The abbe number of diffractive optical element is negative, which is opposite to that of traditional refraction optical element. So diffractive optical element has unique advantages on achromatic and thermal compensation. Therefore, it can be applied to diffractive and refraction hybrid optical systems to simplify the optical structure and improve the imaging quality. However, the diffraction efficiency of the single-layer diffractive optical element depends on the wavelength mightily , However, the diffraction efficiency of the design order of the double-layer diffractive optical element in the whole working band is coincident basically and more than 90%, which can significantly suppress the stray light of the non-design order and advance the image contrast. Therefore, the double-layer diffractive optical elements are adopted in this long-wave infrared wide waveband optical system, and the design idea of superposing the diffractive surface on the aspheric surface is proposed. Only two lenses and two materials were used to realize the optimal design. By matching the microstructure parameters of the double-layer diffractive elements ,the diffraction efficiency of the whole working band reached more than 97%. Imaging quality analysis shows that the chromatic aberration of 8μm-14μm is well corrected. the secondary spectrum is well controlled also, and the MTF is close to the diffraction limit, which meets the design requirements.
Aiming at the requirement of high-precision spectral measurement of transient light source, pulse laser wavelength and spectral resolution in pm order and flash duration in ns-ms order, according to the working principle of the Czerny-Turner spectrometer, a cross-asymmetric optical system of Czerny-Turner spectrometer with a spectral range of 800nm-1800nm is designed. Through the design requirements of resolution and spectral range, the light splitting scheme of scanning grating tower with three gratings spliced is determined. The initial structure calculation includes the calculation of single-shot spectral range, characteristic wavelength and scanning angle, focal length and aperture of collimator, focal length and aperture of focusing mirror. Then, according to the above calculation results, the Zemax optical design software of Zemax Company is used to establish multiple structures to simulate the rotating scanning of grating tower, so as to realize the grating and splitting of spectrum and carry out the simulation optimization of the system. In order to correct the aberration of optical system of spectrometer, x-y polynomial free-forms surface is introduced into the optical system, which is called corrective mirror. The design results show that the optical system of the spectrometer meets the design requirements and has excellent performance. Under the conditions of slit width of 25 μm, grating constant of 0.8333 μm/ line, F Number 4.6, the optical system of the spectrometer can achieve a resolution better than 0.1 nm at a center wavelength of 800nm. This design method is also applicable to the structural design of other wavebands, and has guiding significance for the design of broadband grating spectrometer.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.