JPS63271322A - Transmissivity characteristic varying element - Google Patents

Abstract

PURPOSE:To reduce size and electric power consumption and to speed up wavelength band conversion by laminating plural sheets of transparent films and changing the spacings between the transparent films by means of a piezo-electric actuator element. CONSTITUTION:This transmissivity characteristic varying element is formed by laminating plural sheets of the transparent films 1. The transmissivity characteristic having the wavelength of the certain max. transmissivity is obtd. according to the size of the spacings by changing the spacings between the transparent films with this element. The transmissivity characteristics are superposed and the characteristic to allow transmission of light of a certain wavelength band is obtd. as plural pieces of the spacings exist in the element. The element is so formed that the transmission wavelength band changes with a change in the spacings. The characteristic to reflect light of a certain wavelength band is similarly obtd. and the change in the non-transmission wavelength band is attained. The size over the entire part of the optical system is thereby reduced and the wavelength band conversion is speeded up; in addition, the electric power consumption is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable transmittance characteristic element suitable as a band conversion filter, a color filter for frame sequential color illumination or imaging, and a color temperature conversion filter.

[Prior art and problems to be solved by the invention] Various filters are used in optical systems, including band conversion filters, color filters for frame-sequential color illumination or imaging, and band conversion cut filters. Both color temperature conversion filters convert the wavelength band of transmitted light or non-transmitted light when necessary or in a time-sharing manner, but conventionally, multiple filters with different wavelength bands are prepared and these are inserted and removed. Alternatively, wavelength band conversion was performed by rotating and exchanging them. Therefore, since an electromagnetic/mechanical drive device is required, there are problems in that the entire optical system becomes large in size, it is difficult to increase the wavelength band conversion speed, and power consumption is large.

In view of the above problems, it is an object of the present invention to provide a completely new transmittance characteristic conversion element that contributes to miniaturization of the entire optical system, increases wavelength band conversion speed, and reduces power consumption. .

[Means and effects for solving the problem] The transmittance characteristic variable element according to the present invention has a plurality of transparent films laminated, and the spacing between the transparent films can be changed by a piezoelectric actuator element. Depending on the size of the interval, a transmittance characteristic having a wavelength of a certain maximum transmittance can be obtained, and the presence of a plurality of said intervals makes it possible to obtain a characteristic of transmitting light in a certain wavelength band by superimposing the transmittance characteristics, The transmission wavelength band is changed by changing the interval. In addition, in the same way, the characteristic of reflecting light in a certain wavelength band can be obtained, and the characteristic of reflecting light in a certain wavelength band can also be obtained. (ii) The wavelength band is changed.

A narrow wavelength band is obtained by maintaining the same size of the plurality of intervals or a small difference therebetween, and maintaining a large difference in the size of the plurality of intervals. This makes it possible to obtain a wide wavelength band. Further, by always maintaining a constant difference in size between the plurality of intervals, the wavelength band is moved while remaining constant. Further, the color temperature is changed by linearly changing the density of the difference in the size of the plurality of intervals according to the wavelength, and changing the density distribution while maintaining the linear relationship. be.

〔Example〕

The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 shows a first embodiment, in which numeral 1 is a stack of several to several tens of layers, for example, circular transparent films, and numeral 2 is a cylindrical shape whose inner periphery is fixed to the outer periphery of the fully transparent film 1. In this laminated piezoelectric actuator element, the distances between the transparent films 1 are all equal, and the distances between the mounting positions of the transparent films 1 on the piezoelectric actuator element 2 are all equal. Reference numeral 3 denotes a variable voltage power supply for applying voltage to the piezoelectric actuator element 2, and the piezoelectric actuator element 2 extends in the vertical direction, that is, in the axial direction in FIG. 1, approximately in proportion to the applied voltage. It is assumed that all the transparent films 1 have the same thickness and are made of the same material.

This embodiment is configured as described above, and when there is an air gap d between the transparent films l, interference of λ light occurs there, and the transmittance has a peak at the wavelength where d=-. Characteristics arise. For example, in order to produce a transmittance peak at a wavelength of 0.6μ belonging to the visible light region as shown in FIG. 2, it is sufficient to create an interval of d=0.6 -- 0.15μ; In this embodiment, as described above, the distances d between the transparent films l are all equal.
Therefore, the transmittance characteristic of this embodiment as a whole is obtained by superimposing the transmittance characteristics of FIG. 2 by the number of intervals d, and has a sharp peak as shown in FIG. 3. Therefore, a narrow transmission wavelength band can be obtained.

Further, when a voltage is applied to the piezoelectric actuator element 2 by the power source 3 and the voltage is changed, the piezoelectric element actuator 2 stretches approximately in proportion to the voltage, thereby preventing the attachment of the transparent film 1 to the piezoelectric actuator element 2. Since the distance between the positions changes, the distance d between the transparent films 1 (air distance) also changes.

