Optical components serve as the core elements of astronomical telescopes, with their design and performance directly determining the telescopes' observational capabilities and scientific value. In reflecting telescopes, the primary and secondary mirrors form the critical optical system—the highly polished and coated primary mirror efficiently collects and focuses light, while the secondary mirror precisely adjusts the light path, as seen in Cassegrain designs that use specialized mirrors for compact structures. For refracting telescopes, achromatic and apochromatic lenses combine different optical materials to effectively eliminate chromatic aberration, enhancing image quality, which is why such designs are commonly used in high-end astrophotography. Modern large ground-based telescopes widely employ adaptive optics technology, using deformable mirrors and wavefront sensors to correct atmospheric turbulence-induced aberrations in real time, bringing ground-based observations close to the resolution of space telescopes. For example, the European Southern Observatory's Very Large Telescope (VLT) relies on this technology to capture images of exoplanets. Spectral analysis is a crucial tool in astronomical research, with telescopes equipped with filters to select specific wavelength ranges and diffraction gratings or prisms to disperse light into spectra, helping analyze celestial bodies' chemical composition and physical properties. The Hubble Space Telescope's ultraviolet spectrograph exemplifies this approach by detecting distant galaxies. The detector interface optical system efficiently transmits light to CCD or CMOS detectors; the James Webb Space Telescope (JWST), for instance, features a precisely designed mid-infrared optical system to minimize thermal noise. Specialized optical designs like off-axis systems and aspheric mirrors optimize imaging quality while reducing telescope size, as demonstrated by the Thirty Meter Telescope (TMT), which employs numerous aspheric mirrors. Space telescopes face even more stringent requirements—their optical components must achieve nanometer-level precision and radiation resistance, as seen in the JWST's gold-coated beryllium mirrors, while deployable optical systems solve the launch challenges of large telescopes. Looking ahead, emerging technologies like metasurface optics could bring revolutionary breakthroughs. These continuously advancing optical technologies have not only enabled major current astronomical discoveries, such as exoplanet detection and black hole imaging, but also provide critical technical support for exploring cutting-edge scientific questions like dark matter and extraterrestrial life.