Device for measuring an optical
transmission line a. with at least one
transmitter (H, 2, 3, 4) and b. with a compensation
transmitter (K, 9) and c. with a
receiver (D, 10) and d. with a compensation
transmitter cavity (CAV_K, 28) and e. with a receiving cavity (CAV_D, 28) and f. with a bridge (48, B3) and g. with a barrier (17, B) and h. with an
optical path (49, WK) and i. with a reflector (R) and j. with at least one first optical transmission path (I1) that is only partially part of the device, and k. with a second optical transmission path (I2), which is only partially part of the device, and I. wherein the at least one transmitter (H, 2, 3, 4) emits light with a transmitter
wavelength and m. wherein the compensation transmitter (K, 9) emits light with a compensation transmitter
wavelength and n. wherein the at least one transmitter (H, 2, 3, 4) can transmit into the at least one first transmission path (I1) and o. wherein an object (O), which is not part of the device, can send light into a second optical transmission path (I2) at the end of the at least one first optical transmission path (I1), wherein said compensation transmitter (K, 9) and the
receiver (D, 10) are separated by the at least one bridge (48, B3) in such a way that direct
irradiation of the
receiver (D, 10) by the compensation transmitter (K, 9) is not possible and p. (VI) wherein the compensation transmitter (K, 9) is placed in the compensation transmitter cavity (CAV_K, 28) and wherein the bridge (48, B3) is part of the wall of the compensation transmitter cavity (CAV_K, 28) and q. (VII) wherein the receiver (D, 10) is placed in the receiver cavity (CAV_D, 28) and wherein the web (48, B3) is part of the wall of the receiver cavity (CAV_D, 28) and r. (VIII) wherein at least the receiver (D, 10) and the compensation transmitter (K, 9) are optically connected to each other by the at least one
optical path (49, WK) in which light can be transferred from the compensation transmitter (K, 9) to the receiver (D, 10) by at least one reflection at the reflector (R) and s. (IX) wherein at least the transmitter (H, 2, 3, 4) and at least the receiver (D, 10) are separated by at least the barrier (17, B) in such a way that direct
irradiation of the receiver (D, 10) by the transmitter (H, 2, 3, 4) is not possible and t. wherein the device has an absorber (51, B2, B) and u. (XI) wherein the absorber (51, B2, B) prevents the emission of light from at least the compensation transmitter (K, 9) in at least one predefined direction and / or in the direction of at least one object (O) to be measured and v. wherein the transmitter (H, 2, 3, 4) and the compensation transmitter (K, 9) radiate with different center-of-
mass wavelengths and w. wherein at least one optical transmit path filter (FH) is part of the device and x. wherein the at least one optical transmit path filter (FH) is located in the second transmission path (I2) and y. wherein the transmit path filter (FH) preferably has a transmissivity of at least 75% for the
wavelength of the light from the transmitter (H, 2, 3, 4), i.e. for the transmitter wavelength, and e.g. where the transmit path filter (FH) has a
reflectivity of at most 25% for the wavelength of the light from the transmitter (H, 2, 3, 4), i.e. for the transmitter wavelength, and aa. wherein the transmit path filter (FH) for the wavelength of the light from the compensation transmitter (K, 9), i.e. for the compensation transmitter wavelength, has a transmissivity of at most 25% and bb. wherein the transmit path filter (FH) preferably has an
absorption factor of at least 25% for the wavelength of the light of the compensation transmitter (K, 2, 3, 4), i.e. for the compensation transmitter wavelength.