An optical filter may include a substrate. The optical filter may include a first mirror. The optical filter may include a second mirror. The optical filter may include a spacer. The first mirror, the second mirror, and the spacer may form a plurality of component filters. A first component filter, of the plurality of component filters, may be associated with a first cross-sectional area and a second component filter, of the plurality of component filters, is associated with a second cross-sectional area. The first cross-sectional area and the second cross-sectional area may be configured to response balance the first component filter and the second component filter.

Apparatus and methods are described for performing tear film structure measurement on a tear film of an eye of a subject. A broadband light source (100) is configured to generate broadband light. A spectrometer (250) is configured to measure a spectrum of light of the broadband light that is reflected from at least one spot on the tear film, the spot having a diameter of between 100 microns and 240 microns. A computer processor (28) is coupled to the spectrometer and configured to determine a characteristic of the tear film based upon the spectrum of light measured by the spectrometer. Other applications are also described.

A system generates a prediction model for makeup color matching. The system includes a data storage device and a modeling engine. The data storage device stores a plurality of color sets comprising a skin color set, a makeup color set, and a target color set. The modeling engine is coupled to the data storage device and configured to generate a prediction model and an output color set. The prediction model models generation of the target color set based on inputs from the skin color set and the makeup color set. The output color set approximates the target color set with a predictable accuracy.

Spectrographic measurements are often limited by the amount of light that is available. Photons that are not collected or measured reduce the signal to noise and therefore reduce measurement precision. This invention collects the zero order light and sends it through the spectrometer again. In an atmospheric LIDAR, the zero order recycling is estimated to increase the rotational Raman signal by an additional 20%. A grating based spectrometer where the zero order light is collected by a lens or mirror and focused into a fiber optic that sends the light to the input slit where it is directed into the spectrometer again. There can be a plurality of recycle fibers. The detector can be either a single linear array or a two dimensional array such as a CCD or CMOS camera.

A photodetection device includes: a filter array including a plurality of filters arranged in a two-dimensional array, the plurality of filters including a first filter and a second filter, the first filter and the second filter each including a first reflective layer, a second reflective layer, and an intermediate layer between the first reflective layer and the second reflective layer and having a resonant structure having a plurality of resonant modes differing in order from each other, at least one selected from the group consisting of a refractive index and a thickness of the intermediate layer of the first filter being different from the at least one selected from the group consisting of a refractive index and a thickness of the intermediate layer of the second filter; and an image sensor disposed at a position where the image senor receives light having passed through the filter array.

A system generates a prediction model for makeup color matching. The system includes a data storage device and a modeling engine. The data storage device stores a plurality of color sets comprising a skin color set, a makeup color set, and a target color set. The modeling engine is coupled to the data storage device and configured to generate a prediction model and an output color set. The prediction model models generation of the target color set based on inputs from the skin color set and the makeup color set. The output color set approximates the target color set with a predictable accuracy.

An optical device may include a plurality of sensor elements and a plurality of optical channels. The plurality of sensor elements may include a first set of sensor elements associated with a first wavelength range and a second set of sensor elements associated with a second wavelength range. The plurality of optical channels may include a first set of optical channels associated with the first wavelength range and a second set of optical channels associated with the second wavelength range. A first optical channel, of the first set of optical channels, may be disposed over a first sensor element, of the first set of sensor elements, and a second optical channel, of the second set of optical channels, may be disposed over a second sensor element, of the second set of sensor elements.

An electromagnetic radiation spectrum detection system including a sensor device and an electronic control and processing module. The sensor device may include two photodiodes. The sensor device may convert an incident electromagnetic radiation (EMR) into electrical current. The electronic control and processing module may store numerical calibration values representative of a responsivity matrix of the sensor device. The electronic control and processing module may selectively provide the sensor device with electrical control voltage values (V.sub.B). The electronic control and processing module may process the values of detected electric currents (Iph) and the numerical calibration values to obtain spectrum information related to incident electromagnetic radiation spectrums. The electronic control and processing module may determine power spectral density of incident electromagnetic radiation.

A system and method for controlling an emitter assembly comprising a single electromagnetic radiation source for visualizing a surgical site. The emitter assembly comprises a light valve assembly that is coupled to a control circuit. The emitter assembly is configured to emit visible light, infrared radiation, or a combination thereof in either structured or unstructured formats. The control circuit is configured to control the light valve assembly to control which emitter of the emitter assembly is emitting electromagnetic radiation. The light valve assembly can include light valves for controlling whether an emitter receives electromagnetic radiation. Further, the control circuit can control the wavelength of the electromagnetic radiation emitted by the source in accordance with which emitter is receiving electromagnetic radiation.

A surgical robotic visualization system comprises a first robotic arm, a second robotic arm, a photoacoustic receiver coupled to the first robotic arm, an emitter assembly coupled to the second robotic arm, and a control circuit. The control circuit is configured to cause the emitter assembly to emit electromagnetic radiation toward an anatomical structure at a plurality of wavelengths capable of penetrating the anatomical structure and reaching an embedded structure located below a surface of the anatomical structure, receive an input of the photoacoustic receiver indicative of an acoustic response signal of the embedded structure, and detect the embedded structure based on the input from the photoacoustic receiver.