JP2005102171A - Optical signal receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light receiving system capable of efficiently receiving signal light over a wider-angle range. <P>SOLUTION: In an optical signal receiving system, an optical signal transmitter such as a terminal device connected to a tuner or Internet is arranged in, for example, a room of a house. The optical signal transmitted from it is received, and the video information and voice information are supplied to video equipment such as a television set and audio equipment provided with an amplifier and speaker. The optical signal receiving system comprises an optical system that condenses the optical signal on a light receiving element using a condenser lens. The light receiving element is arranged nearer to the condenser lens side than to a condensing point of the condenser lens. The condenser lens is aspherical to strongly distribute, on the light receiving element, the intensity distribution in the arrangement plane of light receiving element of the light which is obliquely incoming within a prescribed angle range against the optical axis of the condenser lens. Thus, the optical signal incoming to the condenser lens over a wide range is received at a prescribed light receiving intensity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical signal receiving apparatus that receives an optical signal such as a high-frequency modulated optical signal.

  A technique is known in which information is optically modulated and transmitted / received using an LED or other optical device. It is considered that such optical signal communication is applied to a home terminal device or AV equipment. For example, a tuner or the terminal device connected to the Internet is placed in a home room, and video and audio information is transmitted from the video device such as a TV and an audio device equipped with an amplifier, a speaker, and the like to be reproduced. Is possible.

  When optical transmitters and receivers are placed near the corners of the room or near equipment and receive signal light modulated by video information or audio information, the higher the signal, the more scattered light from the ceiling, walls, etc. Therefore, it is necessary to directly receive light, and the relative relationship between the position of the optical transmission device and the light reception possible angle of the light receiving device becomes delicate. Therefore, in the optical system of the optical receiver, the received light intensity varies depending on the incident angle of the received signal light, and there is a problem that sufficient received light intensity cannot be obtained depending on the incident angle.

  As a method of expanding the angle range with high light receiving efficiency for signal light coming from a wide incident angle, it is conceivable to provide a plurality of optical sensors (light receiving elements) in the optical system of the optical receiver. However, when a plurality of optical sensors are provided, the electrical capacity of the entire optical sensor increases, so that the frequency characteristics are lowered and the high-speed transmission performance is reduced (transmission capacity is reduced). In addition, since the plurality of optical sensors are arranged at different positions, it is necessary to adjust the phase of the received light signal. As described above, the method using a plurality of optical sensors has some problems.

  Examples of problems to be solved by the present invention include the above. The present invention has been made in view of the above points, and an object of the present invention is to provide an optical signal receiving apparatus capable of efficiently receiving signal light from a wider angle range.

  The invention according to claim 1 is an optical signal receiving device that collects and receives an optical signal on a light receiving element by a condensing lens, and the light receiving element is located at the collecting point rather than the condensing point of the condensing lens. Arranged on the light lens side, the condenser lens strongly distributes the intensity distribution on the light receiving element arrangement plane of incident light incident on the light axis of the condenser lens with an inclination within a predetermined angle range with respect to the optical axis of the condenser lens. It is characterized by having an aspheric shape.

  In one preferred embodiment of the present invention, an optical signal receiving apparatus that collects and receives an optical signal on a light receiving element with a condenser lens, the light receiving element is more than the light collecting point of the condenser lens. Arranged on the light lens side, the condenser lens strongly distributes the intensity distribution on the light receiving element arrangement plane of incident light incident on the light axis of the condenser lens with an inclination within a predetermined angle range with respect to the optical axis of the condenser lens. It has an aspherical shape.

This optical signal receiving device, for example, arranges an optical signal transmitting device such as a tuner or a terminal device connected to the Internet in a home room, receives an optical signal transmitted therefrom, Video information and audio information are supplied to audio equipment including an amplifier and a speaker. The optical signal receiving apparatus includes an optical system that condenses an optical signal on a light receiving element by a condensing lens. Here, the light receiving element is provided on the condensing lens side with respect to the condensing point of the condensing lens, and the condensing lens is inclined and incident within a predetermined angle range with respect to the optical axis of the condensing lens. It has an aspherical shape that strongly distributes the intensity distribution of the incident light in the light receiving element arrangement plane on the light receiving element. This makes it possible to receive an optical signal incident on the condenser lens from a wide range with a predetermined light receiving intensity. This is suitable for installing an optical signal receiving device at a corner of a room and receiving an optical signal incident from a wide angle range including the direction of the wall or ceiling of the room.

