GB2608800A

GB2608800A - An in-vehicle monitoring system and method for the same

Info

Publication number: GB2608800A
Application number: GB2109785.2A
Authority: GB
Inventors: Soon Ang Kah; Cong Weiquan
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2021-07-07
Filing date: 2021-07-07
Publication date: 2023-01-18
Also published as: GB202109785D0

Abstract

An in-vehicle monitoring system comprising: a light source 102 which emits light 104 towards a reflective surface 112 in a field of view of an imaging device 116 via a light polarization filter 108 such that at least a portion of the emitted light is re-directed and transmitted on a light transmission axis 118; the reflected light passes through a lens polarization filter 114 such that at least a portion of the reflected light is re-directed and transmitted on a lens transmission axis 118’ towards the imaging device. The light transmission axis may be perpendicular to the lens transmission axis. The light and lens polarization filters may be circular, elliptical or quarter-wave polarizers or a dichroic, reflective or thin film linear polarizers and may form a cross or elliptical polarization assembly. The system may reduce visibility of spot reflections. The light source may emit infrared and the imagine device may capture infrared light. A method of reducing image spot reflection is also claimed. The system may be used to monitor driver status including their attention and fatigue levels.

Description

AN IN-VEHICLE MONITORING SYSTEM AND METHOD FOR THE SAME

TECHNICAL FIELD

This disclosure relates to in-vehicle monitoring systems, in particular arrangement of optical assembly within in-vehicle monitoring systems.

BACKGROUND

Increasingly, monitoring systems are becoming a common function in motor vehicle for monitoring activities in a passenger cabin of a motor vehicle. By way of example, monitoring systems are often used to detect a status of a driver, to determine if the driver is fatigue or paying attention on the road. For driver's monitoring systems, status of a driver is often determined through eye tracking function. However, images captured by monitoring systems are often subject to influence from ambient light rays which affects the quality of images captured. Ambient light rays may include light rays external to the motor vehicle, such as sunlight or it may also be stray light rays from interior of motor vehicle, for example reflective surfaces within a passenger cabin. Other example includes an eyewear worn by the driver.

Often times, such reflection shows up as a bright spot or what is known as "spot reflection" in the images captured by the monitoring system, thus deteriorating the image quality. In some circumstances, these spot reflection affects the determination of status of driver, since parts of the facial features, such as the eyes of the driver may be blocked by the spot reflections. This causes inaccuracy or complete loss of information to be determined by the monitoring system.

There is therefore, a need to provide an in -vehicle monitoring system that at least ameliorate the problem described above. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taking in conjunction with the accompanying drawings and this background of the disclosure.

SUMMARY

A purpose of this disclosure is to ameliorate the problem of light rays reflected from a reflective surface captured withing a field of view (FONT) of an in-vehicle monitoring system, thereby showing 15 up as a spot reflection in the images captured.

The objective of this disclosure is solved by an in-vehicle monitoring system comprising: a light polarization filter positioned forward of a light source for emitting light rays; a lens polarization filter positioned forward of a lens of an imaging device; and a reflective surface being captured within a field of view of the imaging device; characterized in that the light polarization filter is operable 70 re-direct and transmit at least a portion of the emitted light rays from the light source in a light transmission axis; and the lens polarization filter is operable to re-direct and transmit at least a portion of the reflected light rays from the reflective surface in a lens transmission axis.

An advantage of the above described aspect of this disclosure yields an in-vehicle monitoring system operable to capture images which at least ameliorate the effects of spot reflection appearing on images captured by the imaging device of a monitoring system, caused by lights rays reflected off reflective surfaces within a passenger cabin of a motor vehicle as a result of the lens polarization filter and the light polarization filter absorbing or re-directing light rays away from a lens of an imaging device of the in-vehicle monitoring system. Examples of reflective surfaces may be parts of a driver's eyewear or a glossy surface within an interior of a passenger cabin of a motor vehicle. The reflected light rays from the targeted objects such as human facial characteristics or human eye will be able to pass through the filter and reach the imaging device. For driver monitoring system applications, in particular eye tracking function, it is important that the reflection from the human eye shall not be filtered out by the lens polarization filter. This is achievable due to the fact that human eye will depolarize majority of the reflected light rays. Consequently, reflected light from the targeted object captured within a FOV of the imaging device, will be able to pass through the lens polarization filter and reach the imaging device, producing images without spot reflections cause by light rays reflecting off reflective surfaces within the passenger cabin of a motor vehicle.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the light transmission axis is operable to transmit the polarized light rays emitted from the light source; and the lens transmission axis is operable to transmit the polarized light rays reflected from the reflective surface in a different transmission axis.

