22.3 Photodiodes
621
(a)
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
(b)
(c)
Fig. 22.45 a Arrangement of colors in a CCD Bayer [1858] color filter (‘R’: red, ‘G’: green, ‘B’: blue). Color splitting
with b static color filters and c rotating color wheel. Parts b and c from [1853]
In Fig. 22.48a a 16-channel array of silicon avalanche photodiodes is shown. It features a quantum
efficiency of > 80% between 760 and 910 nm. The pixel size is 648 × 208 µm
2 on a 320 µ m pitch.
The gain is 100 and the rise time 2 ns.
The InGaAs photodiode array in Fig. 22.48b is hybridized with CMOS read-out integrated circuits.
It is useful for detection in the spectral range 0.8–1.7 µ m. The asymmetric diode size of 25 × 500 µm
is designed for use in the focal plane of a monochromator.
Another special type of photodiode array is the four-quadrant detector. A light beam generates four
photocurrents I a , I b , I c , I d of the respective parts (Fig. 22.49a). A beam deviation in the horizontal or
vertical direction can be detected from the (signed) signals (I a + I d ) − (I b + I c ) or (I a + I b ) − (I c + I d ),
respectively. We note that these signals can also be normalized to the total beam intensity I a +I b +I c +I d .
A further improvement of the microlens technology (cmp. Fig.22.44) is achieved with additional
tapered light pipes [1867], guiding obliquely incoming light to the photo-sensitive pixel in an optimized
(a)
(b)
Fig. 22.46 (a) CMOS linear array sensor in a 8-pin package. b Block diagram, the built-in timing generator allows
operation only with start and clock pulse inputs. Reprinted with permission from [1861]
(a)
(b)
Fig. 22.47 a Scheme of image sensor with depth-dependent light detection. From [1862]. b Schematic layer sequence
for three-color pixel. i b , i g and i r denote the photocurrents for blue, green and red light, respectively. Adapted from [1863]
621
(a)
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
B
G
R G
(b)
(c)
Fig. 22.45 a Arrangement of colors in a CCD Bayer [1858] color filter (‘R’: red, ‘G’: green, ‘B’: blue). Color splitting
with b static color filters and c rotating color wheel. Parts b and c from [1853]
In Fig. 22.48a a 16-channel array of silicon avalanche photodiodes is shown. It features a quantum
efficiency of > 80% between 760 and 910 nm. The pixel size is 648 × 208 µm
2 on a 320 µ m pitch.
The gain is 100 and the rise time 2 ns.
The InGaAs photodiode array in Fig. 22.48b is hybridized with CMOS read-out integrated circuits.
It is useful for detection in the spectral range 0.8–1.7 µ m. The asymmetric diode size of 25 × 500 µm
is designed for use in the focal plane of a monochromator.
Another special type of photodiode array is the four-quadrant detector. A light beam generates four
photocurrents I a , I b , I c , I d of the respective parts (Fig. 22.49a). A beam deviation in the horizontal or
vertical direction can be detected from the (signed) signals (I a + I d ) − (I b + I c ) or (I a + I b ) − (I c + I d ),
respectively. We note that these signals can also be normalized to the total beam intensity I a +I b +I c +I d .
A further improvement of the microlens technology (cmp. Fig.22.44) is achieved with additional
tapered light pipes [1867], guiding obliquely incoming light to the photo-sensitive pixel in an optimized
(a)
(b)
Fig. 22.46 (a) CMOS linear array sensor in a 8-pin package. b Block diagram, the built-in timing generator allows
operation only with start and clock pulse inputs. Reprinted with permission from [1861]
(a)
(b)
Fig. 22.47 a Scheme of image sensor with depth-dependent light detection. From [1862]. b Schematic layer sequence
for three-color pixel. i b , i g and i r denote the photocurrents for blue, green and red light, respectively. Adapted from [1863]