TW201543111A - Spatial light modulator and system thereof - Google Patents

Abstract

The invention discloses a spatial light modulator, used for modulating a variation ratio of a spatial light, comprising a liquid crystal unit and two electrodes, wherein the liquid crystal unit is configured between the two electrodes. A work voltage section without zero is provided by the two electrodes to drive the liquid crystal unit so as the variation ratio of the spatial light transmitting through the spatial light modulator includes more than one period.

Description

Space light modulation module and system thereof

The present invention relates to an optical device, and more particularly to a spatial light modulation device.

The conventional spatial light modulation device operates in a working voltage range of zero to a fixed voltage, and can only cause a periodic change in the transmittance of each liquid crystal cell included in the liquid crystal layer or the liquid crystal layer, so that the spatial light After the conventional spatial light modulation device, the rate of change varies periodically according to the transmittance of the liquid crystal cell.

Referring to the first figure, in the working voltage range, the transmittance of each liquid crystal cell included in the liquid crystal layer or the liquid crystal layer is only periodically changed, so that the rate of change of the spatial light varies with the transmittance of the liquid crystal cell. There is also only one periodic change. In the case of zero voltage operation, the transmittance of the liquid crystal cell is T _min (close to zero value), and when the voltage V _{M is} operated, the transmittance is T _max (close to 100%), at the highest voltage V _H The penetration rate returns to T _min again.

Since only a single periodic change of the transmittance of the liquid crystal cell can be achieved in the working voltage range, when the rate of change of the spatial light such as the transmittance or the reflectance thereof is to be adjusted, it is often necessary to greatly adjust the voltage, for example, when the spatial light is When the modulation device operates at the operating voltage V _M , the transmittance is T _max (close to 100%). To change the transmittance to T _min (to approach zero), the operating voltage must be driven to zero. Or to the highest voltage V _H . The above driving method will cause unnecessary energy waste, and at zero voltage, excessive noise will be generated.

In view of the above background, the embodiment of the present invention provides a spatial light modulation module for modulating a rate of change of a spatial light, comprising a liquid crystal cell and two electrodes, wherein the liquid crystal cell is located between the two electrodes. The two electrodes provide an operating voltage range that does not have a zero value to drive the liquid crystal cell, so that the spatial light changes through the spatial light modulation module, and the rate of change is greater than one periodic change. Wherein, the above change rate includes reflectance or transmittance.

In order to achieve one or a part or all of the above or other objects, another embodiment of the present invention provides a spatial light modulation system for modulating a rate of change of a spatial light, comprising a spatial light modulation device With a drive unit. The spatial light modulation device comprises a first electrode, a second electrode and a liquid crystal layer, wherein the liquid crystal layer is disposed between the first electrode and the second electrode. The driving device outputs a driving signal to the second electrode, so that the first electrode and the second electrode provide a working voltage range that does not have a zero value to drive the liquid crystal layer, so that the spatial light passes through the spatial light modulation module, and the rate of change is generated. More than one periodic change.

In an embodiment, the first electrode and the second electrode are both transparent, and the rate of change is a transmittance. The spatial light enters the liquid crystal layer from the first electrode, and then the second electrode leaves the spatial light modulation module. The penetration rate of spatial light can be made to be greater than one periodic variation.

In an embodiment, the first electrode can transmit light, and the second electrode can reflect spatial light. The rate of change is the reflectivity. The spatial light enters the liquid crystal layer from the first electrode and is reflected by the second electrode. After the first electrode leaves the spatial light modulation module, the reflectance of the spatial light can be greater than one periodic change.

Accordingly, the present invention achieves the following advantages:

1. Shorten the liquid crystal reaction time.

2. Avoid zero level to reduce the noise of the spatial light modulation device.

3. Save the energy required to recalibrate the spatial light modulation device.

4. It is easy to control the spatial light modulation device and improve the stability of the spatial light modulation device.

200‧‧‧Space Light Modulation System

210‧‧‧Spatial light modulation device

212‧‧‧Liquid layer

214‧‧‧First electrode (common electrode)

216‧‧‧Second electrode (pixel electrode)

218‧‧‧First substrate

220‧‧‧second substrate

250‧‧‧ drive

400~410‧‧‧Steps

V _H ‧‧‧highest voltage

V _L ‧‧‧ minimum voltage

V _I , V _II , V _III , V _I' , V _{II '} , V _{III '} , V _M ‧ ‧ voltage

T _max ‧‧‧maximum rate of change

T _min ‧‧‧minimum rate of change

The first figure is a schematic diagram of the rate of change of prior art spatial light modulation modules.

The second figure is a schematic structural view of the spatial light modulation system of the present invention.