The advantage of the above aspect of this disclosure is to yield cross polarization, such that transmission and reception side of polarization filter transmission axis forms different angles from each other. Accordingly, spot reflection effect reduction or eliminated is achieved when all light rays are filtered in a different transmission axis, depending on difference in angle of the polarization light rays and the transmission axis. This provides flexibility of both polarization filters mounting orientation and mounting tolerance. Elimination of spot reflection can be up to 100%. or total elimination. The aforesaid configuration provide the flexibility of both polarizers mounting orientation and mounting tolerance.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the lens transmission axis is operable to transmit the polarize light rays in a transmission axis perpendicular to a polarization direction of the light rays reflected from the 20 reflective surface.

The advantage of the above aspect of this disclosure is to yield a perpendicular angle between the emitted light rays from the light source and the polarized light rays transmitting towards the lens of the imaging device. As a result of the perpendicular angle formed, spot reflection caused by light rays reflecting off reflective surface within the passenger compartment is not captured by within a FOB' of the imaging device.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the light polarization filter and the lens polarization filter are arranged to form a cross polarization assembly.

The advantage of the above aspect of this disclosure is to form an angle between the emitted light rays from the light source and the polarized light rays transmitting towards the lens of the imaging device, such that spot reflection caused by light rays reflecting off reflective surface within the passenger compartment.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the light polarization filter and the lens polarization filter is selected from a group consisting of: * a linear polarizer; * a circular polarizer; or * an elliptical polarizer.

The advantage of the above aspect of this disclosure is to yield an optical polarization filter operable as the lens polarization filter and/or the light polarization filter to achieve the technical objective of this disclosure as discussed above.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the linear polarizer is selected from a group consisting of: * a dichroic polarizer; * a reflective polarizer; or * a thin film polarizer.

The advantage of the above aspect of this disclosure is to yield an optical polarization filter operable as a linear polarizer, to function as a lens polarization filter to absorb or re-direct light rays away from the lens of the imaging device, thereby achieving reduction or total elimination of spot reflection caused by light rays reflected from reflective surfaces captured within a FOV of an imaging device in a passenger cabin of a motor vehicle.

Preferred is an in-vehicle monitoring system as described above 5 or as described above as being preferred, in which: the circular polarizer or the elliptical polarizer comprises: a linear polarizer and a quarter-wave plate.

The advantage of the above aspect of this disclosure is to yield an optical polarization filter operable as a circular polarizer or the elliptical polarizer to function as a lens polarization filter, by using a combination of a linear polarizer and a quarter-wave plate, to absorb or re-direct light rays away from the lens of the imaging device, thereby achieving reduction or total elimination of spot reflection caused by light rays reflected from reflective surfaces captured within a FOV of an imaging device in a passenger cabin of a motor vehicle.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the light polarization filter and the lens polarization filter are arranged in an elliptical polarization assembly.

The advantage of the above aspect of this disclosure is to yield an optical polarization assembly, in particular an elliptical polarization assembly is operable to at least partially reduce spot reflection from images captured by the imaging device of a monitoring system.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the lens transmission axis is operable transmit the reflected light rays from the reflective surface captured by the imaging device, to at least reduce visibility of a spot reflection effect on at least one image captured by the imaging device of the monitoring system.

The advantage of the above aspect of this disclosure is to yield an optical assembly for an in-vehicle monitoring system to achieve reduction or total elimination of the spot reflection effects in images captured by an imaging device within a passenger cabin of a motor vehicle. More advantageously, the main technical objective of the aforesaid arrangement is applicable to imaging devices working in both visible light and other wavelengths, for example infrared wavelengths.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the imaging device is operable to capture images within an 20 infrared wavelength.

