JP2002540448A - Illumination system using optical feedback - Google Patents

Abstract

SUMMARY An illumination system using optical feedback to maintain a predetermined illumination output is disclosed. The illumination system has an electrically controllable optical filter (106) for filtering light incident thereon and a photodetector (304). The photodetector can exchange data with an electrically controllable optical filter. All or part of the light filtered by the electrically controllable optical filter is detected by a photodetector and compared to at least one predetermined value. If the signal generated by the photodetector is different when compared to the at least one predetermined value, one or more filtering characteristics of the electrically controllable optical filter are altered, thereby changing the electrical characteristic. The amount of light filtered by the optically controllable optical filter will vary. Changing the filtering characteristics of the electrically controllable optical filter continues until the signal generated by the photodetector substantially matches at least one predetermined value.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to lighting systems, and more particularly to lighting systems that use optical feedback.

(Description of Related Art) An illumination system generates light for illuminating an object such as an image display. Unfortunately, the output light of conventional lighting systems often has non-uniform light intensity. The dispersion of light intensity may be uniform over the frequency of the spectrum of the output light, or may be unevenly concentrated in one or more of its visible light bandwidths (eg, red, green, or blue light). Such light intensity non-uniformities can be caused by a variety of sources, such as variations in the temperature of the light sources in the lighting system, physical changes in the light sources, or lifetimes associated with changes in the ambient conditions under which the light sources operate. obtain.

SUMMARY OF THE INVENTION The present invention is directed to an illumination system that uses optical feedback to maintain a predetermined light intensity output. The illumination system of the present invention uses an electrically controllable optical filter to filter the received light. Also,
The illumination system includes a photodetector that detects at least a portion of the light filtered by an electrically controllable optical filter. The photodetector exchanges data with an electrically controllable optical filter. All or part of the light filtered by the electrically controllable optical filter is detected by a photodetector, which generates a corresponding signal, which is compared with at least one predetermined value. Is done. If the signal generated by the photodetector is different compared to the at least one predetermined value, one or more filtering characteristics of the electrically controllable optical filter are altered, thereby changing the electrical characteristics. The amount of light filtered by the optically controllable optical filter will vary. Changing the filtering characteristics of the electrically controllable optical filter continues until the signal generated by the photodetector substantially matches the at least one predetermined value.

[0004] In some embodiments, the electrically controllable optical filter has one or more electrically switchable holographic optical elements. Each electrically switchable holographic optical element operates in an active or inactive state depending on the magnitude of the voltage it receives. In the inactive state, light incident on the electrically switchable holographic optical element transmits through it substantially unchanged. In the active state, the electrically switchable holographic optical element diffracts the selected bandwidth of the received incident light into at least a zero-order diffracted component and a first-order diffracted component. Other undiffracted portions of the incident light are transmitted substantially unchanged through the active, electrically switchable holographic optical element. In the active state, the light intensities of the zero-order and first-order diffraction components depend on the magnitude of the voltage received by the electrically switchable holographic optical element.

While the present invention has various embodiments, particular embodiments thereof are shown by way of example and drawings and described in detail below. It should be understood, however, that the disclosure of the examples in the drawings and description of examples is not intended to limit the invention to the form disclosed. On the contrary, the invention encompasses various different forms that may come within the true scope of the invention as defined by the appended claims.

The present invention may be better understood, and its various objects, features and advantages made apparent to those skilled in the art by referencing the drawings.

Description of the Preferred Embodiment FIG. 1 shows one embodiment of an illumination system that uses optical feedback to generate illumination light at one or more predetermined light intensities according to the present invention. The illumination system of FIG. 1 includes a light source 102, a lens 104, an electrically controllable optical filter 106, a light deflector 108, and a feedback system 110.

The light source 102 shown in FIG. 1 generates light having a visible light bandwidth. This light includes primary color components (eg, red, green, and blue bandwidth light). In a preferred embodiment,
The light source 102 continuously emits light of red, green, and blue bandwidth components 1
Light sources. Alternatively, light source 102 may include three independent light sources, each emitting light in the red, green, and blue bandwidths sequentially. In yet another embodiment, whether the light source 102 is a single light source or three independent light sources, it can emit red, green, and blue bandwidth light sequentially. The light source can also be a laser.

In the embodiment shown in FIG. 1, light emitted by the light source 102 is collimated by the lens 104 into a parallel light beam 112. The collimating lens 104 may be constituted by conventional optical elements, i.e., a lens system and / or mirror elements formed from glass, plastic, or the like. This embodiment of the lens 104 is essentially static. Or,
Lens 104 is disclosed in co-pending US patent application Ser. No. 09/366, filed Aug. 3, 1999.
No.449 (Name Pancake Window Display System Employing One Or More Switchab
le Holographic Optical Elements) can take the form of one or more electrically switchable holographic optical elements. The above U.S. patent application is incorporated herein by reference.

The parallel light beam 112 transmitted through the lens 104 is incident on an optically controllable optical filter 106. Filter 106 operates to filter parallel rays 112 according to one or more feedback control signals generated by feedback system 110. The filtered light 114 passing through the filter 106 is incident on a deflector 108, which deflects all or a portion of the filtered light 114 to a feedback system 110. The unpolarized filtered light 114 provides illumination light 116 for illumination of the object.
From the deflector 108.

The deflector 108 may be a static device that continuously deflects a portion of the incident filtered light 114 to a feedback system 110. Alternatively, the deflector 108 continuously deflects a portion of the incident filtered light 114 to the feedback system 110 or feeds back some or all of the incident filtered light 114 at predetermined time intervals. Deflected into the system 1
Or it can be realized in the form of a plurality of electrically switchable holographic optical elements.

A feedback system 110 receives the deflected light 118 from the deflector 108 and generates one or more feedback control signals that control one or more filtering characteristics of the filter 106 in response. Basically, the feedback system 110 provides the continuously or timed polarized light 11 to determine whether the light intensity of the deflected light 118 is one or more predetermined light intensities.
8 functions to measure the light intensity. Specifically, the feedback system 110 compares the light intensity of the deflected light 118 at a point in time with a predetermined light intensity. If the light intensity of the deflected light 118 is equal to or substantially equal to the predetermined light intensity, then the filtered light 114 and the illumination light 116 each have a light intensity equal to or substantially equal to the predetermined value. It is regarded. If the intensity of the deflected light 118 is different from the predetermined light intensity, the feedback system detects the deviation and adjusts one or more control signals provided to the control filter so that the signal is filtered. Adjusting 106 continues until the deflected light 118 returns to its predetermined light intensity.

The feedback system 110 described above controls the filtering characteristics of the filter 106 as a function of the light intensity of a portion of the filtered light 112. However, the present invention is not limited to this mode. The invention also encompasses another embodiment in which, for example, the feedback system measures and compares the light intensity of all or substantially all of the filtered light at predetermined time intervals and controls the filter accordingly. are doing.

FIG. 2 illustrates another embodiment of an illumination system that uses optical feedback to maintain illumination light at one or more predetermined light intensities according to the present invention. 1 and 2
The operation of the embodiment shown in FIG. FIG. 1 shows a transmissive lighting system, whereas FIG. 2 shows a reflective lighting system.

In FIG. 2, the illumination system includes a light source 102, a lens 104, an electrically controllable optical filter 206, a deflector 108, and a feedback system 110. The system shown in FIG. 2 uses many of the same components as FIG. 1 and 2, a common reference numeral is used to identify a common component.

Similar to the filter 106 shown in FIG. 1, the filter 206 receives the collimated light 112 and filters it according to a control signal received from the feedback system 110. The filter 106 emits the filtered light 114 from the side opposite to the side receiving the parallel light 112, while the filter 206 in FIG. 2 uses the filtered light 114 from the same side as the side receiving the parallel light 112. Issue 114. The deflector 108 deflects some or all of the filtered light 114. This deflected light enters the feedback system 110. The remaining portion of the filtered light 114 is not deflected and the illumination light 11
Issued as 6.

