The concept of the receiving complex for the “Millimetron” space radio telescope

Abstract

UDC 520.27We consider the current status of research in the development of a submillimeter and far-infrared receiving instrument and propose promising solutions for the receivers of the spaceborne telescope "Millimetron," which allow one to realize comprehensively the opportunities given by this international project administrated by the Astrospace Center of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences.

A method of studying spectral optical characteristics of a homogeneous medium by means of terahertz time-domain spectroscopy

“…n 0 If the wave (ν t ) passes through an empty cell of the spectrometer, the expression for complex amplitude of the electric field on the detector takes the form . (8) The theoretical complex amplitude coefficient of transmission can be expressed in the form (9) Substituting expressions for the operators , , , , and into (9), we have (10) Procedure of Finding Optical Characteristics. Assume that we know the complex index of refraction of air (ν t ) = = 1.0 + j · 0.0, the number of satellite pulses k = k' in the signal from the sample, and the a priori thickness of the sample l determined with a low precision of ±100-200 μm.…”

“…Therefore, the THz spectral characteristics of water reveal numerous peculiarities and substantially vary upon changes in conditions of the surrounding medium [5][6][7]. Major part of the relict cosmic radiation, which has the spectral composition typical of a blackbody radiation with a temperature of 3 K, falls into the microwave and THz regions of the electromagnetic spectrum [8,9]. THz imaging systems and THz spectroscopy can be used for solving problems related to human safety [10], nondestructive technological and operational testing of construction materials [11][12][13][14], noninvasive diagnostics of human diseases (diagnostics of skin [15][16][17], breast [18,19], and intestine cancer [20]; skin burn assessment [21]; diagnostics of demineralization of tooth enamel [22,23]; and studies of the eye cornea [24]), as well as nondestructive studies of works of art [25,26].…”

“…The layout of a time-domain THz spectrometer: (1) femtosecond Yb-doped fiber laser, (2) beamsplitter,(3,14) lenses, (4) photoconductive antenna, (5, 7) off-axis parabolic mirror, 6) sample,(8)(9)(10)(11)(12)15, and 16) flat mirrors, (13) polarizer, (17-20) electro-optic detector of THz field ((17) ZnTe crystal, (18) quarter-wave plate, (19) Wollaston prism, and (20) balanced photodetector module), (21) lock-in amplifier, and (22) personal computer.…”