The advantage of the above aspect of this disclosure is to yield an in-vehicle monitoring system operable to capture infrared images which at least ameliorate the effects of spot reflection appearing on the infrared images captured by an infrared imaging device of a monitoring system.

Preferred is an in-vehicle monitoring system as described above or as described above as being preferred, in which: the light source is operable to emit light rays within an infrared wavelength.

The advantage of the above aspect of this disclosure is to yield an in-vehicle monitoring system operable to capture infrared images which at least ameliorate the effects of spot reflection appearing on infrared images captured by an infrared imaging device of a monitoring system operable within such wavelengths.

The objective of this disclosure is solved by a method of reducing an effect of spot reflection on images captured by an in-vehicle monitoring system, the method comprising: polarizing light rays emitting from a light source towards a field of view of an imaging device; polarizing light rays reflected from a reflective surface captured within the field of view of the imaging device; characterized in that the method comprises: re-directing at least a portion of the polarized light rays from the light source through a light transmission axis; and re-directing at least a portion of the polarized light rays reflected from the reflective surface through a lens transmission axis, such that spot reflection from the reflective surface is not visible in images captured by the imaging device.

An advantage of the above described aspect of this disclosure yields a method of reducing or totally eliminating spot reflection on images captured by an in-vehicle monitoring system, to at least ameliorate the effects of spot reflection caused by lights rays reflected off reflective surfaces within a passenger cabin of a motor vehicle. More advantageously, a purpose of this disclosure is achieved by absorbing or re-directing light rays away from a lens of an imaging device of the in-vehicle monitoring system. Examples of reflective surfaces maybe parts of a driver's eyewear or a glossy surface within an interior of a passenger cabin of a motor vehicle. Consequently, reflected light from the targeted objects captured within a FaVof the imaging device, for example human face or eyes will be able to pass through the lens polarization filter and reach the imaging device, producing images without spot reflections cause by light rays reflecting off reflective surfaces within the passenger cabin of a motor vehicle Preferred is a method of reducing an effect of spot reflection on images captured by an in-vehicle monitoring system as described above or as described above as being preferred, in 10 which: the light transmission axis is transmitting the polarized light rays emitted from the light source; and the lens transmission axis is transmitting the polarized light rays reflected from the reflective surface in a different transmission axis.

The advantage of the above aspect of this disclosure is to yield a method of reducing an effect of spot reflection on images captured by an in-vehicle monitoring system, by controlling a transmission direction of light rays emitting from the light source and transmission axis of the polarized light rays, to achieve reduction or total elimination of spot reflections appearing in images captured by an imaging device of a monitoring system of a motor vehicle, caused by light rays reflected off reflective surface.

BRIEF DESCRIPTION OF DRAWINGS

Other objects and aspects of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings in which: Fig. lA shows an optical assembly of an in-vehicle monitoring system in accordance with a preferred embodiment.

Fig. 12, shows an optical assembly of an in-vehicle monitoring 5 system in accordance with a preferred embodiment.

Fig. 2A shows a top view of an in-vehicle monitoring system in accordance with a preferred embodiment.

Fig. 2B shows a top view of an in-vehicle monitoring system in accordance with a preferred embodiment.

Fig. 2C shows a top view of an in-vehicle monitoring system in accordance with an alternative preferred embodiment.

In various embodiments described by reference to the above figures, like reference signs refer to like components in several perspective views and/or configurations.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the disclosure or the following detailed description. It is the intent of this disclosure to present an in-vehicle monitoring system operable to filter out light rays reflected off a reflective surface captured withing a field of view of the monitoring system.