The feedback system 110 shown in FIG. 2 operates generally similar to the feedback system described in FIG. The feedback system of FIG. 2 receives the deflected light 118 and generates one or more feedback control signals that control the filter 206. Feedback system 110 provides polarized light 118
Is measured to determine whether the light intensity is equal to or substantially equal to one or more predetermined light intensities. In this embodiment, the one or more predetermined light intensities may be different from the one or more predetermined light intensities used in the system shown in FIG.

Filters 106 and 206 filter collimated light 112 by removing light energy of one or more selected bandwidth components, ie, reducing the light intensity. In a preferred mode of operation, filters 106 and 206 remove all or substantially all of the light intensity of two of the red, green, and blue bandwidth components of collimated light 112 at a given time, The light intensity of the remaining other bandwidth components is variably reduced. The amount of reduction in light of other bandwidth components depends on the target light intensity of the illumination light 116.

The filtering in this preferred mode of operation takes place in an iterative three-stage cycle. In a first phase of the cycle, filters 106 and 206 remove all or substantially all of the green and blue bandwidth components from collimated light 112 according to a first set of control signals generated by feedback system 110. , Variably lowering the red bandwidth component. Therefore, filters 106 and 206
Is the light 1 that variably filtered the portion of the red bandwidth component of the parallel light 112
Emit 14 The filtered light 114 will include only a small amount of the blue or green bandwidth component of the parallel light 112.

The emitted red bandwidth filtered light 114 is polarized light 11
8 by the feedback system 110. The emitted red bandwidth filtered light 114 should have a light intensity that is equal to or substantially equal to a first predetermined value of light intensity. If the light intensity of the red bandwidth filtered light 114 deviates from a first predetermined value, the feedback system 110 generates a new first set of control signals. The feedback system 110 corrects the light intensity shift by adjusting the filtering characteristics of the filters 106 and 206 using the new first set of feedback control signals.

In the second phase of the cycle following the first phase, filters 106 and 206 filter all or all of the red and blue bandwidth components from collimated light 112 according to a second set of control signals generated by feedback system 110. It removes substantially all of it and variably reduces its green bandwidth component. Therefore, filters 106 and 2
06 emits the portion of the green bandwidth component of the parallel light 112 as variably filtered light 114. The filtered light 114 will include only a small amount of the blue or red bandwidth component of the collimated light 112.

The emitted green bandwidth filtered light 114 is polarized light 11
8 via the feedback system 118. The emitted green bandwidth filtered light 114 should have a light intensity that is equal to or substantially equal to a second predetermined value of light intensity. If the light intensity of the green bandwidth filtered light 114 deviates from the second predetermined value, the feedback system 110 generates a new second set of control signals. The feedback system 110 corrects the light intensity deviation by adjusting the filtering characteristics of the filters 106 and 206 using the new set of second feedback control signals.

In the third phase of the cycle following the second phase, filters 106 and 206 filter all or all of the green and red bandwidth components from parallel light 112 according to a third set of control signals generated by feedback system 110. It removes substantially all and variably lowers its blue bandwidth component. Therefore, filters 106 and 2
06 emits the portion of the blue bandwidth component of the parallel light 112 as variably filtered light 114. The filtered light 114 will include only a small amount of the red or green bandwidth component of the parallel light 114.

The emitted blue bandwidth filtered light 114 is polarized light 11
8 by the feedback system 110. The emitted blue bandwidth filtered light 114 should have a light intensity equal to or substantially equal to a third predetermined value of light intensity. If the light intensity of the blue bandwidth filtered light 114 deviates from a third predetermined value, the feedback system 110 generates a new third set of control signals. The feedback system 110 corrects the light intensity deviation by adjusting the filtering characteristics of the filters 106 and 206 using the new third set of feedback control signals.

In a first alternative mode of operation, filters 106 and 206 remove all or substantially all of the optical energy of one of the red, green, and blue bandwidth components of collimated light 112 and , Variably reduce the light intensity included in the remaining two bandwidth components. Similarly, the filtering is performed in repeated cycles. In the first phase of this alternative cycle, filters 106 and 206 remove all or substantially all of the blue bandwidth component of collimated light 112 according to a first set of control signals generated by feedback system 110. At the same time, the red and green bandwidth components of the parallel light 112 are variably reduced. The first set of control signals in this form is:
It is different from the first set of control signals used in the preferred form. Accordingly, filters 106 and 206 emit portions of the red and green bandwidth components of parallel light 112 as variably filtered light 114. Filtered light 1
14 may contain only a small amount of light in the blue bandwidth. The emitted red and green bandwidth filtered light 114 should have an overall light intensity equal to or substantially equal to the first predetermined value. The first predetermined value used in this embodiment may be different from the first predetermined value used in the preferred embodiment. If the light intensity of the red and green bandwidth filtered light 114 deviates from a first predetermined value, the deviation is detected by the feedback system 110 via the deflected light 118 and the feedback system 110 generates a new first set of control signals. Feedback system 11
0 corrects this shift by adjusting filters 106 and 206 using this new first set of feedback control signals.

In the second phase of this alternative cycle, the filters 106 and 206 cause the parallel light 112
, And variably lowers the red and blue bandwidth components of the collimated light 112. The second set of control signals in this embodiment is different from the second set of control signals used in the preferred embodiment.
Accordingly, filters 106 and 206 emit portions of the red and blue bandwidth components of collimated light 112 as variably filtered light 114. Filtered light 114 will include only a small amount of green bandwidth light. The emitted red and blue bandwidth filtered light 114 is generally second
Should have a light intensity equal to or substantially equal to a predetermined value of. The first predetermined value used in this embodiment may be different from the second predetermined value used in the preferred embodiment. Red and blue bandwidth filtered light 11
4 is deviated from the second predetermined value, the deviation is detected by the feedback system 110 via the deflected light 118, and the feedback system 110 outputs a new second control signal. Generates a set of Feedback system 110 corrects this shift by adjusting filters 106 and 206 with the new set of second feedback control signals.

In the third phase of this alternative cycle, filters 106 and 206 cause collimated light 112 according to a third set of control signals generated by feedback system 110.
, While removing all or substantially all of the red bandwidth component, and variably lowering the blue and green bandwidth components of the parallel light 112. The third set of control signals in this embodiment is different from the third set of control signals used in the preferred embodiment.
Thus, filters 106 and 206 emit portions of the blue and green bandwidth components of parallel light 112 as variably filtered light 114. The filtered light 114 may include a small amount of red bandwidth light. The emitted blue and green bandwidth filtered light 114 is generally a third
Should have a light intensity equal to or substantially equal to a predetermined value of. The third predetermined value used in this embodiment may be different from the third predetermined value used in the preferred embodiment. Blue and green bandwidth filtered light 11
4 is deviated from the third predetermined value, the deviation is detected by the feedback system 110 via the deflected light 118, and the feedback system 110 outputs a new third control signal. Generates a set of The feedback system 110 corrects this shift by adjusting the filters 106 and 206 with the new third set of feedback control signals.

In a second alternative mode of operation, filters 106 and 206 include all red, green, and blue bandwidth components of collimated light 112 according to one feedback control signal generated by feedback system 110. It acts so as to variably reduce the applied light intensity. In this second alternative, filters 106 and 20
6 emits respective portions of the red, green and blue bandwidth components of the collimated light 112 as variably filtered light 114. Each of the red, green, and blue bandwidth filtered light 114 emitted by filters 106 and 206 should have a light intensity equal to or substantially equal to a predetermined value. If the light intensity of the combined red, green, and blue bandwidth filtered light 114 deviates from a predetermined value, the deviation is detected by the feedback system 110 via the deflected light 118. . Feedback system 110
Corrects this shift by adjusting the filters 106 and 206 using the new control signal generated by the feedback system 110.

