Where can I purchase an infrared telescope for backyard use?
You can’t. Most infrared light from celestial sources is absorbed by the Earth’s atmosphere. Only a narrow window of near-infrared radiation (at wavelengths less than about 4 microns) reaches the Earth. Observations at these wavelengths requires that the infrared camera be cooled to hundreds of degrees below zero using a cryogen (such as liquid helium) and requires special solid-state infrared detectors (costing tens of thousands of dollars). Hence, it is impractical to consider a true infrared telescope for personal use.