Hereinafter, the term "forward" refers to a position in front of an object. By way of an example, Element A is positioned forward of Element B refers to Element A positioned in front of Element B. Referring to Fig. lA which shows an optical assembly 100a of an in-vehicle monitoring system in accordance with a preferred embodiment, it is shown, the optical assembly 100a includes a light source 102 operable to emit light rays. In a typical configuration, light rays 106 emitting from a light source polarizes in random or multiple directions. In order to control the direction of light rays 106, a light polarization filter 108 may be positioned forward of the light source 102. When the randomly polarized light rays from the light source 102 passes through the light polarization filter 108, only polarized light in the same polarization direction as the transmission axis 118 can be transmitted while the rest are either reflected or absorbed. As shown in Fig. lA, a reflective surface 112 is within a field of view (FOV) of an imaging device 116. Any light rays hitting and reflecting off the reflective surface 112 will be captured by the imaging device 116, which will then show up as a spot reflection on images captured by the imaging device 116. In the context of a passenger cabin of a motor vehicle, examples of reflective surfaces include parts of an eyewear worn by a driver or glossy surfaces within the passenger cabin.

To counter the effects of spot reflection captured within the FOV of the imaging device 116, a lens polarization filter 114 may be positioned forward of the imaging device 116, such that polarized light 120' in the same polarization direction as the transmission axis 118' can be transmitted through transmission axis 118', preferably in a direction away from a lens of the imaging device 116. Advantageously, the problem of spot reflection caused by reflected light rays is solved by re-directing light rays away from the imaging device such that amount of reflected light rays does not reaches the imaging device 116.

In the aforesaid embodiment shown in Fig. 1A, the transmission axis 118' of the lens polarization filter 114 re-directs the polarized light rays 120' in a direction such that the polarized 5 light rays re-directed is substantially perpendicular to the reflected light ray polarization direction. This can be achieved by choosing a polarization filter which has a transmission axis that is substantially perpendicular to the transmission axis of the light source polarization filter 108. When both polarization 10 filters 108, 114 are placed in such relative alignment with each other, they are known as crossed polarizers.

The lens polarization filter 114 only allows light rays that is polarized in the same direction as the lens polarizer transmission axis 118' to pass through. Since the light source 102 polarized light rays' direction, i.e. the light polarization direction 110, is perpendicular to the lens polarization filter 114, reflected light rays cannot transmit through. Consequently, the bright spot reflection is not captured by the imaging device 116. Polarized light rays hitting the driver, for example driver's skin and other diffused surfaces will be randomly polarized and reflected, thus the imaging device 116 will still be operable to capture the image of the driver and environment.

In principle, reflected light rays from a target object such as a driver's face and more specifically, a driver's eye will be able to transmit through and thus captured by the imaging device 116. This is due to depolarization of reflected light rays from the driver's eye, such that at least a portion of the reflected light rays will always be captured by the imaging device 116, thus ensuring eye tracking function of driver's monitoring systems are not effect. On the other hand, as described above, since the lens polarization filter 114 function to re-direct the reflect light rays from the reflective surface 112 in a transmission axis 118' different from the light polarization direction 110, the objective of eliminating spot reflection in images is achieved.

In another embodiment as shown in Fig. 1B, the lens transmission axis 118' may be positioned at an angle, the angle of the transmission axis 118' may be any angle suitable for forming a cross polarization assembly. In this embodiment, spot reflections captured in images by the imaging device 116 is at least partially reduced.

Fig. 2A illustrates a top view of an in-vehicle monitoring system 200a in accordance with a preferred embodiment, of which the system 200a includes a first light source 202 and a second light source 202', an imaging device 208, of which the aforesaid electronic components may be positioned within a housing or spacer 224. The imaging device 208 comprises a lens stack 110 therewithin, an image sensor 212 and a lens 214 of the imaging device 116. A see-through panel may be positioned forward of the electronic components light sources 202, 202' and imaging device 208, to keep dust out.

In certain embodiments, only images captured within an infrared (IR) wavelength by the imaging device 208. In such embodiments, the imaging device 208 is operable within the infrared wavelength.

In this regard, light source 202, 202' shall also be emitting IR light rays and the see-through panel is an IR window 222 positioned forward of the electronic components, such that the lens 214 of the imaging device 116 captures a field of view (FOV) through the IR window 222. An advantage of the aforesaid embodiment is that IR wavelength is less visible or nearly invisible to human eyes. As such, light ray transmission from the in-vehicle monitoring systems causes less distraction to a driver.