FIG. 3 illustrates one embodiment of the feedback system 110. Specifically, FIG. 3 shows a feedback system including a lens 302, an optical deflector 304, and a control circuit 306. In some embodiments, lens 302 is a conventional focusing lens that focuses deflected light 118. Conventional lens 302 may take the form of glass, plastic, or other suitable material. Alternatively, lens 302 may take the form of one or more electrically switchable holographic optical elements with a focusing lens recorded therein. A focusing lens implemented as one or more electrically switchable holographic optical elements is described in US patent application Ser. No. 09 / 313,431, filed May 17, 1999, entitled Switchable Holographic Optical S.
ystem), which is hereby incorporated by reference. Although not shown, the control circuit 306 can be extended to provide a signal for controlling the focusing lens 302 implemented on one or more electrically switchable holographic optical elements. The lens 302 receives the deflected light 1
18 is focused on detector 304.

Light detector 304 takes the form of any one of several types of light detectors, such as photocapacitors, photodiodes, and the like. Basically, the photodetector 304 produces an output signal as a function of the light intensity of the deflected light 118 incident thereon. The magnitude of the detector output signal corresponds to the light intensity of the detected light. This correspondence can be linear. Detector 304 may continuously generate an output signal as a function of the light intensity of the light incident thereon. Alternatively, the detector 304 may detect light at predetermined time intervals according to the control or sample signal received from the control circuit 306 and generate a corresponding output signal.

The polarized light 118 may include one or more of the red, green, or blue bandwidth components, depending on the mode of operation of the filters 106 and 206. Filter 10
6 and 206 remove all or substantially all of the light energy of two of the red, green, and blue bandwidth components of collimated light 112 while variably reducing the energy of the remaining bandwidth components. In an embodiment, the deflected light 118 is red,
Includes only one of the green or blue bandwidths. The remaining bandwidth component will be only slightly present in the deflected light 118. In this embodiment, deflected light 118 will periodically include red, green, and blue bandwidth components. Filters 106 and 206 remove all or substantially all of the optical energy of one of the red, green, and blue bandwidth components of collimated light 112, leaving the remaining two bandwidth components included. In embodiments that variably reduce light energy, the deflected light 118 includes only two of the red, green, or blue bandwidth light. One other bandwidth component will be only slightly present in the deflected light 118. In this embodiment, the deflected light 118 periodically includes two combinations of the red, green, and blue bandwidth components. In an embodiment where filters 106 and 206 act to variably reduce the light energy contained in all three of the red, green, and blue bandwidth components of collimated light 112, deflected light 11
8 will include all three bandwidth components.

The control circuit 306 functions in various ways corresponding to various modes of operation of the filter 106 or 206. The control circuit 306, in one embodiment, has three output registers (the output registers associated with the red, green, and blue bandwidths, respectively, all three of which are not shown). These three output registers output control signals used for controlling the filter 106 or 206 in cooperation. Filter 106 or 206 removes all or substantially all of the light energy of the two of the red, green, and blue bandwidth components of collimated light 112, while the light energy of the remaining bandwidth components is variably reduced. In connection with the above-described embodiment, the control circuit 30
6 will be described, but it should be understood that the control circuit can operate in other modes of operation. In this embodiment, the filters 106 and 206 include first, second, and third filters.
Is repeated periodically. The output register associated with the red bandwidth is the filter 10
A red bandwidth control signal for controlling the amount of red bandwidth light removed by 6 or 206 is stored. The red bandwidth output register is a first red bandwidth control signal that causes filters 106 and 206 to remove all or substantially all of the red bandwidth component from collimated light 112 or the red Store any of the second red bandwidth control signals that cause the variable portion of the bandwidth component to be removed.
In one embodiment, the first red bandwidth control signal is stored in a first red bandwidth control register and the second red bandwidth control signal is stored in a second red bandwidth control register.

An output register associated with the green bandwidth stores a green bandwidth control signal for controlling the amount of green bandwidth light removed by the filter 106 or 206. The green bandwidth output register is a first green bandwidth control signal that causes the filter 106 or 206 to remove all or substantially all of the green bandwidth component from the collimated light 112 or the green color of the collimated light 112 to the filter 106 or 206. Stores any of the second green bandwidth control signals that cause a variable portion of the bandwidth component to be removed. In some embodiments, the first
Are stored in a first green bandwidth control register, and a second green bandwidth control signal is stored in a second green bandwidth control register.

An output register associated with the blue bandwidth stores a blue bandwidth control signal for controlling the amount of blue bandwidth light removed by the filter 106 or 206. The blue bandwidth output register is a first blue bandwidth control signal that causes the filter 106 or 206 to remove all or substantially all of the blue bandwidth component from the collimated light 112 or the blue color of the collimated light 112 to the filter 106 or 206. Store any of the second blue bandwidth control signals that cause the variable portion of the bandwidth component to be removed. In some embodiments, the first
Are stored in a first blue bandwidth control register, and a second blue bandwidth control signal is stored in a second blue bandwidth control register.

The contents of the three output registers are maintained by the control circuit 306 and change depending on the stage of the operating cycle of the filter 106 or 206 at that time. First of cycle
In the stage, the red bandwidth related output register stores the second red bandwidth control signal;
Green and blue bandwidth output registers store the first green and blue bandwidth control signals, respectively. In the second phase of the cycle, the green bandwidth output register stores the second green bandwidth control signal, and the red and blue bandwidth output registers store the first red and blue bandwidth control signals, respectively. In the third stage of the cycle, the blue bandwidth output register stores the second blue bandwidth control signal, and the green and red bandwidth output registers store the first green and red bandwidth control signals, respectively.

The second red, green, and blue bandwidth control signals stored in the second red, green, and blue bandwidth output registers, respectively, are used to check for deviations in light intensity of the deflected light 118. It may change during operation of the lighting system. As described above, the light intensity of the deflected light 118 is checked at each stage of the three-stage cycle. In the first stage, the deflected light 118 comprises essentially only red bandwidth light. In the first stage, a detector output signal is generated that is proportional to the intensity of the red bandwidth deflected light 118. Thereafter, the control circuit 306 compares the detector output signal with a first predetermined value previously stored in the memory of the control circuit 306. If the detector output signal is equal to or substantially equal to the first predetermined value, the second red bandwidth control signal is not changed and in the first stage of the next cycle, the filter 106 or 206 An identical second red bandwidth control signal is provided along with the first green and blue bandwidth control signals. The second red bandwidth control signal, the first green bandwidth control signal, and the first blue bandwidth control signal collectively comprise the first set of control signals described above. If the detector output signal is not equal to or substantially equal to the first predetermined value, the second red bandwidth control signal is updated accordingly. Then, in the next first stage, the updated second red bandwidth control signal is provided to the filter 106 or 206 along with the first green and blue bandwidth control signals. These three signals are provided as a new first set of control signals. The light intensity of the red bandwidth filtered light emitted by the filter 106 or 206 in response to receiving the new first set of control signals is responsive to receiving the first set of control signals. Filter 106 or 2
06 compared to the light intensity of the filtered red bandwidth light emitted by 06.

[0037] The first red bandwidth control signal may be updated in various manners. Specifically, the first
May be increased or decreased by a set amount depending on whether the detector output signal is greater than or less than a first predetermined value. Alternatively, the difference between the detector output signal and the first predetermined value can be calculated, and the first red bandwidth control signal can be increased or decreased by an amount proportional to the difference. In this embodiment, the light intensity of the deflected light 118 is checked at each first stage of each cycle.