  The above condensing lens arranges two curves obtained by correcting even-order arcs so that their vertices coincide with each other and are orthogonal to each other, and one of the two curves follows the other curve. This is realized by having an aspheric surface defined by parallel movement. In the two curves, one radial direction of the condenser lens is an X-axis direction, another radial direction perpendicular to the one radial direction is a Y-axis direction, and an optical axis direction of the condenser lens is a Z-axis direction. Are defined as curves extending in the X and Y directions, respectively.

  The optical signal receiving device may further include another condensing lens that is disposed between the condensing lens and the light receiving element and expands a light receiving angle range of the optical signal by the condensing element. it can. By providing this other condensing lens, the light receiving angle range of the optical signal can be further expanded.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  First, the received light intensity distribution when a spherical lens is used in the optical system of the receiving apparatus will be described. FIG. 1A shows an example of an optical system using a spherical lens. In FIG. 1A, the focal length of the spherical lens 50 is f, and a light receiving element 51 such as an optical sensor is positioned forward or backward on the optical axis 52 of the spherical lens 50 by a predetermined distance d from the focal position. Be placed. In this optical system, as shown in FIGS. 1A and 1B, the X axis is taken in the direction perpendicular to the paper surface, the Y axis is taken in the vertical direction in the figure, and the optical axis of the spherical lens 50 is taken. The Z axis is taken in the direction of 52.

  FIGS. 2A and 2B are schematic contour diagrams showing the received light intensity characteristic (three-dimensional characteristic) 55 of incident light incident on the light receiving element 51 arranged at the position shown in FIG. The received light intensity characteristic 55 is indicated by a plurality of contour lines 56 each corresponding to a predetermined received light intensity. 2A and 2B, the numerical values on the X axis and the Y axis indicate the angles of the incident light with respect to the optical axis 52 in the X axis and Y axis directions shown in FIG. 1, respectively. That is, the received light intensity at a point where both the horizontal direction angle and the vertical direction angle correspond to 0 indicates the received light intensity of light incident parallel to the optical axis 52 of the spherical lens 50 shown in FIG.

  In the example of FIG. 2A, incident light parallel to the optical axis 52 has the highest received light intensity, and the received light intensity rapidly decreases as the incident angle with respect to the optical axis 52 increases in the X-axis direction and the Y-axis direction. To do. That is, incident light having a smaller incident angle with respect to the optical axis 52 (for example, incident light 54 in FIG. 1A) has a higher light receiving intensity by the light receiving element 51 and has a larger incident angle with respect to the optical axis (for example, FIG. 1A). The incident light 53) in FIG.

  In the example of FIG. 2B, the peak of the received light intensity is at a predetermined incident angle. That is, in both the X-axis direction and the Y-axis direction, the received light intensity increases from incident light parallel to the optical axis to incident light at the incident angle, but when the incident angle is exceeded, the example of FIG. Similarly, the received light intensity decreases.

  In the example of FIG. 2A, the received light intensity decreases as the incident angle of incident light with respect to the optical axis 52 increases. In the example of FIG. 2B, the received light intensity remains relatively flat until a predetermined incident angle corresponding to the peak point of the received light intensity. However, when the incident angle is exceeded, the received light intensity decreases. . That is, when the incident angle with respect to the optical axis 52 becomes a certain value or more, the received light intensity decreases rapidly.

  In the examples of FIGS. 2A and 2B, the contour lines of the received light intensity distribution characteristics are almost circular. When the light receiving device is arranged at the corner of the room as described above, the distribution of the incident angle of the signal light incident on the optical system of the light receiving device, that is, the direction of the light source on the transmission side is a distribution that is a rectangle rather than a circle. Have Therefore, it is difficult to sufficiently receive signal light in an optical system having a circular incident angle dependency characteristic.

  FIG. 3 shows a configuration of an optical system according to an embodiment of the present invention, which is improved from the above point. The optical system shown in FIG. 3 is applied to the above-described receiving apparatus and the like, and includes a condenser lens 10 to which the present invention is applied. Note that the X-axis, Y-axis, and Z-axis in FIG. 3 are the same as those defined in FIGS.

  The light receiving element 11 is arranged on the optical axis 52 so as to be shifted by a distance D from the condensing position of the condensing lens 10, that is, from the focal position 12 toward the condensing lens 10. As a result, the angle range of incident light that can be received by the light receiving element 11 is increased.