In this case, as mentioned above, all the distances d between the transparent films 1 are set to be equal, and the distances between the mounting positions of the transparent films 1 to the piezoelectric actuator element 2 are also set to be the same, so all the distances d are set to be equal in size to each other. changes while remaining consistent. Therefore, the transmittance characteristic of the entire embodiment is such that the narrow transmission wavelength band shifts as shown in FIG. Therefore, this embodiment can be used as a spectroscopic band conversion filter for performing spectrum analysis and the like. In that case, this embodiment does not require an electromagnetic/mechanical drive mechanism, so
It has the advantage of contributing to miniaturization of the entire optical system, increasing the transmission wavelength band conversion speed, and reducing power consumption.

Note that even if the elongation of the piezoelectric actuator element 2 is not proportional to the applied voltage, it is possible to obtain the necessary characteristics by appropriately controlling the applied voltage or appropriately arranging the transparent film 1.

FIG. 5 shows a second embodiment, in which the distances between the mounting positions of the piezoelectric actuator elements 2 on the transparent film 1 are all equal, but the distance between the transparent films 1 is dl.

dt, d are all different and the difference between adjacent intervals dt
d+, ds and dt are set to be large.

This embodiment is configured as described above, and the intervals d, d, , d between the transparent films 1 are all different, and the differences dt d+ and dx dz between adjacent intervals are large.
The transmittance characteristics of this embodiment as a whole are as shown in FIG. 6, with the wavelength λ1 at which the transmittance peaks. λ2. λ, are all different and the difference between adjacent wavelengths λ2−λ1. λ, −λ2
As shown in FIG. 7, a plurality of transmittance characteristics having a large transmittance are superimposed, that is, a characteristic having a wide transmission wavelength range is obtained.

Furthermore, the difference between adjacent intervals dz dt , d3−dz
are made equal, the difference λ2−λ1 . between adjacent wavelengths in FIG. Since λ3−λ2 is also equal, balanced transmittance characteristics can be obtained.

When a voltage is applied to the piezoelectric actuator element 2 by the power source 3 and the voltage is changed, the distances d, d2, . . . between the transparent films 1 are changed. d changes, but since the distances between the attachment positions of the transparent film 1 to the piezoelectric actuator element 2 are all set equal as described above, the distances d, d2 . d is the difference between adjacent spacings dz d as shown in FIG.
t and ds −d2 are kept constant and changed. Therefore, the transmission wavelength band is Fig. 7 (A)-CB) → (C
), it moves with a constant width. Therefore, the applied voltage is V
+, Vt, and V3 so that the transmitted light becomes B (blue), G (green), and R (red), respectively.

is selected and the applied voltage is set to repeatedly change stepwise to these potentials V, , Vt, and V3 as shown in FIG. It can be used as a color filter.

FIG. 12 shows a third embodiment, in which the distances between the transparent films 1 are d, d2, . d is zero when no voltage is applied, but the distance between the mounting positions of the piezoelectric actuator elements 2 on the transparent film 1 gradually increases.

This embodiment is constructed as described above, and the distance between the attachment positions of the transparent film 1 to the piezoelectric actuator element 2 gradually increases. When a voltage is applied, the distance d between each retraction B1.

d, ,d, change as shown in FIG. That is, as the intervals d, , d, , d, increase, the difference d between them,
-d, , d, -d also expand, so the transmission wavelength band is the first
As shown in Figure 2, the width becomes wider as you move toward the longer wavelength side.This embodiment has a problem in that the transmission wavelength bandwidth varies in proportion to the wavelength, but it can be used in place of the second embodiment for practical use. It is something that becomes.

FIG. 13 shows a fourth embodiment, in which the outer peripheries of adjacent transparent films 1 are connected by respective piezoelectric actuator elements 2, and each piezoelectric actuator element 2 is provided with an individual variable piezoelectric [ 3 to apply voltage.

Since this embodiment is configured as described above, by controlling each applied voltage, for example, when the intervals d+, dz, ds, and d4 are wide (the wavelength is large) as shown in FIG. 14(A), The difference in size between adjacent intervals dz dt ,
By increasing dz dz and da ds, or conversely by decreasing the interval dl as shown in Fig. 14 (B).
+ When the distance between dt, a,, a4 is narrow (wavelength is small), the difference in size between adjacent distances dz dlr d3
d2+ da d'+ can be made small or large, and the interval d, as shown in Fig. 14 (C),
d,,d,,d,can almost match.

If the transmittance changes as shown in FIG. 14(A) to FIG. 14(B), changes in transmittance characteristics as shown in FIG. 12 can be produced. 14(C), it is possible to produce transmittance characteristics as shown in FIG. 3.

Up to now, we have described the setting of the wavelength band where the transmittance is maximum as λ, but in this embodiment, by setting d=-, it is also possible to set the wavelength band where the reflectance is maximum. Then, the difference between adjacent intervals dz dt , d
By increasing s dz and da ds, a wide opaque wavelength region can be obtained as shown in FIG. 15(A), and the difference between adjacent intervals dz-d, d.