The light intensity of the deflected light 118 is also checked in the second stage of the three-stage cycle in essentially the same manner as the deflected light 118 was checked in the first stage. In the second stage, the deflected light 118 basically contains only green bandwidth light. In the second stage, the detector output signal is generated in proportion to the intensity of the green bandwidth deflected light 118. Thereafter, the control circuit 306 compares the detector output signal with a second predetermined value stored in the memory of the control circuit 306 in advance. If the detector output signal is equal to or substantially equal to the second predetermined value, the second green bandwidth control signal is not changed and in the second stage of the next cycle, the filter 10
At 6 or 206, the same second green bandwidth control signal is provided along with the first red and blue bandwidth control signals. The second green bandwidth control signal, the first red bandwidth control signal, and the first blue bandwidth control signal collectively comprise the second set of control signals described above. If the detector output signal is not equal to or substantially equal to the second predetermined value, the second green bandwidth control signal is updated accordingly. Then, in the next second stage, the updated green bandwidth control signal is supplied to the filter 106 or 206 along with the first red and blue bandwidth control signals. These three signals are provided as a new set of second control signals. The light intensity of the green bandwidth filtered light emitted by the filter 106 or 206 in response to receiving this new second set of control signals is equivalent to receiving the second set of control signals. The light intensity of the filtered green bandwidth light emitted by the filter 106 or 206 accordingly differs.

[0039] The first green bandwidth control signal may be updated in a similar manner as the second red bandwidth control signal is updated. Specifically, the second green bandwidth control signal may be increased or decreased by a set amount depending on whether the detector output signal is greater or less than a second predetermined value. Alternatively, the difference between the detector output signal and the second predetermined value can be calculated, and the second green bandwidth control signal can be increased or decreased by an amount proportional to the difference. In this embodiment, the light intensity of the deflected light 118 is checked at each second stage of each cycle.

The light intensity of the deflected light 118 is checked in the third phase of the three-step cycle in essentially the same manner as the deflected light 118 was checked in the first and second phases. You. In the third stage, the deflected light 118 contains essentially only light of the blue bandwidth. In a third stage, a detector output signal is generated proportional to the intensity of the deflected light 118 in the blue bandwidth. Thereafter, the control circuit 306 compares the detector output signal with a third predetermined value previously stored in the memory of the control circuit 306. If the detector output signal is equal to or substantially equal to the third predetermined value,
The second green bandwidth control signal is not changed, and in the third phase of the next cycle, the same second blue bandwidth control signal along with the first green and red bandwidth control signals is applied to the filter 106 or 206. Supplied. The second blue bandwidth control signal, the first green bandwidth control signal, and the first red bandwidth control signal collectively comprise the third set of control signals described above. If the detector output signal is not equal to or substantially equal to the third predetermined value, the second blue bandwidth control signal is updated accordingly. Then, in a next third stage, the updated blue bandwidth control signal is provided to the filter 106 or 206 along with the first green and red bandwidth control signals. These three signals are supplied as a new set of third control signals. The light intensity of the blue bandwidth filtered light emitted by the filter 106 or 206 in response to receiving this new third set of control signals is equal to receiving the third set of control signals. The light intensity of the filtered blue bandwidth light emitted by the filter 106 or 206 accordingly differs.

The second blue bandwidth control signal may be updated in a manner similar to updating the second red and green bandwidth control signals. Specifically, the second blue bandwidth control signal may be increased or decreased by a set amount depending on whether the detector output signal is greater than or less than a third predetermined value. Alternatively, the difference between the detector output signal and the third predetermined value can be calculated, and the second blue bandwidth control signal can be increased or decreased by an amount proportional to the difference. In this embodiment, the light intensity of the deflected light 118 is checked at each third stage of each cycle.

The filters 106 and 206 are solid state systems. Filter 10
6 and 206 may take any one of several embodiments. Specifically, filters 106 and 206 may be implemented as one or more layers of conventional liquid crystal material. Alternatively, filters 106 and 206 may be implemented as conventional interference filters in combination with liquid crystal-based electrically controllable density filters. U.S. patent application Ser. No. 09 / 478,150, filed Jan. 5, 2000, entitled Optical Filter Employing Holographic Optical Elements And Image Genera
The Ting System Incorporating The Optical Filter) discloses several embodiments of the filters 106 and 206 shown in FIGS. The U.S. patent application is incorporated herein by reference.

Filters 106 and 206 can be in the form of one or more electrically switchable holographic optical elements, each of which can operate independently in an active or inactive state in response to a control signal. In the inactive state, each electrically switchable holographic optical element transmits the collimated light 112 unchanged. In the active state, each electrically switchable holographic optical element diffracts a selected bandwidth (eg, red bandwidth) of the collimated light 112 and the remaining portion of the collimated light 112 (eg, green and blue bandwidth). Are transmitted substantially unchanged. Diffracted light is emitted from the electrically switchable holographic optical element as zero order and first order diffracted light at an angle therebetween. The zero-order diffracted component is emitted from the electrically switchable holographic optical element in a direction perpendicular to its emitting surface. Electrically switchable holographic optical elements can diffract a selected bandwidth into higher order components. However, it is assumed here that all selected bandwidths are diffracted into zero or first order diffracted light. Furthermore, the amount of light energy included in the zero-order and first-order diffraction components depends on the voltage of the control signal applied to the electrically switchable holographic optical element, as will be described in detail below.

FIG. 4 is a cross-sectional view of one embodiment of an electrically switchable holographic optical element that may be used in filter 106 or 206. The switchable holographic optical element of FIG. 4 includes a pair of substantially transparent, non-conductive layers 402, a pair of substantially transparent, conductive layers 404, and, in one embodiment, the above-mentioned US patent application. No. 09
No. 478,150 having a switchable holographic layer 406 formed from a polymer dispersed liquid crystal material. The aforementioned U.S. patent application is incorporated herein by reference. In some embodiments, the substantially transparent non-conductive layer 402 comprises glass and the substantially transparent non-conductive layer 404 comprises tin-doped indium oxide (ITO). ITO
And applying an anti-reflective coating (not shown) on selected surfaces of the switchable holographic optical element, including the surface of the non-conductive layer, to improve the overall transmission efficiency of the optical element and to stray light Can be reduced. As shown in the embodiment of FIG. 4, all layers 402-406 are provided on a common axis 408 in the form of a layer of hot cake.

The layers 402-406 have a substantially thin cross section width, thereby forming a substantially thin cross section stack. Specifically, the cross-sectional width of the switchable holographic layer 406 is 5-12 μm (the exact width depends on the bandwidth of the spectrum and the required diffraction efficiency), and the cross-sectional width of the glass layer 402 is 0.1 μm. It can be 4-0.8 mm. Of course, ITO layer 404 must be substantially thin to be transparent. It should be noted that the holographic layer can be deposited on a thin plastic substrate. This plastic substrate may be flexible.

When a first voltage is applied to the ITO layer 404, the switchable holographic layer 406
An electric field is generated therein, and the switchable holographic element operates in the inactive state described above. However, when a voltage lower than the first voltage is applied to the ITO layer 404, the switchable holographic optical element operates in the active state described above. When active
The electrically switchable holographic optical element diffracts, for example, the red bandwidth component of the collimated incident light 112 and transmits the remaining components of the collimated incident light 112, including the green and blue red bandwidth components, unchanged. Diffracted light is emitted as zero order and first order components. The light intensity of the zero-order and first-order components is determined by the magnitude of the voltage applied to the ITO layer 404. When the voltage applied to the ITO layer 404 decreases, the energy of the zero-order diffraction component decreases, and at the same time, the light energy of the first-order diffraction component increases in inverse proportion thereto. That is, by linearly decreasing the voltage applied to the ITO layer 404, the light energy (that is, light intensity) is linearly shifted from the zero-order component to the first-order component. The filtered light 114 shown in FIG.
Either zero-order or first-order diffracted light can be used. As the filtered light 114 shown in FIG. 2, first-order diffracted light can be used.