  The condensing lens 10 has an aspherical surface 10a on the exit side (right side in the figure) and an incident surface 10b, and is incident on the optical axis 52 of the condensing lens 10 with an inclination within a predetermined angle range. It is formed so that the intensity distribution of the incident light in the light receiving element arrangement plane is strongly distributed on the light receiving element 11. In FIG. 3, light incident parallel to the optical axis 52 of the condenser lens 10 is incident light 15, and light incident at an angle α with respect to the optical axis 52 is indicated by incident light 16. . As described above, the shape of the condensing lens 10, that is, the condensing lens 10 so that the intensity distribution in the light receiving element arrangement plane of the incident light that is inclined with respect to the optical axis 52 is strongly distributed on the light receiving element 11. The shapes of both aspheric surfaces 10a and 10b are determined. A specific example of the shape of the condenser lens 10 will be described later.

  4A to 4C show the case where the inclination angle α with respect to the optical axis 52 of the incident light 16 shown in FIG. 3A is 0 °, 10 °, and 20 ° with respect to a general spherical lens. The received light intensity in the light receiving element 11 is shown. That is, FIG. 3A shows the received light intensity of incident light on the light receiving element 11 when a normal spherical lens is arranged instead of the condenser lens 10. 4 (a) to 4 (c), the horizontal axis represents the distance of deviation from the optical axis 52 of the center position of the light receiving element 11 in the light receiving element arrangement plane (distance SF in FIG. Also referred to as “amount of deviation”). That is, this graph shows the received light intensity when the center of the light receiving element 11 that should originally be on the optical axis 52 is shifted from the optical axis 52 in the X or Y direction by the deviation SF in the XY plane orthogonal to the optical axis. Show.

  In FIG. 4A, the incident light has an inclination angle α = 0 °, and the incident light is transmitted with the required light receiving intensity even when the center of the light receiving element 11 is shifted in the range of about −18 to 18 mm in the X or Y direction. It shows that light can be received. There is a peak of received light intensity at positions where the deviation amount SF of the light receiving element 11 is approximately −18 mm and 18 mm.

  In FIG. 4B, the incident light has an inclination angle α = 10 °, and the incident light is incident with the required light receiving intensity even when the center of the light receiving element 11 is shifted in the range of about −20 to 10 mm in the X or Y direction. It shows that light can be received. There is a peak of received light intensity at the positions of the deviation amount SF of the light receiving element 11 of approximately −20 mm and 10 mm.

  In FIG. 4C, the incident light has an inclination angle α = 20 °, and the incident light is received with the required light receiving intensity even when the center of the light receiving element 11 is shifted in the range of about −17 to 8 mm in the X or Y direction. It shows that light can be received. There is a peak of received light intensity at positions of the deviation amount SF = about −17 mm and 8 mm of the light receiving element 11, but the received light intensity at the peak near the deviation amount SF = 8 mm is more than the received light intensity at the peak near the deviation amount SF = −17 mm. Pretty small.

  4A to 4C, the positions at which the light receiving element 11 can receive incident light satisfactorily (hereinafter referred to as “optimum light receiving position” and indicated by the symbol “CE” in FIG. 4) are almost the same. It is indicated by the position that divides the area of the characteristic into two. In FIG. 4A, since the characteristic is almost symmetrical about the position of the deviation amount SF = 0 mm, the optimum light receiving position CE is at the position of the deviation amount SF = 0 mm, that is, on the optical axis 52. On the other hand, in FIG. 4B, the optimum light receiving position CE is in the vicinity of the position of the deviation amount SF = about −5 mm, and in FIG. 4C, it is in the vicinity of the position of the deviation amount SF = about −8 mm. As described above, when the spherical lens is used, when the inclination angle α of the incident light with respect to the spherical lens is changed from 0 ° to 20 °, the optimum light receiving position CE on the XY plane on which the light receiving element 11 is arranged is obtained. The shift amount SF changes from −5 mm to −8 mm in the negative direction from the optical axis, that is, the direction opposite to the tilt angle α. However, in the actual receiving apparatus, the light receiving element 11 is arranged on the optical axis 52, that is, at a position where the deviation amount SF = 0. Accordingly, the intensity of light received by the light receiving element 11 decreases as the inclination angle α of the incident light with respect to the spherical lens increases. That is, the light that enters the spherical lens from the outside with a large inclination angle is less likely to be received by the light receiving element 11.

