The invention provides a device for a measuring material
refractive index temperature coefficient under low temperature based on a
minimum deviation angle method. The device comprises a collimation
light source system, a spectroscope, a collimation
system, a low-temperature vacuum bin, a low-temperature vacuum
system, a sample bin, a rotary reflection mirror, an electrically-controlled rotary table and an
encoder. The low-temperature vacuum system, the sample bin, the rotary reflection mirror, the electrically-controlled rotary table and the
encoder are subsidiary to the low-temperature vacuum bin. The sample bin and the rotary reflection mirror are driven by a motor respectively and are disposed in the low-temperature vacuum bin. When the device is used for measuring, quasi-monchromatic parallel light beams are emitted from a collimation
light source and are emitted into the low-temperature vacuum bin after refection by the spectroscope, placement angles of reflection mirrors on a triple
prism and the
encoder are rotated to be adjusted to figure out a position of a
minimum deviation angle, the light beams are perpendicularly emitted into the rotary reflection mirror, finally return to the spectroscope and enter the collimation system after being reflected. The traditional
minimum deviation angle method is modified, the auto-collimation principle and the minimum deviation angle method are combined, demands for high precision of a shaft encoder are lowered within equal measuring precision ranges, and accordingly systematic cost is reduced.