The switchable holographic optical element shown in FIG. 4 can be reflective or transmissive. FIG. 4 shows a switchable holographic optical element having opposite front and rear faces 410 and 412. In each of the reflection type and the transmission type, the parallel light 112 is incident on the front surface 410 at a vertical incident angle. To make incident light incident at a normal angle of incidence,
Note that this is a preferred choice for most applications, but is not required. If the switchable holographic optical element is configured as transmissive,
Zero-order and first-order diffracted light components are emitted from the back surface 412. On the other hand, when the electrically switchable holographic optical element is configured as a reflection hologram, the first-order diffracted light component is emitted from the front surface 410 and the zero-order diffracted component is emitted from the back surface. In the filter 106 of FIG. 1, one or more electrically switchable holographic optical elements, either reflective or transmissive, can be used. The filter 206 shown in FIG. 2 may use one or more reflective electrically switchable holographic optical elements.

The switchable holographic layer 406 records holograms using conventional techniques. In one embodiment, the resulting hologram is characterized by high diffraction efficiency and high switching speed between active and inactive states of the optical element. Polymer dispersed liquid crystal (P
In embodiments of the switchable holographic layer 406 formed from DLC) material, the recorded hologram may switch from a diffractive state to a transmissive state in accordance with the creation and disappearance of the electric field described above. The hologram recorded on the holographic layer 406 is
In order to achieve high diffraction efficiency, it is preferably of the Bragg type (also known as the thick-phase or volume-phase type). Raman-Nath
That is, a thin-phase hologram can be used.

The hologram recorded in the switchable holographic layer 406 can be based on the PDLC material described in US patent application Ser. No. 09 / 478,150, which is incorporated herein by reference. In one embodiment, this hologram produces an interference pattern created by the recording beam, the reference beam and the object beam, inside layer 406. Photopolymerization occurs due to the interaction between the laser light and the PDLC material. The liquid crystal particles are buried in the dark areas of the stripe pattern formed by the interaction of the recording beams during the recording process. In other words, the recording material can be a polymer-dispersed liquid crystal mixture that undergoes phase separation in a recording process that produces areas of densely packed liquid crystal particulates scattered by areas of transparent photopolymer. When a voltage of sufficient magnitude is applied to the ITO layer 404, the liquid crystal particles are oriented, the refractive index of the program layer 406 changes, the program stored therein is erased, and all incoming collimated light 112 Will be transmitted almost unchanged. Layer 406
The materials used therein have high switching speeds (eg, material switching can take place in tens of microseconds, which is very fast compared to conventional liquid crystal display materials) and high diffraction efficiency. It is configured to operate.

FIG. 5 shows three separate electrically switchable holographic optical elements 502 R,
One embodiment of a filter 106 or 206 using 502G and 502B is shown. Each of the electrically switchable holographic optical elements 502R-502B is configured to diffract a selected bandwidth of the incident collimated light 112 when the elements are operating in an active state. In particular, the electrically switchable holographic optical element 502R diffracts red bandwidth light when active and produces
The remaining 12 components are configured to transmit substantially unchanged. Similarly,
Electrically switchable holographic optical elements 502G and 502B diffract the green and blue bandwidth components of collimated light 112 when active, respectively, and transmit the remaining components of collimated light 112 unchanged. It is configured as follows. Each of the electrically switchable holographic optical elements 502R-502B, when operating in the inactive state, transmits the entire bandwidth of the collimated light 112 substantially unchanged.

Each of the three electrically switchable holographic optical elements 502 R- 502 G is activated or deactivated in response to a corresponding respective feedback control signal provided by feedback system 110 shown in FIG. In the active state,
Each optical element diffracts a selected bandwidth of the collimated light 112 into zero and first order diffractive components. Furthermore, in the active state, the intensity of the light contained in the zero-order and first-order diffraction components depends on the magnitude of the feedback control signal supplied to the electrically switchable holographic optical element.

In some embodiments, the electrically switchable holographic optical elements 502R,
02G and 502B receive the first or second red bandwidth control signal, the first or second green bandwidth control signal, and the first or second blue bandwidth control signal, respectively, as described above. . Specifically, the first or second red bandwidth control signal is selectively provided to the ITO layer of the electrically switchable holographic optical element 502R, and the first or second green bandwidth control signal is electrically switched. And the first or second blue bandwidth control signal is selectively provided to the ITO layer of the electrically switchable holographic optical element 502B. .

The filter 500 of FIG. 5 can be configured as a transmission type or a reflection type. Whether transmissive or reflective, the filter 500 operates in one of several different modes of operation according to the feedback control signal provided to it. FIG. 5A shows a reflective filter 500 configured to operate in an additive mode. In FIG. 5A, the electrically switchable holographic optical element 502R is activated and the electrically switchable holographic optical elements 502G and 502B are deactivated. As can be seen from FIG. 5A, the collimated light 112 is transmitted through the deactivated electrically switchable holographic optical elements 502B and 502G substantially unchanged. However, the activated electrically switchable holographic optical element 502R diffracts the red bandwidth component of the collimated light 112 into zero and first order diffracted red bandwidth components. In FIG. 5A, light 504 emitted from filter 500 is:
The first-order diffracted red bandwidth light and the other bandwidth components of the very slight parallel light 112. On the other hand, the light 506 emitted from the filter 500 includes zero-order diffracted red bandwidth light in addition to the blue and green bandwidth components of the collimated light 112, the former two being substantially unchanged in the filter. 500.

The filter 500 of FIG. 5A is illustrated as diffracting red bandwidth light and substantially transmitting all green and blue bandwidth light. This filter 500
Operates in the first stage of the three-stage cycle described above.
In response to receiving a first set of control signals or a new first set of control signals. In particular, a second or updated second red bandwidth control signal is provided to the ITO layer of the electrically switchable holographic optical element 502R while the first green and blue bandwidth control signals are provided. It is provided to the ITO layers of the electrically switchable holographic optical elements 502G and 502B, respectively. In this embodiment, the first green and blue bandwidth control signals completely deactivate the electrically switchable holographic optical elements 502G and 502B, respectively. In a preferred embodiment, light 504 comprises filtered light 114 shown in FIG.
(Or filtered light 114) at a first predetermined light intensity, a second or updated second red bandwidth control signal is applied to feedback system 1
10 generated by

The filter 500 of FIG. 5A provides a green bandwidth in response to receiving a second set of control signals or a new second set of control signals in the second stage of the three-stage cycle described above. It can operate in an additive mode that diffracts light while substantially transmitting all light in the red and blue bandwidths. In addition, the filter 500 of FIG. 5A, in the third stage of the three-stage cycle described above, receives a third set of control signals or a new third set of control signals and, in response, receives the blue bandwidth light. And operates in an additive mode that substantially transmits all of the red and green bandwidth light.

FIG. 5B shows a filter 500 configured as a transmissive filter operating in a subtractive mode. In contrast to the additive mode shown in FIG. 5A, each of the electrically switchable holographic optical elements 502R-502B is activated. In this mode of operation, each of the electrically switchable holographic optical elements 502R-502B diffracts a component of the parallel light 112. Parallel light 11
The electrically switchable holographic optical elements 502G and 502B in that all or substantially all of the light energy contained in the two green and blue bandwidth components is diffracted into primary components 510G and 510B, respectively. Fully activated.