  Next, similar characteristics when the condenser lens 10 according to the present invention is used are shown in FIGS. 5A to 5C show light receiving elements when the inclination angle α of the incident light 16 shown in FIG. 3 with respect to the optical axis 52 of the condenser lens 10 is 0 °, 10 °, and 20 °. 11 shows the received light intensity. Similarly to FIGS. 4A to 4C, in FIGS. 5A to 5C, the horizontal axis indicates the deviation SF from the optical axis 52 in the arrangement plane of the light receiving element 11.

  In FIG. 5A, the incident light has an inclination angle α = 0 °, and the incident light is incident with the required light receiving intensity even when the center of the light receiving element 11 is shifted in the range of about −20 to 20 mm in the X or Y direction. It shows that light can be received. Further, the received light intensity is substantially constant within the range of the deviation amount SF of the light receiving element 11 from about -20 to 20 mm. Therefore, the optimum light receiving position CE is approximately on the optical axis, ie, the shift amount SF = 0.

  In FIG. 5B, the incident light has an inclination angle α = 10 °, and the incident light is transmitted with the required light receiving intensity even when the center of the light receiving element 11 is shifted in the range of about −25 to 15 mm in the X or Y direction. It shows that light can be received. Further, since there is no peak with a large light reception intensity on the side of the deviation amount SF = −25 mm of the light receiving element 11 and there is a peak with a large light reception intensity in the vicinity of the deviation amount SF = 15 mm, the optimum light receiving position CE is almost the amount of deviation. SF = 0, that is, maintained on the optical axis.

  In FIG. 5 (c), the incident light has an inclination angle α = 20 °, and even when the center of the light receiving element 11 is shifted in the range of about −25 to 8 mm in the X or Y direction, It shows that light can be received. Further, since there is no peak with a large received light intensity on the side of the shift amount SF = −25 mm of the light receiving element 11 and there is a peak with a large received light intensity near the shift amount = 8 mm, the optimum light receiving position CE is almost equal to the shift amount = 0, that is, maintained on the optical axis 52.

  Thus, by using the aspherical condensing lens 10 of the present invention and disposing the light receiving element 11 closer to the condensing lens 10, even if the inclination angle α of the incident light changes, the optimum light receiving position of the incident light CE, that is, the position where incident light can be received with the required light receiving intensity can be maintained near the deviation SF = 0, that is, substantially on the optical axis 52, so that it is incident on the condenser lens 10 at a wide angle. It is possible to receive incident light with sufficient intensity.

  FIG. 6A shows the received light intensity distribution on the light receiving element 11 of the incident light with respect to the condenser lens 10 in a three-dimensional contour map. The definitions of the X axis and the Y axis are the same as those in FIG. FIG. 6B is a view of the contour map shown in FIG. 6A as viewed from above. As shown in the figure, the received light intensity has a region 70 in which the received light intensity is relatively flat with the inclination angle = 0 in the X-axis direction and the Y-axis direction as the center. As understood from comparison with FIG. 2, it is shown that the collective lens 10 does not significantly reduce the received light intensity even when the incident angle is slightly shifted in the vertical and horizontal directions with respect to the optical axis.

  Next, the manufacturing method of the condensing lens 10 is demonstrated. The condensing lens 10 can be produced based on a curve that is even-order corrected from an arc. A method for producing the condenser lens 10 is schematically shown in FIG. In FIG. 7, the X axis, the Y axis, and the Z axis are defined in the same direction as shown in FIG.

  First, as shown in FIG. 7A, a curve 30 having a predetermined length extending in the Y-axis direction is defined. This curve is defined by even-order correction (second order, fourth order, sixth order,...) Of the arc. The curve 30 has a vertex 30a. Next, as shown in FIG. 7B, a curve 35 having the same shape as the curve 30 and extending in the X-axis direction is defined. The curve 35 has a vertex 35 a corresponding to the vertex 30 a of the curve 30.

  Next, as shown in FIG. 7C, the curves 30 and 35 are orthogonally crossed so that the vertex 30a and the vertex 35a coincide with each other, and as shown in FIG. Translate along the curve 30 (vertical direction in the figure). Thereby, the aspherical surface 37 is defined as shown in FIG. The condensing lens 10 has the aspheric surfaces thus produced on the incident side surface 10b and the emission side surface 10a. The aspheric surfaces of the incident side surface 10b and the emission side surface 10b are formed as aspheric surfaces having different shapes by making the shapes of the curves 30 and 35 different.

