Abstract: The invention provides a simple temperature insensitive optical retarder (waveplate) having a first and a second wedge shaped birefringent crystals, and a crystal mount comprising a first material having a low thermal expansion coefficient and a second material having a high thermal expansion coefficient, wherein the first and the second wedge shaped birefringent crystals are attached onto the first and second materials, respectively, so that the total retardance by the first and second birefringent crystals at a first temperature is substantially the same as that at a second different temperature at a given wavelength. Advantageously, the temperature insensitive optical retarder is simple, easy to construct, can be used for any birefringent crystal and does not require the use of different birefringent crystals.