As mentioned above, the electrically switchable holographic optical element 502 R is also activated. The electrically switchable holographic optical element 502R provides the collimated light 112
Are diffracted into zero-order and first-order diffracted components. The first-order diffracted red bandwidth light is emitted from filter 500 as first-order diffracted red bandwidth light 510R, and the zero-order red bandwidth component is emitted as light 512. If the electrically switchable holographic optical elements 502G and 502B operate with theoretically the highest diffraction efficiency, the light 512 will contain essentially only zero-order diffracted red bandwidth light. In a preferred form, light 512 is used as filtered light 114, as shown in FIG.

The filter 500 of FIG. 5B is shown diffracting all visible light components of the parallel light 112. This mode of operation of the filter 500 may occur in response to the first set of control signals or a new first set of control signals being received by the filter 500 in the first stage of the three-stage cycle described above. The first in this operation mode
Of the first set of control signals and the size of the new first set of control signals supplied to the filter 500 operating in the additive mode described above. The size is different from the set. In the subtractive mode of operation, the second or updated second red bandwidth control signal is an electrically switchable holographic optical element 502.
The first green and blue bandwidth control signals provided to the ITO layer of R are provided to the ITO layers of the electrically switchable holographic optical elements 502G and 502B, respectively. In this mode of operation, the first green and blue bandwidth control signals fully activate the electrically switchable holographic optical elements 502G and 502B, respectively. In a preferred embodiment, light 512 comprises filtered light 114 shown in FIG. 1 and a second or updated light 512 (or filtered light 114) to maintain light at a first light intensity. A second red bandwidth control signal is generated by feedback system 110.

The filter 500 of FIG. 5B responds in the second stage of the three-stage cycle described above, in response to the filter 500 receiving a second set of control signals or a new second set of control signals, Also operates in a subtractive color mode in which all or substantially all of the red and blue bandwidth components of the parallel light 112 are diffracted into first order diffraction components, and the green bandwidth component of the parallel light 112 is diffracted into zero order and first order diffraction components. I can do it. Further, the filter 5 of FIG.
00 represents the red and green bandwidth components of the collimated light 112 in response to receiving a third set of control signals or a new third set of control signals in the third stage of the three-stage cycle described above. Operate in a subtractive mode in which all or substantially all of the light is diffracted into the first-order diffraction component and the blue bandwidth component of the parallel light 112 is diffracted into the zero-order and first-order diffraction components.

As described above, the filter 500 of FIG. 5 can be configured as a reflective filter. FIG. 5C shows the reflective filter 500 operating in additive mode. In FIG. 5C, the electrically switchable holographic optical element 502R is activated and the electrically switchable holographic optical elements 502G and 502B are deactivated.
As can be seen from FIG. 5A, the collimated light 112 is transmitted through the deactivated electrically switchable holographic optical elements 502B and 502G substantially unchanged. However, the activated electrically switchable holographic optical element 502R
Diffracts the red bandwidth component of the parallel light 112 into zero-order and first-order diffracted red bandwidth components. In FIG. 5C, light 504 emitted from filter 500 includes first-order diffracted red bandwidth light and a small amount of other bandwidth components of parallel light 112. In contrast,
Light 706 emitted from filter 500 includes zero order diffracted red bandwidth light in addition to the blue and green bandwidth components of collimated light 112, the former two transmitting through filter 500 substantially unchanged.

The filter 500 of FIG. 5C is shown diffracting the red bandwidth light and transmitting substantially all of the green and blue bandwidth light. This filter 500
Operates in the first stage of the three-stage cycle described above.
In response to receiving a first set of control signals or a new first set of control signals. In particular, a second or updated second red bandwidth control signal is provided to the ITO layer of the electrically switchable holographic optical element 502R, and the first green and blue bandwidth control signals are respectively Provided to the ITO layers of the electrically switchable holographic optical elements 502G and 502B. In this embodiment, the first
Green and blue bandwidth control signals completely deactivate the electrically switchable holographic optical elements 502G and 502B, respectively. In a preferred embodiment,
Light 504 comprises filtered light 114 shown in FIG. 2, and second light 504 (or filtered light 114) is maintained at a first predetermined light intensity.
Or an updated second red bandwidth control signal is generated by feedback system 110.

The filter 500 of FIG. 5C provides a green bandwidth in response to receiving a second set of control signals or a new second set of control signals in the second stage of the three-stage cycle described above. It can also operate in an additive mode that diffracts light and transmits substantially all of the red and blue bandwidth light. Further, the filter 500 of FIG. 5C increases the blue bandwidth in response to receiving a third set of control signals or a new third set of control signals in the third stage of the three-stage cycle described above. It can operate to diffract and transmit substantially all of the red and green bandwidth light.

FIG. 5D shows the reflective filter 500 operating in the subtractive color mode. In contrast to the additive mode shown in FIG. 5C, each electrically switchable holographic optical element 502
R-502B is activated. In this mode of operation, each of the electrically switchable holographic optical elements 502R-502B diffracts a component of the parallel light 112. An electrically switchable optical element in that all or substantially all of the light energy contained in each of the red and blue bandwidth components of the collimated light 112 is diffracted into primary components 510G and 510B, respectively. 502G and 502B are fully activated.

As described above, the electrically switchable holographic optical element 502R is also activated. The electrically switchable holographic optical element 502R provides the collimated light 112
Is diffracted into zero-order and first-order diffraction components. The first-order diffracted red bandwidth light is emitted from filter 500 as first-order diffracted red bandwidth light 510R, and the zero-order red bandwidth component is emitted as light 512. If the electrically switchable holographic optical elements 502G and 502B are operating at the theoretically highest diffraction efficiency, light 512 will include essentially only zero-order diffracted red bandwidth light. In a preferred form, light 512 is used as filtered light 114 shown in FIG.

The filter 500 of FIG. 5D is shown diffracting all visible light components of the parallel light 112. The operation mode of the filter 500 is such that in the first stage of the above-described three-stage cycle, the filter 500 sets the first set of control signals or the new first set of control signals.
In response to receiving a set of control signals. The first in this operation mode
Of the first set of control signals and the new first set of control signals supplied to the reflective filter 500 operating in the additive mode described above.
Is different from the set of control signals described above. In the subtractive mode of operation, the second or updated second red bandwidth control signal is an electrically switchable holographic optical element 50.
The first green and blue bandwidth control signals are provided to the 2R ITO layer and the first green and blue bandwidth control signals, respectively, of the electrically switchable holographic optical elements 502G and 502B.
It is supplied to the O layer. In this mode, the first green and blue bandwidth control signals fully activate the electrically switchable holographic optical elements 502G and 502B, respectively. In a preferred embodiment, light 512 comprises filtered light 114 shown in FIG. 1, and light 512 (or filtered light 114) is first light.
A second or updated second red bandwidth control signal is generated by feedback system 110 to maintain at a predetermined light intensity.

The filter 500 of FIG. 5D operates in parallel in response to the filter 500 receiving a second set of control signals or a new second set of control signals in the second stage of the three-stage cycle described above. It may also operate in a subtractive mode that diffracts all or substantially all of the red and blue bandwidth components of light 112 while diffracting the green bandwidth components of parallel light 112 into zero and first order diffraction components. In addition, the filter 500 of FIG. 5B may be configured such that, in the third phase of the three-phase cycle described above, the filter 500 receives a third set of control signals or a new third set of control signals, It also operates in a subtractive mode in which all or substantially all of the red and green bandwidth components of the parallel light 112 are diffracted into first order diffraction components, and the blue bandwidth component of the parallel light 112 is diffracted into zero order and first order diffraction components. I can do it.

