Nanoscale materials are governed by their structures. Once dimensions fall below a micron, geometry becomes a primary driver of optical behavior and often has a greater influence than chemical composition. Subtle asymmetries in nanoscale structures, such as twists, offsets, or handed features can dictate how light is absorbed, transmitted, or rotated, producing optical responses that vary across a sample. Circular dichroism (CD) spectroscopy has long been used to measure chirality, but conventional CD instruments operate at the bulk level, meaning local variation within nanoscale materials is averaged out. Averaging over large areas masks the local variation that defines nanoscale systems. This limitation has led to the use of circular dichroism microspectroscopy, where CD measurements are performed at defined locations rather than across bulk samples. With CD microspectroscopy, the chiroptical properties of nanoscale materials can be examined at the length scale where structural variation occurs.

Circular dichroism (CD) spectroscopy is used to study molecular chirality in biological systems, delivering insight into biomolecular conformation and secondary structure through interaction between circularly polarized light and chiral molecules. In its conventional form, however, CD analysis is largely limited to bulk, homogeneous samples measured in solution, such as purified proteins, peptides, or nucleic acids dissolved in buffer. A number of biologically relevant materials do not fit this model and instead exhibit meaningful structural variation at the microscale. These include protein aggregates, crystalline domains, biological tissues, and solid pharmaceutical formulations. Circular dichroism microspectroscopy combines CD spectroscopy with optical microscopy, enabling researchers to target specific regions within complex samples and obtain localized structural information that better reflects real biological and pharmaceutical systems.

Perovskite materials are known for their strong light absorption and tunable emission, which is why they are widely studied for use in solar cells, LEDs, and other optoelectronic devices. However, anyone working with perovskites soon discovers their behavior is rarely uniform. Small variations in grain structure, composition, or thickness can change how the perovskite sample behaves, ultimately altering the results of a study. Traditional optical measurements often miss the differences between individual regions of a perovskite film, limiting the insight researchers can gain about how the material truly behaves. Such complexities demand spatially resolved measurements, and these can be provided through microspectrophotometers. They can measure optical properties within specific microsized regions, ensuring researchers have direct access to the optical signatures of individual grains, grain boundaries, and other microstructural features that define perovskite materials.

Designs in nature stand as some of the clearest examples of how intricate structures can manipulate light to produce vivid optical effects. This principle is displayed by the tiny Australian Maratus, or peacock spiders, whose iridescent abdomens shift through rainbows of color with every movement. Their microscopic scales use structure, not pigment, to generate intense, angle-dependent color, an optical mechanism that researchers are now adapting to form super-iridescent nanomaterials for components such as sensors, spectrometers, and pigment-free coatings.