US 12,392,659 B2
Photometric device
Tsugumi Umanodan, Osaka (JP); Toru Nakatani, Osaka (JP); and Yusuke Hirao, Takatsuki (JP)
Assigned to KONICA MINOLTA, INC., Tokyo (JP)
Appl. No. 18/025,381
Filed by KONICA MINOLTA, INC., Tokyo (JP)
PCT Filed Aug. 4, 2021, PCT No. PCT/JP2021/028941
§ 371(c)(1), (2) Date Mar. 8, 2023,
PCT Pub. No. WO2022/054469, PCT Pub. Date Mar. 17, 2022.
Claims priority of application No. 2020-151214 (JP), filed on Sep. 9, 2020.
Prior Publication US 2023/0341261 A1, Oct. 26, 2023
Int. Cl. G02B 5/28 (2006.01); G01J 3/02 (2006.01); G01J 3/18 (2006.01); G01J 3/26 (2006.01); G01J 3/28 (2006.01); G02B 26/02 (2006.01)
CPC G01J 3/02 (2013.01) [G01J 3/0208 (2013.01); G01J 3/0256 (2013.01); G01J 3/26 (2013.01); G01J 3/2803 (2013.01); G02B 5/28 (2013.01); G02B 26/02 (2013.01); G01J 3/18 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A photometric device, comprising:
a variable light attenuator including a plurality of light attenuation filters and a driving device; and
a photodetector that receives light that has passed through the variable light attenuator, wherein
the driving device is capable of inserting the plurality of light attenuation filters into an optical axis of the light and retracting the plurality of light attenuation filters from the optical axis independently of each other, and
the plurality of light attenuation filters is arranged at different positions in a direction along the optical axis,
each of the plurality of light attenuation filters includes an interference multilayer film and a transparent substrate that supports the interference multilayer film, and
when a combination of any two of the plurality of light attenuation filters is set as a first light attenuation filter and a second light attenuation filter,
the second light attenuation filter is closer to the photodetector than the first light attenuation filter in the direction along the optical axis,
the first light attenuation filter includes a first interference multilayer film as the interference multilayer film and a first transparent substrate as the transparent substrate,
the second light attenuation filter includes a second interference multilayer film as the interference multilayer film and a second transparent substrate as the transparent substrate, and
a first optical path length of the first transparent substrate is different from a second optical path length of the second transparent substrate.