FIGS. 6 and 7 show another embodiment of the system shown in FIG. In FIG. 6, FIG.
Take the form of a beam splitter 608. 7, the deflector 108 of FIG. 1 takes the form of a prism 708. In the system shown in FIG. 2, a beam splitter or a prism can be used as the deflector 108. The deflector is
Multi-layer coatings are used to reflect specific portions of the incident light.

FIGS. 8 and 9 show another embodiment of the illumination system shown in FIG. 1, wherein the deflector 108 takes the form of one or more electrically switchable holographic optical elements. 8, the deflector 108 of FIG. 1 is implemented as one or more transmissive electrically switchable holographic optical elements 808. In FIG. 9, the deflector 108 of FIG.
However, it takes the form of one or more reflective electrically switchable holographic optical elements 908. Each of the one or more transmissive or reflective electrically switchable holographic optical elements shown in FIG. 8 or FIG. 9 can be controlled by an appropriately extended feedback system 110.

In one embodiment, the deflectors 808 and / or 908 include three different electrically switchable holographic optical elements, each of which is in the red, green, and blue bands of the incident filtered light 114. Acts independently on different widths. That is, one of the electrically switchable holographic optical elements of the deflector 808 or 908 diffracts the red, blue, or green bandwidth component of the light 114 when operating in an active state and filters Other components of the light 114 are transmitted substantially unchanged. 8 and 9, the deflector 808 or 908
The filtered light 114 sequentially diffracted by is incident on the feedback control system 110. The remaining components of the filtered light 114 that have passed through the deflector 808 or 908 substantially unchanged are emitted therefrom as illumination light 116. 8 and 9, deflectors 808 and 908 are controlled by feedback system 110. The deflectors 808 and 908 shown in FIGS. 8 and 9 can be used in a form similar to the reflective system shown in FIG.

FIG. 10 is another embodiment of the system shown in FIG. 1 using the filter 500 shown in FIG. In FIG. 10, the control circuit 1002 operates so that the filter 500 operates in the detection mode or the illumination mode. In the illumination mode, the control circuit 1002 generates a control signal for operating the filter 500 in the color reduction mode shown in FIG. 5B. In the illumination mode, the zero-order diffracted light 506 is used as the illumination light 116. However, in the sample mode, the control circuit 1002 causes the filter 500 to operate in the additive mode shown in FIG. 5A. In the detection mode, the control circuit 1002 detects the light intensity of the first-order diffraction component 504 and compares it with one or more predetermined values. Based on the difference in intensity between the diffractive component 504 and one or more predetermined values, the circuit 1002 adjusts a control signal provided to the filter 500 when the filter 500 operates in the illumination mode.

The lighting system described above may have various applications. For example, it can be used to adjust the color balance by compensating for a color change caused by a variation in the temperature of the light source or a color shift due to aging.

[Brief description of the drawings]

FIG. 1 is a block diagram of a lighting system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a lighting system according to another embodiment of the present invention.

FIG. 3 is a block diagram of a feedback system that can be used to control the electrically controllable optical filters shown in FIGS. 1 and 2.

FIG. 4 is a cross-sectional view of an electrically switchable holographic optical element that may be used in the electrically controllable optical filters shown in FIGS. 1 and 2.

FIG. 5 is a block diagram of an electrically switchable holographic optical element that may be used in the electrically controllable optical filters shown in FIGS. 1 and 2.

FIG. 5A shows the electrically switchable holographic optical element of FIG. 5 configured as a transmissive filter operating in additive mode.

FIG. 5B shows the electrically switchable holographic optical element of FIG. 5 configured as a transmissive filter operating in a subtractive mode.

FIG. 5C illustrates the electrically switchable holographic optical element of FIG. 5 configured as a reflective filter operating in additive mode.

FIG. 5D illustrates the electrically switchable holographic optical element of FIG. 5 configured as a reflective filter operating in a subtractive mode.

FIG. 6 illustrates an embodiment of the lighting system shown in FIG.

FIG. 7 is a view showing another embodiment of the lighting system shown in FIG. 1;

FIG. 8 is a diagram showing still another embodiment of the lighting system shown in FIG. 1;

FIG. 9 is a view showing still another embodiment of the illumination system shown in FIG. 1;

FIG. 10 is a block diagram of a lighting system according to yet another embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/34 G09G 3/34 DJ (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD) , RU, TJ, TM), AE, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM , EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR , TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventors Waldan, Jonathan Dee, 94024 Los Altos Hills Old Ranch Road 11491, California, United States 11491 (72) Inventors Adams, Michael Earl Leicestershire EL 14 United Kingdom 4 AR Melton Mowbray Sol Toby Cherry Tree Barn Bucks Treat (no address) -David 94087, California, USA Sunnyvale Corvallis Drive 849 (72) Inventor Street, John Jay Nottingham Energy 8, England 2 SB Wallaton Charcoal Drive 66 F-term (reference) 2H049 AA25 AA34 AA43 AA50 AA60 AA68 2H079 AA02 AA13 CA07 DA08 FA01 KA08 KA19 2H089 KA04 QA16 TA16 TA17 TA18 2H091 FA14X FA19Y FA26X FA37X FA41Z JA02 LA30 5C080 CC03 DD03 EE28 JJ02

Claims (31)

