The MOS-4 crystal is a type of quartz crystal used in the electronics industry for frequency control. It is a four-finger crystal and is used for applications ranging from low power to high power circuit applications. It is known for its stability, long-term reliability and excellent temperature stability characteristics. The MOS-4 crystal offers good performance at both low and high temperatures, and also can be used in applications that require high levels of accuracy and precision. The magnetooptic parameters of the MOS-4 crystal depend on the thickness and structure of the crystal material. The key parameters include the magnetic moment, Faraday rotation angle, and Kerr rotation angle. The magnetic moment measures the ability of the crystal to interact with an external magnetic field. The Faraday rotation angle measures the deviation in the polarization of the incident light after passing through the crystal material. Finally, the Kerr rotation angle measures the deviation in the polarization of reflected light after passing through the crystal material. The MOS-4 crystal has a wide range of applications in the electronics industry, including use in oscillators, filters, logic circuits, analog circuits, signal generators, voltage controlled oscillators, and many other components. It is also used in automotive, aerospace, and medical applications, as well as communication systems where precision control is required. MOS-4 and MOS-10 are types of magneto-optical glasses. Both glasses utilize Faraday effect to achieve light modulation, meaning the polarization state can be varied by applying an external magnetic field. The main difference between MOS-4 and MOS-10 glasses is the refractive index - MOS-4 glass has a higher refractive index than MOS-10 glass, resulting in a larger birefringence effect. Both glasses have excellent temperature stability, making them suitable for use in high performance applications.