  In the above method, an aspherical surface is formed by translating a curve 35 having the same shape as the curve 30 extending in the Y-axis direction along the Y-axis direction, but conversely, a curve extending in the X-axis direction. It is also possible to form an aspherical surface by translating the same shape of the curve along the X-axis direction.

  FIG. 8 shows an example of a condensing lens manufactured according to the above method. In this example, the shape of the curve 30 extending in the Y direction is defined by Equation 1.

Here, C indicates the curvature of the aspheric surface, and k is a coefficient that defines the shape of the aspheric surface.

In Equation 1, the value of Z is a function of Y ² , and Equation 1 shows a curve 30 obtained by correcting the circular arc in quadratic order. The equation of the curve obtained by correcting the circular arc in the fourth, sixth, etc. has terms such as Y ² and Y ^{4 in} Equation 1, and each term is multiplied by a coefficient k (k1, k2,...). It will be. Further, the curve 35 in the X-axis direction is also defined by the same expression 2 relating to X.

  Each value in the example of the condenser lens 10 shown in FIG. 8 is as follows, and the Y-axis direction and the X-axis direction are the same.

・ Lens width: 70mm
-Refractive index: 1.41
-Curvature Cin of incident side aspheric surface: 40 mm ^-1
-Shape factor of incident aspheric surface: -1
-Output side aspheric curvature Cout: 50 mm ^-1
-Shape factor of exit aspheric surface: -5
・ Lens thickness: 15mm
Light receiving position: 50 mm from the incident side of the lens (position of the light receiving element 11 in FIG. 8)
In this example of the condensing lens, the light receiving element 11 is arranged at the position shown in FIG. 8, and the light receiving intensity of light incident on the condensing lens 10 at an incident angle α = 20 ° (see FIG. 3) is shown in FIG. Show. As in the example shown in FIG. 5C, it can be seen that the center of the received light intensity distribution, that is, the optimum light receiving position CE is in the vicinity of the shift amount SF = 0.

  FIG. 10 shows an application example of the optical system of the receiving apparatus according to the present invention. As shown in FIG. 10, the 2nd condensing lens 14 can be arrange | positioned between the condensing lens 10 and the light receiving element 11 of this invention. The second condenser lens 14 can be a spherical lens. With the second condenser lens 14, the amount of incident light received by the condenser lens 10 can be improved, and the light receiving angle range can be expanded.

[Example of receiver]
Next, an application example of the above receiving apparatus will be described. FIG. 11A shows a basic configuration of an optical communication system to which the receiving apparatus of the present invention is applied. The optical modulation wave 101 is transmitted from the transmission device 100 and is received by the reception device 200.

  FIG. 11B shows configurations of the transmission device 100 and the reception device 200. As illustrated, the transmission device 100 includes a modulation unit 110 and an optical transmission unit 120. The modulation unit 110 receives data to be transmitted, modulates the data to generate a modulated wave M1Tx, and supplies the modulated wave M1Tx to the optical transmission unit 120. The optical transmission unit 120 converts the modulated wave M1Tx into an optical signal and transmits it as the optical modulated wave 101.

  The receiving device 200 includes an optical receiving unit 220 and a demodulating unit 210. The optical receiving unit 220 receives the modulated optical wave 101, converts it into an electrical signal, generates a modulated wave M1Rx, and supplies the modulated wave M1Rx to the demodulating unit 210. The demodulation unit 210 performs demodulation processing according to the modulation scheme of the modulation unit 110 of the transmission device 100 and restores data.

  FIG. 12A shows the configuration of the modulation unit 110. Modulation section 110 includes a modulation processing section 111, a root Nyquist filter 112, an up converter 113, a D / A converter 114, and a smoothing filter 115. The data is subjected to predetermined modulation by the modulation processing unit 111, band-limited by the root Nyquist filter 112, and then up-converted to a carrier frequency by the up-converter 113. The signal converted to the carrier frequency is converted into an analog signal by the D / A converter 114, and the aliasing component due to the D / A conversion is removed by the smoothing filter which is a low-pass filter. In this way, the modulated wave M1Tx is generated.

  FIG. 13A shows the configuration of the optical transmitter 120. The optical transmission unit 120 includes a voltage / current conversion unit 121, an optical device 122, and a lens 123. As the optical device 122, a laser diode, an SLD (super luminescent diode) that is an intermediate device between an LED and a laser, an LED, or the like can be used. The voltage-current converter 121 converts the voltage of the modulated wave M1Tx into a current, and generates a current that is passed through the optical device 122. The optical device 122 is driven by the generated current to emit light, and outputs a light modulation wave L1. The modulated light wave L1 is collected by the lens 123 and transmitted.