[Claims] An optically controllable optical filter configured to receive incident light and one or more control signals; a photodetector; the photodetector and the electrically controllable optical filter; Wherein the electrically controllable optical filter outputs light in response to receiving the incident light and the one or more control signals. Wherein the output light includes only a portion of the incident light, wherein a portion of the incident light varies in response to the one or more control signals received by the electrically controllable optical filter. Wherein the photodetector is configured to detect a part of the output light and to generate an output signal in response to detecting the part of the output light, wherein the control signal The circuit detects that the photodetector is Apparatus characterized by being configured to generate the one or more control signals in response to the generated signals. 2. The apparatus according to claim 1, wherein a part of the incident light changes according to a magnitude of the one or more control signals. 3. The apparatus of claim 1, wherein said electrically controllable optical filter comprises an electrically switchable holographic optical element. 4. The apparatus of claim 1, wherein said electrically controllable optical filter comprises an electrically switchable liquid crystal optical element. 5. The holographic optical element, wherein the electrically switchable holographic optical element comprises a holographic recording medium for recording a hologram, wherein the holographic recording medium comprises a monomer dipentaerythritol hydroxypentaacrylate.
4. The device according to claim 3, comprising dipentaerythritol hydroxypentaacrylate), a liquid crystal, a cross-linking monomer, a coinitiator, and a photoinitiator dye. . 6. The electrically switchable holographic optical element comprises a hologram created by exposing interference fringes in a volimer dispersed liquid crystal material, wherein the polymer dispersed liquid crystal material before exposure comprises: 4. The device according to claim 3, comprising a polymerizable monomer, a liquid crystal, a crosslinking monomer, a coinitiator, and a photoinitiator dye. 7. A beam splitter configured to receive and deflect a portion of the output light, wherein the photodetector includes a portion of the output light after being deflected by the beam splitter. The apparatus according to claim 1, wherein the detection is performed. 8. The apparatus according to claim 1, further comprising a collection lens disposed between the beam splitter and the photodetector, wherein the collection lens is configured to output one of the output lights after being deflected by the beam splitter. 9. The apparatus of claim 7, wherein the light detector is configured to receive and focus a portion of the output light after being focused by the focusing lens. apparatus. 9. A condenser lens, further comprising a condenser lens configured to collimate the incident light before the electrically controllable optical filter receives the incident light. The device of claim 1, wherein the device is: 10. The apparatus according to claim 1, wherein the light intensity of a part of the incident light changes. 11. The apparatus of claim 1, wherein a bandwidth of a portion of the incident light varies. 12. The apparatus according to claim 1, wherein a light intensity and a bandwidth of a part of the incident light are changed. 13. The apparatus of claim 1, further comprising a digitally controlled reflective display, wherein the digitally controlled reflective display is configured to receive a portion of the output light. 14. The micromirror of claim 1, further comprising an array of switchable micromirrors, wherein the array of switchable micromirrors is configured to receive a portion of the output light. Equipment. 15. The electronically controllable optical filter is configured to receive a first set of control signals, the output light comprising only a first bandwidth portion of the incident light, and A first bandwidth portion of the incident light that varies light intensity in accordance with the first set of control signals received by the electrically controllable optical filter; A filter is configured to receive a second set of control signals, wherein the output light includes only a second bandwidth portion of the incident light, and wherein the second bandwidth portion of the incident light includes the electrical signal. Varying the light intensity in accordance with the second set of control signals received by an optically controllable optical filter, wherein the electrically controllable optical filter receives a third set of control signals. Composed The output light includes only a third bandwidth portion of the incident light, wherein the third bandwidth portion of the incident light is received by the electrically controllable optical filter. The apparatus according to claim 1, characterized in that the light intensity is changed according to a set of the first, second, and third bandwidths, and wherein the first, second, and third bandwidths are different from each other. 16. The method of claim 1, wherein the first bandwidth portion of the incident light changes light intensity according to one of the first set of control signals received by the electrically controllable optical filter. A second bandwidth portion of the incident light that varies light intensity according to one of the second set of control signals received by the electrically controllable optical filter; 16. The apparatus of claim 15, wherein a third bandwidth portion of the optics varies light intensity according to one of the third set of control signals received by the electrically controllable optical filter. . 17. The method of claim 17, wherein the first bandwidth portion of the incident light varies light intensity according to a magnitude of one of the first set of control signals received by the electrically controllable optical filter. Wherein a second bandwidth portion of the incident light varies light intensity according to a magnitude of one of the second set of control signals received by the electrically controllable optical filter. The third bandwidth portion of the incident light varies light intensity according to one magnitude of the third set of control signals received by the electrically controllable optical filter. Item 16. The apparatus according to Item 15. 18. The apparatus of claim 18, wherein the electrically controllable optical filter is configured to diffract incident light. 19. The apparatus of claim 18, wherein the output light includes only a diffracted portion of the incident light. 20. The optical filter of claim 15, wherein the electrically controllable optical filter is configured to sequentially and repeatedly receive the first, second, and third sets of control signals. An apparatus according to claim 1. 21. The electrically controllable optical filter includes a first holographic optical element having opposite front and back faces, wherein the first holographic optical element has an active state and an inactive state. Switchable between the first holographic optical element, the first holographic optical element being incident on its front surface when operating in an active state.
Diffracted by the first holographic optical element, the first bandwidth light diffracted by the first holographic optical element is emitted from the back surface, and the first holographic optical element operates in an active state. 2. The apparatus of claim 1, wherein the first bandwidth of light is transmitted substantially unchanged when the light is transmitted. 22. The electrically controllable optical filter includes a second holographic optical element having opposite front and back faces, wherein the second holographic optical element has an active state and an inactive state. Switchable between the second holographic optical element, the second holographic optical element being incident on its front surface when operating in the active state.
Diffracted by the second holographic optical element, the second bandwidth light diffracted by the second holographic optical element is emitted from the back surface, and the second holographic optical element operates in an active state. Transmitting the second bandwidth of light without substantially changing when the first and second holographic optical elements are disposed adjacent to each other;
The apparatus of claim 21, wherein the first and second bandwidth lights are different from each other. 23. The front surface of the first and second holographic optical elements,
23. The holographic optical element of claim 22, being aligned in a direction orthogonal to a common axis, a back surface of the first holographic optical element is opposed to a front surface of the second holographic optical element. Equipment. 24. The holographic optical element further comprising an optical rotation device disposed between the first and second holographic optical elements, wherein each of the first and second holographic optical elements includes a diffraction grating, and 3. The holographic optical element according to claim 2, wherein the second holographic optical elements are arranged such that their diffraction gratings are parallel to one another.
An apparatus according to claim 3. 25. The first holographic optical element includes a first diffraction grating, the second holographic optical element includes a second diffraction grating, and the first diffraction grating includes the second diffraction grating. 24. The device according to claim 23, wherein the device is arranged in a direction orthogonal to. 26. A first group of first, second, and third holographic optical elements, wherein the electrically controllable optical filter is electrically switchable between an active state and an inactive state. And a second group of first, second, and third holographic optical elements electrically switchable between an active state and an inactive state, wherein each holographic optical element comprises: Wherein each of the first holographic optical elements diffracts light of a first bandwidth incident on its front surface when operating in an active state; Light of a first bandwidth diffracted by each of the first holographic optical elements is emitted from a respective one of the back surfaces, wherein each of the first holographic optical elements operates in an active state. When the first holographic optical elements transmit the first bandwidth light incident on their front surfaces substantially unchanged, the first bandwidth light transmitted by each of the first holographic optical elements is Wherein each of the second holographic optical elements diffracts light of a second bandwidth incident on its front surface when operating in an active state; Light of a second bandwidth diffracted by each of the holographic optical elements is emitted from a respective one of the rear surfaces, and each of the second holographic optical elements has a corresponding one of the front surfaces thereof when active. A second bandwidth of light incident on the second holographic optical element is transmitted substantially unchanged. Wherein light is emitted from each of said rear surfaces, wherein each of said third holographic optical elements diffracts light of a third bandwidth incident on its front surface when operating in an active state; Light of a third bandwidth diffracted by each of the third holographic optical elements is emitted from the respective back surface, and when each of the third holographic optical elements is operating in an active state, Third bandwidth light incident on the front surfaces thereof is transmitted substantially unchanged, and light of the third bandwidth transmitted by each of the third holographic optical elements is transmitted to the respective back surface. Wherein the first and second groups of holographic optical elements are arranged adjacent to each other; The apparatus of claim 1, wherein the first, second, and third bandwidths are different from each other. 27. The front face of each holographic optical element is orthogonally aligned with respect to a common axis, and the front face of each holographic optical element of the second group is aligned with each front face of the first group. 27. The device of claim 26, facing the back of the holographic optical element. 28. The holographic optical element further comprising a polarizer disposed between the first and second groups of holographic optical elements, wherein each holographic optical element includes a diffraction grating, and wherein all holographic optical elements have respective diffraction elements. 28. The device according to claim 27, wherein the gratings are arranged parallel to each other. 29. Each of the first group of holographic optical elements comprises a first holographic optical element.
Wherein each second holographic optical element of the second group comprises a second diffraction grating, and wherein the first and second groups of holographic optical elements comprise: 28. The device according to claim 27, wherein the device is arranged to be orthogonal to the second diffraction grating. 30. The electrically controllable element includes a first holographic optical element having opposite front and back faces, wherein the first holographic optical element is between an active state and an inactive state. Wherein the first holographic optical element diffracts a first bandwidth of light incident on its front surface when operating in an active state and is diffracted by the first holographic optical element. The first bandwidth of light is emitted from the front surface, and the first holographic optical element substantially alters the first bandwidth of light incident on the front surface when operating in an active state. The device according to claim 1, wherein the light is transmitted through the device. 31. The electrically controllable element includes a second holographic optical element having opposite front and back faces, wherein the second holographic optical element is between an active state and an inactive state. Wherein the second holographic optical element diffracts light of a first bandwidth incident on its front surface when operating in an active state and is diffracted by the second holographic optical element. The first bandwidth of light is emitted from the front surface, and wherein the second holographic optical element transmits the first bandwidth of light substantially unchanged when operating in an active state; 31. The apparatus of claim 30, wherein the first and second holographic optical elements are located adjacent to each other.