The third A diagram and the third B diagram are schematic diagrams of the rate of change of the spatial light modulation module of the present invention.

The fourth A diagram and the fourth B diagram are diagrams showing the rate of change and structure of the spatial light modulation module of the present invention.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. Directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are for reference only. With the direction of the drawing. Therefore, the directional terms are used for illustration only and are not intended to limit the invention.

Referring to the second figure, the present invention provides a spatial light modulation system 200 for modulating a rate of change of a spatial light. The spatial light modulation system 200 includes a spatial light modulation (SLM) device 210 and a driving device 250, wherein the driving device 250 outputs a driving signal to the spatial light modulation device 210. The spatial light modulation device 200 includes a liquid crystal layer 212, a first electrode 214 and a second electrode 216. The liquid crystal layer 212 is disposed between the first electrode 214 and the second electrode 216. In this embodiment, the first electrode 214 is a common electrode, and the second electrode 216 is a pixel electrode. The common electrode 214 provides a driving voltage, and the pixel electrode 216 receives the driving signal to adjust the voltage thereof, so that an electric field between the common electrode 214 and the pixel electrode 216 generates an operating voltage interval, and the operating voltage interval does not include a zero value. The liquid crystal layer 212 is driven such that after the spatial light passes through the spatial light modulation device 210, the rate of change produces more than one periodic change. The rate of change of the spatial light includes a reflectance or a transmittance.

In an embodiment, the materials of the first electrode 214 and the second electrode 216 are transparent to light, for example, a light-transmitting conductive glass. The spatial light (not shown) enters the liquid crystal layer 212 by the first electrode 214, and then the second electrode 216 leaves the spatial light modulation device 200, so that the rate of change of the spatial light, that is, the transmittance, can be generated more than once. Variety.

In an embodiment, the first electrode 214 can transmit light, and the second electrode 216 can reflect spatial light. For example, the first electrode 214 located above uses light-transmissive conductive glass, and the second electrode 216 located below has a product. An intergration circuit is formed on the substrate to form a reflective liquid crystal on-chip (LCoS) spatial light modulation device 200. The spatial light enters the liquid crystal layer by the first electrode 214, is reflected by the second electrode 216, and leaves the space of the reflective 矽-based liquid crystal by the first electrode 214. After the light modulation device 200, the rate of change of the spatial light, that is, the reflectance, can be made to be greater than one periodic change.

In the above operating voltage interval, the rate of change of the spatial light is greater than one periodic variation, such that the rate of change of the spatial light includes at least one maximum value and at least one minimum value in each periodic variation. However, please refer to the third A diagram, which illustrates the second periodic variation to simultaneously illustrate the application of more than one periodic variation and the second periodic variation. In the first cycle and the second cycle, the maximum change rate of the spatial light is T _max , and the minimum value of the change rate is T _min . The lowest voltage of the working voltage range is V _L , and the lowest voltage V _L and the highest voltage V _{H of the} working voltage interval are greater than zero, that is, the working voltage interval does not include zero voltage.

In one embodiment, the operating voltage interval is selected to be adjusted to the interval I, and the operating voltage interval is between the voltages V _I to V _I′ such that the rate of change of the spatial light includes a maximum value and a minimum value in each periodic variation. value. In another embodiment, the operating voltage interval is selected to be adjusted to the interval II, and the operating voltage interval is between the voltages V _II to V _II′ such that the rate of change of the spatial light includes two maximum values and one for each periodic variation. Minimum value. In another embodiment, the operating voltage interval is selected to be adjusted to the interval III, and the operating voltage interval is between the voltages V _III to V _{III ′} such that the rate of change of the spatial light includes a maximum value and two in each periodic variation. Minimum value.

The pixel electrode 216 includes a plurality of sub-electrodes, and the liquid crystal layer 212 includes a plurality of liquid crystal cells. The driving signal includes a plurality of driving sub-signals, wherein each driving sub-signal is input to the corresponding sub-electrode, respectively, to respectively control the director direction of the corresponding liquid crystal unit by the electric field between each sub-electrode and the common electrode 220, The voltage between each of the sub-electrodes and the common electrode 220 is located between the aforementioned operating voltage intervals, so that the rate of change can be greater than one periodic variation. In other words, the rate of change of spatial light can be generated to be greater than one periodic change.

The driving signal can be a Pulse Width Modulation (PWM) signal, that is, each driving sub-signal can be a pulse width modulation signal. When each of the driving sub-signals is a pulse width modulation signal, the voltage of the pixel electrode 216 is proportional to the opening number of the duty cycle of the pulse width modulation signal in a driving period, wherein the duty ratio is The ratio of the duration of the positive pulse to the drive period in the drive cycle.