The electronic components are powered by an electrical circuitry 224, for example a printed circuit board (PCB). Applying the inventive concept of this disclosure as explained using Fig. lA and Fig. 1B above, a light polarization filter 216, 216 is positioned forward of the light source 202, 202', to absorb or re-direct light rays emitted from light source 202, 202'. A lens polarization filter 218 is positioned forward of the imaging device 208, to absorb or re-direct light rays reflected from a reflective surface 220 within a FOV of the imaging device 116.

The advantage of reducing or eliminating spot reflection captured by the imaging device 116 reflected from the reflective surface 22 is achieved by using a lens polarization filter to absorb or re-direct reflected light rays away from a lens of the imaging device of the in-vehicle monitoring system. Further, light source 202, 202' emit light rays in multiple directions, or randomly polarized. By positioning a light polarization filter 216, 216' forward of the light source 202, 202', emitted light rays from the light source 202, 202' are re-directed to a same direction as a transmission axis of the light polarization filer 216, 216'.

In a preferred embodiment as shown in Fig. 2B, the light polarization filter 118, 218 and the lens polarization filter 114,218 is a linear polarizer 226 positioned forward of an IR window 222 in a way that all the electronic components 202, 202' and 208 housed in an in-vehicle monitoring system. 200b are covered by the forward placing linear polarizer 226. A quarter-wave plate 228 is positioned forward of the linear polarizer 226, thus creating a circular polarizer or an elliptical polarizer. Consequently, spot reflection caused by light rays reflecting from reflective surface within a FOV of the imaging device is reduced or eliminated. Advantageously, unlike linear polarizer, a circular polarizer is operable to transmit light rays at aside of the polarizer and receive light rays at another side of the polarizer to realize cross polarization by a single piece of optical element without the need to adjust the angle between two polarization filters to achieve cross polarization.

Turning now to Fig. 2C which shows a top view of an in-vehicle monitoring system 200c in accordance with an alternative embodiment, a linear polarizer 226' is positioned on a first side of an IR window 222 nearer to the electronic components, i.e. light source 202, 202' and an imaging device 208 and a second side is positioned with a quarter-wave plate 228'. As with the above embodiment, the advantage of this embodiment is that a single piece of polarization filter is configured to cover both the light source 202, 202' and the imaging device as both polarization axis should be the same, thus removing the need to align them into a cross polarization arrangement. The layers of optical elements may be adhere together using clear adhesive.

In all of the above embodiments, it is preferred the lens polarization filter and the light polarization filter may be a circular polarizer, an elliptical polarizer or a linear polarizer. More preferably, the linear polarizer may be selected from a group consisting of a dichroic polarizer, a reflective polarizer, e.g. a wire grid polarizer, or a thin film polarizer. Even more preferably, the linear polarizer further includes a quarter-wave plate, thereby creating a circular polarizer and/or an elliptical polarizer.

The main inventive concept of this disclosure maybe applicable as a method of reducing an effect of spot reflection on images captured by an in-vehicle monitoring system for a motor vehicle.

The method includes polarizing light rays emitting from a light source towards a field of view of an imaging device and polarizing light rays reflected from a reflective surface captured within the field of view of the imaging device. At least a portion of the polarized light rays from the light source may be re-directed through a light transmission axis and at least a portion of the polarized light rays reflected from the reflective surface may be re-directed through a lens transmission axis, such that spot reflection from the reflective surface is not visible in images captured by the imaging device.

Preferably, the light transmission axis is transmitting the polarized light rays emitted from the light source. Further, the lens transmission axis is transmitting the polarized light rays reflected from the reflective surface in a different transmission axis. Consequently, the purpose of reducing or eliminating spot reflection caused by polarized light rays reflecting from reflective surface captured by an in-vehicle monitoring system is achieved.

Thus, it can be seen that an in-vehicle monitoring system and method having the advantage of reducing or eliminating spot reflection caused by light reflecting from reflective surface, such as a driver's eyewear, captured within a FOV of an imaging device of the in-vehicle monitoring system has been provided. By eliminating spot reflection in images captured by the imaging device, accuracy of eye tracking function is improved. While exemplary embodiments have been presented in the foregoing detailed description of the disclosure, it should be appreciated that a vast number of variations exist.

