Thermal compensation for optical apparatus

In a spectrograph of the type wherein at least one optical element aligned on an optical axis is used to direct optical spectra onto a detector plane, thermal compensation apparatus, comprising:

• a stationary mount;
• a floating flange connected to the optical element;
• and
• two or more spacers physically coupling the floating flange to the stationary mount, the spacers having a thermal coefficient of expansion causing the optical element to move in a direction parallel to the optical axis to compensate for the normal increase in optical element-detector spacing that arises with temperature increases.

In a spectrograph of the type wherein at least one optical element aligned on an optical axis is used to focus spectral lines onto a plurality of detector pixel elements, thermal compensation apparatus, comprising:

• a stationary mount;
• a floating plate;
• a floating flange to which the optical element is attached;
• two or more first temperature-sensitive elements connecting the floating plate to the stationary mount, the first elements being operative to bend a predetermined amount in the presence of temperature fluctuations, thereby maintaining the positional stability of given spectral lines on their respective detector pixel elements;
• and
• two or more second temperature-sensitive elements connecting the floating flange to the floating plate, the second elements have a thermal coefficient of expansion such that when the temperature increases, the optical element is moved toward the detector to compensate for the normal increase in optical element-detector spacing that arises with temperature increases.