The spatial light modulation device 210 described above can be applied to the field of Adaptive Optics, Liquid Crystal Space Light Modulator (LC-SLM), holography 3D measurement, and optical aperture (Optical). Tweezer), Wavelength Selective Switch (WSS), Liquid Crystal Lens. The liquid crystal spatial light modulator includes a reflective 矽-based liquid crystal (LCoS) spatial light modulator. The wavelength selective switch includes a Dynamic Wavelength Processor and an Edge Wavelength Prossor (EWP).

According to the above, the present invention provides a spatial light modulation unit comprising a liquid crystal cell and two electrodes, wherein the liquid crystal cell is disposed between the two electrodes. The two electrodes provide an operating voltage range having no zero value to drive the liquid crystal cell, so that the rate of change of the spatial light is greater than one periodic variation. In each periodic variation, the rate of change includes at least one maximum value and at least one minimum value, as shown in FIG. 3A. The voltage of the working voltage range is greater than zero, and the two electrodes are a common electrode and a pixel electrode, respectively.

The rate of change shown in the third A diagram is a second periodic variation, but the rate of change of the present invention is limited to more than one periodic variation, and is not limited to an integer periodic variation. In each periodic variation, the rate of change may include only a maximum value and a minimum value, for example, the phase of the periodic variation of the rate of change is between 0.7 π and 2.7 π , that is, the voltage selection operation is at work. The voltage interval I is between V _I and V _I′ ; at this time, the rate of change curve is higher than a periodic change, but lower than the second periodic change, that is, only needs to have more than one periodic change to achieve . In each periodic variation, the rate of change may comprise two maximum values and a minimum value, for example, the phase of the periodic variation of the rate of change is between 1 π and 3 π , that is, the voltage is selected to operate at the operating voltage. The voltage of interval II is between V _II and V _{II '} ; at this time, the rate of change curve has more than one periodic variation. Or, in each periodic variation, the rate of change may include a maximum value and a minimum value, for example, the phase of the periodic variation of the rate of change is between 2 π and 4 π , that is, the voltage selection operation is performed. The voltage between the working voltage interval III is between V _III and V _{III '} ; at this time, the rate of change curve needs to have at least a second periodic change.

Referring to an embodiment of the third B diagram, in the above operating voltage range, the rate of change may be higher than the second periodic variation, but less than three periodic variations, and the operating voltage range still has to avoid the voltage. Start with a zero value. However, the rate of change of this embodiment is not limited to less than three periodic variations, as long as the above is greater than one periodic (2π) change, and the voltage is non-zero, any cycle (2π) is applied. can. In a preferred embodiment, the application of various spatial light modulation systems is complemented by the number of periodic changes.

The present invention can implement one of the above-described methods for controlling the number of periodic changes, as shown in the fourth A diagram and the fourth B diagram. The spatial light modulation device 210 further includes a first substrate 218 and a second substrate 220. The liquid crystal layer 212 is located between the first substrate 218 and the second substrate 220 and has a gap d (Cell gap). By adjusting the distance of the gap d, the periodic change of the spatial light change rate more than once can be adjusted. When the gap d of the liquid crystal layer 212 is adjusted to be twice the distance 2d, the rate of change is adjusted from a single periodic variation ( 2π ) to a quadratic periodic variation ( 4π ) under the same operating voltage interval. The first substrate 218 may be a transparent glass substrate such as an indium tin oxide (ITO) conductive substrate, a transparent plastic substrate or another material substrate, and the second substrate 220 may be a germanium substrate, a glass substrate, a plastic substrate or other material substrate. The spatial light modulation unit of the preferred embodiment of the present invention uses a liquid crystal on silicon (LCOS). Another method for controlling the number of times of the above periodic changes can be directly adjusted by changing the material properties of different liquid crystal cells, for example, increasing the birefringence of the liquid crystal material.

Referring to the second figure, the present invention provides a spatial light modulation device 210 for modulating the rate of change of a spatial light, comprising a liquid crystal layer 212 and two electrodes 214, 216, wherein the liquid crystal layer 212 is located at the two electrodes 214, 216. between. The two electrodes 214, 216 provide an operating voltage interval that does not have a value of zero to drive the liquid crystal layer 212. After the spatial light passes through the spatial light modulation device 210, the rate of change is greater than one periodic change. The rate of change of the spatial light includes a reflectance or a transmittance. In each periodic variation, the rate of change of spatial light includes at least a maximum value and at least a minimum value, as shown in the third figure. The voltage of the working voltage range is greater than zero, and the two electrodes 214 and 216 are a common electrode 214 and a pixel electrode 216, respectively.

