High-Resolution Defocus Compensating Spectrograph

An optical instrument, comprising:

• a housing;
• a first adjustment device secured to the housing;
• a detector secured to the first adjustment device;
• and
• a dispersive optical element configured to receive an incident optical signal propagating along an incident optical axis (AI) and diffract a portion of the incident optical signal as a diffracted optical signal propagating toward the detector, wherein the detector is configured to measure at least one property of the diffracted optical signal,
• wherein the first adjustment device is configured to change a position of the detector along the direction of propagation of the diffracted optical signal relative to the dispersive optical element;
• wherein the first adjustment device is a linear motion stage having a fixed portion secured to the housing and a movable portion secured to the detector, wherein the movable portion of the first adjustment device is configured to be actuated by an actuator chosen from the group consisting of piezo actuators, servomotor actuators, stepper motor actuators, and linear motor actuators,
• wherein the first adjustment device is configured to change an angular orientation of the detector relative to the dispersive optical element,
• wherein the first adjustment device is selected from the group consisting of optical mounts, tip-tilt platforms, gimballed platforms, goniometers, angular stages, and flexure mounts,
• wherein the dispersive optical element is secured to a second adjustment device configured to change the position or angular orientation of the dispersive optical element relative to the detector or the incident optical signal,
• wherein the dispersive optical element is a diffraction grating selected from the group consisting of echelle gratings, replicated gratings, dual-blaze gratings, and mosaic gratings, or a holographic grating having a groove profile selected from the group consisting of sinusoidal, trapeze, bump, cycloid, inverted cycloid, saw-tooth, and trapezoidal saw tooth profiles, and
• wherein the at least one property of the diffracted optical signal is an image width (W) of at least one wavelength component of the diffracted optical signal.