It should further be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, operation or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the disclosure, it being understood that various changes maybe made in the function and arrangement of elements and method of operation described in the exemplary embodiment without departing from the scope of the disclosure as set forth in the appended claims.

List of Reference Signs 100a, 100b Optical Assembly of an in-vehicle monitoring system 102 Light source 104 Emitted light rays 106 Light rays polarizing in multiple directions 108 Light polarization filter Polarized light rays transmission direction 112 Reflective surface 114 Lens polarization filter 116 Imaging device 118, 118' Transmission axis Polarized light rays 200a, 200c 200b, In-vehicle monitoring system 202 Light source 204 Emitted light rays 206 Reflected light rays from reflective surface 208 Imaging device 210 Lens stack 212 Image sensor 214 Lens imaging device 216, 216' Light polarization filter 218 Lens polarization filter 220 Reflective surface 222 Infrared (IR) window 224 Printed Circuit Board (PCB) 226, 226' Linear polarizer 228, 228' Quarter-wave plate 234 Spacer / Housing

Claims

Patent claims 1. An in-vehicle monitoring system comprising: a light polarization filter positioned forward of a light source for emitting light rays; a lens polarization filter positioned forward of a lens of an imaging device; a reflective surface being captured within a field of view of the imaging device; characterized in that the light polarization filter is operable no re-direct and transmit at least a portion of the emitted light rays from the light source in a light transmission axis; and the lens polarization filter is operable to re-direct and transmit at least a portion of the reflected light rays from the reflective surface in a lens transmission axis.
2. The system of claim 1, wherein the light transmission axis is operable to transmit the polarized light rays emitted from the light source; and the lens transmission axis is operable to transmit the polarized light rays reflected from the reflective surface in a different transmission axis.
3. The system of claim 2, wherein the lens transmission axis is operable to transmit the polarize light rays in a transmission axis perpendicular to a polarization direction of the light rays reflected from the reflective surface.
4. The system of any one of claims 1 to 3, wherein the light polarization filter and the lens polarization filter are arranged to form a cross polarization assembly.
5. The system according to any one of the preceding claims, wherein the light polarization filter and the lens polarization filter is selected from a group consisting of: * a linear polarizer; * a circular polarizer; or * an elliptical polarizer.
6. The system according to claim 5, wherein the linear polarizer is selected from a group consisting of: * a dichroic polarizer; * a reflective polarizer; or * a thin film polarizer.
7. The system according to anyone of claim 5 or 6, wherein the circular polarizer and the elliptical polarizer comprises: a linear polarizer and a quarter-wave plate.
8. The system according to anyone of claims 1, 5 or 8, wherein the light polarization filter and the lens polarization filter are arranged in an elliptical polarization assembly.
9. The system according to any one of the preceding claims, wherein the lens transmission axis is operable transmit the reflected light rays from the reflective surface captured by the imaging device, to at least reduce visibility of a spot reflection effect on at least one image captured by the imaging device of the monitoring system.
10. The system according to any one of the preceding claims, wherein the imaging device is operable to capture images within an infrared wavelength.
11. The system according to any one of the preceding claims, wherein the light source is operable to emit light rays within an infrared wavelength.
12. A method of reducing an effect of spot reflection on images captured by an in-vehicle monitoring system, the method comprising: polarizing light rays emitting from a ligh7 source towards a field of view of an imaging device; polarizing light rays reflected from a reflective surface captured within the field of view of the imaging device; characterized in that the method comprises: re-directing at least a portion of the polarized light rays from the light source through a light transmission axis; and re-directing at least a portion of the polarized light rays reflected from the reflective surface through a lens transmission axis, such that spot reflection from the reflective surface is not visible in images captured by the imaging device.
13. The method of claim 12, wherein the light transmission axis is transmitting the polarized light rays emitted from the light source; and the lens transmission axis is transmitting the polarized light rays reflected from the reflective surface in a different transmission axis.