Furthermore, the present invention further provides a spatial light modulation system 250, comprising the spatial light modulation device 210 and the driving device 250, wherein the two electrodes 214 and 216 are a first electrode 214 and a second electrode 216, respectively. . The driving device 250 outputs a driving signal to the second electrode 216, so that the first electrode 214 and the second electrode 216 provide an operating voltage interval to drive the liquid crystal layer 212, so that the spatial light passes through the spatial light modulation system 250, and the rate of change thereof Produces more than one periodic change. The first electrode 214 is the aforementioned common electrode 214, and the second electrode 216 is the pixel electrode 216 described above.

The above driving signal includes a Pulse Width Modulation (PWM) signal. The second electrode 216 includes a plurality of sub-electrodes, and the liquid crystal layer 212 is packaged The plurality of liquid crystal cells are included, and the driving signal includes a plurality of driving sub-signals, wherein each driving sub-signal is respectively input to the corresponding sub-electrode, so that each sub-electrode and the common electrode 214 respectively control the director direction of the corresponding liquid crystal cell (director The voltage between each of the sub-electrodes and the common electrode 214 is located between the aforementioned operating voltage intervals. After the spatial light passes through the spatial light modulation system 250, the rate of change is greater than one periodic variation. In each periodic variation, the rate of change includes at least one maximum value and at least one minimum value, and the voltage of the operating voltage interval is greater than zero.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

V _H ‧‧‧highest voltage

V _L ‧‧‧ minimum voltage

T _max ‧‧‧maximum rate of change

T _min ‧‧‧minimum rate of change

Claims (14)

A spatial light modulation module (SLM) for modulating a rate of change of a spatial light, comprising: a liquid crystal cell; and two electrodes, providing a working voltage range having no zero value to drive the a liquid crystal cell, wherein the liquid crystal cell is located between the two electrodes; wherein, after the spatial light passes through the spatial light modulation module, the rate of change is greater than one periodic change. The spatial light modulation module of claim 1, wherein the rate of change comprises reflectance or transmittance. The spatial light modulation module of claim 2, wherein the rate of change comprises at least one maximum value and at least one minimum value in each periodic variation. The spatial light modulation module of claim 3, wherein the rate of change comprises a maximum value and a minimum value in each periodic variation. The spatial light modulation module of claim 3, wherein in each periodic variation, the rate of change comprises a maximum value and a minimum value. A spatial light modulation system for modulating a rate of change of a spatial light, comprising: a spatial light modulation device comprising: a first electrode; a second electrode; and a liquid crystal layer disposed between the first electrode and the second electrode; and a driving device that outputs a driving signal to the second The electrode, the first electrode and the second electrode are provided with a working voltage range having no zero value to drive the liquid crystal layer, and after the spatial light passes through the spatial light modulation module, the rate of change may generate more than one cycle. Sexual change. The spatial light modulation system of claim 6, wherein the rate of change comprises at least one maximum value and at least one minimum value in each periodic variation. The spatial light modulation device of claim 6, wherein in each periodic variation, the rate of change comprises a maximum value and a minimum value. The spatial light modulation device of claim 6, wherein in each periodic variation, the rate of change comprises a maximum value and a minimum value. The spatial light modulation system of claim 6-9, wherein the first electrode and the second electrode are both transparent, the rate of change is a transmittance, and the spatial light is from the first electrode. After entering the liquid crystal layer, and then leaving the spatial light modulation module by the second electrode, the transmittance can be greater than one periodic change. The spatial light modulation system of claim 6-9, wherein the first electrode is transparent to light, and the second electrode is reflective to the spatial light, and the rate of change is reflectance, and the spatial light is The first electrode enters the liquid crystal layer and is reflected by the second electrode. After the first electrode leaves the spatial light modulation module, the reflectivity can be greater than one periodic change. The spatial light modulation system of claim 11, wherein the second electrode comprises a plurality of sub-electrodes, the liquid crystal layer comprises a plurality of liquid crystal cells, and the driving signal comprises a plurality of driving sub-signals, wherein each driving The sub-signals are respectively input to the corresponding sub-electrodes, so that each sub-electrode and the first electrode respectively control a diector of the corresponding liquid crystal cell, wherein a voltage between each sub-electrode and the first electrode is located at the working voltage Between the intervals, the rate of change is made greater than a periodic change. The spatial light modulation system of claim 12, wherein each of the driver signals comprises a Pulse Width Modulation (PWM) signal. The spatial light modulation system of claim 12, wherein the voltage of each of the sub-electrodes is proportional to the opening number of the duty cycle of the corresponding pulse width modulation signal.