UT 15-color dichroic-mirror camera and future prospects

We describe the design and performance of a dichroic-mirror camera (DMC) which can take 15 narrow-band images simultaneously. We separate the wavelength range of 390 - 950 nm into 15 narrow bands with 14 dichroic mirrors. The detector of DMC is a mosaic CCD camera which has 15 CCDs (TI TC-215). When we put DMC to the MAGNUM 2-m (F/9) telescope being built at Haleakala, Hawaii, the field of view becomes about 4.5 arcmin in diameter. The design of optics shows that we can get an image size of about 0.13 arcsec r.m.s. or better (without atmosphere), though we use only two different kind of lenses (the camera lens and the collimator lens). The system throughput of DMC as a function of wavelength is quantitatively estimated. Simulations using spectra of galaxies ad Qnd QSOs show that DMC can get a signal-to-noise (S/N) of approximately greater than 5/band/object for galaxies (IAB equals 22) and QSOs (IAB equals 23) in the images of 30 min - 1 hour exposure taken with a 2-m telescope. Future prospects for possible enhancements and applications of dichroic-mirror system are also discussed. Having a DMC with resolution of about 30 would be very adequate for high redshift supernovae search. To get higher resolution, DMC combined with Fabry-Perot's is an interesting possibility.