Table 5 λ. =837nm λ. = 870 nm Table 6 [Effects of the Invention] As described above, the combined light generation device of the present invention requires a phase shifter etc. to be provided when combining lights composed of the same polarization components to obtain the same beam shape. This makes it possible to generate multiplexed light with a desired spectral composition without
With the reduction in the number of parts, it has become possible to provide a combined light generation device that can simplify the configuration and reduce costs.

[Brief explanation of drawings]

The drawings show an embodiment of the combined light generating device according to the present invention, FIG. 1 is a schematic diagram of a recording head of an optical disk, FIG. 2 is a schematic diagram of the combined light generating device, and FIG. 3 is a spectroscopic diagram of a semi-transparent film. Graph showing the characteristics, Figure 4 is a schematic diagram of the laser beam printer,
Figures 5 to 7 are schematic configuration diagrams of a combined light generating device showing different embodiments, and Figures 8 to 12 are spectral characteristics of semi-transparent membranes in the embodiments shown in Figures 5 to 7. This is a graph showing. (1), (2), (3)...Light source, (4)
, (4A), (4B)... Multiplexing device, (4
a), (4Aa), (4Ba) -- Semipermeable membrane. Diagram

Claims (1)

[Claims] 1. A plurality of light sources that emit light of the same polarization direction and different wavelengths, and a semi-transparent film that reflects the incident light from the first direction and reflects the incident light from the second direction. In a combined light generation device that generates combined light including a plurality of wavelength components, the combined light generation device includes a multiplexing device that combines both incident lights by transmitting the incident light through its semi-transparent membrane, and a combined light generating device that generates combined light that includes a plurality of wavelength components. Accordingly, light of a wavelength that requires a large energy intensity is transmitted from one of the first direction and the second direction in which energy loss in the semi-transparent membrane portion is small, and from the other direction of a wavelength that requires a small energy intensity. A combined light generation device, wherein the plurality of light sources are arranged with respect to the multiplexing device so that the light is incident on the semi-transparent film from a direction in which energy loss is large. 2. A combined light generation device including a plurality of the multiplexing devices, in which light of a wavelength that requires maximum energy intensity in the combined light is converted to other wavelengths using only one of the multiple multiplexing devices. 2. The combined light generating device according to claim 1, wherein said plurality of light sources are arranged so as to combine with the light of said light source.