If -d, d, -d are made small, a narrow non-transmissive wavelength range can be obtained as shown in FIG. 15(B).

This is, for example, B (blue), G (green), R (red) ten NOR
Observation using three colors of B, G, and R using a field-sequential color imaging device that sequentially irradiates (near infrared) light and B, G, and NI
It is effective as a filter to be installed in the imaging system when switching between observation using the R pseudo three colors. Furthermore, by superimposing two spacing groups having different non-transparent wavelength bands, a transmittance characteristic having two non-transparent wavelength bands can be obtained as shown in FIG. It is also possible to make a transmission wavelength band appear.

For example, when using a 11060n YAG laser (infrared laser) for processing in a medical endoscope, this prevents the reflected light of the YAG laser from entering the solid-state image sensor and causing smear etc. useful for.

Further, in the fourth embodiment, as shown in FIG. 16(A), as the distance between the transparent films 1 increases, the difference between the adjacent distances dz d+ and ds da increases.

When d and -d are made small, the peaks of each transmittance become denser on the longer wavelength side as shown in FIG. It becomes like this. Furthermore, as shown in FIG. 16(B), as the distance between the transparent films 1 becomes smaller, the difference between the adjacent distances d4 d3+
If we make d, dt, dz-d small,
As shown in FIG. 17(B), the peaks of each transmittance become denser on the shorter wavelength side, so the transmittance characteristics become as shown by the dotted line in FIG. 18. Therefore, if the intervals d+, dz, di, and da are controlled by each variable voltage power supply 3 as described above, it can be used as a color temperature conversion filter.

FIG. 19 shows the main part of the fifth embodiment, in which a single-layer coating layer 4 with different characteristics from the transparent film 1 is provided on both sides of the transparent film 1 so that predetermined characteristics can be obtained when changing the spacing. This is what I did. In FIG. 19(A), the distance including the coating layer 4 is λ/
Figure 19 (B) shows the air spacing λ/4.
In C), the air spacing is λ/2.

This embodiment has the advantage that by providing the coating layer 4 as described above, the range of application is expanded and the performance is further improved.

FIG. 20 shows the main part of the sixth embodiment, which is made by providing a multilayer coating N5, 6.7 with various characteristics different from the transparent film 1 on both sides of the transparent film 1 so as to obtain the optimum characteristics. This is what I did.

FIG. 21 shows the main part of the seventh embodiment, which is similar to the fourth embodiment.
A transmittance characteristic element having the same basic structure as that of the embodiment is fixed to the imaging surface of the solid-state image sensor 8 to be integrated.

〔Effect of the invention〕

As described above, the variable transmittance characteristic element according to the present invention has important practical advantages in that it contributes to miniaturization of the entire optical system, can increase the wavelength band conversion speed, and can reduce power consumption.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of a variable transmittance characteristic element according to the present invention, FIG. 2 is a diagram showing transmittance characteristics by a single aperture in the first embodiment, and FIG. Fig. 4 is a diagram showing the transmittance characteristics when the applied voltage is changed in the first embodiment, and Fig. 5 is a cross section of the second embodiment. 6 is a diagram showing the transmittance characteristics in the second embodiment, and FIG. 7 is a diagram showing the transmittance characteristics when the applied voltage is changed in the second embodiment.
FIG. 8 is a diagram showing the change characteristics of the interval in the second embodiment, FIG. 9 is a diagram showing one change characteristic of the applied voltage in the second embodiment, and FIG. 10 is a cross-sectional view of the third embodiment. Fig. 11 is a diagram showing the interval change characteristics of the third embodiment, Fig. 12 is a diagram showing the transmittance characteristics when the applied voltage is changed in the third embodiment, and Fig. 13 is a cross section of the fourth embodiment. 14 is a diagram showing the interval change characteristics that can be created in the fourth embodiment. FIG. 15 is a diagram showing the transmittance characteristics that can be created in the fourth embodiment.
Figure 6 is a diagram showing other interval change characteristics that can be created in the fourth embodiment, Figure 17 is a diagram showing transmittance characteristics corresponding to Figure 16, and Figure 18 is a diagram showing the transmittance that combines the characteristics in Figure 17. Figures 19 to 21 showing the characteristics are sectional views of main parts of the fifth to seventh embodiments, respectively. DESCRIPTION OF SYMBOLS 1... Transparent film, 2... Piezoelectric actuator element, 3... Variable voltage power supply, 4, 5, 6.7... Covering layer, 8... Solid-state image sensor. Off figure 18 figure: I+! To Figure 12 Liquid length Liquid length: X & 1 ■ - 6r! Figure 15 (A) (B) Figure 19 Figure 16 (A) Figure 17 (A) Figure (B) Figure (B)

Claims (1)

[Claims] A transmittance characteristic variable element comprising a plurality of transparent films stacked together and the distance between the transparent films being changed by a piezoelectric actuator element.