  FIG. 13B shows the configuration of the optical receiver 220. The optical receiver 220 includes a lens 221, an optical device 222, a current-voltage converter 223, and an amplifier 224. The lens 221 collects the modulated light wave L1 and sends it to the optical device 222. The optical device 222 outputs a current corresponding to the received light amount, and the current / voltage converter 223 converts the current into a voltage and supplies the voltage to the amplifier 224. The amplifier 224 amplifies the input signal at a predetermined ratio and outputs a modulated wave M1Rx. The condensing lens 10 of the present invention can be used as this lens 221. The optical device 222 corresponds to the light receiving element 11 described above. As the light receiving element, a PIN photodiode, an avalanche photodiode, or the like can be used.

  FIG. 3B shows the configuration of the demodulator 210. The demodulator 210 includes an anti-aliasing filter 211, an A / D converter 212, a down converter 213, a root Nyquist filter 214, and a demodulation processor 215. The modulated wave M1Rx is input to the anti-aliasing filter 211, band-limited, and then converted into a digital signal by the A / D converter 212. Since the digital signal has a carrier frequency, the down-converter 213 converts the frequency to baseband. Then, the bandwidth is limited to the use band by the route Nyquist filter 214, and the original data is restored by the demodulation processing unit 215.

  As described above, data communication from the transmission apparatus 100 to the reception apparatus 200 is performed using the optical device.

An example of a configuration of an optical system of an optical signal receiving apparatus using a spherical lens will be described. An intensity distribution example (incident angle vs. received light intensity) with respect to a received light angle by an optical system of an optical signal receiving device using a spherical lens is shown. 1 shows a configuration of an optical system of an optical signal receiving apparatus using a condenser lens according to the present invention. An example of the incident angle dependence of the received light intensity distribution by the optical system of the optical signal receiving device using a spherical lens (the amount of deviation from the optical axis vs the received light intensity, the parameter being the incident angle) is shown. An example of the incident angle dependence of the received light intensity distribution by the optical system of the optical signal receiving apparatus using the condensing lens of the present invention (amount of deviation from the optical axis vs received light intensity, the parameter being the incident angle) is shown. The example of intensity distribution (incident angle vs. received light intensity) with respect to the received light angle by the optical system of the optical signal receiving apparatus using the condensing lens of the present invention is shown. It is explanatory drawing of the manufacturing method of the condensing lens of this invention. An example of the condensing lens of this invention is shown. FIG. 8 shows an incident angle dependency example of the received light intensity distribution of the condenser lens shown in FIG. 8 (deviation amount from the optical axis vs received light intensity, parameters are incident angles). The other example of the optical system of the optical signal receiver using the condensing lens of this invention is shown. 1 shows a basic configuration of an optical communication system using an optical signal receiving device of the present invention, and a configuration of a transmitting device and a receiving device thereof. The structure of the modulation part shown in FIG. 11 and a demodulation part is shown. The structure of the optical transmission part shown in FIG. 11 and an optical reception part is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Condensing lens 11 Light receiving element 14 2nd condensing lens 15, 16 Incident light 100 Transmission apparatus 200 Reception apparatus

Claims (4)

An optical signal receiving device that collects and receives an optical signal on a light receiving element with a condenser lens,
The light receiving element is disposed closer to the condenser lens than the condensing point of the condenser lens,
The condensing lens has an aspherical shape that strongly distributes the intensity distribution in the light receiving element arrangement plane of incident light incident with an inclination within a predetermined angle range with respect to the optical axis of the condensing lens on the light receiving element. An optical signal receiving device. The condensing lens arranges two curves obtained by even-order correction of an arc so that the vertices coincide with each other and are orthogonal to each other, and one of the two curves extends along the other curve. The optical signal receiving apparatus according to claim 1, wherein the optical signal receiving apparatus has an aspherical surface defined by translation. When one radial direction of the condenser lens is an X-axis direction, another radial direction perpendicular to the one radial direction is a Y-axis direction, and an optical axis direction of the condenser lens is a Z-axis direction, the two Each curve is

as well as

The optical signal receiving apparatus according to claim 2, wherein the optical signal receiving apparatus is defined by: The optical signal reception according to claim 1, further comprising another condensing lens that is disposed between the condensing lens and the light receiving element and expands a light receiving angle range of the optical signal by the condensing element. apparatus.

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